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• CodePlex Daily Summary for Tuesday, April 27, 2010

  CodePlex Daily Summary for Tuesday, April 27, 2010New ProjectsActive Directory User Properties Change: A complete application in VS 2005 and VB.NET, for Request Request in User Details in Active Directory, with flow to HR and then to IT for approval ...AVR Terminal: A Windows application for connecting to an AVR via RS232 serial or USB-to-COM FTDI ports. Works on Arduino, Bare Bones Board, and any custom board...Battle Droids: AVR-based Network Combat!: A Battle Droid is an AVR® microcontroller running the BattleDroid firmware. This firmware turns your AVR into a lean, mean, fighting machine, and ...Camp Foundation: Camp Foundationchakma: chakma is a question - answer based web application to make people get questions from anybody around the world and being able to answer them. c...Document.Editor: Document.Editor is a multitab text editor for Windows. It includes plain and rich text format support, multi tab interface so you can edit multiple...Dot Net Marche Music Store Demo Application: This is a demo application that the DotNetMarche user gorup (www.dotnetmarche.org) use to make experiments and prepare demos for our workshopselivators: a monitor which enables the user to view the movement of the elivators in a buildingExtended SSIS Package Execute: The SSIS package execute task is flawed as it does not support passing variables. Here we have a custom task that will pass items in a dataflow as...File tools: File toolsFileExplorer.NET: FileExplorer.NET is a .net usercontrol which tries to mimic the Windows FileExplorer treeview.Kazuku: ASP.NET MVC 2 Content Management SystemKSharp Ajax Control Toolkit Library: Built ontop of the Microsoft ASP.NET Ajax Control Toolkit, this library offers enhanced versions of the controls found in the Ajax Control Toolkit....Nitrous - An Aspx ViewEngine for ASP.NET MVC: Near drop-in replacement ASP.NET ViewEngine for MVC.Open Data Protocol - Client Libraries: This is an Open Source release of the .NET and Silverlight Client Libraries for the Open Data Protocol (OData). For more information on odata, see ...ORAYLIS BI.SmartDiff: BI.SmartDiff is a helper to connect the functionality of BIDS Helper – SmartDiff to TortoiseSVN. BIDS Helper – SmartDiff helps you to get more read...RicciWebSiteSystem: soon websiteSynapse:Silverlight A Simple Silverlight Framework: Synapse:Silverlight is a simplified framework for Silverlight. It's purpose is to help developers and designers produce basic LOB solutions that do...TestProjectMB: Testing Team Foundation ServerThoughtWorks Cruise Notification Interceptor: Cruise notification interceptorThreadSafeControls: ThreadSafeControls is a C# project that greatly simplifies the process of transitioning Windows Forms applications to a multithreaded environment b...Unscrambler: Unscrambler is a multitouch WPF word game built with MVVM Light in order to show how to use the touch maniupation and inertia features included in ...Web Utilities: web utilitiesNew Releases7zbackup - PowerShell Script to Backup Files with 7zip: 7zBackup v. 1.7.1 Stable: Bug Solved : Presence of junction.exe is wrongly referred to 7z.exeAVR Terminal: AVR Terminal v0.2: Here is an Alpha-almost-BETA release of the AVR Terminal. That being said, I use it almost daily and it shouldn't break anything on your system, b...Bistro FSharp Extensions: 0.9.7.0: This is the VS 2010 release of BistroFS extensions. This release focused on usability, adding key functionality such as resource aliasing and secur...Bojinx: Bojinx Dialog Management V1.0: Stable release of the Bojinx Dialog Management library.BOWIE: BOWIE 2010: This new version works on Outlook 2007/2010 and TFS 2008/2010 RTM. Details about all features in this version on the Home Page : http://bowie.code...Catharsis: Catharsis 2.5 on catarsa.com: The Catharsis framework has finally its own portal http://catarsa.com Example - documented steps to create Web-Application http://catarsa.com/Arti...Colorful Expression: Expression Blend 3: Alpha Version, Read Issues and Installing! Colorful Expression is an add-in for Expression Blend and Expression Design that brings you the Adobe K...Colorful Expression: Expression Blend 4: Read Issues and Installing! Colorful Expression is an add-in for Expression Blend and Expression Design that brings you the Adobe Kuler and ColorLo...Courier: Version 1.0: This release includes integration with the Reactive Framework for more elegant message handling and allowing more succinct client code. Full suite...CRM 4.0 Contract Utilities: Release 1.0: Project Description List of Contract Utilities (i.e. custom workflow actions) 1. Change contract status from Active to Draft 2. Copy Contract (with...Document.Editor: 0.9.0: Whats New?: New icon set Bug fix'sDotNetNuke® Blog: 04.00.00: Minimum Required DNN Version: 4.06.02General Code organization * Converted project to .NET 3.5 * Converted solution to Visual Stud...EPiAbstractions: EPiAbstractions 1.2: Updated for EPiServer CMS 6. Only features abstractions for EPiServer CMS. For abstractions for EPiServer.Common and EPiServer.Community use versio...Fluent ViewModel Configuration for WPF (MVVM): FluentViewModel Alpha2: Added support for view model validation using FluentValidation (http://fluentvalidation.codeplex.com/) Fixed exception from Blend while in design...GArphics: Beta v0.9: Beta v0.9. Practically all of the planned features have been implemented and are available to the users. For the version 1.0 mainly just some minor...HTML Ruby: 6.22.2.1: Fixed a bug where HTML Ruby's options window will generate entries in the error log when applying option changes (regression from 6.21.8)HTML Ruby: 6.22.3: Add/remove stop spacing event listener as needed for possible fix to 4620iTuner - The iTunes Companion: iTuner 1.2.3768 Beta 3b: Beta 3 requires iTunes 9.1.0.79 or later A Librarian status panel showing active and queued Librarian scanners. This will be hidden behind the "bi...LiveUpload to Facebook: LiveUpload to Facebook 3.2.3: Version 3.2.3Become a fan on Facebook! Features Quickly and easily upload your photos and videos to Facebook, including any people tags added in W...Maintainance Schedule: Maintenance Scheduler: The first Alpha release of the project.NetSockets: NetSockets (1.2): The NetSockets library (DLL)NSIS Autorun: NSIS Autorun 0.1.2: NSIS Autorun 0.1.1 This release includes source code, application binary, and example materials.OpenSceneGraph glsl samples: OsgGlslSamples Win32 binaries: Project binary release for Windows. The effects shown are: Ambient Occlusion, Depth of Field, DoF with alpha channel, Fire effects, HDR, Light Ma...ORAYLIS BI.SmartDiff: ORAYLIS BI.SmartDiff 0.6.1: First public versionpatterns & practices - Windows Azure Guidance: Code Drop 4 - Content Complete: This release includes documentation and all code samples intended for this first guide. As before, this code release builds on the previous one an...Pex Custom Arithmetic Solver: Custom Solver Package: This is the custom solvers packaged together. To use simply include the dll in your project and add [assembly: PexCustomArithmeticSolver] to your P...PokeIn Comet Ajax Library: PokeIn v08 x86: New FeatureFrom this version forward, PokeIn will define a way between the main page and client side automaticly based to security level. Add "pub...Proxi [Proxy Interface]: Proxi Release 1.0.0.426: Proxi Release 1.0.0.426QuestTracker: QuestTracker 0.3: This release includes recurring quests! Now you can set a quest to uncomplete itself every X minutes, hours, or days! And the quests still retain t...Rensea Image Viewer: RIV 0.4.5: RIV Fix Version. You would need .NET Framework 4.0 to make it run RIVU Improved Version. With separated RIV up-loader, to upload images to Renjian...SCC Switch Provider: Provides a GUI to Switch Source Code Control Provi: Transferred from GotDotNet Workplace. Initial public Release. Downloaded ~922 times from original post.sTASKedit: sTASKedit v0.7a (Alpha): + Fixed: XOR text encoding + Fixed: adding timed rewards missing values + Fixed: occupations in clone()Synapse:Silverlight A Simple Silverlight Framework: Synapse Silverlight Alpha Release: Initial Road-map is being defined.ThoughtWorks Cruise Notification Interceptor: 1.0.0: Initial release.UDC indexes parser: UDC indexex parser Beta 2: Добавлена возможность работать с распределением определителей как если бы генератор был бы LALR(2) То что осталось: Если текстовое дополнение начи...Unscrambler: Release 1.0: Here's the first release of Unscrambler.WinXound: WinXound 3.3.0 Beta 2 for Mac OsX: New: Code Repository (for UDO and personal code) New: Format Code - Added the ability to format only the selected text of the code New: Explore...WPF Inspirational Quote Management System: Release 1.2.2: - Fixed issue some users were having when the application is minimised.Most Popular ProjectsRawrWBFS ManagerAJAX Control ToolkitSilverlight Toolkitpatterns & practices – Enterprise LibraryMicrosoft SQL Server Product Samples: DatabaseWindows Presentation Foundation (WPF)ASP.NETMicrosoft SQL Server Community & SamplesPHPExcelMost Active Projectspatterns & practices – Enterprise LibraryRawrGMap.NET - Great Maps for Windows Forms & PresentationParticle Plot PivotBlogEngine.NETNB_Store - Free DotNetNuke Ecommerce Catalog ModuleFarseer Physics EngineIonics Isapi Rewrite FilterN2 CMSDotNetZip Library

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• C#: String Concatenation vs Format vs StringBuilder

  - by James Michael Hare

  I was looking through my groups’ C# coding standards the other day and there were a couple of legacy items in there that caught my eye.  They had been passed down from committee to committee so many times that no one even thought to second guess and try them for a long time.  It’s yet another example of how micro-optimizations can often get the best of us and cause us to write code that is not as maintainable as it could be for the sake of squeezing an extra ounce of performance out of our software. So the two standards in question were these, in paraphrase: Prefer StringBuilder or string.Format() to string concatenation. Prefer string.Equals() with case-insensitive option to string.ToUpper().Equals(). Now some of you may already know what my results are going to show, as these items have been compared before on many blogs, but I think it’s always worth repeating and trying these yourself.  So let’s dig in. The first test was a pretty standard one.  When concattenating strings, what is the best choice: StringBuilder, string concattenation, or string.Format()? So before we being I read in a number of iterations from the console and a length of each string to generate.  Then I generate that many random strings of the given length and an array to hold the results.  Why am I so keen to keep the results?  Because I want to be able to snapshot the memory and don’t want garbage collection to collect the strings, hence the array to keep hold of them.  I also didn’t want the random strings to be part of the allocation, so I pre-allocate them and the array up front before the snapshot.  So in the code snippets below: num – Number of iterations. strings – Array of randomly generated strings. results – Array to hold the results of the concatenation tests. timer – A System.Diagnostics.Stopwatch() instance to time code execution. start – Beginning memory size. stop – Ending memory size. after – Memory size after final GC. So first, let’s look at the concatenation loop: 1: // build num strings using concattenation. 2: for (int i = 0; i < num; i++) 3: { 4: results[i] = "This is test #" + i + " with a result of " + strings[i]; 5: } Pretty standard, right?  Next for string.Format(): 1: // build strings using string.Format() 2: for (int i = 0; i < num; i++) 3: { 4: results[i] = string.Format("This is test #{0} with a result of {1}", i, strings[i]); 5: }   Finally, StringBuilder: 1: // build strings using StringBuilder 2: for (int i = 0; i < num; i++) 3: { 4: var builder = new StringBuilder(); 5: builder.Append("This is test #"); 6: builder.Append(i); 7: builder.Append(" with a result of "); 8: builder.Append(strings[i]); 9: results[i] = builder.ToString(); 10: } So I take each of these loops, and time them by using a block like this: 1: // get the total amount of memory used, true tells it to run GC first. 2: start = System.GC.GetTotalMemory(true); 3:  4: // restart the timer 5: timer.Reset(); 6: timer.Start(); 7:  8: // *** code to time and measure goes here. *** 9:  10: // get the current amount of memory, stop the timer, then get memory after GC. 11: stop = System.GC.GetTotalMemory(false); 12: timer.Stop(); 13: other = System.GC.GetTotalMemory(true); So let’s look at what happens when I run each of these blocks through the timer and memory check at 500,000 iterations: 1: Operator + - Time: 547, Memory: 56104540/55595960 - 500000 2: string.Format() - Time: 749, Memory: 57295812/55595960 - 500000 3: StringBuilder - Time: 608, Memory: 55312888/55595960 – 500000   Egad!  string.Format brings up the rear and + triumphs, well, at least in terms of speed.  The concat burns more memory than StringBuilder but less than string.Format().  This shows two main things: StringBuilder is not always the panacea many think it is. The difference between any of the three is miniscule! The second point is extremely important!  You will often here people who will grasp at results and say, “look, operator + is 10% faster than StringBuilder so always use StringBuilder.”  Statements like this are a disservice and often misleading.  For example, if I had a good guess at what the size of the string would be, I could have preallocated my StringBuffer like so:   1: for (int i = 0; i < num; i++) 2: { 3: // pre-declare StringBuilder to have 100 char buffer. 4: var builder = new StringBuilder(100); 5: builder.Append("This is test #"); 6: builder.Append(i); 7: builder.Append(" with a result of "); 8: builder.Append(strings[i]); 9: results[i] = builder.ToString(); 10: }   Now let’s look at the times: 1: Operator + - Time: 551, Memory: 56104412/55595960 - 500000 2: string.Format() - Time: 753, Memory: 57296484/55595960 - 500000 3: StringBuilder - Time: 525, Memory: 59779156/55595960 - 500000   Whoa!  All of the sudden StringBuilder is back on top again!  But notice, it takes more memory now.  This makes perfect sense if you examine the IL behind the scenes.  Whenever you do a string concat (+) in your code, it examines the lengths of the arguments and creates a StringBuilder behind the scenes of the appropriate size for you. But even IF we know the approximate size of our StringBuilder, look how much less readable it is!  That’s why I feel you should always take into account both readability and performance.  After all, consider all these timings are over 500,000 iterations.   That’s at best  0.0004 ms difference per call which is neglidgable at best.  The key is to pick the best tool for the job.  What do I mean?  Consider these awesome words of wisdom: Concatenate (+) is best at concatenating.  StringBuilder is best when you need to building. Format is best at formatting. Totally Earth-shattering, right!  But if you consider it carefully, it actually has a lot of beauty in it’s simplicity.  Remember, there is no magic bullet.  If one of these always beat the others we’d only have one and not three choices. The fact is, the concattenation operator (+) has been optimized for speed and looks the cleanest for joining together a known set of strings in the simplest manner possible. StringBuilder, on the other hand, excels when you need to build a string of inderterminant length.  Use it in those times when you are looping till you hit a stop condition and building a result and it won’t steer you wrong. String.Format seems to be the looser from the stats, but consider which of these is more readable.  Yes, ignore the fact that you could do this with ToString() on a DateTime.  1: // build a date via concatenation 2: var date1 = (month < 10 ? string.Empty : "0") + month + '/' 3: + (day < 10 ? string.Empty : "0") + '/' + year; 4:  5: // build a date via string builder 6: var builder = new StringBuilder(10); 7: if (month < 10) builder.Append('0'); 8: builder.Append(month); 9: builder.Append('/'); 10: if (day < 10) builder.Append('0'); 11: builder.Append(day); 12: builder.Append('/'); 13: builder.Append(year); 14: var date2 = builder.ToString(); 15:  16: // build a date via string.Format 17: var date3 = string.Format("{0:00}/{1:00}/{2:0000}", month, day, year); 18:  So the strength in string.Format is that it makes constructing a formatted string easy to read.  Yes, it’s slower, but look at how much more elegant it is to do zero-padding and anything else string.Format does. So my lesson is, don’t look for the silver bullet!  Choose the best tool.  Micro-optimization almost always bites you in the end because you’re sacrificing readability for performance, which is almost exactly the wrong choice 90% of the time. I love the rules of optimization.  They’ve been stated before in many forms, but here’s how I always remember them: For Beginners: Do not optimize. For Experts: Do not optimize yet. It’s so true.  Most of the time on today’s modern hardware, a micro-second optimization at the sake of readability will net you nothing because it won’t be your bottleneck.  Code for readability, choose the best tool for the job which will usually be the most readable and maintainable as well.  Then, and only then, if you need that extra performance boost after profiling your code and exhausting all other options… then you can start to think about optimizing.

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• C#: My World Clock

  - by Bruce Eitman

  [Placeholder:  I will post the entire project soon] I have been working on cleaning my office of 8 years of stuff from several engineers working on many projects.  It turns out that we have a few extra single board computers with displays, so at the end of the day last Friday I though why not create a little application to display the time, you know, a clock.  How difficult could that be?  It turns out that it is quite simple – until I decided to gold plate the project by adding time displays for our offices around the world. I decided to use C#, which actually made creating the main clock quite easy.   The application was simply a text box and a timer.  I set the timer to fire a couple of times a second, and when it does use a DateTime object to get the current time and retrieve a string to display. And I could have been done, but of course that gold plating came up.   Seems simple enough, simply offset the time from the local time to the location that I want the time for and display it.    Sure enough, I had the time displayed for UK, Italy, Kansas City, Japan and China in no time at all. But it is October, and for those of us still stuck with Daylight Savings Time, we know that the clocks are about to change.   My first attempt was to simply check to see if the local time was DST or Standard time, then change the offset for China.  China doesn’t have Daylight Savings Time. If you know anything about the time changes around the world, you already know that my plan is flawed – in a big way.   It turns out that the transitions in and out of DST take place at different times around the world.   If you didn’t know that, do a quick search for “Daylight Savings” and you will find many WEB sites dedicated to tracking the time changes dates, and times. Now the real challenge of this application; how do I programmatically find out when the time changes occur and handle them correctly?  After a considerable amount of research it turns out that the solution is to read the data from the registry and parse it to figure out when the time changes occur. Reading Time Change Information from the Registry Reading the data from the registry is simple, using the data is a little more complicated.  First, reading from the registry can be done like:             byte[] binarydata = (byte[])Registry.GetValue("HKEY_LOCAL_MACHINE\\Time Zones\\Eastern Standard Time", "TZI", null);   Where I have hardcoded the registry key for example purposes, but in the end I will use some variables.   We now have a binary blob with the data, but it needs to be converted to use the real data.   To start we will need a couple of structs to hold the data and make it usable.   We will need a SYSTEMTIME and REG_TZI_FORMAT.   You may have expected that we would need a TIME_ZONE_INFORMATION struct, but we don’t.   The data is stored in the registry as a REG_TZI_FORMAT, which excludes some of the values found in TIME_ZONE_INFORMATION.     struct SYSTEMTIME     {         internal short wYear;         internal short wMonth;         internal short wDayOfWeek;         internal short wDay;         internal short wHour;         internal short wMinute;         internal short wSecond;         internal short wMilliseconds;     }       struct REG_TZI_FORMAT     {         internal long Bias;         internal long StdBias;         internal long DSTBias;         internal SYSTEMTIME StandardStart;         internal SYSTEMTIME DSTStart;     }   Now we need to convert the binary blob to a REG_TZI_FORMAT.   To do that I created the following helper functions:         private void BinaryToSystemTime(ref SYSTEMTIME ST, byte[] binary, int offset)         {             ST.wYear = (short)(binary[offset + 0] + (binary[offset + 1] << 8));             ST.wMonth = (short)(binary[offset + 2] + (binary[offset + 3] << 8));             ST.wDayOfWeek = (short)(binary[offset + 4] + (binary[offset + 5] << 8));             ST.wDay = (short)(binary[offset + 6] + (binary[offset + 7] << 8));             ST.wHour = (short)(binary[offset + 8] + (binary[offset + 9] << 8));             ST.wMinute = (short)(binary[offset + 10] + (binary[offset + 11] << 8));             ST.wSecond = (short)(binary[offset + 12] + (binary[offset + 13] << 8));             ST.wMilliseconds = (short)(binary[offset + 14] + (binary[offset + 15] << 8));         }             private REG_TZI_FORMAT ConvertFromBinary(byte[] binarydata)         {             REG_TZI_FORMAT RTZ = new REG_TZI_FORMAT();               RTZ.Bias = binarydata[0] + (binarydata[1] << 8) + (binarydata[2] << 16) + (binarydata[3] << 24);             RTZ.StdBias = binarydata[4] + (binarydata[5] << 8) + (binarydata[6] << 16) + (binarydata[7] << 24);             RTZ.DSTBias = binarydata[8] + (binarydata[9] << 8) + (binarydata[10] << 16) + (binarydata[11] << 24);             BinaryToSystemTime(ref RTZ.StandardStart, binarydata, 4 + 4 + 4);             BinaryToSystemTime(ref RTZ.DSTStart, binarydata, 4 + 16 + 4 + 4);               return RTZ;         }   I am the first to admit that there may be a better way to get the settings from the registry and into the REG_TXI_FORMAT, but I am not a great C# programmer which I have said before on this blog.   So sometimes I chose brute force over elegant. Now that we have the Bias information and the start date information, we can start to make sense of it.   The bias is an offset, in minutes, from local time (if already in local time for the time zone in question) to get to UTC – or as Microsoft defines it: UTC = local time + bias.  Standard bias is an offset to adjust for standard time, which I think is usually zero.   And DST bias is and offset to adjust for daylight savings time. Since we don’t have the local time for a time zone other than the one that the computer is set to, what we first need to do is convert local time to UTC, which is simple enough using:                 DateTime.Now.ToUniversalTime(); Then, since we have UTC we need to do a little math to alter the formula to: local time = UTC – bias.  In other words, we need to subtract the bias minutes. I am ahead of myself though, the standard and DST start dates really aren’t dates.   Instead they indicate the month, day of week and week number of the time change.   The dDay member of SYSTEM time will be set to the week number of the date change indicating that the change happens on the first, second… day of week of the month.  So we need to convert them to dates so that we can determine which bias to use, and when to change to a different bias.   To do that, I wrote the following function:         private DateTime SystemTimeToDateTimeStart(SYSTEMTIME Time, int Year)         {             DayOfWeek[] Days = { DayOfWeek.Sunday, DayOfWeek.Monday, DayOfWeek.Tuesday, DayOfWeek.Wednesday, DayOfWeek.Thursday, DayOfWeek.Friday, DayOfWeek.Saturday };             DateTime InfoTime = new DateTime(Year, Time.wMonth, Time.wDay == 1 ? 1 : ((Time.wDay - 1) * 7) + 1, Time.wHour, Time.wMinute, Time.wSecond, DateTimeKind.Utc);             DateTime BestGuess = InfoTime;             while (BestGuess.DayOfWeek != Days[Time.wDayOfWeek])             {                 BestGuess = BestGuess.AddDays(1);             }             return BestGuess;         }   SystemTimeToDateTimeStart gets two parameters; a SYSTEMTIME and a year.   The reason is that we will try this year and next year because we are interested in start dates that are in the future, not the past.  The function starts by getting a new Datetime with the first possible date and then looking for the correct date. Using the start dates, we can then determine the correct bias to use, and the next date that time will change:             NextTimeChange = StandardChange;             CurrentBias = TimezoneSettings.Bias + TimezoneSettings.DSTBias;             if (DSTChange.Year != 1 && StandardChange.Year != 1)             {                 if (DSTChange.CompareTo(StandardChange) < 0)                 {                     NextTimeChange = DSTChange;                     CurrentBias = TimezoneSettings.StdBias + TimezoneSettings.Bias;                 }             }             else             {                 // I don't like this, but it turns out that China Standard Time                 // has a DSTBias of -60 on every Windows system that I tested.                 // So, if no DST transitions, then just use the Bias without                 // any offset                 CurrentBias = TimezoneSettings.Bias;             }   Note that some time zones do not change time, in which case the years will remain set to 1.   Further, I found that the registry settings are actually wrong in that the DST Bias is set to -60 for China even though there is not DST in China, so I ignore the standard and DST bias for those time zones. There is one thing that I have not solved, and don’t plan to solve.  If the time zone for this computer changes, this application will not update the clock using the new time zone.  I tell  you this because you may need to deal with it – I do not because I won’t let the user get to the control panel applet to change the timezone. Copyright © 2012 – Bruce Eitman All Rights Reserved

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• C#/.NET &ndash; Finding an Item&rsquo;s Index in IEnumerable&lt;T&gt;

  - by James Michael Hare

  Sorry for the long blogging hiatus.  First it was, of course, the holidays hustle and bustle, then my brother and his wife gave birth to their son, so I’ve been away from my blogging for two weeks. Background: Finding an item’s index in List<T> is easy… Many times in our day to day programming activities, we want to find the index of an item in a collection.  Now, if we have a List<T> and we’re looking for the item itself this is trivial: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // can find the exact item using IndexOf() 5: var pos = list.IndexOf(64); This will return the position of the item if it’s found, or –1 if not.  It’s easy to see how this works for primitive types where equality is well defined.  For complex types, however, it will attempt to compare them using EqualityComparer<T>.Default which, in a nutshell, relies on the object’s Equals() method. So what if we want to search for a condition instead of equality?  That’s also easy in a List<T> with the FindIndex() method: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // finds index of first even number or -1 if not found. 5: var pos = list.FindIndex(i => i % 2 == 0);   Problem: Finding an item’s index in IEnumerable<T> is not so easy... This is all well and good for lists, but what if we want to do the same thing for IEnumerable<T>?  A collection of IEnumerable<T> has no indexing, so there’s no direct method to find an item’s index.  LINQ, as powerful as it is, gives us many tools to get us this information, but not in one step.  As with almost any problem involving collections, there are several ways to accomplish the same goal.  And once again as with almost any problem involving collections, the choice of the solution somewhat depends on the situation. So let’s look at a few possible alternatives.  I’m going to express each of these as extension methods for simplicity and consistency. Solution: The TakeWhile() and Count() combo One of the things you can do is to perform a TakeWhile() on the list as long as your find condition is not true, and then do a Count() of the items it took.  The only downside to this method is that if the item is not in the list, the index will be the full Count() of items, and not –1.  So if you don’t know the size of the list beforehand, this can be confusing. 1: // a collection of extra extension methods off IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // Finds an item in the collection, similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: // note if item not found, result is length and not -1! 8: return list.TakeWhile(i => !finder(i)).Count(); 9: } 10: } Personally, I don’t like switching the paradigm of not found away from –1, so this is one of my least favorites.  Solution: Select with index Many people don’t realize that there is an alternative form of the LINQ Select() method that will provide you an index of the item being selected: 1: list.Select( (item,index) => do something here with the item and/or index... ) This can come in handy, but must be treated with care.  This is because the index provided is only as pertains to the result of previous operations (if any).  For example: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // you'd hope this would give you the indexes of the even numbers 5: // which would be 2, 3, 8, but in reality it gives you 0, 1, 2 6: list.Where(item => item % 2 == 0).Select((item,index) => index); The reason the example gives you the collection { 0, 1, 2 } is because the where clause passes over any items that are odd, and therefore only the even items are given to the select and only they are given indexes. Conversely, we can’t select the index and then test the item in a Where() clause, because then the Where() clause would be operating on the index and not the item! So, what we have to do is to select the item and index and put them together in an anonymous type.  It looks ugly, but it works: 1: // extensions defined on IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // finds an item in a collection, similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: // if you don't name the anonymous properties they are the variable names 8: return list.Select((item, index) => new { item, index }) 9: .Where(p => finder(p.item)) 10: .Select(p => p.index + 1) 11: .FirstOrDefault() - 1; 12: } 13: }     So let’s look at this, because i know it’s convoluted: First Select() joins the items and their indexes into an anonymous type. Where() filters that list to only the ones matching the predicate. Second Select() picks the index of the matches and adds 1 – this is to distinguish between not found and first item. FirstOrDefault() returns the first item found from the previous clauses or default (zero) if not found. Subtract one so that not found (zero) will be –1, and first item (one) will be zero. The bad thing is, this is ugly as hell and creates anonymous objects for each item tested until it finds the match.  This concerns me a bit but we’ll defer judgment until compare the relative performances below. Solution: Convert ToList() and use FindIndex() This solution is easy enough.  We know any IEnumerable<T> can be converted to List<T> using the LINQ extension method ToList(), so we can easily convert the collection to a list and then just use the FindIndex() method baked into List<T>. 1: // a collection of extension methods for IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // find the index of an item in the collection similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: return list.ToList().FindIndex(finder); 8: } 9: } This solution is simplicity itself!  It is very concise and elegant and you need not worry about anyone misinterpreting what it’s trying to do (as opposed to the more convoluted LINQ methods above). But the main thing I’m concerned about here is the performance hit to allocate the List<T> in the ToList() call, but once again we’ll explore that in a second. Solution: Roll your own FindIndex() for IEnumerable<T> Of course, you can always roll your own FindIndex() method for IEnumerable<T>.  It would be a very simple for loop which scans for the item and counts as it goes.  There’s many ways to do this, but one such way might look like: 1: // extension methods for IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // Finds an item matching a predicate in the enumeration, much like List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: int index = 0; 8: foreach (var item in list) 9: { 10: if (finder(item)) 11: { 12: return index; 13: } 14:  15: index++; 16: } 17:  18: return -1; 19: } 20: } Well, it’s not quite simplicity, and those less familiar with LINQ may prefer it since it doesn’t include all of the lambdas and behind the scenes iterators that come with deferred execution.  But does having this long, blown out method really gain us much in performance? Comparison of Proposed Solutions So we’ve now seen four solutions, let’s analyze their collective performance.  I took each of the four methods described above and run them over 100,000 iterations of lists of size 10, 100, 1000, and 10000 and here’s the performance results.  Then I looked for targets at the begining of the list (best case), middle of the list (the average case) and not in the list (worst case as must scan all of the list). Each of the times below is the average time in milliseconds for one execution as computer over the 100,000 iterations: Searches Matching First Item (Best Case)   10 100 1000 10000 TakeWhile 0.0003 0.0003 0.0003 0.0003 Select 0.0005 0.0005 0.0005 0.0005 ToList 0.0002 0.0003 0.0013 0.0121 Manual 0.0001 0.0001 0.0001 0.0001   Searches Matching Middle Item (Average Case)   10 100 1000 10000 TakeWhile 0.0004 0.0020 0.0191 0.1889 Select 0.0008 0.0042 0.0387 0.3802 ToList 0.0002 0.0007 0.0057 0.0562 Manual 0.0002 0.0013 0.0129 0.1255   Searches Where Not Found (Worst Case)   10 100 1000 10000 TakeWhile 0.0006 0.0039 0.0381 0.3770 Select 0.0012 0.0081 0.0758 0.7583 ToList 0.0002 0.0012 0.0100 0.0996 Manual 0.0003 0.0026 0.0253 0.2514   Notice something interesting here, you’d think the “roll your own” loop would be the most efficient, but it only wins when the item is first (or very close to it) regardless of list size.  In almost all other cases though and in particular the average case and worst case, the ToList()/FindIndex() combo wins for performance, even though it is creating some temporary memory to hold the List<T>.  If you examine the algorithm, the reason why is most likely because once it’s in a ToList() form, internally FindIndex() scans the internal array which is much more efficient to iterate over.  Thus, it takes a one time performance hit (not including any GC impact) to create the List<T> but after that the performance is much better. Summary If you’re concerned about too many throw-away objects, you can always roll your own FindIndex() method, but for sheer simplicity and overall performance, using the ToList()/FindIndex() combo performs best on nearly all list sizes in the average and worst cases.    Technorati Tags: C#,.NET,Litte Wonders,BlackRabbitCoder,Software,LINQ,List

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• CodePlex Daily Summary for Saturday, June 09, 2012

  CodePlex Daily Summary for Saturday, June 09, 2012Popular ReleasesARCBots API Program: ARCBots API Program v3 STABLE: Stable Release, you can find the update notes in the source code.Microsoft SQL Server Product Samples: Database: AdventureWorks Sample Reports 2008 R2: AdventureWorks Sample Reports 2008 R2.zip contains several reports include Sales Reason Comparisons SQL2008R2.rdl which uses Adventure Works DW 2008R2 as a data source reference. For more information, go to Sales Reason Comparisons report.RULI Chain Code Image Generator: RULI Chain Code BW Image Generator v. 0.4: added features: - 3x3 bitmask support - 7x7 bitmask support - app icon added some refactoring for later library-creationThe Chronicles of Asku: Alpha Test v1.1: Welcome to the Chronicles of Asku alpha test. The current state of the game is 2 tomb floors, level 10 cap, and almost all core systems in the game, excluding a store that you buy armor in. This is just a test for downloading the game, and severe bug hunts... INSTRUCTIONS: When you download the folder, right click within the folder and select EXTRACT ALL Run Setup.exe Follow any on screen instructions DO NOT TRY TO LOAD A CHARACTER IF YOU HAVE NEVER SAVED ONE BEFORE Patch 1.1 -Added a...Json.NET: Json.NET 4.5 Release 7: Fix - Fixed Metro build to pass Windows Application Certification Kit on Windows 8 Release Preview Fix - Fixed Metro build error caused by an anonymous type Fix - Fixed ItemConverter not being used when serializing dictionaries Fix - Fixed an incorrect object being passed to the Error event when serializing dictionaries Fix - Fixed decimal properties not being correctly ignored with DefaultValueHandlingLINQ Extensions Library: 1.0.3.0: New to release 1.0.3.0:Combinatronics: Combinations (unique) Combinations (with repetition) Permutations (unique) Permutations (with repetition) Convert jagged arrays to fixed multidimensional arrays Convert fixed multidimensional arrays to jagged arrays ElementAtMax ElementAtMin ElementAtAverage New set of array extension (1.0.2.8):Rotate Flip Resize (maintaing data) Split Fuse Replace Append and Prepend extensions (1.0.2.7) IndexOf extensions (1.0.2.7) Ne...Audio Pitch & Shift: Audio Pitch And Shift 4.5.0: Added Instruments tab for modules Open folder content feature Some bug fixesPython Tools for Visual Studio: 1.5 Beta 1: We’re pleased to announce the release of Python Tools for Visual Studio 1.5 Beta. Python Tools for Visual Studio (PTVS) is an open-source plug-in for Visual Studio which supports programming with the Python language. PTVS supports a broad range of features including: • Supports CPython, IronPython, Jython and PyPy • Python editor with advanced member, signature intellisense and refactoring • Code navigation: “Find all refs”, goto definition, and object browser • Local and remote debugging •...Circuit Diagram: Circuit Diagram 2.0 Beta 1: New in this release: Automatically flip components when placing Delete components using keyboard delete key Resize document Document properties window Print document Recent files list Confirm when exiting with unsaved changes Thumbnail previews in Windows Explorer for CDDX files Show shortcut keys in toolbox Highlight selected item in toolbox Zoom using mouse scroll wheel while holding down ctrl key Plugin support for: Custom export formats Custom import formats Open...Umbraco CMS: Umbraco CMS 5.2 Beta: The future of Umbracov5 represents the future architecture of Umbraco, so please be aware that while it's technically superior to v4 it's not yet on a par feature or performance-wise. What's new? For full details see our http://progress.umbraco.org task tracking page showing all items complete for 5.2. In a nutshellPackage Builder Starter Kits Dynamic Extension Methods Querying / IsHelpers Friendly alt template URLs Localization Various bug fixes / performance enhancements Gett...JayData - The cross-platform HTML5 data-management library for JavaScript: JayData 1.0.5: JayData is a unified data access library for JavaScript developers to query and update data from different sources like WebSQL, IndexedDB, OData, Facebook or YQL. See it in action in this 6 minutes video New features in JayData 1.0.5http://jaydata.org/blog/jaydata-1.0.5-is-here-with-authentication-support-and-more http://jaydata.org/blog/release-notes Sencha Touch 2 module (read-only)This module can be used to bind data retrieved by JayData to Sencha Touch 2 generated user interface. (exam...32feet.NET: 3.5: This version changes the 32feet.NET library (both desktop and NETCF) to use .NET Framework version 3.5. Previously we compiled for .NET v2.0. There are no code changes from our version 3.4. See the 3.4 release for more information. Changes due to compiling for .NET 3.5Applications should be changed to use NET/NETCF v3.5. Removal of class InTheHand.Net.Bluetooth.AsyncCompletedEventArgs, which we provided on NETCF. We now just use the standard .NET System.ComponentModel.AsyncCompletedEvent...DotNetNuke® Links: 06.02.01: Added new DNN 6.2.0 beta social feature "friends" BugfixesApplication Architecture Guidelines: Application Architecture Guidelines 3.0.7: 3.0.7Jolt Environment: Jolt v2 Stable: Many new features. Follow development here for more information: http://www.rune-server.org/runescape-development/rs-503-client-server/projects/298763-jolt-environment-v2.html Setup instructions in downloadSharePoint Euro 2012 - UEFA European Football Predictor: havivi.euro2012.wsp (1.5): New fetures:Multilingual Support Max users property in Standings Web Part Games time zone change (UTC +1) bug fix - Version 1.4 locking problem http://euro2012.codeplex.com/discussions/358262 bug fix - Field Title not found (v.1.3) German SP http://euro2012.codeplex.com/discussions/358189#post844228 Bug fix - Access is denied.for users with contribute rights Bug fix - Installing on non-English version of SharePoint Bug fix - Title Rules Installing SharePoint Euro 2012 PredictorSharePoint E...myManga: myManga v1.0.0.4: ChangeLogUpdating from Previous Version: Extract contents of Release - myManga v1.0.0.4.zip to previous version's folder. Replaces: myManga.exe BakaBox.dll CoreMangaClasses.dll Manga.dll Plugins/MangaReader.manga.dll Plugins/MangaFox.manga.dll Plugins/MangaHere.manga.dll Plugins/MangaPanda.manga.dllMVVM Light Toolkit: V4RC (binaries only) including Windows 8 RP: This package contains all the latest DLLs for MVVM Light V4 RC. It includes the DLLs for Windows 8 Release Preview. An updated Nuget package is also available at http://nuget.org/packages/MvvmLightLibsPreviewExtAspNet: ExtAspNet v3.1.7: +2012-06-03 v3.1.7 -?????????BUG，??????RadioButtonList?，AJAX????????BUG（swtseaman、????）。 +?Grid?BoundField、HyperLinkField、LinkButtonField、WindowField??HtmlEncode?HtmlEncodeFormatString（TiDi）。 -HtmlEncode?HtmlEncodeFormatString??????true，??????HTML????????。 -??????Asp.Net??GridView?BoundField?????????。 -http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.boundfield.htmlencode -?Grid?HyperLinkField、WindowField??UrlEncode??，????URL??（???true）。 -?????????????，?????????????...LiveChat Starter Kit: LCSK v1.5.2: New features: Visitor location (City - Country) from geo-location Pass configuration via javascript for the chat box New visitor identification (no more using the IP address as visitor identification) To update from 1.5.1 Run the /src/1.5.2-sql-updates.txt SQL script to update your database tables. If you have it installed via NuGet, simply update your package and the file will be included so you can run the update script. New installation The easiest way to add LCSK to your app is by...New ProjectsAdvanceWars: Advance Wars For NetARCBots API Program: This is a simple API program designed for quick use for the ARCBots API.AutoUpdaterdotNET: AutoUpdater.NET is a class library that allows .net developers to easily add auto update functionality to their project.C++ AMP Conformance Test Suite: C++ AMP Conformance Test Suite contains a set of tests to aid in verifying compiler, library, and runtime behaviors as specified in the C++ AMP open specification. DynamicObjectProxy: DOP (Dynamic Object Proxy) é uma biblioteca que permite que qualquer método de qualquer objeto possa ser interceptado através de um proxy dinâmico. Ao interceptar um método, pode-se decorar o objeto, alterando ou recuperando informações sobre o seu comportamento. Extremamente útil para logs, verificações de transações, etc. DOP (Dynamic Object Proxy) is a library that contains classes that makes it possible that any method of any object can be intercepted by a dynamic proxy. By interceptin...EAIP: ???????? Flatland: Artificial life, or A-Life, is a broad and ever emerging field that has found its applications in almost any field: economics, medicine, traffic planning, shopping habits, patterns in music. And it is evident that work with modelling logical life in artificial environments is a necessity for the future software developer. Abbots novella "Flatland: A Romance of Many Dimensions" describes the two dimensional world "Flatland", where life is geometrical shapes that have human-like emotions, but...GameAudioSystem: Simple Audio Game System written with OpenAL to be used with Ogre3D.HyperionSS2P - Simple scan to pdf solution: Simple scan to pdf solution.Issue Impala: Issue Impala is a powerful and elegant issue tracker.KoekyGL Wrapper: A .net wrapper for OpenGL aimed at making it easy to use OpenGL.Marik Sample Project: This is a sample by KitMongoDB Managment Client: Development MongoDB Web client. HTML 5 jQuery. One page web application. When Windows 8 metro is released then Metro style application To.MongoDB.Dynamic: MongoDB.Dynamic is a personal project that I’ve started when I was developing my first application targeting MongoDB as DBMS, using the “official driver” MongoDB.Driver, supported by 10gen. The objective is to provide a lightweight library with some interesting features that speed up development for desktop/web applications that accesses MongoDB databases. MongoDB.Dynamic is oriented to interfaces. You don’t need to create concrete classes of your entities, all you need to do is setup your...My Google Workspace: An easy way to create documents search at Google and read your emails and Much moreqzgfjava: git????，?android??“??”???SP Sticky Notes: SP Sticky Notes allows your users to add sticky notes to a page on your SharePoint site.Weather3: It's Metro Style AppXNA Scumm: This is a rewrite of the ScummVM engine using XNA. ScummVM is an engine that runs old school LucasArts graphical adventure games. It is written completely in C# and the first version will run on PC and Xbox 360. A Windows phone version will probably follow. Of course, you will need to own the original games in order to use it. I will start my work by The Secret of Monkey Island, more specifically the VGA CD version. Monkey Island 2: LeChuck's Revenge and Indiana Jones 4 and Fate of Atl...YoG Community Game: This project is a game, being developed by several members of the Yogscast Community Forums. It is a top-down shooter, based around the protagonist 'Joe', and his adventures through TV shows every day.

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• Code Golf: Finite-state machine!

  - by Adam Matan

  Finite state machine A deterministic finite state machine is a simple computation model, widely used as an introduction to automata theory in basic CS courses. It is a simple model, equivalent to regular expression, which determines of a certain input string is Accepted or Rejected. Leaving some formalities aside, A run of a finite state machine is composed of: alphabet, a set of characters. states, usually visualized as circles. One of the states must be the start state. Some of the states might be accepting, usually visualized as double circles. transitions, usually visualized as directed arches between states, are directed links between states associated with an alphabet letter. input string, a list of alphabet characters. A run on the machine begins at the starting state. Each letter of the input string is read; If there is a transition between the current state and another state which corresponds to the letter, the current state is changed to the new state. After the last letter was read, if the current state is an accepting state, the input string is accepted. If the last state was not an accepting state, or a letter had no corresponding arch from a state during the run, the input string is rejected. Note: This short descruption is far from being a full, formal definition of a FSM; Wikipedia's fine article is a great introduction to the subject. Example For example, the following machine tells if a binary number, read from left to right, has an even number of 0s: The alphabet is the set {0,1}. The states are S1 and S2. The transitions are (S1, 0) -> S2, (S1, 1) -> S1, (S2, 0) -> S1 and (S2, 1) -> S2. The input string is any binary number, including an empty string. The rules: Implement a FSM in a language of your choice. Input The FSM should accept the following input: <States> List of state, separated by space mark. The first state in the list is the start state. Accepting states begin with a capital letter. <transitions> One or more lines. Each line is a three-tuple: origin state, letter, destination state) <input word> Zero or more characters, followed by a newline. For example, the aforementioned machine with 1001010 as an input string, would be written as: S1 s2 S1 0 s2 S1 1 S1 s2 0 S1 s2 1 s2 1001010 Output The FSM's run, written as <State> <letter> -> <state>, followed by the final state. The output for the example input would be: S1 1 -> S1 S1 0 -> s2 s2 0 -> S1 S1 1 -> S1 S1 0 -> s2 s2 1 -> s2 s2 0 -> S1 ACCEPT For the empty input '': S1 ACCEPT For 101: S1 1 -> S1 S1 0 -> s2 s2 1 -> s2 REJECT For '10X': S1 1 -> S1 S1 0 -> s2 s2 X REJECT Prize A nice bounty will be given to the most elegant and short solution. Reference implementation A reference Python implementation will be published soon.

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• Pyramind of DIVs

  - by sebastian

  Hi there, I'm trying to build a pyramid that's made of 4 DIVs. The layout looks like this: ------ | #1 | ------ ---------------- | #2 | #3 | #4 | ---------------- Moreover I need 3 additional DIVs starting at the center DIV (#3) and containing either #1, #2 or #3 additionally. These DIVs are used the build a sliding effect with jQueryUI later on. It's supposed to look like #1, #2 and #4 slide out of #3. The margin between the DIVs is supposed to be 2 pixels. I also want the whole block to be centered. Even with display: inline; and position: absolute; enabled on the visible and invisible DIVs I can't get the layout right. I used some negative margins and when it looked ok for the first time I saw that my top DIV was positioned outside of the html body. I suppose there is a more simple and elegant way to achieve what I want. Thanks in advance Sebastian Here's what I've got so far: HTML: <div id="centerbox"> <div id="main">main</div> <div id="rail_top"> <div id="top">top</div> </div> <div id="rail_left"> <div id="left">left</div> </div> <div id="rail_right"> <div id="right">right</div> </div> </div> CSS: #centerbox { height: 602px; width: 904px; margin-top: 640px; margin-left: auto; margin-right: auto; } /* blue */ #main { background-color: #33F; height: 300px; width: 300px; margin: 2px; z-index: 9999; position: absolute; display: inline; margin-left: 302px; } /* green */ #top { background-color: #3F0; height: 300px; width: 300px; z-index: 1; position: absolute; display: inline; } /* pink */ #left { background-color: #F06; height: 300px; width: 300px; z-index: 1; } /* orange */ #right { background-color: #FC0; height: 300px; width: 300px; z-index: 1; margin-left: 302px; } #rail_top { height: 602px; width: 300px; display: inline; position: absolute; margin-top: -300px; margin-left: 302px; } #rail_left { height: 300px; width: 602px; float: left; position: absolute; display: inline; margin-top: 2px; } #rail_right { height: 300px; width: 602px; float: right; position: absolute; display: inline; margin-left: 302px; margin-top: 2px; }

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• Introduction to LinqPad Driver for StreamInsight 2.1

  - by Roman Schindlauer

  We are announcing the availability of the LinqPad driver for StreamInsight 2.1. The purpose of this blog post is to offer a quick introduction into the new features that we added to the StreamInsight LinqPad driver. We’ll show you how to connect to a remote server, how to inspect the entities present of that server, how to compose on top of them and how to manage their lifetime. Installing the driver Info on how to install the driver can be found in an earlier blog post here. Establishing connections As you click on the “Add Connection” link in the left pane you will notice that now it’s possible to build the data context automatically. The new driver appears as an option in the upper list, and if you pick it you will open a connection dialog that lets you connect to a remote StreamInsight server. The connection dialog lets you specify the address of the remote server. You will notice that it’s possible to pick up the binding information from the configuration file of the LinqPad application (which is normally in the same folder as LinqPad.exe and is called LinqPad.exe.config). In order for the context to be generated you need to pick an application from the server. The control is editable hence you can create a new application if you don’t want to make changes to an existing application. If you choose a new application name you will be prompted for confirmation before this gets created. Once you click OK the connection is created and you can start issuing queries against the remote server. If there’s any connectivity error the connection is marked with a red X and you can see the error message informing you what went wrong (i.e., the remote server could not be reached etc.). The context for remote servers Let’s take a look at what happens after we are connected successfully. Every LinqPad query runs inside a context – think of it as a class that wraps all the code that you’re writing. If you’re connecting to a live server the context will contain the following: The application object itself. All entities present in this application (sources, sinks, subjects and processes). The picture below shows a snapshot of the left pane of LinqPad after a successful connection. Every entity on the server has a different icon which will allow users to figure out its purpose. You will also notice that some entities have a string in parentheses following the name. It should be interpreted as such: the first name is the name of the property of the context class and the second name is the name of the entity as it exists on the server. Not all valid entity names are valid identifier names so in cases where we had to make a transformation you see both. Note also that as you hover over the entities you get IntelliSense with their types – more on that later. Remoting is not supported As you play with the entities exposed by the context you will notice that you can’t read and write directly to/from them. If for instance you’re trying to dump the content of an entity you will get an error message telling you that in the current version remoting is not supported. This is because the entity lives on the remote server and dumping its content means reading the events produced by this entity into the local process. ObservableSource.Dump(); Will yield the following error: Reading from a remote 'System.Reactive.Linq.IQbservable`1[System.Int32]' is not supported. Use the 'Microsoft.ComplexEventProcessing.Linq.RemoteProvider.Bind' method to read from the source using a remote observer. This basically tells you that you can call the Bind() method to direct the output of this source to a sink that has to be defined on the remote machine as well. You can’t bring the results to the LinqPad window unless you write code specifically for that. Compose queries You may ask – what's the purpose of all that? After all the same information is present in the EventFlowDebugger, why bother with showing it in LinqPad? First of all, What gets exposed in LinqPad is not what you see in the debugger. In LinqPad we have a property on the context class for every entity that lives on the server. Because LinqPad offers IntelliSense we in fact have much more information about the entity, and more importantly we can compose with that entity very easily. For example, let’s say that this code creates an entity: using (var server = Server.Connect(...)) {     var a = server.CreateApplication("WhiteFish");     var src = a         .DefineObservable<int>(() => Observable.Range(0, 3))         .Deploy("ObservableSource"); If later we want to compose with the source we have to fetch it and then we can bind something to     a.GetObservable<int>("ObservableSource)").Bind(... This means that we had to know a bunch of things about this: that it’s a source, that it’s an observable, it produces a result with payload Int32 and it’s named “ObservableSource”. Only the second and last bits of information are present in the debugger, by the way. As you type in the query window you see that all the entities are present, you get IntelliSense support for them and it’s much easier to make sense of what’s available. Let’s look at a scenario where composition is plausible. With the new programming model it’s possible to create “cold” sources that are parameterized. There was a way to accomplish that even in the previous version by passing parameters to the adapters, but this time it’s much more elegant because the expression declares what parameters are required. Say that we hover the mouse over the ThrottledSource source – we will see that its type is Func<int, int, IQbservable<int>> - this in effect means that we need to pass two int parameters before we can get a source that produces events, and the type for those events is int – in the particular case of my example I had the source produce a range of integers and the two parameters were the start and end of the range. So we see how a developer can create a source that is not running yet. Then someone else (e.g. an administrator) can pass whatever parameters appropriate and run the process. Proxy Types Here’s an interesting scenario – what if someone created a source on a server but they forgot to tell you what type they used. Worse yet, they might have used an anonymous type and even though they can refer to it by name you can’t figure out how to use that type. Let’s walk through an example that shows how you can compose against types you don’t need to have the definition of. This is how we can create a source that returns an anonymous type: Application.DefineObservable(() => Observable.Range(1, 10).Select(i => new { I = i })).Deploy("O1"); Now if we refresh the connection we can see the new source named O1 appear in the list. But what’s more important is that we now have a type to work with. So we can compose a query that refers to the anonymous type. var threshold = new StreamInsightDynamicDriver.TypeProxies.AnonymousType1_0<int>(5); var filter = from i in O1              where i > threshold              select i; filter.Deploy("O2"); You will notice that the anonymous type defined with this statement: new { I = i } can now be manipulated by a client that does not have access to it because the LinqPad driver has generated another type in its stead, named StreamInsightDynamicDriver.TypeProxies.AnonymousType1_0. This type has all the properties and fields of the type defined on the server, except in this case we can instantiate values and use it to compose more queries. It is worth noting that the same thing works for types that are not anonymous – the test is if the LinqPad driver can resolve the type or not. If it’s not possible then a new type will be generated that approximates the type that exists on the server. Control metadata In addition to composing processes on top of the existing entities we can do other useful things. We can delete them – nothing new here as we simply access the entities through the Entities collection of the application class. Here is where having their real name in parentheses comes handy. There’s another way to find out what’s behind a property – dump its expression. The first line in the output tells us what’s the name of the entity used to build this property in the context. Runtime information So let’s create a process to see what happens. We can bind a source to a sink and run the resulting process. If you right click on the connection you can refresh it and see the process present in the list of entities. Then you can drag the process to the query window and see that you can have access to process object in the Processes collection of the application. You can then manipulate the process (delete it, read its diagnostic view etc.). Regards, The StreamInsight Team

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• A tale from a Stalker

  - by Peter Larsson

  Today I thought I should write something about a stalker I've got. Don't get me wrong, I have way more fans than stalkers, but this stalker is particular persistent towards me. It all started when I wrote about Relational Division with Sets late last year(http://weblogs.sqlteam.com/peterl/archive/2010/07/02/Proper-Relational-Division-With-Sets.aspx) and no matter what he tried, he didn't get a better performing query than me. But this I didn't click until later into this conversation. He must have saved himself for 9 months before posting to me again. Well... Some days ago I get an email from someone I thought i didn't know. Here is his first email Hi, I want a proper solution for achievement the result. The solution must be standard query, means no using as any native code like TOP clause, also the query should run in SQL Server 2000 (no CTE use). We have a table with consecutive keys (nbr) that is not exact sequence. We need bringing all values related with nearest key in the current key row. See the DDL: CREATE TABLE Nums(nbr INTEGER NOT NULL PRIMARY KEY, val INTEGER NOT NULL); INSERT INTO Nums(nbr, val) VALUES (1, 0),(5, 7),(9, 4); See the Result: pre_nbr     pre_val     nbr         val         nxt_nbr     nxt_val ----------- ----------- ----------- ----------- ----------- ----------- NULL        NULL        1           0           5           7 1           0           5           7           9           4 5           7           9           4           NULL        NULL The goal is suggesting most elegant solution. I would like see your best solution first, after that I will send my best (if not same with yours)   Notice there is no name, no please or nothing polite asking for my help. So, on the top of my head I sent him two solutions, following the rule "Work on SQL Server 2000 and only standard non-native code".     -- Peso 1 SELECT               pre_nbr,                              (                                                           SELECT               x.val                                                           FROM                dbo.Nums AS x                                                           WHERE              x.nbr = d.pre_nbr                              ) AS pre_val,                              d.nbr,                              d.val,                              d.nxt_nbr,                              (                                                           SELECT               x.val                                                           FROM                dbo.Nums AS x                                                           WHERE              x.nbr = d.nxt_nbr                              ) AS nxt_val FROM                (                                                           SELECT               (                                                                                                                     SELECT               MAX(x.nbr) AS nbr                                                                                                                     FROM                dbo.Nums AS x                                                                                                                     WHERE              x.nbr < n.nbr                                                                                        ) AS pre_nbr,                                                                                        n.nbr,                                                                                        n.val,                                                                                        (                                                                                                                     SELECT               MIN(x.nbr) AS nbr                                                                                                                     FROM                dbo.Nums AS x                                                                                                                     WHERE              x.nbr > n.nbr                                                                                        ) AS nxt_nbr                                                           FROM                dbo.Nums AS n                              ) AS d -- Peso 2 CREATE TABLE #Temp                                                         (                                                                                        ID INT IDENTITY(1, 1) PRIMARY KEY,                                                                                        nbr INT,                                                                                        val INT                                                           )   INSERT                                            #Temp                                                           (                                                                                        nbr,                                                                                        val                                                           ) SELECT                                            nbr,                                                           val FROM                                             dbo.Nums ORDER BY         nbr   SELECT                                            pre.nbr AS pre_nbr,                                                           pre.val AS pre_val,                                                           t.nbr,                                                           t.val,                                                           nxt.nbr AS nxt_nbr,                                                           nxt.val AS nxt_val FROM                                             #Temp AS pre RIGHT JOIN      #Temp AS t ON t.ID = pre.ID + 1 LEFT JOIN         #Temp AS nxt ON nxt.ID = t.ID + 1   DROP TABLE    #Temp Notice there are no indexes on #Temp table yet. And here is where the conversation derailed. First I got this response back Now my solutions: --My 1st Slt SELECT T2.*, T1.*, T3.*   FROM Nums AS T1        LEFT JOIN Nums AS T2          ON T2.nbr = (SELECT MAX(nbr)                         FROM Nums                        WHERE nbr < T1.nbr)        LEFT JOIN Nums AS T3          ON T3.nbr = (SELECT MIN(nbr)                         FROM Nums                        WHERE nbr > T1.nbr); --My 2nd Slt SELECT MAX(CASE WHEN N1.nbr > N2.nbr THEN N2.nbr ELSE NULL END) AS pre_nbr,        (SELECT val FROM Nums WHERE nbr = MAX(CASE WHEN N1.nbr > N2.nbr THEN N2.nbr ELSE NULL END)) AS pre_val,        N1.nbr AS cur_nbr, N1.val AS cur_val,        MIN(CASE WHEN N1.nbr < N2.nbr THEN N2.nbr ELSE NULL END) AS nxt_nbr,        (SELECT val FROM Nums WHERE nbr = MIN(CASE WHEN N1.nbr < N2.nbr THEN N2.nbr ELSE NULL END)) AS nxt_val   FROM Nums AS N1,        Nums AS N2  GROUP BY N1.nbr, N1.val;   /* My 1st Slt Table 'Nums'. Scan count 7, logical reads 14 My 2nd Slt Table 'Nums'. Scan count 4, logical reads 23 Peso 1 Table 'Nums'. Scan count 9, logical reads 28 Peso 2 Table '#Temp'. Scan count 0, logical reads 7 Table 'Nums'. Scan count 1, logical reads 2 Table '#Temp'. Scan count 3, logical reads 16 */  To this, I emailed him back asking for a scalability test What if you try with a Nums table with 100,000 rows? His response to that started to get nasty.  I have to say Peso 2 is not acceptable. As I said before the solution must be standard, ORDER BY is not part of standard SELECT. Try this without ORDER BY:  Truncate Table Nums INSERT INTO Nums (nbr, val) VALUES (1, 0),(9,4), (5, 7)  So now we have new rules. No ORDER BY because it's not standard SQL! Of course I asked him  Why do you have that idea? ORDER BY is not standard? To this, his replies went stranger and stranger Standard Select = Set-based (no any cursor) It’s free to know, just refer to Advanced SQL Programming by Celko or mail to him if you accept comments from him. What the stalker probably doesn't know, is that I and Mr Celko occasionally are involved in some conversation and thus we exchange emails. I don't know if this reference to Mr Celko was made to intimidate me either. So I answered him, still polite, this What do you mean? The SELECT itself has a ”cursor under the hood”. Now the stalker gets rude  But however I mean the solution must no containing any order by, top... No problem, I do not like Peso 2, it’s very non-intelligent and elementary. Yes, Peso 2 is elementary but most performing queries are... And now is the time where I started to feel the stalker really wanted to achieve something else, so I wrote to him So what is your goal? Have a query that performs well, or a query that is super-portable? My Peso 2 outperforms any of your code with a factor of 100 when using more than 100,000 rows. While I awaited his answer, I posted him this query Ok, here is another one -- Peso 3 SELECT             MAX(CASE WHEN d = 1 THEN nbr ELSE NULL END) AS pre_nbr,                    MAX(CASE WHEN d = 1 THEN val ELSE NULL END) AS pre_val,                    MAX(CASE WHEN d = 0 THEN nbr ELSE NULL END) AS nbr,                    MAX(CASE WHEN d = 0 THEN val ELSE NULL END) AS val,                    MAX(CASE WHEN d = -1 THEN nbr ELSE NULL END) AS nxt_nbr,                    MAX(CASE WHEN d = -1 THEN val ELSE NULL END) AS nxt_val FROM               (                              SELECT    nbr,                                        val,                                        ROW_NUMBER() OVER (ORDER BY nbr) AS SeqID                              FROM      dbo.Nums                    ) AS s CROSS JOIN         (                              VALUES    (-1),                                        (0),                                        (1)                    ) AS x(d) GROUP BY           SeqID + x.d HAVING             COUNT(*) > 1 And here is the stats Table 'Nums'. Scan count 1, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. It beats the hell out of your queries…. Now I finally got a response from my stalker and now I also clicked who he was. This is his reponse Why you post my original method with a bit change under you name? I do not like it. See: http://www.sqlservercentral.com/Forums/Topic468501-362-14.aspx ;WITH C AS ( SELECT seq_nbr, k,        DENSE_RANK() OVER(ORDER BY seq_nbr ASC) + k AS grp_fct   FROM [Sample]         CROSS JOIN         (VALUES (-1), (0), (1)         ) AS D(k) ) SELECT MIN(seq_nbr) AS pre_value,        MAX(CASE WHEN k = 0 THEN seq_nbr END) AS current_value,        MAX(seq_nbr) AS next_value   FROM C GROUP BY grp_fct HAVING min(seq_nbr) < max(seq_nbr); These posts: Posted Tuesday, April 12, 2011 10:04 AM Posted Tuesday, April 12, 2011 1:22 PM Why post a solution where will not work in SQL Server 2000? Wait a minute! His own solution is using both a CTE and a ranking function so his query will not work on SQL Server 2000! Bummer... The reference to "Me not like" are my exact words in a previous topic on SQLTeam.com and when I remembered the phrasing, I also knew who he was. See this topic http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=159262 where he writes a query and posts it under my name, as if I wrote it. So I answered him this (less polite). Like I keep track of all topics in the whole world… J So you think you are the only one coming up with this idea? Besides, “M S solution” doesn’t work.   This is the result I get pre_value        current_value                             next_value 1                           1                           5 1                           5                           9 5                           9                           9   And I did nothing like you did here, where you posted a solution which you “thought” I should write http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=159262 So why are you yourself using ranking function when this was not allowed per your original email, and no cte? You use CTE in your link above, which do not work in SQL Server 2000. All this makes no sense to me, other than you are trying your best to once in a lifetime create a better performing query than me? After a few hours I get this email back. I don't fully understand it, but it's probably a language barrier. >>Like I keep track of all topics in the whole world… J So you think you are the only one coming up with this idea?<< You right, but do not think you are the first creator of this.   >>Besides, “M S Solution” doesn’t work. This is the result I get <<   Why you get so unimportant mistake? See this post to correct it: Posted 4/12/2011 8:22:23 PM >> So why are you yourself using ranking function when this was not allowed per your original email, and no cte? You use CTE in your link above, which do not work in SQL Server 2000. <<  Again, why you get some unimportant incompatibility? You offer that solution for current goals not me  >> All this makes no sense to me, other than you are trying your best to once in a lifetime create a better performing query than me? <<  No, I only wanted to know who you will solve it. Now I know you do not have a special solution. No problem. No problem for me either. So I just answered him I am not the first, and you are not the first to come up with this idea. So what is your problem? I am pretty sure other people have come up with the same idea before us. I used this technique all the way back to 2007, see http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=93911 Let's see if he returns...  He did! >> So what is your problem? << Nothing Thanks for all replies; maybe we have some competitions in future, maybe. Also I like you but you do not attend it. Your behavior with me is not friendly. Not any meeting… Regards //Peso

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• Hibernate - how to delete bidirectional many-to-many association

  - by slomir

  Problem: I have many-to-many association between two entities A and B. I set A entity as an owner of their relationship(inverse=true is on A's collection in b.hbm.xml). When i delete an A entity, corresponding records in join table are deleted. When i delete an B entity, corresponding records in join table are not deleted (integrity violation exception). -- Let's consider some very simple example: class A{ Set<B> bset=new HashSet<B>(); //... } class B{ Set<A> aset=new HashSet<A>(); //... } File a.hbm.xml [m-to-m mappings only]: <set name="bset" table="AB"> <key name="a_id"/> <many-to-many column="b_id" class="B"/> </set> File b.hbm.xml [m-to-m mappings only]: <set name="aset" table="AB" inverse="true"> <key name="b_id"/> <many-to-many column="a_id" class="A"/> </set> Database relations: A(id,...) B(id,...) AB(a_id,b_id) Suppose that we have some records in AB joint table. For example: AB = {(1,1),(1,2)} where AB= { (a_id , b_id) | ... ... } -- Situation 1 - works probably because A is owner of AB relationship: A a=aDao.read(1); //read A entity with id=1 aDao.delete(a); //delete 'a' entity and both relations with B-entities Situation 2 - doesn't work: B b=bDao.read(1); //read B entity with id=1 bDao.delete(b); //foreign key integrity violation On the one hand, this is somehow logical to me, because the A entity is responsible for his relation with B. But, on the other hand, it is not logical or at least it is not orm-like solution that I have to explicitly delete all records in join table where concrete B entity appears, and then to delete the B entity, as I show in situation 3: Situation 3 - works, but it is not 'elegant': B b=bDao.read(1); Set<A> aset=b.getA(); //get set with A entities Iterator i=aset.iterator(); //while removes 'b' from all related A entities //while breaks relationships on A-side of relation (A is owner) while(i.hasNext()){ A a=i.next(); a.bset.remove(b); //remove entity 'b' from related 'a' entity aDao.update(a); //key point!!! this line breaks relation in database } bDao.delete(b); //'b' is deleted because there is no related A-entities -- So, my question: is there any more convenient way to delete no-owner entity (B in my example) in bidirectional many-to-many association and all of his many-to-many relations from joint table?

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• Introduction to LinqPad Driver for StreamInsight 2.1

  - by Roman Schindlauer

  We are announcing the availability of the LinqPad driver for StreamInsight 2.1. The purpose of this blog post is to offer a quick introduction into the new features that we added to the StreamInsight LinqPad driver. We’ll show you how to connect to a remote server, how to inspect the entities present of that server, how to compose on top of them and how to manage their lifetime. Installing the driver Info on how to install the driver can be found in an earlier blog post here. Establishing connections As you click on the “Add Connection” link in the left pane you will notice that now it’s possible to build the data context automatically. The new driver appears as an option in the upper list, and if you pick it you will open a connection dialog that lets you connect to a remote StreamInsight server. The connection dialog lets you specify the address of the remote server. You will notice that it’s possible to pick up the binding information from the configuration file of the LinqPad application (which is normally in the same folder as LinqPad.exe and is called LinqPad.exe.config). In order for the context to be generated you need to pick an application from the server. The control is editable hence you can create a new application if you don’t want to make changes to an existing application. If you choose a new application name you will be prompted for confirmation before this gets created. Once you click OK the connection is created and you can start issuing queries against the remote server. If there’s any connectivity error the connection is marked with a red X and you can see the error message informing you what went wrong (i.e., the remote server could not be reached etc.). The context for remote servers Let’s take a look at what happens after we are connected successfully. Every LinqPad query runs inside a context – think of it as a class that wraps all the code that you’re writing. If you’re connecting to a live server the context will contain the following: The application object itself. All entities present in this application (sources, sinks, subjects and processes). The picture below shows a snapshot of the left pane of LinqPad after a successful connection. Every entity on the server has a different icon which will allow users to figure out its purpose. You will also notice that some entities have a string in parentheses following the name. It should be interpreted as such: the first name is the name of the property of the context class and the second name is the name of the entity as it exists on the server. Not all valid entity names are valid identifier names so in cases where we had to make a transformation you see both. Note also that as you hover over the entities you get IntelliSense with their types – more on that later. Remoting is not supported As you play with the entities exposed by the context you will notice that you can’t read and write directly to/from them. If for instance you’re trying to dump the content of an entity you will get an error message telling you that in the current version remoting is not supported. This is because the entity lives on the remote server and dumping its content means reading the events produced by this entity into the local process. ObservableSource.Dump(); Will yield the following error: Reading from a remote 'System.Reactive.Linq.IQbservable`1[System.Int32]' is not supported. Use the 'Microsoft.ComplexEventProcessing.Linq.RemoteProvider.Bind' method to read from the source using a remote observer. This basically tells you that you can call the Bind() method to direct the output of this source to a sink that has to be defined on the remote machine as well. You can’t bring the results to the LinqPad window unless you write code specifically for that. Compose queries You may ask – what's the purpose of all that? After all the same information is present in the EventFlowDebugger, why bother with showing it in LinqPad? First of all, What gets exposed in LinqPad is not what you see in the debugger. In LinqPad we have a property on the context class for every entity that lives on the server. Because LinqPad offers IntelliSense we in fact have much more information about the entity, and more importantly we can compose with that entity very easily. For example, let’s say that this code creates an entity: using (var server = Server.Connect(...)) {     var a = server.CreateApplication("WhiteFish");     var src = a         .DefineObservable<int>(() => Observable.Range(0, 3))         .Deploy("ObservableSource"); If later we want to compose with the source we have to fetch it and then we can bind something to     a.GetObservable<int>("ObservableSource)").Bind(... This means that we had to know a bunch of things about this: that it’s a source, that it’s an observable, it produces a result with payload Int32 and it’s named “ObservableSource”. Only the second and last bits of information are present in the debugger, by the way. As you type in the query window you see that all the entities are present, you get IntelliSense support for them and it’s much easier to make sense of what’s available. Let’s look at a scenario where composition is plausible. With the new programming model it’s possible to create “cold” sources that are parameterized. There was a way to accomplish that even in the previous version by passing parameters to the adapters, but this time it’s much more elegant because the expression declares what parameters are required. Say that we hover the mouse over the ThrottledSource source – we will see that its type is Func<int, int, IQbservable<int>> - this in effect means that we need to pass two int parameters before we can get a source that produces events, and the type for those events is int – in the particular case of my example I had the source produce a range of integers and the two parameters were the start and end of the range. So we see how a developer can create a source that is not running yet. Then someone else (e.g. an administrator) can pass whatever parameters appropriate and run the process. Proxy Types Here’s an interesting scenario – what if someone created a source on a server but they forgot to tell you what type they used. Worse yet, they might have used an anonymous type and even though they can refer to it by name you can’t figure out how to use that type. Let’s walk through an example that shows how you can compose against types you don’t need to have the definition of. This is how we can create a source that returns an anonymous type: Application.DefineObservable(() => Observable.Range(1, 10).Select(i => new { I = i })).Deploy("O1"); Now if we refresh the connection we can see the new source named O1 appear in the list. But what’s more important is that we now have a type to work with. So we can compose a query that refers to the anonymous type. var threshold = new StreamInsightDynamicDriver.TypeProxies.AnonymousType1_0<int>(5); var filter = from i in O1              where i > threshold              select i; filter.Deploy("O2"); You will notice that the anonymous type defined with this statement: new { I = i } can now be manipulated by a client that does not have access to it because the LinqPad driver has generated another type in its stead, named StreamInsightDynamicDriver.TypeProxies.AnonymousType1_0. This type has all the properties and fields of the type defined on the server, except in this case we can instantiate values and use it to compose more queries. It is worth noting that the same thing works for types that are not anonymous – the test is if the LinqPad driver can resolve the type or not. If it’s not possible then a new type will be generated that approximates the type that exists on the server. Control metadata In addition to composing processes on top of the existing entities we can do other useful things. We can delete them – nothing new here as we simply access the entities through the Entities collection of the application class. Here is where having their real name in parentheses comes handy. There’s another way to find out what’s behind a property – dump its expression. The first line in the output tells us what’s the name of the entity used to build this property in the context. Runtime information So let’s create a process to see what happens. We can bind a source to a sink and run the resulting process. If you right click on the connection you can refresh it and see the process present in the list of entities. Then you can drag the process to the query window and see that you can have access to process object in the Processes collection of the application. You can then manipulate the process (delete it, read its diagnostic view etc.). Regards, The StreamInsight Team

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• C#: Handling Notifications: inheritance, events, or delegates?

  - by James Michael Hare

  Often times as developers we have to design a class where we get notification when certain things happen. In older object-oriented code this would often be implemented by overriding methods -- with events, delegates, and interfaces, however, we have far more elegant options. So, when should you use each of these methods and what are their strengths and weaknesses? Now, for the purposes of this article when I say notification, I'm just talking about ways for a class to let a user know that something has occurred. This can be through any programmatic means such as inheritance, events, delegates, etc. So let's build some context. I'm sitting here thinking about a provider neutral messaging layer for the place I work, and I got to the point where I needed to design the message subscriber which will receive messages from the message bus. Basically, what we want is to be able to create a message listener and have it be called whenever a new message arrives. Now, back before the flood we would have done this via inheritance and an abstract class: 1:  2: // using inheritance - omitting argument null checks and halt logic 3: public abstract class MessageListener 4: { 5: private ISubscriber _subscriber; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber) 11: { 12: _subscriber = subscriber; 13: _messageThread = new Thread(MessageLoop); 14: _messageThread.Start(); 15: } 16:  17: // user will override this to process their messages 18: protected abstract void OnMessageReceived(Message msg); 19:  20: // handle the looping in the thread 21: private void MessageLoop() 22: { 23: while(!_isHalted) 24: { 25: // as long as processing, wait 1 second for message 26: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 27: if(msg != null) 28: { 29: OnMessageReceived(msg); 30: } 31: } 32: } 33: ... 34: } It seems so odd to write this kind of code now. Does it feel odd to you? Maybe it's just because I've gotten so used to delegation that I really don't like the feel of this. To me it is akin to saying that if I want to drive my car I need to derive a new instance of it just to put myself in the driver's seat. And yet, unquestionably, five years ago I would have probably written the code as you see above. To me, inheritance is a flawed approach for notifications due to several reasons: Inheritance is one of the HIGHEST forms of coupling. You can't seal the listener class because it depends on sub-classing to work. Because C# does not allow multiple-inheritance, I've spent my one inheritance implementing this class. Every time you need to listen to a bus, you have to derive a class which leads to lots of trivial sub-classes. The act of consuming a message should be a separate responsibility than the act of listening for a message (SRP). Inheritance is such a strong statement (this IS-A that) that it should only be used in building type hierarchies and not for overriding use-specific behaviors and notifications. Chances are, if a class needs to be inherited to be used, it most likely is not designed as well as it could be in today's modern programming languages. So lets look at the other tools available to us for getting notified instead. Here's a few other choices to consider. Have the listener expose a MessageReceived event. Have the listener accept a new IMessageHandler interface instance. Have the listener accept an Action<Message> delegate. Really, all of these are different forms of delegation. Now, .NET events are a bit heavier than the other types of delegates in terms of run-time execution, but they are a great way to allow others using your class to subscribe to your events: 1: // using event - ommiting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private bool _isHalted = false; 6: private Thread _messageThread; 7:  8: // assign the subscriber and start the messaging loop 9: public MessageListener(ISubscriber subscriber) 10: { 11: _subscriber = subscriber; 12: _messageThread = new Thread(MessageLoop); 13: _messageThread.Start(); 14: } 15:  16: // user will override this to process their messages 17: public event Action<Message> MessageReceived; 18:  19: // handle the looping in the thread 20: private void MessageLoop() 21: { 22: while(!_isHalted) 23: { 24: // as long as processing, wait 1 second for message 25: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 26: if(msg != null && MessageReceived != null) 27: { 28: MessageReceived(msg); 29: } 30: } 31: } 32: } Note, now we can seal the class to avoid changes and the user just needs to provide a message handling method: 1: theListener.MessageReceived += CustomReceiveMethod; However, personally I don't think events hold up as well in this case because events are largely optional. To me, what is the point of a listener if you create one with no event listeners? So in my mind, use events when handling the notification is optional. So how about the delegation via interface? I personally like this method quite a bit. Basically what it does is similar to inheritance method mentioned first, but better because it makes it easy to split the part of the class that doesn't change (the base listener behavior) from the part that does change (the user-specified action after receiving a message). So assuming we had an interface like: 1: public interface IMessageHandler 2: { 3: void OnMessageReceived(Message receivedMessage); 4: } Our listener would look like this: 1: // using delegation via interface - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private IMessageHandler _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler.OnMessageReceived(msg); 28: } 29: } 30: } 31: } And they would call it by creating a class that implements IMessageHandler and pass that instance into the constructor of the listener. I like that this alleviates the issues of inheritance and essentially forces you to provide a handler (as opposed to events) on construction. Well, this is good, but personally I think we could go one step further. While I like this better than events or inheritance, it still forces you to implement a specific method name. What if that name collides? Furthermore if you have lots of these you end up either with large classes inheriting multiple interfaces to implement one method, or lots of small classes. Also, if you had one class that wanted to manage messages from two different subscribers differently, it wouldn't be able to because the interface can't be overloaded. This brings me to using delegates directly. In general, every time I think about creating an interface for something, and if that interface contains only one method, I start thinking a delegate is a better approach. Now, that said delegates don't accomplish everything an interface can. Obviously having the interface allows you to refer to the classes that implement the interface which can be very handy. In this case, though, really all you want is a method to handle the messages. So let's look at a method delegate: 1: // using delegation via delegate - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler(msg); 28: } 29: } 30: } 31: } Here the MessageListener now takes an Action<Message>.  For those of you unfamiliar with the pre-defined delegate types in .NET, that is a method with the signature: void SomeMethodName(Message). The great thing about delegates is it gives you a lot of power. You could create an anonymous delegate, a lambda, or specify any other method as long as it satisfies the Action<Message> signature. This way, you don't need to define an arbitrary helper class or name the method a specific thing. Incidentally, we could combine both the interface and delegate approach to allow maximum flexibility. Doing this, the user could either pass in a delegate, or specify a delegate interface: 1: // using delegation - give users choice of interface or delegate 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // passes the interface method as a delegate using method group 19: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 20: : this(subscriber, handler.OnMessageReceived) 21: { 22: } 23:  24: // handle the looping in the thread 25: private void MessageLoop() 26: { 27: while(!_isHalted) 28: { 29: // as long as processing, wait 1 second for message 30: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 31: if(msg != null) 32: { 33: _handler(msg); 34: } 35: } 36: } 37: } } This is the method I tend to prefer because it allows the user of the class to choose which method works best for them. You may be curious about the actual performance of these different methods. 1: Enter iterations: 2: 1000000 3:  4: Inheritance took 4 ms. 5: Events took 7 ms. 6: Interface delegation took 4 ms. 7: Lambda delegate took 5 ms. Before you get too caught up in the numbers, however, keep in mind that this is performance over over 1,000,000 iterations. Since they are all < 10 ms which boils down to fractions of a micro-second per iteration so really any of them are a fine choice performance wise. As such, I think the choice of what to do really boils down to what you're trying to do. Here's my guidelines: Inheritance should be used only when defining a collection of related types with implementation specific behaviors, it should not be used as a hook for users to add their own functionality. Events should be used when subscription is optional or multi-cast is desired. Interface delegation should be used when you wish to refer to implementing classes by the interface type or if the type requires several methods to be implemented. Delegate method delegation should be used when you only need to provide one method and do not need to refer to implementers by the interface name.

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• Problem using form builder & DOM manipulation in Rails with multiple levels of nested partials

  - by Chris Hart

  I'm having a problem using nested partials with dynamic form builder code (from the "complex form example" code on github) in Rails. I have my top level view "new" (where I attempt to generate the template): <% form_for (@transaction_group) do |txngroup_form| %> <%= txngroup_form.error_messages %> <% content_for :jstemplates do -%> <%= "var transaction='#{generate_template(txngroup_form, :transactions)}'" %> <% end -%> <%= render :partial => 'transaction_group', :locals => { :f => txngroup_form, :txn_group => @transaction_group }%> <% end -%> This renders the transaction_group partial: <div class="content"> <% logger.debug "in partial, class name = " + txn_group.class.name %> <% f.fields_for txn_group.transactions do |txn_form| %> <table id="transactions" class="form"> <tr class="header"><td>Price</td><td>Quantity</td></tr> <%= render :partial => 'transaction', :locals => { :tf => txn_form } %> </table> <% end %> <div>&nbsp;</div><div id="container"> <%= link_to 'Add a transaction', '#transaction', :class => "add_nested_item", :rel => "transactions" %> </div> <div>&nbsp;</div> ... which in turn renders the transaction partial: <tr><td><%= tf.text_field :price, :size => 5 %></td> <td><%= tf.text_field :quantity, :size => 2 %></td></tr> The generate_template code looks like this: def generate_html(form_builder, method, options = {}) options[:object] ||= form_builder.object.class.reflect_on_association(method).klass.new options[:partial] ||= method.to_s.singularize options[:form_builder_local] ||= :f form_builder.fields_for(method, options[:object], :child_index => 'NEW_RECORD') do |f| render(:partial => options[:partial], :locals => { options[:form_builder_local] => f }) end end def generate_template(form_builder, method, options = {}) escape_javascript generate_html(form_builder, method, options) end (Obviously my code is not the most elegant - I was trying to get this nested partial thing worked out first.) My problem is that I get an undefined variable exception from the transaction partial when loading the view: /Users/chris/dev/ss/app/views/transaction_groups/_transaction.html.erb:2:in _run_erb_app47views47transaction_groups47_transaction46html46erb_locals_f_object_transaction' /Users/chris/dev/ss/app/helpers/customers_helper.rb:29:in generate_html' /Users/chris/dev/ss/app/helpers/customers_helper.rb:28:in generate_html' /Users/chris/dev/ss/app/helpers/customers_helper.rb:34:in generate_template' /Users/chris/dev/ss/app/views/transaction_groups/new.html.erb:4:in _run_erb_app47views47transaction_groups47new46html46erb' /Users/chris/dev/ss/app/views/transaction_groups/new.html.erb:3:in _run_erb_app47views47transaction_groups47new46html46erb' /Users/chris/dev/ss/app/views/transaction_groups/new.html.erb:1:in _run_erb_app47views47transaction_groups47new46html46erb' /Users/chris/dev/ss/app/controllers/transaction_groups_controller.rb:17:in new' I'm pretty sure this is because the do loop for form_for hasn't executed yet (?)... I'm not sure that my approach to this problem is the best, but I haven't been able to find a better solution for dynamically adding form partials to the DOM. Basically I need a way to add records to a has_many model dynamically on a nested form. Any recommendations on a way to fix this particular problem or (even better!) a cleaner solution are appreciated. Thanks in advance. Chris

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• How to find the insertion point in an array using binary search?

  - by ????

  The basic idea of binary search in an array is simple, but it might return an "approximate" index if the search fails to find the exact item. (we might sometimes get back an index for which the value is larger or smaller than the searched value). For looking for the exact insertion point, it seems that after we got the approximate location, we might need to "scan" to left or right for the exact insertion location, so that, say, in Ruby, we can do arr.insert(exact_index, value) I have the following solution, but the handling for the part when begin_index >= end_index is a bit messy. I wonder if a more elegant solution can be used? (this solution doesn't care to scan for multiple matches if an exact match is found, so the index returned for an exact match may point to any index that correspond to the value... but I think if they are all integers, we can always search for a - 1 after we know an exact match is found, to find the left boundary, or search for a + 1 for the right boundary.) My solution: DEBUGGING = true def binary_search_helper(arr, a, begin_index, end_index) middle_index = (begin_index + end_index) / 2 puts "a = #{a}, arr[middle_index] = #{arr[middle_index]}, " + "begin_index = #{begin_index}, end_index = #{end_index}, " + "middle_index = #{middle_index}" if DEBUGGING if arr[middle_index] == a return middle_index elsif begin_index >= end_index index = [begin_index, end_index].min return index if a < arr[index] && index >= 0 #careful because -1 means end of array index = [begin_index, end_index].max return index if a < arr[index] && index >= 0 return index + 1 elsif a > arr[middle_index] return binary_search_helper(arr, a, middle_index + 1, end_index) else return binary_search_helper(arr, a, begin_index, middle_index - 1) end end # for [1,3,5,7,9], searching for 6 will return index for 7 for insertion # if exact match is found, then return that index def binary_search(arr, a) puts "\nSearching for #{a} in #{arr}" if DEBUGGING return 0 if arr.empty? result = binary_search_helper(arr, a, 0, arr.length - 1) puts "the result is #{result}, the index for value #{arr[result].inspect}" if DEBUGGING return result end arr = [1,3,5,7,9] b = 6 arr.insert(binary_search(arr, b), b) p arr arr = [1,3,5,7,9,11] b = 6 arr.insert(binary_search(arr, b), b) p arr arr = [1,3,5,7,9] b = 60 arr.insert(binary_search(arr, b), b) p arr arr = [1,3,5,7,9,11] b = 60 arr.insert(binary_search(arr, b), b) p arr arr = [1,3,5,7,9] b = -60 arr.insert(binary_search(arr, b), b) p arr arr = [1,3,5,7,9,11] b = -60 arr.insert(binary_search(arr, b), b) p arr arr = [1] b = -60 arr.insert(binary_search(arr, b), b) p arr arr = [1] b = 60 arr.insert(binary_search(arr, b), b) p arr arr = [] b = 60 arr.insert(binary_search(arr, b), b) p arr and result: Searching for 6 in [1, 3, 5, 7, 9] a = 6, arr[middle_index] = 5, begin_index = 0, end_index = 4, middle_index = 2 a = 6, arr[middle_index] = 7, begin_index = 3, end_index = 4, middle_index = 3 a = 6, arr[middle_index] = 5, begin_index = 3, end_index = 2, middle_index = 2 the result is 3, the index for value 7 [1, 3, 5, 6, 7, 9] Searching for 6 in [1, 3, 5, 7, 9, 11] a = 6, arr[middle_index] = 5, begin_index = 0, end_index = 5, middle_index = 2 a = 6, arr[middle_index] = 9, begin_index = 3, end_index = 5, middle_index = 4 a = 6, arr[middle_index] = 7, begin_index = 3, end_index = 3, middle_index = 3 the result is 3, the index for value 7 [1, 3, 5, 6, 7, 9, 11] Searching for 60 in [1, 3, 5, 7, 9] a = 60, arr[middle_index] = 5, begin_index = 0, end_index = 4, middle_index = 2 a = 60, arr[middle_index] = 7, begin_index = 3, end_index = 4, middle_index = 3 a = 60, arr[middle_index] = 9, begin_index = 4, end_index = 4, middle_index = 4 the result is 5, the index for value nil [1, 3, 5, 7, 9, 60] Searching for 60 in [1, 3, 5, 7, 9, 11] a = 60, arr[middle_index] = 5, begin_index = 0, end_index = 5, middle_index = 2 a = 60, arr[middle_index] = 9, begin_index = 3, end_index = 5, middle_index = 4 a = 60, arr[middle_index] = 11, begin_index = 5, end_index = 5, middle_index = 5 the result is 6, the index for value nil [1, 3, 5, 7, 9, 11, 60] Searching for -60 in [1, 3, 5, 7, 9] a = -60, arr[middle_index] = 5, begin_index = 0, end_index = 4, middle_index = 2 a = -60, arr[middle_index] = 1, begin_index = 0, end_index = 1, middle_index = 0 a = -60, arr[middle_index] = 9, begin_index = 0, end_index = -1, middle_index = -1 the result is 0, the index for value 1 [-60, 1, 3, 5, 7, 9] Searching for -60 in [1, 3, 5, 7, 9, 11] a = -60, arr[middle_index] = 5, begin_index = 0, end_index = 5, middle_index = 2 a = -60, arr[middle_index] = 1, begin_index = 0, end_index = 1, middle_index = 0 a = -60, arr[middle_index] = 11, begin_index = 0, end_index = -1, middle_index = -1 the result is 0, the index for value 1 [-60, 1, 3, 5, 7, 9, 11] Searching for -60 in [1] a = -60, arr[middle_index] = 1, begin_index = 0, end_index = 0, middle_index = 0 the result is 0, the index for value 1 [-60, 1] Searching for 60 in [1] a = 60, arr[middle_index] = 1, begin_index = 0, end_index = 0, middle_index = 0 the result is 1, the index for value nil [1, 60] Searching for 60 in [] [60]

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• Passing unknown amounts of variables using through a string string and eval and multiple functions a

  - by user300797

  I'm not sure how best to describe this problem... In short, I want to use object literal to allow me to pass a random amount of variables in any order to a function. Whilst this is not big deal in theory, in my code, this object literal is passed to a second function call on_change. on_change works comparing an element inner HTML to a string. if it is the same, it sets a time out of to call the function again (this is sort of/almost recursive, but the function dose actually get to end before it is called again). if the elements inner HTML is different from the string, then the third parameter is executed. this will either be a function or a string. either way it will execute. I have tested this function plenty and used it for a while now. how ever, it cannot seem to get the object literal to flow through the function calls... var params = { xpos:'false'}; on_change('window_3_cont_buffer','',' if(Window_manager.windows[3].window_cont_buffer.getElementsByTagName(\'content\')[0].getElementsByTagName(\'p\')[0].innerHTML == \'ERROR\'){ alert(Window_manager.windows[3].window_cont_buffer.getElementsByTagName(\'content\')[0].getElementsByTagName(\'p\')[1].innerHTML); return false; } else { Window_manager.windows[3].load_xml(\'location/view.php?location_ID=3\', \'\', ' + params + ' ); } '); I call this as part of the form submission. after this line, I then call a function to load some content via ajax, which works fine and will trigger the code from the on_change function. I have tested load_xml function it is able to call alert(param.xpos) and get the correct response. I can even added in a check for being undefined so that rest of the times I cam load_xml I don't get swamped with alerts. The load_xml function first set up the on_change function, then calls the function to load the content to a hidden div. Once the AJAX request has updated that DIV, the on_change function should now call the parse_xml function. This pulls out the information from the xml file. How ever... The idea of this object literal param is that it can tell this parse_xml function to ignore certain things. on_change("window_" + this.id + "_cont_buffer", "", "Window_manager.windows[" + this.id + "].parse_xml('" + param + "')"); this is part of load_xml. it works perfectly fine, even with the param bit in there. except, parse_xml dose not seem to be able to use that parameter. I have been able to get it to a point where parse_xml can alert(param) and give [object object] which I would of thought meant that the object litteral had been passed through, but when I try and call alert(param.xpos) I get undefined. I know this is a pig of a problem, and I could get around it by just having the function take a zillion boolean parameters, but its just not practical or elegant. I'm sure you will need to ask me plenty more questions before I can solve this. I will post more complete code, I just cut it down to what is actually going on. Thanks

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• Auto-hydrate your objects with ADO.NET

  - by Jake Rutherford

  Recently while writing the monotonous code for pulling data out of a DataReader to hydrate some objects in an application I suddenly wondered "is this really necessary?" You've probably asked yourself the same question, and many of you have: - Used a code generator - Used a ORM such as Entity Framework - Wrote the code anyway because you like busy work     In most of the cases I've dealt with when making a call to a stored procedure the column names match up with the properties of the object I am hydrating. Sure that isn't always the case, but most of the time it's 1 to 1 mapping.  Given that fact I whipped up the following method of hydrating my objects without having write all of the code. First I'll show the code, and then explain what it is doing.      /// <summary>     /// Abstract base class for all Shared objects.     /// </summary>     /// <typeparam name="T"></typeparam>     [Serializable, DataContract(Name = "{0}SharedBase")]     public abstract class SharedBase<T> where T : SharedBase<T>     {         private static List<PropertyInfo> cachedProperties;         /// <summary>         /// Hydrates derived class with values from record.         /// </summary>         /// <param name="dataRecord"></param>         /// <param name="instance"></param>         public static void Hydrate(IDataRecord dataRecord, T instance)         {             var instanceType = instance.GetType();                         //Caching properties to avoid repeated calls to GetProperties.             //Noticable performance gains when processing same types repeatedly.             if (cachedProperties == null)             {                 cachedProperties = instanceType.GetProperties().ToList();             }                         foreach (var property in cachedProperties)             {                 if (!dataRecord.ColumnExists(property.Name)) continue;                 var ordinal = dataRecord.GetOrdinal(property.Name);                 var isNullable = property.PropertyType.IsGenericType &&                                  property.PropertyType.GetGenericTypeDefinition() == typeof (Nullable<>);                 var isNull = dataRecord.IsDBNull(ordinal);                 var propertyType = property.PropertyType;                 if (isNullable)                 {                     if (!string.IsNullOrEmpty(propertyType.FullName))                     {                         var nullableType = Type.GetType(propertyType.FullName);                         propertyType = nullableType != null ? nullableType.GetGenericArguments()[0] : propertyType;                     }                 }                 switch (Type.GetTypeCode(propertyType))                 {                     case TypeCode.Int32:                         property.SetValue(instance,                                           (isNullable && isNull) ? (int?) null : dataRecord.GetInt32(ordinal), null);                         break;                     case TypeCode.Double:                         property.SetValue(instance,                                           (isNullable && isNull) ? (double?) null : dataRecord.GetDouble(ordinal),                                           null);                         break;                     case TypeCode.Boolean:                         property.SetValue(instance,                                           (isNullable && isNull) ? (bool?) null : dataRecord.GetBoolean(ordinal),                                           null);                         break;                     case TypeCode.String:                         property.SetValue(instance, (isNullable && isNull) ? null : isNull ? null : dataRecord.GetString(ordinal),                                           null);                         break;                     case TypeCode.Int16:                         property.SetValue(instance,                                           (isNullable && isNull) ? (int?) null : dataRecord.GetInt16(ordinal), null);                         break;                     case TypeCode.DateTime:                         property.SetValue(instance,                                           (isNullable && isNull)                                               ? (DateTime?) null                                               : dataRecord.GetDateTime(ordinal), null);                         break;                 }             }         }     }   Here is a class which utilizes the above: [Serializable] [DataContract] public class foo : SharedBase<foo> {     [DataMember]     public int? ID { get; set; }     [DataMember]     public string Name { get; set; }     [DataMember]     public string Description { get; set; }     [DataMember]     public string Subject { get; set; }     [DataMember]     public string Body { get; set; }            public foo(IDataRecord record)     {         Hydrate(record, this);                }     public foo() {} }   Explanation: - Class foo inherits from SharedBase specifying itself as the type. (NOTE SharedBase is abstract here in the event we want to provide additional methods which could be overridden by the instance class) public class foo : SharedBase<foo> - One of the foo class constructors accepts a data record which then calls the Hydrate method on SharedBase passing in the record and itself. public foo(IDataRecord record) {      Hydrate(record, this); } - Hydrate method on SharedBase will use reflection on the object passed in to determine its properties. At the same time, it will effectively cache these properties to avoid repeated expensive reflection calls public static void Hydrate(IDataRecord dataRecord, T instance) {      var instanceType = instance.GetType();      //Caching properties to avoid repeated calls to GetProperties.      //Noticable performance gains when processing same types repeatedly.      if (cachedProperties == null)      {           cachedProperties = instanceType.GetProperties().ToList();      } . . . - Hydrate method on SharedBase will iterate each property on the object and determine if a column with matching name exists in data record foreach (var property in cachedProperties) {      if (!dataRecord.ColumnExists(property.Name)) continue;      var ordinal = dataRecord.GetOrdinal(property.Name); . . . NOTE: ColumnExists is an extension method I put on IDataRecord which I’ll include at the end of this post. - Hydrate method will determine if the property is nullable and whether the value in the corresponding column of the data record has a null value var isNullable = property.PropertyType.IsGenericType && property.PropertyType.GetGenericTypeDefinition() == typeof (Nullable<>); var isNull = dataRecord.IsDBNull(ordinal); var propertyType = property.PropertyType; . . .  - If Hydrate method determines the property is nullable it will determine the underlying type and set propertyType accordingly - Hydrate method will set the value of the property based upon the propertyType   That’s it!!!   The magic here is in a few places. First, you may have noticed the following: public abstract class SharedBase<T> where T : SharedBase<T> This says that SharedBase can be created with any type and that for each type it will have it’s own instance. This is important because of the static members within SharedBase. We want this behavior because we are caching the properties for each type. If we did not handle things in this way only 1 type could be cached at a time, or, we’d need to create a collection that allows us to cache the properties for each type = not very elegant.   Second, in the constructor for foo you may have noticed this (literally): public foo(IDataRecord record) {      Hydrate(record, this); } I wanted the code for auto-hydrating to be as simple as possible. At first I wasn’t quite sure how I could call Hydrate on SharedBase within an instance of the class and pass in the instance itself. Fortunately simply passing in “this” does the trick. I wasn’t sure it would work until I tried it out, and fortunately it did.   So, to actually use this feature when utilizing ADO.NET you’d do something like the following:        public List<foo> GetFoo(int? fooId)         {             List<foo> fooList;             const string uspName = "usp_GetFoo";             using (var conn = new SqlConnection(_dbConnection))             using (var cmd = new SqlCommand(uspName, conn))             {                 cmd.CommandType = CommandType.StoredProcedure;                 cmd.Parameters.Add(new SqlParameter("@FooID", SqlDbType.Int)                                        {Direction = ParameterDirection.Input, Value = fooId});                 conn.Open();                 using (var dr = cmd.ExecuteReader())                 {                     fooList= (from row in dr.Cast<DbDataRecord>()                                             select                                                 new foo(row)                                            ).ToList();                 }             }             return fooList;         }   Nice! Instead of having line after line manually assigning values from data record to an object you simply create a new instance and pass in the data record. Note that there are certainly instances where columns returned from stored procedure do not always match up with property names. In this scenario you can still use the above method and simply do your manual assignments afterward.

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• CodePlex Daily Summary for Saturday, September 15, 2012

  CodePlex Daily Summary for Saturday, September 15, 2012Popular ReleasesMCEBuddy 2.x: MCEBuddy 2.2.15: Changelog for 2.2.15 (32bit and 64bit) 1. Added support for %originalfilepath% to get the source file full path. Used for custom commands only. 2. Added support for better parsing of Media Portal XML files to extract ShowName and Episode Name and download additional details from TVDB (like Season No, Episode No etc). 3. Added support for TVDB seriesID in metadata 4. Added support for eMail non blocking UI testCrashReporter.NET : Exception reporting library for C# and VB.NET: CrashReporter.NET 1.2: *Added html mail format which shows hierarchical exception report for better understanding.VCC: Latest build, v2.3.00914.0: Automatic drop of latest buildScarlet Road: Scarlet Road Test Build 007: Playable game. Includes source.DotNetNuke Search Engine Sitemaps Provider: Version 02.00.00: New release of the Search Engine Sitemap Providers New version - not backwards compatible with 1.x versions New sandboxing to prevent exceptions in module providers interfering with main provider Now installable using the Host->Extensions page New sitemaps available for Active Forums and Ventrian Property Agent Now derived from DotNetNuke Provider base for better framework integration DotNetNuke minimum compatibility raised to DNN 5.2, .NET to 3.5PDF Viewer Web part: PDF Viewer Web Part: PDF Viewer Web PartChris on SharePoint Solutions: View Grid Banding - v1.0: Initial release of the View Creation and Management Page Column Selector Banding solution.$linq - A Javascript LINQ library: Version 1.0: Version 1.0 Initial releasePowerConverter: PowerConverter Beta: This is the first release of PowerConverter. Allows for converting PE code to Power code.NetView Control for Microsoft Access: DevVersion 19852 - More Databinding and Resizing: NetView Renamed event GotFocus to Clicked Added events Clicked/DoubleClicked Added event BackgroundDoubleClicked Changed nomenclature for world coordinates to (Position1, Position2)|Extent1xExtent2 Renamed Locked -> Readonly Added properties Minimum1/Maximum1 and Minimum2/Maximum2 Removed NetView.DeviceDefinitionArea, obsolete properties Support for resizing Added properties BackColor and BorderColor NetView Properties form added binding field for BusinessId propagate erro...Runtime Dynamic Data Model Builder: Main Library Version 1.0.0.0: Main Library Version 1.0.0.0Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.67: Fix issue #18629 - incorrectly handling null characters in string literals and not throwing an error when outside string literals. update for Issue #18600 - forgot to make the ///#DEBUG= directive also set a known-global for the given debug namespace. removed the kill-switch for disregarding preprocessor define-comments (///#IF and the like) and created a separate CodeSettings.IgnorePreprocessorDefines property for those who really need to turn that off. Some people had been setting -kil...Lakana - WPF Framework: Lakana V2: Lakana V2 contains : - Lakana WPF Forms (with sample project) - Lakana WPF Navigation (with sample project)Microsoft SQL Server Product Samples: Database: OData QueryFeed workflow activity: The OData QueryFeed sample activity shows how to create a workflow activity that consumes an OData resource, and renders entity properties in a Microsoft Excel 2010 worksheet or Microsoft Word 2010 document. Using the sample QueryFeed activity, you can consume any OData resource. The sample activity uses LINQ to project OData metadata into activity designer expression items. By setting activity expressions, a fully qualified OData query string is constructed consisting of Resource, Filter, Or...Arduino for Visual Studio: Arduino 1.x for Visual Studio 2012, 2010 and 2008: Register for the visualmicro.com forum for more news and updates Version 1209.10 includes support for VS2012 and minor fixes for the Arduino debugger beta test team. Version 1208.19 is considered stable for visual studio 2010 and 2008. If you are upgrading from an older release of Visual Micro and encounter a problem then uninstall "Visual Micro for Arduino" using "Control Panel>Add and Remove Programs" and then run the install again. Key Features of 1209.10 Support for Visual Studio 2...Social Network Importer for NodeXL: SocialNetImporter(v.1.5): This new version includes: - Fixed the "resource limit" bug caused by Facebook - Bug fixes To use the new graph data provider, do the following: Unzip the Zip file into the "PlugIns" folder that can be found in the NodeXL installation folder (i.e "C:\Program Files\Social Media Research Foundation\NodeXL Excel Template\PlugIns") Open NodeXL template and you can access the new importer from the "Import" menuAcDown????? - AcDown Downloader Framework: AcDown????? v4.1: ??●AcDown??????????、??、??、???????。????，????，?????????????????????????。???????????Acfun、????(Bilibili)、??、??、YouTube、??、???、??????、SF????、????????????。 ●??????AcPlay?????，??????、????????????????。 ● AcDown??????????????????，????????????????????????????。 ● AcDown???????C#??，????.NET Framework 2.0??。?????"Acfun?????"。 ????32??64? Windows XP/Vista/7/8 ???? 32??64? ???Linux ????(1)????????Windows XP???,?????????.NET Framework 2.0???(x86)，?????"?????????"??? (2)???????????Linux???，????????Mono?? ??...Move Mouse: Move Mouse 2.5.2: FIXED - Minor fixes and improvements.MVC Controls Toolkit: Mvc Controls Toolkit 2.3: Added The new release is compatible with Mvc4 RTM. Support for handling Time Zones in dates. Specifically added helper methods to convert to UTC or local time all DateTimes contained in a model received by a controller, and helper methods to handle date only fileds. This together with a detailed documentation on how TimeZones are handled in all situations by the Asp.net Mvc framework, will contribute to mitigate the nightmare of dates and timezones. Multiple Templates, and more options to...DNN Metro7 style Skin package: Metro7 style Skin for DotNetNuke 06.02.00: Maintenance Release Changes on Metro7 06.02.00 Fixed width and height on the jQuery popup for the Editor. Navigation Provider changed to DDR menu Added menu files and scripts Changed skins to Doctype HTML Changed manifest to dnn6 manifest file Changed License to HTML view Fixed issue on Metro7/PinkTitle.ascx with double registering of the Actions Changed source folder structure and start folder, so the project works with the default DNN structure on developing Added VS 20...New ProjectsBizTalk Zombie Management: A powerful tool to handle zombie. As a service you can monitor all zombie instance and process them. For the moment only file is supporting.bxkw8: oooooooooooh long johnsonCellularSolver: The main idea of a this project - create cellular automation (CA) simulation system. We try to reduce ODE/PDE/Integral Equations models to CA-modelEAWebService: EAWebService is web service that executes parallel evolutionary algorithm. Finite Element Method Samples with C#: Finite Element Method Samples with C# Game Jolt C# Trophy API: The Game Jolt Trophy API provides dotNET developers with access to the Game Jolt services including Trophies, High Scores, Data Storage and many more.GNSystem: GNSystem is a simple (yet, no so elegant) Web-Application which contains a Forum system and a CMS\Blog system. GNSystem is written in ASP.Net MVC 4 using C#Hospital Management System (HMS): HMS is a software basically working to make the hospital management much easier and fasterInfinity - WPF.MVC: Framework for WPF/SL/WinFormsKindle: Kindle PublisherMetroCash: A personal finance management programmetroCIS: metroCIS - Eine open-source Anwendung für Windows8 Verwalte dein Studium an der FH Technikum Wien mit dieser App und erleichter dir damit dein Studentenleben.MTAC: MTAC, for My Tfs Administration Center, is a centralized administration tool for TFSMyStart: Create an Open Source implementation of the Windows Start Menu (based initially on Windows 7), to be used on Windows 8.NLite Data Framework: NLite Linq ORM frameworkPDF Viewer Web part: Here now presenting PDF Viewer web part solution with code. Project91405: dfgfdgfdrProject91407: awqwqProject91407M: 111Purchasesales(??????): a simple Sales Manage Project.QueryOver Specification: A simple implementation of the Specification Pattern using NHibernate QueryOver.Shopping Analytics: Esta aplicacion muestra como aprovechar diversas caracteristicas de la plataforma Windows Phone.simbo: Simbo is a simple, fun app for sharing small notes with friends where many of the concepts in your note can be represented by a symbols.SISLOG: El sistema de logística SISLOG es un software que cual será capaz de automatizar y optimizar los procesos que se llevan a cabo en el área de logística.SQL Server Scripts - A RSSUG CodePlex Project: The SQL Server Scripts project is dedicated to supplying high quality scripts to help with the maintenance and development of SQL Server in every environment.Talqum.League: Talqum.League is a League organisator and statistics app.The Pratoriate Foundation: used for all software dev projects for the non profit Pratoriate Foundation.

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• Are XML Comments Necessary Documentation?

  - by Bob Horn

  I used to be a fan of requiring XML comments for documentation. I've since changed my mind for two main reasons: Like good code, methods should be self-explanatory. In practice, most XML comments are useless noise that provide no additional value. Many times we simply use GhostDoc to generate generic comments, and this is what I mean by useless noise: /// <summary> /// Gets or sets the unit of measure. /// </summary> /// <value> /// The unit of measure. /// </value> public string UnitOfMeasure { get; set; } To me, that's obvious. Having said that, if there were special instructions to include, then we should absolutely use XML comments. I like this excerpt from this article: Sometimes, you will need to write comments. But, it should be the exception not the rule. Comments should only be used when they are expressing something that cannot be expressed in code. If you want to write elegant code, strive to eliminate comments and instead write self-documenting code. Am I wrong to think we should only be using XML comments when the code isn't enough to explain itself on its own? I believe this is a good example where XML comments make pretty code look ugly. It takes a class like this... public class RawMaterialLabel : EntityBase { public long Id { get; set; } public string ManufacturerId { get; set; } public string PartNumber { get; set; } public string Quantity { get; set; } public string UnitOfMeasure { get; set; } public string LotNumber { get; set; } public string SublotNumber { get; set; } public int LabelSerialNumber { get; set; } public string PurchaseOrderNumber { get; set; } public string PurchaseOrderLineNumber { get; set; } public DateTime ManufacturingDate { get; set; } public string LastModifiedUser { get; set; } public DateTime LastModifiedTime { get; set; } public Binary VersionNumber { get; set; } public ICollection<LotEquipmentScan> LotEquipmentScans { get; private set; } } ... And turns it into this: /// <summary> /// Container for properties of a raw material label /// </summary> public class RawMaterialLabel : EntityBase { /// <summary> /// Gets or sets the id. /// </summary> /// <value> /// The id. /// </value> public long Id { get; set; } /// <summary> /// Gets or sets the manufacturer id. /// </summary> /// <value> /// The manufacturer id. /// </value> public string ManufacturerId { get; set; } /// <summary> /// Gets or sets the part number. /// </summary> /// <value> /// The part number. /// </value> public string PartNumber { get; set; } /// <summary> /// Gets or sets the quantity. /// </summary> /// <value> /// The quantity. /// </value> public string Quantity { get; set; } /// <summary> /// Gets or sets the unit of measure. /// </summary> /// <value> /// The unit of measure. /// </value> public string UnitOfMeasure { get; set; } /// <summary> /// Gets or sets the lot number. /// </summary> /// <value> /// The lot number. /// </value> public string LotNumber { get; set; } /// <summary> /// Gets or sets the sublot number. /// </summary> /// <value> /// The sublot number. /// </value> public string SublotNumber { get; set; } /// <summary> /// Gets or sets the label serial number. /// </summary> /// <value> /// The label serial number. /// </value> public int LabelSerialNumber { get; set; } /// <summary> /// Gets or sets the purchase order number. /// </summary> /// <value> /// The purchase order number. /// </value> public string PurchaseOrderNumber { get; set; } /// <summary> /// Gets or sets the purchase order line number. /// </summary> /// <value> /// The purchase order line number. /// </value> public string PurchaseOrderLineNumber { get; set; } /// <summary> /// Gets or sets the manufacturing date. /// </summary> /// <value> /// The manufacturing date. /// </value> public DateTime ManufacturingDate { get; set; } /// <summary> /// Gets or sets the last modified user. /// </summary> /// <value> /// The last modified user. /// </value> public string LastModifiedUser { get; set; } /// <summary> /// Gets or sets the last modified time. /// </summary> /// <value> /// The last modified time. /// </value> public DateTime LastModifiedTime { get; set; } /// <summary> /// Gets or sets the version number. /// </summary> /// <value> /// The version number. /// </value> public Binary VersionNumber { get; set; } /// <summary> /// Gets the lot equipment scans. /// </summary> /// <value> /// The lot equipment scans. /// </value> public ICollection<LotEquipmentScan> LotEquipmentScans { get; private set; } }

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• Unnecessary Java context switches

  - by Paul Morrison

  I have a network of Java Threads (Flow-Based Programming) communicating via fixed-capacity channels - running under WindowsXP. What we expected, based on our experience with "green" threads (non-preemptive), would be that threads would switch context less often (thus reducing CPU time) if the channels were made bigger. However, we found that increasing channel size does not make any difference to the run time. What seems to be happening is that Java decides to switch threads even though channels aren't full or empty (i.e. even though a thread doesn't have to suspend), which costs CPU time for no apparent advantage. Also changing Thread priorities doesn't make any observable difference. My question is whether there is some way of persuading Java not to make unnecessary context switches, but hold off switching until it is really necessary to switch threads - is there some way of changing Java's dispatching logic? Or is it reacting to something I didn't pay attention to?! Or are there other asynchronism mechanisms, e.g. Thread factories, Runnable(s), maybe even daemons (!). The answer appears to be non-obvious, as so far none of my correspondents has come up with an answer (including most recently two CS profs). Or maybe I'm missing something that's so obvious that people can't imagine my not knowing it... I've added the send and receive code here - not very elegant, but it seems to work...;-) In case you are wondering, I thought the goLock logic in 'send' might be causing the problem, but removing it temporarily didn't make any difference. I have added the code for send and receive... public synchronized Packet receive() { if (isDrained()) { return null; } while (isEmpty()) { try { wait(); } catch (InterruptedException e) { close(); return null; } if (isDrained()) { return null; } } if (isDrained()) { return null; } if (isFull()) { notifyAll(); // notify other components waiting to send } Packet packet = array[receivePtr]; array[receivePtr] = null; receivePtr = (receivePtr + 1) % array.length; //notifyAll(); // only needed if it was full usedSlots--; packet.setOwner(receiver); if (null == packet.getContent()) { traceFuncs("Received null packet"); } else { traceFuncs("Received: " + packet.toString()); } return packet; } synchronized boolean send(final Packet packet, final OutputPort op) { sender = op.sender; if (isClosed()) { return false; } while (isFull()) { try { wait(); } catch (InterruptedException e) { indicateOneSenderClosed(); return false; } sender = op.sender; } if (isClosed()) { return false; } try { receiver.goLock.lockInterruptibly(); } catch (InterruptedException ex) { return false; } try { packet.clearOwner(); array[sendPtr] = packet; sendPtr = (sendPtr + 1) % array.length; usedSlots++; // move this to here if (receiver.getStatus() == StatusValues.DORMANT || receiver.getStatus() == StatusValues.NOT_STARTED) { receiver.activate(); // start or wake up if necessary } else { notifyAll(); // notify receiver // other components waiting to send to this connection may also get // notified, // but this is handled by while statement } sender = null; Component.network.active = true; } finally { receiver.goLock.unlock(); } return true; }

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• Isn't it better to use a single try catch instead of tons of TryParsing and other error handling sometimes?

  - by Ryan Peschel

  I know people say it's bad to use exceptions for flow control and to only use exceptions for exceptional situations, but sometimes isn't it just cleaner and more elegant to wrap the entire block in a try-catch? For example, let's say I have a dialog window with a TextBox where the user can type input in to be parsed in a key-value sort of manner. This situation is not as contrived as you might think because I've inherited code that has to handle this exact situation (albeit not with farm animals). Consider this wall of code: class Animals { public int catA, catB; public float dogA, dogB; public int mouseA, mouseB, mouseC; public double cow; } class Program { static void Main(string[] args) { string input = "Sets all the farm animals CAT 3 5 DOG 21.3 5.23 MOUSE 1 0 1 COW 12.25"; string[] splitInput = input.Split(' '); string[] animals = { "CAT", "DOG", "MOUSE", "COW", "CHICKEN", "GOOSE", "HEN", "BUNNY" }; Animals animal = new Animals(); for (int i = 0; i < splitInput.Length; i++) { string token = splitInput[i]; if (animals.Contains(token)) { switch (token) { case "CAT": animal.catA = int.Parse(splitInput[i + 1]); animal.catB = int.Parse(splitInput[i + 2]); break; case "DOG": animal.dogA = float.Parse(splitInput[i + 1]); animal.dogB = float.Parse(splitInput[i + 2]); break; case "MOUSE": animal.mouseA = int.Parse(splitInput[i + 1]); animal.mouseB = int.Parse(splitInput[i + 2]); animal.mouseC = int.Parse(splitInput[i + 3]); break; case "COW": animal.cow = double.Parse(splitInput[i + 1]); break; } } } } } In actuality there are a lot more farm animals and more handling than that. A lot of things can go wrong though. The user could enter in the wrong number of parameters. The user can enter the input in an incorrect format. The user could specify numbers too large or too small for the data type to handle. All these different errors could be handled without exceptions through the use of TryParse, checking how many parameters the user tried to use for a specific animal, checking if the parameter is too large or too small for the data type (because TryParse just returns 0), but every one should result in the same thing: A MessageBox appearing telling the user that the inputted data is invalid and to fix it. My boss doesn't want different message boxes for different errors. So instead of doing all that, why not just wrap the block in a try-catch and in the catch statement just display that error message box and let the user try again? Maybe this isn't the best example but think of any other scenario where there would otherwise be tons of error handling that could be substituted for a single try-catch. Is that not the better solution?

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• Advice on Factory Method

  - by heath

  Using php 5.2, I'm trying to use a factory to return a service to the controller. My request uri would be of the format www.mydomain.com/service/method/param1/param2/etc. My controller would then call a service factory using the token sent in the uri. From what I've seen, there are two main routes I could go with my factory. Single method: class ServiceFactory { public static function getInstance($token) { switch($token) { case 'location': return new StaticPageTemplateService('location'); break; case 'product': return new DynamicPageTemplateService('product'); break; case 'user' return new UserService(); break; default: return new StaticPageTemplateService($token); } } } or multiple methods: class ServiceFactory { public static function getLocationService() { return new StaticPageTemplateService('location'); } public static function getProductService() { return new DynamicPageTemplateService('product'); } public static function getUserService() { return new UserService(); } public static function getDefaultService($token) { return new StaticPageTemplateService($token); } } So, given this, I will have a handful of generic services in which I will pass that token (for example, StaticPageTemplateService and DynamicPageTemplateService) that will probably implement another factory method just like this to grab templates, domain objects, etc. And some that will be specific services (for example, UserService) which will be 1:1 to that token and not reused. So, this seems to be an ok approach (please give suggestions if it is not) for a small amount of services. But what about when, over time and my site grows, I end up with 100s of possibilities. This no longer seems like a good approach. Am I just way off to begin with or is there another design pattern that would be a better fit? Thanks. UPDATE: @JSprang - the token is actually sent in the uri like mydomain.com/location would want a service specific to loction and mydomain.com/news would want a service specific to news. Now, for a lot of these, the service will be generic. For instance, a lot of pages will call a StaticTemplatePageService in which the token is passed in to the service. That service in turn will grab the "location" template or "links" template and just spit it back out. Some will need DynamicTemplatePageService in which the token gets passed in, like "news" and that service will grab a NewsDomainObject, determine how to present it and spit that back out. Others, like "user" will be specific to a UserService in which it will have methods like Login, Logout, etc. So basically, the token will be used to determine which service is needed AND if it is generic service, that token will be passed to that service. Maybe token isn't the correct terminology but I hope you get the purpose. I wanted to use the factory so I can easily swap out which Service I need in case my needs change. I just worry that after the site grows larger (both pages and functionality) that the factory will become rather bloated. But I'm starting to feel like I just can't get away from storing the mappings in an array (like Stephen's solution). That just doesn't feel OOP to me and I was hoping to find something more elegant.

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• Typesafe fire-and-forget asynchronous delegate invocation in C#

  - by LBushkin

  I recently found myself needing a typesafe "fire-and-forget" mechanism for running code asynchronously. Ideally, what I would want to do is something like: var myAction = (Action)(() => Console.WriteLine("yada yada")); myAction.FireAndForget(); // async invocation Unfortunately, the obvious choice of calling BeginInvoke() without a corresponding EndInvoke() does not work - it results in a slow resource leak (since the asyn state is held by the runtime and never released ... it's expecting an eventual call to EndInvoke(). I also can't run the code on the .NET thread pool because it may take a very long time to complete (it's advised to only run relatively short-lived code on the thread pool) - this makes it impossible to use the ThreadPool.QueueUserWorkItem(). Initially, I only needed this behavior for methods whose signature matches Action, Action<...>, or Func<...>. So I put together a set of extension methods (see listing below) that let me do this without running into the resource leak. There are overloads for each version of Action/Func. Unfortunately, I now want to port this code to .NET 4 where the number of generic parameters on Action and Func have been increased substantially. Before I write a T4 script to generate these, I was also hoping to find a simpler more elegant way to do this. Any ideas are welcome. public static class AsyncExt { public static void FireAndForget( this Action action ) { action.BeginInvoke(OnActionCompleted, action); } public static void FireAndForget<T1>( this Action<T1> action, T1 arg1 ) { action.BeginInvoke(arg1, OnActionCompleted<T1>, action); } public static void FireAndForget<T1,T2>( this Action<T1,T2> action, T1 arg1, T2 arg2 ) { action.BeginInvoke(arg1, arg2, OnActionCompleted<T1, T2>, action); } public static void FireAndForget<TResult>(this Func<TResult> func, TResult arg1) { func.BeginInvoke(OnFuncCompleted<TResult>, func); } public static void FireAndForget<T1,TResult>(this Func<T1, TResult> action, T1 arg1) { action.BeginInvoke(arg1, OnFuncCompleted<T1,TResult>, action); } // more overloads of FireAndForget<..>() for Action<..> and Func<..> private static void OnActionCompleted( IAsyncResult result ) { var action = (Action)result.AsyncState; action.EndInvoke(result); } private static void OnActionCompleted<T1>( IAsyncResult result ) { var action = (Action<T1>)result.AsyncState; action.EndInvoke( result ); } private static void OnActionCompleted<T1,T2>(IAsyncResult result) { var action = (Action<T1,T2>)result.AsyncState; action.EndInvoke(result); } private static void OnFuncCompleted<TResult>( IAsyncResult result ) { var func = (Func<TResult>)result.AsyncState; func.EndInvoke( result ); } private static void OnFuncCompleted<T1,TResult>(IAsyncResult result) { var func = (Func<T1, TResult>)result.AsyncState; func.EndInvoke(result); } // more overloads of OnActionCompleted<> and OnFuncCompleted<> }

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• How to best propagate changes upwards a hierarchical structure for binding?

  - by H.B.

  If i have a folder-like structure that uses the composite design pattern and i bind the root folder to a TreeView. It would be quite useful if i can display certain properties that are being accumulated from the folder's contents. The question is, how do i best inform the folder that changes occurred in a child-element so that the accumulative properties get updated? The context in which i need this is a small RSS-FeedReader i am trying to make. This are the most important objects and aspects of my model: Composite interface: public interface IFeedComposite : INotifyPropertyChanged { string Title { get; set; } int UnreadFeedItemsCount { get; } ObservableCollection<FeedItem> FeedItems { get; } } FeedComposite (aka Folder) public class FeedComposite : BindableObject, IFeedComposite { private string title = ""; public string Title { get { return title; } set { title = value; NotifyPropertyChanged("Title"); } } private ObservableCollection<IFeedComposite> children = new ObservableCollection<IFeedComposite>(); public ObservableCollection<IFeedComposite> Children { get { return children; } set { children.Clear(); foreach (IFeedComposite item in value) { children.Add(item); } NotifyPropertyChanged("Children"); } } public FeedComposite() { } public FeedComposite(string title) { Title = title; } public ObservableCollection<FeedItem> FeedItems { get { ObservableCollection<FeedItem> feedItems = new ObservableCollection<FeedItem>(); foreach (IFeedComposite child in Children) { foreach (FeedItem item in child.FeedItems) { feedItems.Add(item); } } return feedItems; } } public int UnreadFeedItemsCount { get { return (from i in FeedItems where i.IsUnread select i).Count(); } } Feed: public class Feed : BindableObject, IFeedComposite { private string url = ""; public string Url { get { return url; } set { url = value; NotifyPropertyChanged("Url"); } } ... private ObservableCollection<FeedItem> feedItems = new ObservableCollection<FeedItem>(); public ObservableCollection<FeedItem> FeedItems { get { return feedItems; } set { feedItems.Clear(); foreach (FeedItem item in value) { AddFeedItem(item); } NotifyPropertyChanged("Items"); } } public int UnreadFeedItemsCount { get { return (from i in FeedItems where i.IsUnread select i).Count(); } } public Feed() { } public Feed(string url) { Url = url; } Ok, so here's the thing, if i bind a TextBlock.Text to the UnreadFeedItemsCount there won't be simple notifications when an item is marked unread, so one of my approaches has been to handle the PropertyChanged event of every FeedItem and if the IsUnread-Property is changed i have my Feed make a notification that the property UnreadFeedItemsCount has been changed. With this approach i also need to handle all PropertyChanged events of all Feeds and FeedComposites in Children of FeedComposite, from the sound of it, it should be obvious that this is not such a very good idea, you need to be very careful that items never get added or removed to any collection without having attached the PropertyChanged event handler first and things like that. Also: What do i do with the CollectionChanged-Events which necessarily also cause a change in the sum of the unread items count? Sounds like more event handling fun. It is such a mess, it would be great if anyone has an elegant solution to this since i don't want the feed-reader to end up as awful as my first attempt years ago when i didn't even know about DataBinding...

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• ZF: Form array field - how to display values in the view correctly

  - by Wojciech Fracz

  Let's say I have a Zend_Form form that has a few text fields, e.g: $form = new Zend_Form(); $form->addElement('text', 'name', array( 'required' => true, 'isArray' => true, 'filters' => array( /* ... */ ), 'validators' => array( /* ... */ ), )); $form->addElement('text', 'surname', array( 'required' => true, 'isArray' => true, 'filters' => array( /* ... */ ), 'validators' => array( /* ... */ ), )); After rendering it I have following HTML markup (simplified): <div id="people"> <div class="person"> <input type="text" name="name[]" /> <input type="text" name="surname[]" /> </div> </div> Now I want to have the ability to add as many people as I want. I create a "+" button that in Javascript appends next div.person to the container. Before I submit the form, I have for example 5 names and 5 surnames, posted to the server as arrays. Everything is fine unless somebody puts the value in the field that does not validate. Then the whole form validation fails and when I want to display the form again (with errors) I see the PHP Warning: htmlspecialchars() expects parameter 1 to be string, array given Which is more or less described in ticket: http://framework.zend.com/issues/browse/ZF-8112 However, I came up with a not-very-elegant solution. What I wanted to achieve: have all fields and values rendered again in the view have error messages only next to the fields that contained bad values Here is my solution (view script): <div id="people"> <?php $names = $form->name->getValue(); // will have an array here if the form were submitted $surnames= $form->surname->getValue(); // only if the form were submitted we need to validate fields' values // and display errors next to them; otherwise when user enter the page // and render the form for the first time - he would see Required validator // errors $needsValidation = is_array($names) || is_array($surnames); // print empty fields when the form is displayed the first time if(!is_array($names))$names= array(''); if(!is_array($surnames))$surnames= array(''); // display all fields! foreach($names as $index => $name): $surname = $surnames[$index]; // validate value if needed if($needsValidation){ $form->name->isValid($name); $form->surname->isValid($surname); } ?> <div class="person"> <?=$form->name->setValue($name); // display field with error if did not pass the validation ?> <?=$form->surname->setValue($surname);?> </div> <?php endforeach; ?> </div> The code work, but I want to know if there is an appropriate, more comfortable way to do this? I often hit this problem when there is a need for a more dynamic - multivalue forms and have not find better solution for a long time.

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• Stumbling Through: Visual Studio 2010 (Part III)

  The last post ended with us just getting started on stumbling into text template file customization, a task that required a Visual Studio extension (Tangible T4 Editor) to even have a chance at completing.  Despite the benefits of the Tangible T4 Editor, I still had a hard time putting together a solid text template that would be easy to explain.  This is mostly due to the way the files allow you to mix code (encapsulated in <# #>) with straight-up text to generate.  It is effective to be sure, but not very readable.  Nevertheless, I will try and explain what was accomplished in my custom tt file, though the details of which are not really the point of this article (my way of saying dont criticize my crappy code, and certainly dont use it in any somewhat real application.  You may become dumber just by looking at this code.  You have been warned really the footnote I should put at the end of all of my blog posts). To begin with, there were two basic requirements that I needed the code generator to satisfy:  Reading one to many entity framework files, and using the entities that were found to write one to many class files.  Thankfully, using the Entity Object Generator as a starting point gave us an example on how to do exactly that by using the MetadataLoader and EntityFrameworkTemplateFileManager you include references to these items and use them like so: // Instantiate an entity framework file reader and file writer MetadataLoader loader = new MetadataLoader(this); EntityFrameworkTemplateFileManager fileManager = EntityFrameworkTemplateFileManager.Create(this); // Load the entity model metadata workspace MetadataWorkspace metadataWorkspace = null; bool allMetadataLoaded =loader.TryLoadAllMetadata("MFL.tt", out metadataWorkspace); EdmItemCollection ItemCollection = (EdmItemCollection)metadataWorkspace.GetItemCollection(DataSpace.CSpace); // Create an IO class to contain the 'get' methods for all entities in the model fileManager.StartNewFile("MFL.IO.gen.cs"); Next, we want to be able to loop through all of the entities found in the model, and then each property for each entity so we can generate classes and methods for each.  The code for that is blissfully simple: // Iterate through each entity in the model foreach (EntityType entity in ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name)) {     // Iterate through each primitive property of the entity     foreach (EdmProperty edmProperty in entity.Properties.Where(p => p.TypeUsage.EdmType is PrimitiveType && p.DeclaringType == entity))     {         // TODO:  Create properties     }     // Iterate through each relationship of the entity     foreach (NavigationProperty navProperty in entity.NavigationProperties.Where(np => np.DeclaringType == entity))     {         // TODO:  Create associations     } } There really isnt anything more advanced than that going on in the text template the only thing I had to blunder through was realizing that if you want the generator to interpret a line of code (such as our iterations above), you need to enclose the code in <# and #> while if you want the generator to interpret the VALUE of code, such as putting the entity name into the class name, you need to enclose the code in <#= and #> like so: public partial class <#=entity.Name#> To make a long story short, I did a lot of repetition of the above to come up with a text template that generates a class for each entity based on its properties, and a set of IO methods for each entity based on its relationships.  The two work together to provide lazy-loading for hierarchical data (such getting Team.Players) so it should be pretty intuitive to use on a front-end.  This text template is available here you can tweak the inputFiles array to load one or many different edmx models and generate the basic xml IO and class files, though it will probably only work correctly in the simplest of cases, like our MFL model described in the previous post.  Additionally, there is no validation, logging or error handling which is something I want to handle later by stumbling through the enterprise library 5.0. The code that gets generated isnt anything special, though using the LINQ to XML feature was something very new and exciting for me I had only worked with XML in the past using the DOM or XML Reader objects along with XPath, and the LINQ to XML model is just so much more elegant and supposedly efficient (something to test later).  For example, the following code was generated to create a Player object for each Player node in the XML:         return from element in GetXmlData(_PlayerDataFile).Descendants("Player")             select new Player             {                 Id = int.Parse(element.Attribute("Id").Value)                 ,ParentName = element.Parent.Name.LocalName                 ,ParentId = long.Parse(element.Parent.Attribute("Id").Value)                 ,Name = element.Attribute("Name").Value                 ,PositionId = int.Parse(element.Attribute("PositionId").Value)             }; It is all done in one line of code, no looping needed.  Even though GetXmlData loads the entire xml file just like the old XML DOM approach would have, it is supposed to be much less resource intensive.  I will definitely put that to the test after we develop a user interface for getting at this data.  Speaking of the data where IS the data?  Weve put together a pretty model and a bunch of code around it, but we dont have any data to speak of.  We can certainly drop to our favorite XML editor and crank out some data, but if it doesnt totally match our model, it will not load correctly.  To help with this, Ive built in a method to generate xml at any given layer in the hierarchy.  So for us to get the closest possible thing to real data, wed need to invoke MFL.IO.GenerateTeamXML and save the results to file.  Doing so should get us something that looks like this: <Team Id="0" Name="0">   <Player Id="0" Name="0" PositionId="0">     <Statistic Id="0" PassYards="0" RushYards="0" Year="0" />   </Player> </Team> Sadly, it is missing the Positions node (havent thought of a way to generate lookup xml yet) and the data itself isnt quite realistic (well, as realistic as MFL data can be anyway).  Lets manually remedy that for now to give us a decent starter set of data.  Note that this is TWO xml files Lookups.xml and Teams.xml: <Lookups Id=0>   <Position Id="0" Name="Quarterback"/>   <Position Id="1" Name="Runningback"/> </Lookups> <Teams Id=0>   <Team Id="0" Name="Chicago">     <Player Id="0" Name="QB Bears" PositionId="0">       <Statistic Id="0" PassYards="4000" RushYards="120" Year="2008" />       <Statistic Id="1" PassYards="4200" RushYards="180" Year="2009" />     </Player>     <Player Id="1" Name="RB Bears" PositionId="1">       <Statistic Id="2" PassYards="0" RushYards="800" Year="2007" />       <Statistic Id="3" PassYards="0" RushYards="1200" Year="2008" />       <Statistic Id="4" PassYards="3" RushYards="1450" Year="2009" />     </Player>   </Team> </Teams> Ok, so we have some data, we have a way to read/write that data and we have a friendly way of representing that data.  Now, what remains is the part that I have been looking forward to the most: present the data to the user and give them the ability to add/update/delete, and doing so in a way that is very intuitive (easy) from a development standpoint.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? 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