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• How to design a RESTful collection resource?

  - by Suresh Kumar

  I am trying to design a "collection of items" resource. I need to support the following operations: Create the collection Remove the collection Add a single item to the collection Add multiple items to the collection Remove a single item from the collection Remove multiple items from the collection This is as far as I have gone: Create collection: ==> POST /service Host: www.myserver.com Content-Type: application/xml <collection name="items"> <item href="item1"/> <item href="item2"/> <item href="item3"/> </collection> <== 201 Created Location: http://myserver.com/service/items Content-Type: application/xml ... Remove collection: ==> DELETE /service/items <== 200 OK Removing a single item from the collection: ==> DELETE /service/items/item1 <== 200 OK However, I am finding supporting the other operations a bit tricky i.e. what methods can I use to: Add single or multiple items to the collection. (PUT doesn't seem to be right here as per HTTP 1.1 RFC Remove multiple items from the collection in one transaction. (DELETE doesn't seem to right here either)

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• How to use a int2 database-field as a boolean in Java using JPA/Hibernate

  - by mg

  Hello... I write an application based on an already existing database (postgreSQL) using JPA and Hibernate. There is a int2-column (activeYN) in a table, which is used as a boolean (0 = false (inactive), not 0 = true (active)). In the Java application i want to use this attribute as a boolean. So i defined the attribute like this: @Entity public class ModelClass implements Serializable { /*..... some Code .... */ private boolean active; @Column(name="activeYN") public boolean isActive() { return this.active; } /* .... some other Code ... */ } But there ist an exception because Hibernate expects an boolean database-field and not an int2. Can i do this mapping i any way while using a boolean in java?? I have a possible solution for this, but i don't really like it: My "hacky"-solution is the following: @Entity public class ModelClass implements Serializable { /*..... some Code .... */ private short active_USED_BY_JPA; //short because i need int2 /** * @Deprecated this method is only used by JPA. Use the method isActive() */ @Column(name="activeYN") public short getActive_USED_BY_JPA() { return this.active_USED_BY_JPA; } /** * @Deprecated this method is only used by JPA. * Use the method setActive(boolean active) */ public void setActive_USED_BY_JPA(short active) { this.active_USED_BY_JPA = active; } @Transient //jpa will ignore transient marked methods public boolean isActive() { return getActive_USED_BY_JPA() != 0; } @Transient public void setActive(boolean active) { this.setActive_USED_BY_JPA = active ? -1 : 0; } /* .... some other Code ... */ } Are there any other solutions for this problem? The "hibernate.hbm2ddl.auto"-value in the hibernate configuration is set to "validate". (sorry, my english is not the best, i hope you understand it anyway)..

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• XSL-FO: Static content AND Flow content in Region-Body: Possible?

  - by Peterdk

  I have the following problem: I need to use XSLFO to generate a 2-column multipage document. Problem is: I need to have a vertical line between the 2 columns. Since XSLFO does not seem to specify a option for creating such a divider, I need to manually put it there. I was thinking of using a static rotated blockcontainer with a leader in it. However, it looks like it's not possible to use static-content on the same region as where the flow content comes. <fo:layout-master-set> <fo:simple-page-master page-width="170mm" page-height="222mm" master-name="page" > <fo:region-body region-name="xsl-region-body" margin-top="2mm" margin-bottom="2mm" margin-left="10mm" margin-right="10mm" column-count="2" column-gap="5mm" /> </fo:simple-page-master> </fo:layout-master-set> <fo:page-sequence master-reference="page"> <fo:static-content flow-name="xsl-region-body" ><!-- This gives a error --> <fo:block>test</fo:block> </fo:static-content> <fo:flow flow-name="xsl-region-body"> <xsl:apply-templates/> </fo:flow> </fo:page-sequence> Results in (XEP): [error] Duplicate identifier: flow-name="xsl-region-body". Property 'flow-name' should be unique within 'fo:page-sequence'. Are there any methods to place static content on the main region when also flow content is placed there? Or: Is there a way to define the divider that divides a 2-column layout?

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• DataGridView not displaying a row after it is created

  - by joslinm

  Hi, I'm using Visual Studio 10 and I just created a Database using SQL Server CE. Within it, I made a table CSLDataTable and that automatically created a CSLDataSet & CSLDataTableTableAdapter. The three variables were automatically created in my MainWindow.cs class: cSLDataSet cSLDataTableTableAdapter cSLDataTableBindingSource I have added a DataGridView in my Form called dataGridView and datasource cSLDataTableBindingSource. In my MainWindow(), I tried adding a row as a test: public MainWindow() { InitializeComponent(); CSLDataSet.CSLDataTableRow row = cSLDataSet.CSLDataTable.NewCSLDataTableRow(); row.File_ = "file"; row.Artist = "artist11"; row.Album = "album"; row.Save_Structure = "save"; row.Sent = false; row.Error = true; row.Release_Format = "release"; row.Bit_Rate = "bitrate.."; row.Year = "year"; row.Physical_Format = "format"; row.Bit_Format = "bitformat"; row.File_Path = "File!!path"; row.Site_Origin = "what"; cSLDataSet.CSLDataTable.Rows.Add(row); cSLDataSet.AcceptChanges(); cSLDataTableTableAdapter.Fill(cSLDataSet.CSLDataTable); cSLDataTableTableAdapter.Update(cSLDataSet); dataGridView.Refresh(); dataGridView.Update(); } In regards to the DataSet methods I tried calling, I had been trying to find a "correct" way to interact with the adapter, dataset, and datatable to successfully show the row, but to no avail. I'm rather new to using SQL Server CE Database, and read a lot of the MSDN sites & thought I was on the right track, but I've had no luck. The DataGridView shows the headers correctly, but that new row does not show up.

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• How to use reflection to call a method and pass parameters whose types are unknown at compile time?

  - by MandoMando

  I'd like to call methods of a class dynamically with parameter values that are "parsed" from a string input. For example: I'd like to call the following program with these commands: c:myprog.exe MethodA System.Int32 777 c:myprog.exe MethodA System.float 23.17 c:myprog.exe MethodB System.Int32& 777 c:myprog.exe MethodC System.Int32 777 System.String ThisCanBeDone static void Main(string[] args) { ClassA aa = new ClassA(); System.Type[] types = new Type[args.Length / 2]; object[] ParamArray = new object[types.Length]; for (int i=0; i < types.Length; i++) { types[i] = System.Type.GetType(args[i*2 + 1]); // LINE_X: this will obviously cause runtime error invalid type/casting ParamArray[i] = args[i*2 + 2]; MethodInfo callInfo = aa.GetType().GetMethod(args[0],types); callInfo.Invoke(aa, ParamArray); } // In a non-changeable classlib: public class ClassA { public void MethodA(int i) { Console.Write(i.ToString()); } public void MethodA(float f) { Console.Write(f.ToString()); } public void MethodB(ref int i) { Console.Write(i.ToString()); i++; } public void MethodC(int i, string s) { Console.Write(s + i.ToString()); } public void MethodA(object o) { Console.Write("Argg! Type Trapped!"); } } "LINE_X" in the above code is the sticky part. For one, I have no idea how to assign value to a int or a ref int parameter even after I create it using Activator.CreatInstance or something else. The typeConverter does come to mind, but then that requires an explicit compile type casting as well. Am I looking at CLR with JavaScript glasses or there is way to do this?

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• Method that does conditional return of method calling it?

  - by Mattias Konradsson

  Ok this might be a bit of hack but bear with me :) The background is that i'm tired of methods that that some if-statement to that messes up indention for the whole method, like: public SomeClass DoStuff(string inputStr) { SomeClass result =null; if (IsOpenFilter(inputStr)) { .... } return result; } So I was thinking , wouldn't it be neat if I could do something like this instead: public SomeClass DoStuff(string inputStr) { Require(IsOpenFilter(inputStr),null); .... return result; } The idea is that if the statement does not evaluates to true it would return null. If there wasn't a return type for the method it would simply be: Require(IsOpenFilter(inputStr)); I realize that this is kinda overlapping with code contracts but these would be more like "conditional" or "soft" contracts evaluated at runtime rather than compile time. So I guess there's two questions, can this be done somehow? I'm stumped on how to do a conditional return from calling a method. The other question is, is this a good idea? It's a bit weird to monkeypatch the language like this but I'd rather like the way the code reads. I would be even cleaner if it could be put into an attribute above the method: [Require(IsOpenFilter(inputStr))]

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• What is SSIS order of data transformation component method calls

  - by Ron Ruble

  I am working on a custom data transformation component. I'm using NUnit and NMock2 to test as I code. Testing and getting the custom UI and other features right is a huge pain, in part because I can't find any documentation about the order in which SSIS invokes methods on the component at design time as well as runtime. I can correct the issues readily enough, but it's tedious and time consuming to unregister the old version, register the new version, fire up the test ssis package, try to display the UI, get an obscure error message, backtrace it, modify the component and continue. One of the big issues involves the UI component needing access to the componentmetadata and buffermanager properties of the component at design time, and what I need to provide for to support properties that won't be initialized until after the user enters them in the UI. I can work through it; but if someone knows of some docs or tips that would speed me up, I'd greatly appreciate it. The samples I've found havn't been much use; they seem to be directed to showing off cool stuff (Twitter, weather.com) rather than actual work. Thanks in advance.

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• Retrieving dll version info via Win32 - VerQueryValue(...) crashes under Win7 x64

  - by user256890

  The respected open source .NET wrapper implementation (SharpBITS) of Windows BITS services fails identifying the underlying BITS version under Win7 x64. Here is the source code that fails. NativeMethods are native Win32 calls wrapped by .NET methods and decorated via DllImport attribute. private static BitsVersion GetBitsVersion() { try { string fileName = Path.Combine( System.Environment.SystemDirectory, "qmgr.dll"); int handle = 0; int size = NativeMethods.GetFileVersionInfoSize(fileName, out handle); if (size == 0) return BitsVersion.Bits0_0; byte[] buffer = new byte[size]; if (!NativeMethods.GetFileVersionInfo(fileName, handle, size, buffer)) { return BitsVersion.Bits0_0; } IntPtr subBlock = IntPtr.Zero; uint len = 0; if (!NativeMethods.VerQueryValue(buffer, @"\VarFileInfo\Translation", out subBlock, out len)) { return BitsVersion.Bits0_0; } int block1 = Marshal.ReadInt16(subBlock); int block2 = Marshal.ReadInt16((IntPtr)((int)subBlock + 2 )); string spv = string.Format( @"\StringFileInfo\{0:X4}{1:X4}\ProductVersion", block1, block2); string versionInfo; if (!NativeMethods.VerQueryValue(buffer, spv, out versionInfo, out len)) { return BitsVersion.Bits0_0; } ... The implementation follows the MSDN instructions by the letter. Still during the second VerQueryValue(...) call, the application crashes and kills the debug session without hesitation. Just a little more debug info right before the crash: spv = "\StringFileInfo\040904B0\ProductVersion" buffer = byte[1900] - full with binary data block1 = 1033 block2 = 1200 I looked at the targeted "C:\Windows\System32\qmgr.dll" file (The implementation of BITS) via Windows. It says that the Product Version is 7.5.7600.16385. Instead of crashing, this value should return in the verionInfo string. Any advice?

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• How to exit an if clause

  - by Roman Stolper

  What sorts of methods exist for prematurely exiting an if clause? There are times when I'm writing code and want to put a break statement inside of an if clause, only to remember that those can only be used for loops. Lets take the following code as an example: if some_condition: ... if condition_a: # do something # and then exit the outer if block ... if condition_b: # do something # and then exit the outer if block # more code here I can think of one way to do this: assuming the exit cases happen within nested if statements, wrap the remaining code in a big else block. Example: if some_condition: ... if condition_a: # do something # and then exit the outer if block else: ... if condition_b: # do something # and then exit the outer if block else: # more code here The problem with this is that more exit locations mean more nesting/indented code. Alternatively, I could write my code to have the if clauses be as small as possible and not require any exits. Does anyone know of a good/better way to exit an if clause? If there are any associated else-if and else clauses, I figure that exiting would skip over them.

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• Playing wav files with AudioServices in iPhone

  - by Biranchi

  Hi All, I am trying to play two .wav files in my appllication, but i am only able to play the first wav file , the second file is not at all playing. I have added the AudioToolbox framework. In my .h file i have included the Audiotoolbox.h file and has the following declarations //Beep Sound SystemSoundID soundFileObject; SystemSoundID recycleFileObject; In my .m file i am registering both the wav files as following CFURLRef soundFileURLRef = CFBundleCopyResourceURL (CFBundleGetMainBundle (),CFSTR ("Beep"),CFSTR ("wav"),NULL ); AudioServicesCreateSystemSoundID (soundFileURLRef,&soundFileObject ); CFURLRef soundFileURLRef2 = CFBundleCopyResourceURL (CFBundleGetMainBundle (),CFSTR ("Recycle"),CFSTR ("wav"),NULL ); AudioServicesCreateSystemSoundID (soundFileURLRef2,&recycleFileObject ); And i have written two methods for playing each file individually. -(void)playBeepSound { NSLog(@"Beep sound called : %d", soundFileObject); AudioServicesPlaySystemSound (soundFileObject); } -(void)playRecycleSound { NSLog(@"Recycle sound called : %d", recycleFileObject); AudioServicesPlaySystemSound (recycleFileObject); } But i am only able to play the Beep sound , but not the second sound wav file. What is the error ??? Thanks

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• How can I create object in abstract class without having knowledge of implementation?

  - by Greg

  Hi, Is there a way to implement the "CreateNode" method in my library abstract below? Or can this only be done in client code outside the library? I current get the error "Cannot create an instance of the abstract class or interface 'ToplogyLibrary.AbstractNode" public abstract class AbstractTopology<T> { // Properties public Dictionary<T, AbstractNode<T>> Nodes { get; private set; } public List<AbstractRelationship<T>> Relationships { get; private set; } // Constructors protected AbstractTopology() { Nodes = new Dictionary<T, AbstractNode<T>>(); } // Methods public AbstractNode<T> CreateNode() { var node = new AbstractNode<T>(); // ** Does not work ** Nodes.Add(node.Key, node); } } } public abstract class AbstractNode<T> { public T Key { get; set; } } public abstract class AbstractRelationship<T> { public AbstractNode<T> Parent { get; set; } public AbstractNode<T> Child { get; set; } }

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• Apple's Sample App TopSongs has 26 Leaks, Ugh!

  - by RoLYroLLs

  Hey all, I've been building an app for a client and part of it uses Apple's TopSongs sample app to download data on another thread. I finally got enough done to start testing that part and found 1000 leaks!!! A closer look at the leaks made me check TopSongs for leaks, since none of the my methods were in leaks report. Running TopSongs returned 26 leaks. Not quite sure how to fix them, or if they are part of some library from Apple. I bet you're asking if it has 26, why do you have 1000? Well, I use their sample to make roughly 48 calls to webservices to get all the information needed on initial install (48 calls x 26 leaks = 1248 leaks!!). Later it makes at least 12 calls + 4 to check for updated information on other sections of the app. Can't do a thing about it, can't make one call, or less calls, please don't comment about this part. I seen people respond to posts that aren't necessarily answering the question the user originally posted, which in this case is has anyone tried patching up the leaks, if they are patchable, or is this a bug in Apple's libraries? Thanks so much.

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• GUI toolkit for Unicode text app?

  - by wrp

  In developing a tool for processing text in exotic scripts, I'm having trouble choosing a GUI toolkit. The main part of the interface is to be a text editor, not much more elaborate than Notepad, but with its own input method editor. It is to be extensible in a scripting language so that non-programmers can develop their own input methods and display routines. It will be assumed that all files are UTF-8. More elaborate support like regexes is not needed. The main sticking points are: characters beyond the Basic Multilingual Plane right-to-left and bi-directional text extension in a scripting language cross-platform Linux/Windows/OS X My first choice was Tcl/Tk, but it lacks bidi and going beyond the BMP seems dodgy. At the other extreme, I've considered Qt with embedded ECMAScript, but that might be heavier and less malleable than I would like. I'm even thinking about making it browser based, but I'm concerned that the IM for large scripts would be too heavy for client-side processing. I've also looked at a few similar projects in Java, but the quality of the font rendering in SWING has been unacceptable. What are your experiences in handling Unicode with various toolkits? Are there other serious issues I haven't considered? What would you recommend for doing this in the lightest way?

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• Initial text and paperclipped-URL for action in UIActivityViewController & UIActivityItemSource?

  - by Benjamin Kreeger

  Finally been making it through Apple's (rather dismal) documentation on the new UIActivityViewController class and the UIActivityItemSource protocol, and I'm trying to send different data sets to different actions called from the activity view. To simplify things, I'm looking at two things. A Facebook posting action, which should say "Check this out!" and also attach a URL to the post (with that cute little paperclip). A Twitter posting action, which should say "Check this out, with #hashtag!" and also attach that same URL (with the same paperclip). Here's the code I've got implemented right now. - (id)activityViewController:(UIActivityViewController *)activityViewController itemForActivityType:(NSString *)activityType { if ([activityType isEqualToString:UIActivityTypePostToFacebook]) { return @"Check this out!"; } else if ([activityType isEqualToString:UIActivityTypePostToTwitter]) { return @"Check this out, with #hashtag!"; } return @""; } - (id)activityViewControllerPlaceholderItem:(UIActivityViewController *)activityViewController { return @""; } And then when I set up this activity view controller (it's in the same class), this is what I do. UIActivityViewController *activityView = [[UIActivityViewController alloc] initWithActivityItems:@[self] applicationActivities:nil]; [self presentViewController:activityView animated:YES completion:nil]; My dilemma is how to attach that NSURL object. It's relatively easy when calling the iOS 6 SL-class posting modals; you just call the individual methods to attach a URL or an image. How would I go about doing this here? I'll note that instead of returning NSString objects from -activityViewController:itemForActivityType, if I return just NSURL objects, they show up with that paperclip, with no body text in the post. If I return an array of those two items, nothing shows up at all.

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• How do I improve this design for dealing with intersecting date ranges and resolving date range conf

  - by derdo

  I am working on some code that deals with date ranges. I have pricing activities that have a starting-date and an end-date to set a certain price for that range. There are multiple pricing activities with intersecting date ranges. What I ultimately need is the ability to query valid prices for a date range. I pass in (jan1,jan31) and I get back a list that says jan1--jan10 $4 , jan11--jan19 $3 jan20--jan31 $4. There are priorities between pricing activities. Some type of pricing activities have high priority, so they override other pricing activities and for certain type of pricing activities lowest price wins etc. I currently have a class that holds these pricing activities and keeps a resolved pricing calendar. As I add new pricing activities I update the resolved calendar. As I write more tests/code, it started to get very complicated with all the different cases (pricing activities intersecting in different ways). I am ending up with very complicated code where I am resolving a newly added pricing activity. See AddPricingActivity() method below. Can anybody think of a simpler way to deal with this? Could there be similar code somewhere out there? Public class PricingActivity() { DateTime startDate; DateTime endDate; Double price; Public bool StartsBeforeEndsAfter (PricingActivity pAct) { // pAct covers this pricing activity } Public bool StartsMiddleEndsAfter (PricingActivity pAct){ // early part of pAct Itersects with later part of this pricing activity } //more similar methods to cover all the combinations of intersecting } Public Class PricingActivityList() { List<PricingActivity> activities; SortedDictionary<Date, PricingActivity> resolvedPricingCalendar; Public void AddPricingActivity(PricingActivity pAct) { //update the resolvedCalendar //go over each activity and find intersecting ones //update the resolved calendar correctly //depending on the type of the intersection //this part is getting out of hand….. } }

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• How to handle dates that repeat indefinitely

  - by Addsy

  I am implementing a fairly simple calendar on a website using PHP and MySQL. I want to be able to handle dates that repeat indefinitely and am not sure of the best way to do it. For a time limited repeating event it seems to make sense to just add each event within the timeframe into my db table and group them with some form of recursion id. But when there is no limit to how often the event repeats, is it better to a) put records in the db for a specific time frame (eg the next 2 years) and then periodically check and add new records as time goes by - The problem with this is that if someone is looking 3 years ahead, the event won't show up b) not actually have records for each event but instead when i check in my php code for events within a specified time period, calculate wether a repeated event will occur within this time period - The problem with this is that it means there isn't a specific record for each event which i can see being a pain when i then want to associate other info (attendance etc) with that event. It also seems like it might be a bit slow Has anyone tried either of these methods? If so how did it work out? Or is there some other ingenious crafty method i'm missing?

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• Rhino Mocks and ordered test with unordered calls

  - by Shaddix

  I'm using Rhino.Mocks for testing the system. I'm going to check the order of calling .LoadConfig and .Backup methods. I need .LoadConfig to be the first. Currently the code is like this: var module1 = mocks.Stub<IBackupModule>(); var module2 = mocks.Stub<IBackupModule>(); module1.Expect(x => x.Name).Return("test"); module2.Expect(x => x.Name).Return("test2"); using (mocks.Ordered()) { module1.Expect(x => x.LoadConfig(null)); module2.Expect(x => x.LoadConfig(null)); module1.Expect(x => x.Backup()); module2.Expect(x => x.Backup()); } mocks.ReplayAll(); The problem is, that there's also a call to .Name property, and i'm not interesting when it'll be called: before .LoadConfig or after the .Backup - it just doesn't matter. And when I run this I'm getting Exception: Unordered method call! The expected call is: 'Ordered: { IConfigLoader.LoadConfig(null); }' but was: 'IIdentification.get_Name();' Is there a way to deal with this? Thanks

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• How to remove a status message added by the seam security module?

  - by Joshua

  I would like to show a different status message, when a suspended user tries to login. If the user is active we return true from the authenticate method, if not we add a custom StatusMessage message mentioning that the "User X has been suspended". The underlying Identity authentication also fails and adds a StatusMessage. I tried removing the seam generated statusMessage with the following methods, but it doesn't seem to work and shows me 2 different status messages (my custom message, seam generated). What would be the issue here? StatusMessages statusMessages; statusMessages.clear() statusMessages.clearGlobalMessages() statusMessages.clearKeyedMessages(id) EDIT1: public boolean authenticate() { log.info("Authenticating {0}", identity.getCredentials().getUsername()); String username = identity.getCredentials().getUsername(); String password = identity.getCredentials().getPassword(); // return true if the authentication was // successful, false otherwise try { Query query = entityManager.createNamedQuery("user.by.login.id"); query.setParameter("loginId", username); // only active users can log in query.setParameter("status", "ACTIVE"); currentUser = (User)query.getSingleResult(); } catch (PersistenceException ignore) { // Provide a status message for the locked account statusMessages.clearGlobalMessages(); statusMessages.addFromResourceBundle( "login.account.locked", new Object[] { username }); return false; } IdentityManager identityManager = IdentityManager.instance(); if (!identityManager.authenticate(username, "password")) { return false; } else { log.info("Authenticated user {0} successfully", username); } }

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• How can I create a new Person object correctly in Javascript?

  - by TimDog

  I'm still struggling with this concept. I have two different Person objects, very simply: ;Person1 = (function() { function P (fname, lname) { P.FirstName = fname; P.LastName = lname; return P; } P.FirstName = ''; P.LastName = ''; var prName = 'private'; P.showPrivate = function() { alert(prName); }; return P; })(); ;Person2 = (function() { var prName = 'private'; this.FirstName = ''; this.LastName = ''; this.showPrivate = function() { alert(prName); }; return function(fname, lname) { this.FirstName = fname; this.LastName = lname; } })(); And let's say I invoke them like this: var s = new Array(); //Person1 s.push(new Person1("sal", "smith")); s.push(new Person1("bill", "wonk")); alert(s[0].FirstName); alert(s[1].FirstName); s[1].showPrivate(); //Person2 s.push(new Person2("sal", "smith")); s.push(new Person2("bill", "wonk")); alert(s[2].FirstName); alert(s[3].FirstName); s[3].showPrivate(); The Person1 set alerts "bill" twice, then alerts "private" once -- so it recognizes the showPrivate function, but the local FirstName variable gets overwritten. The second Person2 set alerts "sal", then "bill", but it fails when the showPrivate function is called. The new keyword here works as I'd expect, but showPrivate (which I thought was a publicly exposed function within the closure) is apparently not public. I want to get my object to have distinct copies of all local variables and also expose public methods -- I've been studying closures quite a bit, but I'm still confused on this one. Thanks for your help.

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• Creating a property setter delegate

  - by Jim C

  I have created methods for converting a property lambda to a delegate: public static Delegate MakeGetter<T>(Expression<Func<T>> propertyLambda) { var result = Expression.Lambda(propertyLambda.Body).Compile(); return result; } public static Delegate MakeSetter<T>(Expression<Action<T>> propertyLambda) { var result = Expression.Lambda(propertyLambda.Body).Compile(); return result; } These work: Delegate getter = MakeGetter(() => SomeClass.SomeProperty); object o = getter.DynamicInvoke(); Delegate getter = MakeGetter(() => someObject.SomeProperty); object o = getter.DynamicInvoke(); but these won't compile: Delegate setter = MakeSetter(() => SomeClass.SomeProperty); setter.DynamicInvoke(new object[]{propValue}); Delegate setter = MakeSetter(() => someObject.SomeProperty); setter.DynamicInvoke(new object[]{propValue}); The MakeSetter lines fail with "The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly." Is what I'm trying to do possible? Thanks in advance.

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• Boost lambda: Invoke method on object

  - by ckarras

  I'm looking at boost::lambda as a way to to make a generic algorithm that can work with any "getter" method of any class. The algorithm is used to detect duplicate values of a property, and I would like for it to work for any property of any class. In C#, I would do something like this: class Dummy { public String GetId() ... public String GetName() ... } IEnumerable<String> FindNonUniqueValues<ClassT> (Func<ClassT,String> propertyGetter) { ... } Example use of the method: var duplicateIds = FindNonUniqueValues<Dummy>(d => d.GetId()); var duplicateNames = FindNonUniqueValues<Dummy>(d => d.GetName()); I can get the for "any class" part to work, using either interfaces or template methods, but have not found yet how to make the "for any method" part work. Is there a way to do something similar to the "d = d.GetId()" lambda in C++ (either with or without Boost)? Alternative, more C++ian solutions to make the algorithm generic are welcome too. I'm using C++/CLI with VS2008, so I can't use C++0x lambdas.

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• Applying for .net jobs as a "self learner"

  - by DeanMc

  Hi All, I have recently started applying for .Net jobs. I currently work in a sales role with a large telco. I found out quite late that I like programming and as such bought my house and made commitments that mean college is not an option. What I would like to know is, is it harder to get a junior job as a self learner? I have gotten a few enquiries regarding my C.V but nothing concrete yet. I try to be involved in projects as I get the chance and tend to put up any worthwhile projects as I develop them. Some examples of my work are: A Xaml lexer and parser: http://www.xlight.mendhak.com A font obfuscation tool: http://www.silverlightforums.com/showthread.php?1516-Font-Obsfucation-Tool-ALPHA A tagger for m4a: http://projectaudiophile.codeplex.com/SourceControl/list/changesets I, of course think that these are great examples of my work but that is my opinion based on self learning. The other query is how much should I actually know? I've never used linked lists but I know that strings are immutable and I understand what that means. I am only touching on T-SQL but I understand things like how properties function in IL (as two standard methods :) ). I suppose I understand a lot of concepts but specific features need some looking up to implement as I may not know the syntax off the top of my head.

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• Why do pure virtual base classes get direct access to static data members while derived instances do

  - by Shamster

  I've created a simple pair of classes. One is pure virtual with a static data member, and the other is derived from the base, as follows: #include <iostream> template <class T> class Base { public: Base (const T _member) { member = _member; } static T member; virtual void Print () const = 0; }; template <class T> T Base<T>::member; template <class T> void Base<T>::Print () const { std::cout << "Base: " << member << std::endl; } template <class T> class Derived : public Base<T> { public: Derived (const T _member) : Base<T>(_member) { } virtual void Print () const { std::cout << "Derived: " << this->member << std::endl; } }; I've found from this relationship that when I need access to the static data member in the base class, I can call it with direct access as if it were a regular, non-static class member. i.e. - the Base::Print() method does not require a this- modifier. However, the derived class does require the this-member indirect access syntax. I don't understand why this is. Both class methods are accessing the same static data, so why does the derived class need further specification? A simple call to test it is: int main () { Derived<double> dd (7.0); dd.Print(); return 0; } which prints the expected "Derived: 7"

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• In Javascript, is it true that function aliasing works as long as the function being aliased doesn't

  - by Jian Lin

  In Javascript, if we are aliasing a function, such as in: f = g; f = obj.display; obj.f = foo; all the 3 lines above, they will work as long as the function / method on the right hand side doesn't touch this? Since we are passing in all the arguments, the only way it can mess up is when the function / method on the right uses this? Actually, line 1 is probably ok if g is also a property of window? If g is referencing obj.display, then the same problem is there. In line 2, when obj.display touches this, it is to mean the obj, but when f() is invoked, the this is window, so they are different. In line 3, it is the same: when f() is invoked inside of obj's code, then the this is obj, while foo might be using this to refer to window if it were a property of window. (global function). So line 2 can be written as f = function() { obj.display.apply(obj, arguments) } and line 3: obj.f = function() { foo.apply(window, arguments) } Is this the correct method, and are there there other methods besides this?

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• Listing serial (COM) ports on Windows?

  - by Eli Bendersky

  Hello, I'm looking for a robust way to list the available serial (COM) ports on a Windows machine. There's this post about using WMI, but I would like something less .NET specific - I want to get the list of ports in a Python or a C++ program, without .NET. I currently know of two other approaches: Reading the information in the HARDWARE\\DEVICEMAP\\SERIALCOMM registry key. This looks like a great option, but is it robust? I can't find a guarantee online or in MSDN that this registry cell indeed always holds the full list of available ports. Tryint to call CreateFile on COMN with N a number from 1 to something. This isn't good enough, because some COM ports aren't named COMN. For example, some virtual COM ports created are named CSNA0, CSNB0, and so on, so I wouldn't rely on this method. Any other methods/ideas/experience to share? Edit: by the way, here's a simple Python implementation of reading the port names from registry: import _winreg as winreg import itertools def enumerate_serial_ports(): """ Uses the Win32 registry to return a iterator of serial (COM) ports existing on this computer. """ path = 'HARDWARE\\DEVICEMAP\\SERIALCOMM' try: key = winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE, path) except WindowsError: raise IterationError for i in itertools.count(): try: val = winreg.EnumValue(key, i) yield (str(val[1]), str(val[0])) except EnvironmentError: break

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