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  • Naming methods that do the same thing but return different types

    - by Konstantin Ð.
    Let's assume that I'm extending a graphical file chooser class (JFileChooser). This class has methods which display the file chooser dialog and return a status signature in the form of an int: APPROVE_OPTION if the user selects a file and hits Open /Save, CANCEL_OPTION if the user hits Cancel, and ERROR_OPTION if something goes wrong. These methods are called showDialog(). I find this cumbersome, so I decide to make another method that returns a File object: in the case of APPROVE_OPTION, it returns the file selected by the user; otherwise, it returns null. This is where I run into a problem: would it be okay for me to keep the showDialog() name, even though methods with that name — and a different return type — already exist? To top it off, my method takes an additional parameter: a File which denotes in which directory the file chooser should start. My question to you: Is it okay to call a method the same name as a superclass method if they return different types? Or would that be confusing to API users? (If so, what other name could I use?) Alternatively, should I keep the name and change the return type so it matches that of the other methods? public int showDialog(Component parent, String approveButtonText) // Superclass method public File showDialog(Component parent, File location) // My method

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  • Types of quotes for an HTML templating language

    - by Ralph
    I'm developing a templating language, and now I'm trying to decide on what I should do with quotes. I'm thinking about having 3 different types of quotes which are all handled differently: backtick ` double quote " single quote ' expand variables ? yes no escape sequences no yes ? escape html no yes yes Backticks Backticks are meant to be used for outputting JavaScript or unescaped HTML. It's often handy to be able to pass variables into JS, but it could also cause issues with things being treated as variables that shouldn't. My variables are PHP-style ($var) so I'm thinking that might mess with jQuery pretty bad... but if I disable variable expansion w/ backticks then, I'm not sure how would insert a variable into a JS code block? Single Quotes Not sure if escape sequences like \n should be treated as literals or converted. I find it pretty rare that I want to disable escape sequences, but if you do, you could use backticks. So I'm leaning towards "yes" for this one, but that would be contrary to how PHP does it. Double Quotes Pretty certain I want everything enabled for this one. Modifiers I'm also thinking about adding modifiers like @ or r in front of the string that would change some of these options to enable a few more combinations. I would need 9 different quotes or 3 quotes and 2 modifiers to get every combination wouldn't I? My language also supports "filters" which can be applied against any "term" (number, variable, string) so you could always write something like "blah blah $var blah"|expandvars Or "my string"|escapehtml Thoughts? What would you prefer? What would be least confusing/most intuitive?

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  • Object inheritance and method parameters/return types - Please check my logic

    - by user2368481
    I'm preparing for a test and doing practice questions, this one in particular I am unsure I did correctly: We are given a very simple UML diagram to demonstrate inheritance: I hope this is clear, it shows that W inherits from V and so on: |-----Y V <|----- W<|-----| |-----X<|----Z and this code: public X method1(){....} method2(new Y()); method2(method1()); method2(method3()); The questions and my answers: Q: What types of objects could method1 actually return? A: X and Z, since the method definition includes X as the return type and since Z is a kind of X is would be OK to return either. Q: What could the parameter type of method2 be? A: Since method2 in the code accepts Y, X and Z (as the return from method1), the parameter type must be either V or W, as Y,X and Z inherit from both of these. Q: What could return type of method3 be? A: Return type of method3 must be V or W as this would be consistent with answer 2.

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  • SQL SERVER – DMV – sys.dm_os_wait_stats Explanation – Wait Type – Day 3 of 28

    - by pinaldave
    The key Dynamic Management View (DMV) that helps us to understand wait stats is sys.dm_os_wait_stats; this DMV gives us all the information that we need to know regarding wait stats. However, the interpretation is left to us. This is a challenge as understanding wait stats can often be quite tricky. Anyway, we will cover few wait stats in one of the future articles. Today we will go over the basic understanding of the DMV. The Official Book OnLine Reference for DMV is over here: sys.dm_os_wait_stats. I suggest you all to refer this for all the accuracy. Following is a statement from the online book: “Specific types of wait times during query execution can indicate bottlenecks or stall points within the query. Similarly, high wait times, or wait counts server wide can indicate bottlenecks or hot spots in interaction query interactions within the server instance.” This is the statement which has inspired me to write this series. Let us first run the following statement from DMV. SELECT * FROM sys.dm_os_wait_stats ORDER BY wait_time_ms DESC GO Above statement will show us few of the columns. Here it is quick explanation of each of the column. wait_type – this is the name of the wait type. There can be three different kinds of wait types – resource, queue and external. waiting_tasks_count – this incremental counter is a good indication of frequent the wait is happening. If this number is very high, it is good indication for us to investigate that particular wait type. It is quite possible that the wait time is considerably low, but the frequency of the wait is much high. wait_time_ms – this is total wait accumulated for any type of wait. This is the total wait time and includes singal_wait_time_ms. max_wait_time_ms – this indicates the maximum wait type ever occurred for that particular wait type. Using this, one can estimate the intensity of the wait type in past. Again, it is not necessary that this max wait time will occur every time; so do not over invest yourself here. signal_wait_time_ms – this is the wait time when thread is marked as runnable and it gets to the running state. If the runnable queue is very long, you will find that this wait time becomes high. Additionally, please note that this DMV does not show current wait type or wait stats. This is cumulative view of the all the wait stats since server (instance) restarted or wait stats have been cleared. In future blog post, we will also cover two more DMVs which can be helpful to identify wait-related issues. ?sys.dm_os_waiting_tasks sys.dm_exec_requests Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • Enum types, FlagAttribute & Zero value

    - by nmgomes
    We all know about Enums types and use them every single day. What is not that often used is to decorate the Enum type with the FlagsAttribute. When an Enum type has the FlagsAttribute we can assign multiple values to it and thus combine multiple information into a single enum. The enum values should be a power of two so that a bit set is achieved. Here is a typical Enum type: public enum OperationMode { /// <summary> /// No operation mode /// </summary> None = 0, /// <summary> /// Standard operation mode /// </summary> Standard = 1, /// <summary> /// Accept bubble requests mode /// </summary> Parent = 2 } In such scenario no values combination are possible. In the following scenario a default operation mode exists and combination is used: [Flags] public enum OperationMode { /// <summary> /// Asynchronous operation mode /// </summary> Async = 0, /// <summary> /// Synchronous operation mode /// </summary> Sync = 1, /// <summary> /// Accept bubble requests mode /// </summary> Parent = 2 } Now, it’s possible to do statements like: [DefaultValue(OperationMode.Async)] [TypeConverter(typeof(EnumConverter))] public OperationMode Mode { get; set; } /// <summary> /// Gets a value indicating whether this instance supports request from childrens. /// </summary> public bool IsParent { get { return (this.Mode & OperationMode.Parent) == OperationMode.Parent; } } or switch (this.Mode) { case OperationMode.Sync | OperationMode.Parent: Console.WriteLine("Sync,Parent"); break;[…]  But there is something that you should never forget: Zero is the absorber element for the bitwise AND operation. So, checking for OperationMode.Async (the Zero value) mode just like the OperationMode.Parent mode makes no sense since it will always be true: (this.Mode & 0x0) == 0x0 Instead, inverse logic should be used: OperationMode.Async = !OperationMode.Sync public bool IsAsync { get { return (this.Mode & ContentManagerOperationMode.Sync) != ContentManagerOperationMode.Sync; } } or public bool IsAsync { get { return (int)this.Mode == 0; } } Final Note: Benefits Allow multiple values combination The above samples snippets were taken from an ASP.NET control and enabled the following markup usage: <my:Control runat="server" Mode="Sync,Parent"> Drawback Zero value is the absorber element for the bitwise AND operation Be very carefully when evaluating the Zero value, either evaluate the enum value as an integer or use inverse logic.

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  • Enum types, FlagsAttribute & Zero value – Part 2

    - by nmgomes
    In my previous post I wrote about why you should pay attention when using enum value Zero. After reading that post you are probably thinking like Benjamin Roux: Why don’t you start the enum values at 0x1? Well I could, but doing that I lose the ability to have Sync and Async mutually exclusive by design. Take a look at the following enum types: [Flags] public enum OperationMode1 { Async = 0x1, Sync = 0x2, Parent = 0x4 } [Flags] public enum OperationMode2 { Async = 0x0, Sync = 0x1, Parent = 0x2 } To achieve mutually exclusion between Sync and Async values using OperationMode1 you would have to operate both values: protected void CheckMainOperarionMode(OperationMode1 mode) { switch (mode) { case (OperationMode1.Async | OperationMode1.Sync | OperationMode1.Parent): case (OperationMode1.Async | OperationMode1.Sync): throw new InvalidOperationException("Cannot be Sync and Async simultaneous"); break; case (OperationMode1.Async | OperationMode1.Parent): case (OperationMode1.Async): break; case (OperationMode1.Sync | OperationMode1.Parent): case (OperationMode1.Sync): break; default: throw new InvalidOperationException("No default mode specified"); } } but this is a by design constraint in OperationMode2. Why? Simply because 0x0 is the neutral element for the bitwise OR operation. Knowing this singularity, replacing and simplifying the previous method, you get: protected void CheckMainOperarionMode(OperationMode2 mode) { switch (mode) { case (OperationMode2.Sync | OperationMode2.Parent): case (OperationMode2.Sync): break; case (OperationMode2.Parent): default: break; } This means that: if both Sync and Async values are specified Sync value always win (Zero is the neutral element for bitwise OR operation) if no Sync value specified, the Async method is used. Here is the final method implementation: protected void CheckMainOperarionMode(OperationMode2 mode) { if (mode & OperationMode2.Sync == OperationMode2.Sync) { } else { } } All content above prove that Async value (0x0) is useless from the arithmetic perspective, but, without it we lose readability. The following IF statements are logically equals but the first is definitely more readable: if (OperationMode2.Async | OperationMode2.Parent) { } if (OperationMode2.Parent) { } Here’s another example where you can see the benefits of 0x0 value, the default value can be used explicitly. <my:Control runat="server" Mode="Async,Parent"> <my:Control runat="server" Mode="Parent">

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  • Copying Properties between 2 Different Types&hellip;

    - by Shawn Cicoria
    I’m not sure where I had seen some of this base code, but this comes up time & time again on projects. Here’s a little method that copies all the R/W properties (public) between 2 distinct class definitions: It’s called as follows: private static void Test1() { MyClass obj1 = new MyClass() { Prop1 = "one", Prop2 = "two", Prop3 = 100 }; MyOtherClass obj2 = null; obj2 = CopyClass(obj1); Console.WriteLine(obj1); Console.WriteLine(obj2); } namespace Space1 { public class MyClass { public string Prop1 { get; set; } public string Prop2 { get; set; } public int Prop3 { get; set; } public override string ToString() { var rv = string.Format("MyClass: {0} Prop2: {1} Prop3 {2}", Prop1, Prop2, Prop3); return rv; } } } namespace Space2 { public class MyOtherClass { public string Prop1 { get; set; } public string Prop2 { get; set; } public int Prop3 { get; set; } public override string ToString() { var rv = string.Format("MyOtherClass: {0} Prop2: {1} Prop3 {2}", Prop1, Prop2, Prop3); return rv; } } Source of the method: /// /// Provides a Copy of Public fields between 2 distinct classes /// /// Source class name /// Target class name /// Instance of type Source /// An instance of type Target copying all public properties matching name from the Source. public static T CopyClass(S source) where T : new() { T target = default(T); BindingFlags flags = BindingFlags.Public | BindingFlags.Instance; if (source == null) { return (T)target; } if (target == null) target = new T(); PropertyInfo[] objProperties = target.GetType().GetProperties(flags); foreach (PropertyInfo pi in objProperties) { string name = pi.Name; PropertyInfo sourceProp = source.GetType().GetProperty(name, flags); if (sourceProp == null) { throw new ApplicationException(string.Format("CopyClass - object type {0} & {1} mismatch in property:{2}", source.GetType(), target.GetType(), name)); } if (pi.CanWrite && sourceProp.CanRead) { object sourceValue = sourceProp.GetValue(source, null); pi.SetValue(target, sourceValue, null); } else { throw new ApplicationException(string.Format("CopyClass - can't read/write a property object types {0} & {1} property:{2}", source.GetType(), target.GetType(), name)); } } return target; }

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  • Whats the most efficient MySQL column types for this data?

    - by AlabamaKush
    I have several tables with some pretty standard data in each. Can somebody help me optimize them by telling me the best column types for this data. Whats beside them is what I have currently. Number (max length 7) --> MEDIUMINT(8) Unsigned Text (max length 30) --> VARCHAR(30) Text (max length 200) --> VARCHAR(200) Number (max length 4) --> SMALLINT(5) Unsigned Number (either 0 or 1) --> TINYINT(1) Unsigned Text (max length 500) --> TEXT Any suggestions? I'm just guessing with this so I know some of them are wrong...

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  • MSSQL: Primary Key Schema Largely Guid but Sometimes Integer Types...

    - by Code Sherpa
    OK, this may be a silly question but... I have inherited a project and am tasked with going over the primary key relationships. The project largely uses Guids. I say "largely" because there are examples where tables use integral types to reflect enumerations. For example, dbo.MessageFolder has MessageFolderId of type int to reflect public emum MessageFolderTypes { inbox = 1, sent = 2, trash = 3, etc... } This happens a lot. There are tables with primary keys of type int which is unavoidable because of their reliance on enumerations and tables with primary keys of type Guid which reflect the primary key choice on the part of the previous programmer. Should I care that the PK schema is spotty like this? It doesn't feel right but does it really matter? If this could create a problem, how do I get around it (I really can't move all PKs to type int without serious legwork and I have never heard of enumerations that have guid values)? Thanks.

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  • SQL Server: Primary Key Schema Largely Guid but Sometimes Integer Types...

    - by Code Sherpa
    OK, this may be a silly question but... I have inherited a project and am tasked with going over the primary key relationships. The project largely uses Guids. I say "largely" because there are examples where tables use integral types to reflect enumerations. For example, dbo.MessageFolder has MessageFolderId of type int to reflect public emum MessageFolderTypes { inbox = 1, sent = 2, trash = 3, etc... } This happens a lot. There are tables with primary keys of type int which is unavoidable because of their reliance on enumerations and tables with primary keys of type Guid which reflect the primary key choice on the part of the previous programmer. Should I care that the PK schema is spotty like this? It doesn't feel right but does it really matter? If this could create a problem, how do I get around it (I really can't move all PKs to type int without serious legwork and I have never heard of enumerations that have guid values)? Thanks.

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  • Pass Types as arguments to a function in Haskell?

    - by Charles Peng
    The following two functions are extremely similar. They read from a [String] n elements, either [Int] or [Float]. How can I factor the common code out? I don't know of any mechanism in Haskell that supports passing types as arguments. readInts n stream = foldl next ([], stream) [1..n] where next (lst, x:xs) _ = (lst ++ [v], xs) where v = read x :: Int readFloats n stream = foldl next ([], stream) [1..n] where next (lst, x:xs) _ = (lst ++ [v], xs) where v = read x :: Float I am at a beginner level of Haskell, so any comments on my code are welcome.

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  • .NET security mechanism to restrict access between two Types in the same Website project?

    - by jdk
    Question: Is there a mechanism in the .NET Framework to hide one custom Type from another without using separate projects/assemblies? I'm using C# with ASP.NET in a Website project (Note: Not a Web Application). Obviously there's not a way to enforce this restriction using language-specific OO keywords so I am looking for something else, for example: maybe a permission framework or code access mechanism, maybe something that uses meta data like Attributes. I'm unsure. I don't really care whether the solution actually hides classes from each other or just makes them inaccessible, etc. A runtime or design time answer will suffice. Looking for something easy to implement otherwise it's not worth the effort ... Background: I'm working in an ASP.NET Website project and the team has decided not to use separate project assemblies for different software layers. Therefore I'm looking for a way to have, for example, a DataAccess/ folder of which I disallow its classes to access other Types in the ASP.NET Website project.

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  • Pecl complies .so extensions for OSX built-in PHP and not MAMP

    - by Camsoft
    I've installed the sphinx binaries and libraries and am now trying to install the PECL sphinx module. My system is running OS X 10.6 with MAMP 1.8.2 installed. I try to install sphinx using the following command: sudo pecl install sphinx The PECL command outputs the following: running: phpize Configuring for: PHP Api Version: 20090626 Zend Module Api No: 20090626 Zend Extension Api No: 220090626 The versions above don't match the versions listed when doing a phpinfo(). It seems that PECL is trying to complie against the built-in version of PHP. If I ignore the errors and continue the it will successfully compile and place the sphinx.so file in: /usr/lib/php/extensions/no-debug-non-zts-20090626/sphinx.so when in fact it should be: /Applications/MAMP/bin/php5/lib/php/extensions/no-debug-non-zts-20060613/ I've tried copying the sphinx.so file to the MAMP extensions dir but when I restart apache PHP displays the following warning: PHP Startup: Unable to load dynamic library '/Applications/MAMP/bin/php5/lib/php/extensions/no-debug-non-zts-20060613/sphinx.so I think this is because MAMP is 32bit and the built-in PHP is 64bit so PECL complies for 64bit. I might be completely wrong but I did read this when I goggled on the topic. Does anyone know how to get PECL to map to the MAMP version of PHP instead of the built-in version?

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  • 11 Types of Developers

    - by Lee Brandt
    Jack Dawson Jack Dawson is the homeless drifter in Titanic. At one point in the movie he says, “I figure life’s a gift, and I don’t intend on wasting it.” He is happy to wander wherever life takes him. He works himself from place to place, making just enough money to make it to his next adventure. The “Jack Dawson” developer clings on to any new technology as the ‘next big thing’, and will find ways to shoe-horn it in to places where it is not a fit. He is very appealing to the other developers because they want to try the newest techniques and tools too, He will only stay until the new technology either bores him or becomes problematic. Jack will also be hard to find once the technology has been implemented, because he will be on to the next shiny thing. However, having a Jack Dawson on your team can be beneficial. Jack can be a great ally when attempting to convince a stodgy, corporate entity to upgrade. Jack usually has an encyclopedic recall of all the new features of the technology upgrade and is more than happy to interject them in any conversation. Tom Smykowski Tom is the neurotic employee in Office Space, and is deathly afraid of being fired. He will do only what is necessary to keep the status quo. He believes as long as nothing changes, his job is safe. He will scoff at anything new and be the naysayer during any change initiative. Tom can be useful in off-setting Jack Dawson. Jack will constantly be pushing for change and Tom will constantly be fighting it. When you see that Jack is getting kind of bored with a new technology and Tom has finally stopped wetting himself at the mere mention of it, then it is probably the sweet spot of beginning to implement that new technology (providing it is the right tool for the job). Ray Consella Ray is the guy who built the Field of Dreams. He took a risk. Sometimes he screwed it up, but he knew he didn’t want to end up regretting not attempting it. He constantly doubted himself, but he knew he had to keep going. Granted, he was doing what the voices in his head were telling him to do, but my point is he was driven to do something that most people considered crazy. Even when his friends, his wife and even he told himself he was crazy, somewhere inside himself, he knew it was the right thing to do. These are the innovators. These are the Bill Gates and Steve Jobs of the world. The take risks, they fail, they learn and the get better. Obviously, this kind of person thrives in start-ups and smaller companies, but that is due to their natural aversion to bureaucracy. They want to see their ideas put into motion quickly, and withdrawn quickly if it doesn’t work. Short feedback cycles are essential to Ray. He wants to know if his idea is working or not. He wants to modify or reverse his idea if it is not working or makes things worse. These are the agilistas. May I always be one.

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  • SQL SERVER – CXPACKET – Parallelism – Usual Solution – Wait Type – Day 6 of 28

    - by pinaldave
    CXPACKET has to be most popular one of all wait stats. I have commonly seen this wait stat as one of the top 5 wait stats in most of the systems with more than one CPU. Books On-Line: Occurs when trying to synchronize the query processor exchange iterator. You may consider lowering the degree of parallelism if contention on this wait type becomes a problem. CXPACKET Explanation: When a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. There is an organizer/coordinator thread (thread 0), which takes waits for all the threads to complete and gathers result together to present on the client’s side. The organizer thread has to wait for the all the threads to finish before it can move ahead. The Wait by this organizer thread for slow threads to complete is called CXPACKET wait. Note that not all the CXPACKET wait types are bad. You might experience a case when it totally makes sense. There might also be cases when this is unavoidable. If you remove this particular wait type for any query, then that query may run slower because the parallel operations are disabled for the query. Reducing CXPACKET wait: We cannot discuss about reducing the CXPACKET wait without talking about the server workload type. OLTP: On Pure OLTP system, where the transactions are smaller and queries are not long but very quick usually, set the “Maximum Degree of Parallelism” to 1 (one). This way it makes sure that the query never goes for parallelism and does not incur more engine overhead. EXEC sys.sp_configure N'cost threshold for parallelism', N'1' GO RECONFIGURE WITH OVERRIDE GO Data-warehousing / Reporting server: As queries will be running for long time, it is advised to set the “Maximum Degree of Parallelism” to 0 (zero). This way most of the queries will utilize the parallel processor, and long running queries get a boost in their performance due to multiple processors. EXEC sys.sp_configure N'cost threshold for parallelism', N'0' GO RECONFIGURE WITH OVERRIDE GO Mixed System (OLTP & OLAP): Here is the challenge. The right balance has to be found. I have taken a very simple approach. I set the “Maximum Degree of Parallelism” to 2, which means the query still uses parallelism but only on 2 CPUs. However, I keep the “Cost Threshold for Parallelism” very high. This way, not all the queries will qualify for parallelism but only the query with higher cost will go for parallelism. I have found this to work best for a system that has OLTP queries and also where the reporting server is set up. Here, I am setting ‘Cost Threshold for Parallelism’ to 25 values (which is just for illustration); you can choose any value, and you can find it out by experimenting with the system only. In the following script, I am setting the ‘Max Degree of Parallelism’ to 2, which indicates that the query that will have a higher cost (here, more than 25) will qualify for parallel query to run on 2 CPUs. This implies that regardless of the number of CPUs, the query will select any two CPUs to execute itself. EXEC sys.sp_configure N'cost threshold for parallelism', N'25' GO EXEC sys.sp_configure N'max degree of parallelism', N'2' GO RECONFIGURE WITH OVERRIDE GO Read all the post in the Wait Types and Queue series. Additionally a must read comment of Jonathan Kehayias. Note: The information presented here is from my experience and I no way claim it to be accurate. I suggest you all to read the online book for further clarification. All the discussion of Wait Stats over here is generic and it varies from system to system. It is recommended that you test this on the development server before implementing on the production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • How to specialize a type parameterized argument to multiple different types for in Scala?

    - by jmount
    I need a back-check (please). In an article ( http://www.win-vector.com/blog/2010/06/automatic-differentiation-with-scala/ ) I just wrote I stated that it is my belief in Scala that you can not specify a function that takes an argument that is itself a function with an unbound type parameter. What I mean is you can write: def g(f:Array[Double]=>Double,Array[Double]):Double but you can not write something like: def g(f[Y]:Array[Y]=>Double,Array[Double]):Double because Y is not known. The intended use is that inside g() I will specialize fY to multiple different types at different times. You can write: def g[Y](f:Array[Y]=>Double,Array[Double]):Double but then f() is of a single type per call to g() (which is exactly what we do not want). However, you can get all of the equivalent functionality by using a trait extension instead insisting on passing around a function. What I advocated in my article was: 1) Creating a trait that imitates the structure of Scala's Function1 trait. Something like: abstract trait VectorFN { def apply[Y](x:Array[Y]):Y } 2) declaring def g(f:VectorFN,Double):Double (using the trait is the type). This works (people here on StackOverflow helped me find it, and I am happy with it)- but am I mis-representing Scala by missing an even better solution?

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  • Generic Event Generator and Handler from User Supplied Types?

    - by JaredBroad
    I'm trying to allow the user to supply custom data and manage the data with custom types. The user's algorithm will get time synchronized events pushed into the event handlers they define. I'm not sure if this is possible but here's the "proof of concept" code I'd like to build. It doesn't detect T in the for loop: "The type or namespace name 'T' could not be found" class Program { static void Main(string[] args) { Algorithm algo = new Algorithm(); Dictionary<Type, string[]> userDataSources = new Dictionary<Type, string[]>(); // "User" adding custom type and data source for algorithm to consume userDataSources.Add(typeof(Weather), new string[] { "temperature data1", "temperature data2" }); for (int i = 0; i < 2; i++) { foreach (Type T in userDataSources.Keys) { string line = userDataSources[typeof(T)][i]; //Iterate over CSV data.. var userObj = new T(line); algo.OnData < typeof(T) > (userObj); } } } //User's algorithm pattern. interface IAlgorithm<TData> where TData : class { void OnData<TData>(TData data); } //User's algorithm. class Algorithm : IAlgorithm<Weather> { //Handle Custom User Data public void OnData<Weather>(Weather data) { Console.WriteLine(data.date.ToString()); Console.ReadKey(); } } //Example "user" custom type. public class Weather { public DateTime date = new DateTime(); public double temperature = 0; public Weather(string line) { Console.WriteLine("Initializing weather object with: " + line); date = DateTime.Now; temperature = -1; } } }

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  • WCF – interchangeable data-contract types

    - by nmarun
    In a WSDL based environment, unlike a CLR-world, we pass around the ‘state’ of an object and not the reference of an object. Well firstly, what does ‘state’ mean and does this also mean that we can send a struct where a class is expected (or vice-versa) as long as their ‘state’ is one and the same? Let’s see. So I have an operation contract defined as below: 1: [ServiceContract] 2: public interface ILearnWcfServiceExtend : ILearnWcfService 3: { 4: [OperationContract] 5: Employee SaveEmployee(Employee employee); 6: } 7:  8: [ServiceBehavior] 9: public class LearnWcfService : ILearnWcfServiceExtend 10: { 11: public Employee SaveEmployee(Employee employee) 12: { 13: employee.EmployeeId = 123; 14: return employee; 15: } 16: } Quite simplistic operation there (which translates to ‘absolutely no business value’). Now, the data contract Employee mentioned above is a struct. 1: public struct Employee 2: { 3: public int EmployeeId { get; set; } 4:  5: public string FName { get; set; } 6: } After compilation and consumption of this service, my proxy (in the Reference.cs file) looks like below (I’ve ignored the rest of the details just to avoid unwanted confusion): 1: public partial struct Employee : System.Runtime.Serialization.IExtensibleDataObject, System.ComponentModel.INotifyPropertyChanged I call the service with the code below: 1: private static void CallWcfService() 2: { 3: Employee employee = new Employee { FName = "A" }; 4: Console.WriteLine("IsValueType: {0}", employee.GetType().IsValueType); 5: Console.WriteLine("IsClass: {0}", employee.GetType().IsClass); 6: Console.WriteLine("Before calling the service: {0} - {1}", employee.EmployeeId, employee.FName); 7: employee = LearnWcfServiceClient.SaveEmployee(employee); 8: Console.WriteLine("Return from the service: {0} - {1}", employee.EmployeeId, employee.FName); 9: } The output is: I now change my Employee type from a struct to a class in the proxy class and run the application: 1: public partial class Employee : System.Runtime.Serialization.IExtensibleDataObject, System.ComponentModel.INotifyPropertyChanged { The output this time is: The state of an object implies towards its composition, the properties and the values of these properties and not based on whether it is a reference type (class) or a value type (struct). And as shown above, we’re actually passing an object by its state and not by reference. Continuing on the same topic of ‘type-interchangeability’, WCF treats two data contracts as equivalent if they have the same ‘wire-representation’. We can do so using the DataContract and DataMember attributes’ Name property. 1: [DataContract] 2: public struct Person 3: { 4: [DataMember] 5: public int Id { get; set; } 6:  7: [DataMember] 8: public string FirstName { get; set; } 9: } 10:  11: [DataContract(Name="Person")] 12: public class Employee 13: { 14: [DataMember(Name = "Id")] 15: public int EmployeeId { get; set; } 16:  17: [DataMember(Name="FirstName")] 18: public string FName { get; set; } 19: } I’ve created two data contracts with the exact same wire-representation. Just remember that the names and the types of data members need to match to be considered equivalent. The question then arises as to what gets generated in the proxy class. Despite us declaring two data contracts (Person and Employee), only one gets emitted – Person. This is because we’re saying that the Employee type has the same wire-representation as the Person type. Also that the signature of the SaveEmployee operation gets changed on the proxy side: 1: [System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "4.0.0.0")] 2: [System.ServiceModel.ServiceContractAttribute(ConfigurationName="ServiceProxy.ILearnWcfServiceExtend")] 3: public interface ILearnWcfServiceExtend 4: { 5: [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/ILearnWcfServiceExtend/SaveEmployee", ReplyAction="http://tempuri.org/ILearnWcfServiceExtend/SaveEmployeeResponse")] 6: ClientApplication.ServiceProxy.Person SaveEmployee(ClientApplication.ServiceProxy.Person employee); 7: } But, on the service side, the SaveEmployee still accepts and returns an Employee data contract. 1: [ServiceBehavior] 2: public class LearnWcfService : ILearnWcfServiceExtend 3: { 4: public Employee SaveEmployee(Employee employee) 5: { 6: employee.EmployeeId = 123; 7: return employee; 8: } 9: } Despite all these changes, our output remains the same as the last one: This is type-interchangeability at work! Here’s one more thing to ponder about. Our Person type is a struct and Employee type is a class. Then how is it that the Person type got emitted as a ‘class’ in the proxy? It’s worth mentioning that WSDL describes a type called Employee and does not say whether it is a class or a struct (see the SOAP message below): 1: <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" 2: xmlns:tem="http://tempuri.org/" 3: xmlns:ser="http://schemas.datacontract.org/2004/07/ServiceApplication"> 4: <soapenv:Header/> 5: <soapenv:Body> 6: <tem:SaveEmployee> 7: <!--Optional:--> 8: <tem:employee> 9: <!--Optional:--> 10: <ser:EmployeeId>?</ser:EmployeeId> 11: <!--Optional:--> 12: <ser:FName>?</ser:FName> 13: </tem:employee> 14: </tem:SaveEmployee> 15: </soapenv:Body> 16: </soapenv:Envelope> There are some differences between how ‘Add Service Reference’ and the svcutil.exe generate the proxy class, but turns out both do some kind of reflection and determine the type of the data contract and emit the code accordingly. So since the Employee type is a class, the proxy ‘Person’ type gets generated as a class. In fact, reflecting on svcutil.exe application, you’ll see that there are a couple of places wherein a flag actually determines a type as a class or a struct. One example is in the ExportISerializableDataContract method in the System.Runtime.Serialization.CodeExporter class. Seems like these flags have a say in deciding whether the type gets emitted as a struct or a class. This behavior is different if you use the WSDL tool though. WSDL tool does not do any kind of reflection of the data contract / serialized type, it emits the type as a class by default. You can check this using the two command lines below:   Note to self: Remember ‘state’ and type-interchangeability when traversing through the WSDL planet!

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  • Checking type sizes in C with macros.

    - by Seisatsu
    I'm writing a program that needs to have unsigned types with definite sizes. I need a uint8, uint16, uint32, and uint64, and I need them defined in types.h, in a way that they will always be defined correctly regardless of platform. My question is, how can I check the sizes of different types on each platform using preprocessor macros, so that I can define my custom types correctly in the types.h header?

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  • SQL SERVER – DMV – sys.dm_os_waiting_tasks and sys.dm_exec_requests – Wait Type – Day 4 of 28

    - by pinaldave
    Previously, we covered the DMV sys.dm_os_wait_stats, and also saw how it can be useful to identify the major resource bottleneck. However, at the same time, we discussed that this is only useful when we are looking at an instance-level picture. Quite often we want to know about the processes going in our server at the given instant. Here is the query for the same. This DMV is written taking the following into consideration: we want to analyze the queries that are currently running or which have recently ran and their plan is still in the cache. SELECT dm_ws.wait_duration_ms, dm_ws.wait_type, dm_es.status, dm_t.TEXT, dm_qp.query_plan, dm_ws.session_ID, dm_es.cpu_time, dm_es.memory_usage, dm_es.logical_reads, dm_es.total_elapsed_time, dm_es.program_name, DB_NAME(dm_r.database_id) DatabaseName, -- Optional columns dm_ws.blocking_session_id, dm_r.wait_resource, dm_es.login_name, dm_r.command, dm_r.last_wait_type FROM sys.dm_os_waiting_tasks dm_ws INNER JOIN sys.dm_exec_requests dm_r ON dm_ws.session_id = dm_r.session_id INNER JOIN sys.dm_exec_sessions dm_es ON dm_es.session_id = dm_r.session_id CROSS APPLY sys.dm_exec_sql_text (dm_r.sql_handle) dm_t CROSS APPLY sys.dm_exec_query_plan (dm_r.plan_handle) dm_qp WHERE dm_es.is_user_process = 1 GO You can change CROSS APPLY to OUTER APPLY if you want to see all the details which are omitted because of the plan cache. Let us analyze the result of the above query and see how it can be helpful to identify the query and the kind of wait type it creates. Click to Enlarage The above query will return various columns. There are various columns that provide very important details. e.g. wait_duration_ms – it indicates current wait for the query that executes at that point of time. wait_type – it indicates the current wait type for the query text – indicates the query text query_plan – when clicked on the same, it will display the query plans There are many other important information like CPU_time, memory_usage, and logical_reads, which can be read from the query as well. In future posts on this series, we will see how once identified wait type we can attempt to reduce the same. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: DMV, Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQLAuthority News – I am Presenting 2 Sessions at TechEd India

    - by pinaldave
    TechED is the event which I am always excited about. It is one of the largest technology in India. Microsoft Tech Ed India 2011 is the premier technical education and networking event for tech professionals interested in learning, connecting and exploring a broad set of current and soon-to-be released Microsoft technologies, tools, platforms and services. I am going to speak at the TechED on two very interesting and advanced subjects. Venue: The LaLiT Ashok Kumara Krupa High Grounds Bangalore – 560001, Karnataka, India Sessions Date: March 25, 2011 Understanding SQL Server Behavioral Pattern – SQL Server Extended Events Date and Time: March 25, 2011 12:00 PM to 01:00 PM History repeats itself! SQL Server 2008 has introduced a very powerful, yet very minimal reoccurring feature called Extended Events. This advanced session will teach experienced administrators’ capabilities that were not possible before. From T-SQL error to CPU bottleneck, error login to deadlocks –Extended Event can detect it for you. Understanding the pattern of events can prevent future mistakes. SQL Server Waits and Queues – Your Gateway to Perf. Troubleshooting Date and Time: March 25, 2011 04:15 PM to 05:15 PM Just like a horoscope, SQL Server Waits and Queues can reveal your past, explain your present and predict your future. SQL Server Performance Tuning uses the Waits and Queues as a proven method to identify the best opportunities to improve performance. A glance at Wait Types can tell where there is a bottleneck. Learn how to identify bottlenecks and potential resolutions in this fast paced, advanced performance tuning session. My session will be on the third day of the event and I am very sure that everybody will be in groove to learn new interesting subjects. I will have few give-away during and at the end of the session. I will not tell you what I will have but it will be for sure something you will love to have. Please make a point and reserve above time slots to attend my session. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology Tagged: SQL Extended Events

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  • What is meant by a primitive data type?

    - by Appy
    My understanding of a primitive datatype is that It is a datatype provided by a language implicitly (Others are user defined classes) So different languages have different sets of datatypes which are considered primitive for that particular language. Is that right? And what is the difference between a "basic datatype" and "built-in datatype". Wikipedia says a primitive datatype is either of the two. PS - Why is "string" type considered as a primitive type in SNOBOL4 and not in Java ?

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  • Rosetta Stone Network V3 doesn't recognize built-in microphone in OSX Lion

    - by zarose
    I am using Rosetta Stone Network V3 on an early 2011 MacBook Pro running OSX Lion 10.7.3. When I log in, select a language and level, and then a lesson, I am prompted to select a microphone. The built in microphone doesn't show up, yet I've used it multiple times for other applications. I heard from another user that it doesn't work if headphones with a built-in microphone are used. I have not yet tried a USB microphone. Is there some free work around to this? I would prefer to not have to buy a USB microphone, but if that is the only solution, then I'll live. Edit: I noticed that Rosetta Stone tells me that if I don't have a microphone I should disable speech to move on, but that option is grayed out for me.

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  • Force Colloquy not to use built-in Growl notifications

    - by thepurplepixel
    Whenever Colloquy needs to pop up a notification (for example, when you are PM'd), it uses its built-in Growl notifications, which really annoy me because they stay on the screen until they are clicked (at least NOTICE's do anyways). I'd like to make Colloquy use the Growl that I have installed on my Mac, not its built-in Growl notifications. That way, I could change its preferences from the Growl .prefpane and it would match the look of all my other notifications. I seem to remember this being possible (maybe in a bug report or something), but I can't remember how. Thanks!

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