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  • What are the advantages of learning Go?

    - by Pangea
    What is so unique about Go? Over the 11 years of my career I've learnt Pascal, C, C++, COBOL and then Java. I always felt that going from C to C++ to Java was a incremental and value added progression. Now I see a proliferation of functional programming languages and I understand the benefit of learning few of them (like actors in scala etc). Now I was going through the Go programming language and was wondering why would I want to learn this? Is this going to simplify how I have been writing the code? What are its use cases? How can I make a case to promote it in my team? What is the next programming language that a Java team that builds business applications like us can benefit from? Appreciate your comments on this.

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  • generic function for extracting values from an array with one particular key in PHP

    - by Sabya
    Is it possible in PHP to extract values from an array with a particular key path and return an array of those values? I'll explain with an example: $user = array ( array( id => 1, email =>'[email protected]', project => array ('project_id' => 222, 'project_name' => 'design') ), array( id => 2, email =>'[email protected]', project => array ('project_id' => 333, 'project_name' => 'design') ) ); /** I have to write a function something like: */ $projectIds = extractValuesWithKey($user, array('project', 'project_id')); print_r($projectIds); Output: Array( [0] => 222, [1] => 333 )

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  • Create generic class instance throws TypeLoadException

    - by Elisa
    My TestLayer class has the namespace: "BLL.Infrastructure.TestLayer" and is inside the assembly: "BLL" public class LayerFactory<T, U> { public static IBaseLayer<T, U> Get() { var obj = Activator.CreateInstance("BLL", "BLL.Infrastructure.TestLayer", new object[] { (IBaseLayer<T, U>)null }); } } When I run the code the Activator throws an TypeLoadException with no more details Thats the concrete class it should create: GenericBaseLayer implements the IBaseLayer. public class TestLayer<T, U> : GenericBaseLayer<MyRequest, MyInfo.ActionType> { public TestLayer(IBaseLayer<MyRequest, MyInfo.ActionType> layer) : base(layer) { } } What do I wrong?

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  • Experiences with D-programming-language

    - by Dario
    Has someone here ever had experience with the D programming language? It seems to have many nice features but will it ever reach the popularity of those currently widespread languages like C++, Java or C#? So is it worth learning or is it an isolated language with minor prospects.

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  • Overloading generic implicit conversions

    - by raichoo
    Hi I'm having a little scala (version 2.8.0RC1) problem with implicit conversions. Whenever importing more than one implicit conversion the first one gets shadowed. Here is the code where the problem shows up: // containers class Maybe[T] case class Nothing[T]() extends Maybe[T] case class Just[T](value: T) extends Maybe[T] case class Value[T](value: T) trait Monad[C[_]] { def >>=[A, B](a: C[A], f: A => C[B]): C[B] def pure[A](a: A): C[A] } // implicit converter trait Extender[C[_]] { class Wrapper[A](c: C[A]) { def >>=[B](f: A => C[B])(implicit m: Monad[C]): C[B] = { m >>= (c, f) } def >>[B](b: C[B])(implicit m: Monad[C]): C[B] = { m >>= (c, { (x: A) => b } ) } } implicit def extendToMonad[A](c: C[A]) = new Wrapper[A](c) } // instance maybe object maybemonad extends Extender[Maybe] { implicit object MaybeMonad extends Monad[Maybe] { override def >>=[A, B](a: Maybe[A], f: A => Maybe[B]): Maybe[B] = { a match { case Just(x) => f(x) case Nothing() => Nothing() } } override def pure[A](a: A): Maybe[A] = Just(a) } } // instance value object identitymonad extends Extender[Value] { implicit object IdentityMonad extends Monad[Value] { override def >>=[A, B](a: Value[A], f: A => Value[B]): Value[B] = { a match { case Value(x) => f(x) } } override def pure[A](a: A): Value[A] = Value(a) } } import maybemonad._ //import identitymonad._ object Main { def main(args: Array[String]): Unit = { println(Just(1) >>= { (x: Int) => MaybeMonad.pure(x) }) } } When uncommenting the second import statement everything goes wrong since the first "extendToMonad" is shadowed. However, this one works: object Main { implicit def foo(a: Int) = new { def foobar(): Unit = { println("Foobar") } } implicit def foo(a: String) = new { def foobar(): Unit = { println(a) } } def main(args: Array[String]): Unit = { 1 foobar() "bla" foobar() } } So, where is the catch? What am I missing? Regards, raichoo

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  • Generic documentation guide-lines for implementation details

    - by mgj
    Hi..:) For documentation and presentation purposes, we often find professionals/students creating SRS, coding guidelines etc. for these things there is some kind of a checklist which one could use to appropriately match what could relate to a specific case and accordingly one does a documentation for each. On those grounds could you please give me some sort of a checklist( any points/guidelines) one could use for going about Implementation( in the form of Implementation Details) in Python and C++ . Although this might sound specific as the query is "Implementation Details" and is different for different cases as one goes about the REAL implementation, I just want a SET of guidelines one should follow ( Preferably In Python, C++ specific, even for any other language is Welcome) if this( Implementation Details ) has to also be documented or presented. Hope the question is clear, I am sorry if it still sounds ambiguous, I guess this is the best I could do to frame my query. Thank you for your time...:)

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  • Call Javascript method from .ashx file

    - by Prasad Jadhav
    From my previous question(Create json using JavaScriptSerializer), In .ashx file I am printing the json object using: context.Response.ContentType = "application/json"; context.Response.Write(json); I am calling this .ashx file from default.aspx which has some javascript function inside its <head> tag. My question is : How will I be able to call the javascript function from .ashx file after context.Response.Write(json);?

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  • Wildcards vs. generic methods

    - by FredOverflow
    Is there any practical difference between the following approaches to print all elements in a range? public static void printA(Iterable<?> range) { for (Object o : range) { System.out.println(o); } } public static <T> void printB(Iterable<T> range) { for (T x : range) { System.out.println(x); } } Apparently, printB involves an additional checked cast to Object (see line 16), which seems rather stupid to me -- isn't everything an Object anyway? public static void printA(java.lang.Iterable); Code: 0: aload_0 1: invokeinterface #18, 1; //InterfaceMethod java/lang/Iterable.iterator:()Ljava/util/Iterator; 6: astore_2 7: goto 24 10: aload_2 11: invokeinterface #24, 1; //InterfaceMethod java/util/Iterator.next:()Ljava/lang/Object; 16: astore_1 17: getstatic #30; //Field java/lang/System.out:Ljava/io/PrintStream; 20: aload_1 21: invokevirtual #36; //Method java/io/PrintStream.println:(Ljava/lang/Object;)V 24: aload_2 25: invokeinterface #42, 1; //InterfaceMethod java/util/Iterator.hasNext:()Z 30: ifne 10 33: return public static void printB(java.lang.Iterable); Code: 0: aload_0 1: invokeinterface #18, 1; //InterfaceMethod java/lang/Iterable.iterator:()Ljava/util/Iterator; 6: astore_2 7: goto 27 10: aload_2 11: invokeinterface #24, 1; //InterfaceMethod java/util/Iterator.next:()Ljava/lang/Object; 16: checkcast #3; //class java/lang/Object 19: astore_1 20: getstatic #30; //Field java/lang/System.out:Ljava/io/PrintStream; 23: aload_1 24: invokevirtual #36; //Method java/io/PrintStream.println:(Ljava/lang/Object;)V 27: aload_2 28: invokeinterface #42, 1; //InterfaceMethod java/util/Iterator.hasNext:()Z 33: ifne 10 36: return

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  • c# Reflection - Find the Generic Type of a Collection

    - by Andy Clarke
    Hi, I'm reflecting a property 'Blah' its Type is ICollection public ICollection<string> Blah { get; set; } private void button1_Click(object sender, RoutedEventArgs e) { var pi = GetType().GetProperty("Blah"); MessageBox.Show(pi.PropertyType.ToString()); } This gives me (as you'd expect!) ICollection<string> ... But really I want to get the collection type i.e. ICollection (rather than ICollection<string>) - does anyone know how i'd do this please?

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  • Applying to a international programming jobs

    - by Shawn Mclean
    If this question is not suited at stackoverflow, could you tell me in comments and suggest a site that I can ask this question and I'll close this. I'm located in Jamaica and in my final semester of a bsc computer science degree. I would like to apply to programming jobs abroad. How do I go about this? What is the sequence to follow and documents needed? Thanks.

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  • Linq generic Expression in query on "element" or on IQueryable (multiple use)

    - by Bogdan Maxim
    Hi, I have the following expression public static Expression<Func<T, bool>> JoinByDateCheck<T>(T entity, DateTime dateToCheck) where T : IDateInterval { return (entityToJoin) => entityToJoin.FromDate.Date <= dateToCheck.Date && (entityToJoin.ToDate == null || entityToJoin.ToDate.Value.Date >= dateToCheck.Date); } IDateInterval interface is defined like this: interface IDateInterval { DateTime FromDate {get;} DateTime? ToDate {get;} } and i need to apply it in a few ways: (1) Query on Linq2Sql Table: var q1 = from e in intervalTable where FunctionThatCallsJoinByDateCheck(e, constantDateTime) select e; or something like this: intervalTable.Where(FunctionThatCallsJoinByDateCheck(e, constantDateTime)) (2) I need to use it in some table joins (as linq2sql doesn't provide comparative join): var q2 = from e1 in t1 join e2 in t2 on e1.FK == e2.PK where OtherFunctionThatCallsJoinByDateCheck(e2, e1.FromDate) or var q2 = from e1 in t1 from e2 in t2 where e1.FK == e2.PK && OtherFunctionThatCallsJoinByDateCheck(e2, e1.FromDate) (3) I need to use it in some queries like this: var q3 = from e in intervalTable.FilterFunctionThatCallsJoinByDateCheck(constantDate); Dynamic linq is not something that I can use, so I have to stick to plain linq. Thank you Clarification: Initially I had just the last method (FilterFunctionThatCallsJoinByDateCheck(this IQueryable<IDateInterval> entities, DateTime dateConstant) ) that contained the code from the expression. The problem is that I get a SQL Translate exception if I write the code in a method and call it like that. All I want is to extend the use of this function to the where clause (see the second query in point 2)

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  • Creating a Type object corresponding to a generic type

    - by Alexey Romanov
    In Java, how can I construct a Type object for Map<String, String>? System.out.println(Map<String, String>.class); doesn't compile. One workaround I can think of is private Map<String, String> dummy() { throw new Error(); } Type mapStringString = Class.forName("ThisClass").getMethod("dummy", null).getGenericReturnType(); Is this the correct way?

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  • Generic Lists copying references rather than creating a copiedList

    - by Dean
    I was developing a small function when trying to run an enumerator across a list and then carry out some action. (Below is an idea of what I was trying to do. When trying to remove I got a "Collection cannot be modified" which after I had actually woken up I realised that tempList must have just been assigned myLists reference rather than a copy of myLists. After that I tried to find a way to say tempList = myList.copy However nothing seems to exist?? I ended up writing a small for loop that then just added each item from myLsit into tempList but I would have thought there would have been another mechanism (like clone??) So my question(s): is my assumption about tempList receiving a reference to myList correct How should a list be copied to another list? private myList as List (Of something) sub new() myList.add(new Something) end sub sub myCalledFunction() dim tempList as new List (Of Something) tempList = myList Using i as IEnumerator = myList.getEnumarator while i.moveNext 'if some critria is met then tempList.remove(i.current) end end using end sub

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  • Stepping into Ruby Meta-Programming: Generating proxy methods for multiple internal methods

    - by mstksg
    Hi all; I've multiply heard Ruby touted for its super spectacular meta-programming capabilities, and I was wondering if anyone could help me get started with this problem. I have a class that works as an "archive" of sorts, with internal methods that process and output data based on an input. However, the items in the archive in the class itself are represented and processed with integers, for performance purposes. The actual items outside of the archive are known by their string representation, which is simply number_representation.to_s(36). Because of this, I have hooked up each internal method with a "proxy method" that converts the input into the integer form that the archive recognizes, runs the internal method, and converts the output (either a single other item, or a collection of them) back into strings. The naming convention is this: internal methods are represented by _method_name; their corresponding proxy method is represented by method_name, with no leading underscore. For example: class Archive ## PROXY METHODS ## ## input: string representation of id's ## output: string representation of id's def do_something_with id result = _do_something_with id.to_i(36) return nil if result == nil return result.to_s(36) end def do_something_with_pair id_1,id_2 result = _do_something_with_pair id_1.to_i(36), id_2.to_i(36) return nil if result == nil return result.to_s(36) end def do_something_with_these ids result = _do_something_with_these ids.map { |n| n.to_i(36) } return nil if result == nil return result.to_s(36) end def get_many_from id result = _get_many_from id return nil if result == nil # no sparse arrays returned return result.map { |n| n.to_s(36) } end ## INTERNAL METHODS ## ## input: integer representation of id's ## output: integer representation of id's def _do_something_with id # does something with one integer-represented id, # returning an id represented as an integer end def do_something_with_pair id_1,id_2 # does something with two integer-represented id's, # returning an id represented as an integer end def _do_something_with_these ids # does something with multiple integer ids, # returning an id represented as an integer end def _get_many_from id # does something with one integer-represented id, # returns a collection of id's represented as integers end end There are a couple of reasons why I can't just convert them if id.class == String at the beginning of the internal methods: These internal methods are somewhat computationally-intensive recursive functions, and I don't want the overhead of checking multiple times at every step There is no way, without adding an extra parameter, to tell whether or not to re-convert at the end I want to think of this as an exercise in understanding ruby meta-programming Does anyone have any ideas? edit The solution I'd like would preferably be able to take an array of method names @@PROXY_METHODS = [:do_something_with, :do_something_with_pair, :do_something_with_these, :get_many_from] iterate through them, and in each iteration, put out the proxy method. I'm not sure what would be done with the arguments, but is there a way to test for arguments of a method? If not, then simple duck typing/analogous concept would do as well.

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  • Trouble rendering a view inside a generic class

    - by Horace Loeb
    I'm trying to encapsulate the logic for generating my sitemap in a separate class so I can use Delayed::Job to generate it out of band: class ViewCacher include ActionController::UrlWriter def initialize @av = ActionView::Base.new(Rails::Configuration.new.view_path) @av.class_eval do include ApplicationHelper end end def cache_sitemap songs = Song.all sitemap = @av.render 'sitemap/sitemap', :songs => songs Rails.cache.write('sitemap', sitemap) end end But whenever I try ViewCacher.new.cache_sitemap I get this error: ActionView::TemplateError: ActionView::TemplateError (You have a nil object when you didn't expect it! The error occurred while evaluating nil.url_for) on line #5 of app/views/sitemap/_sitemap.builder: I assume this means that ActionController::UrlWriter is not included in the right place, but I really don't know

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  • Generic JSON parser in .NET / WPF?

    - by niklassaers
    I've read lots of tutorials on how to deserialize a JSON object to an object of a particular using DataContractJsonSerializer. However, I'd like to deserialize my object to a Dictionary consisting of either Strings, Arrays or Dictionaries, such as System.Json does with SilverLight when I say JsonObject.Parse(myJSONstring). Is there an equivalent to System.Json that I can use in my WPF project? (just a short background: I'm fetching JSON objects that have way to much info, and I just want to use a little bit to fill out a String array) Cheers Nik

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  • K/APL style programming in C++?

    - by anon
    I'm writing code in C++, but I really like K/APL's array-oriented style. Does anyone know of a good set of operator overloading tricks / macros / ... to allow some K/APL -style programming in C++? Thanks!

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  • Exporting data to an accounting system for billing and invoicing - is there any generic standard pra

    - by Ali
    Hi guys, I've built a web application which basically logs work that has been done upon projects plus maintain resources used etc. What I need now is to set it up so that projects can be billed. Billed such that - each task that has been undertaken in a project is regarded as a billable service. Instead of building my own invoicing system and accounts management system I was wondering if there was any standard data format i.e in xml DTD or so to which I could set up the information so it could be imported by a third party accounting system for billing - or if not then what is the best way to accomplish this. I need to integrate invoicing capabilities somehow - better if its third party as I don't wish to have to go through building an entire accounting system.

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  • Create Generic Class Instance from Static Method in a Derived Class

    - by user343547
    I have a class in C# with a template and static method similar to class BClass<T> { public static BClass<T> Create() { return new BClass<T>(); } } From this I derive a class and specify a template parameter to the base class class DClass : BClass<int> { } A problem occurs when I try to use the static method to create an instance of D class Program { static void Main(string[] args) { DClass d = DClass.Create(); } } Gives a compiler error "Cannot implicitly convert type 'Test.BClass<int ' to 'Test.DClass'." Adding the below cast leads to a runtime casting exception. DClass d = (DClass)DClass.Create(); Is there any succint way to allow the static method to create instances of the derived class? Ideally I would like the equivalent of a c++ typedef and I don't want the below syntax (which does work). BClass<int> d = DClass.Create();

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  • Good Open Source Code to learn Web Programming

    - by Prabu
    Hi can someone point me to some Good Open Source Code to learn Web Programming (Language doesn't matter). i'm looking for source code of web-applications not frameworks I'm not a beginner, I can code to some extent. I want to know how stuffs are done in real world applications.

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  • Best programming language for a beginner to learn?

    - by Dean
    I am teaching my friend how to program in C, he has no programming experience. He wants to learn C so that he can program different microprocessors. I have suggested he learn another language something like java or ruby so that he can learn basics before moving on to a language like C. Is this advisable or should i just teach him C?

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  • An analog of String.Join(string, string[]) for List<T> or other generic enumerable

    - by abatishchev
    class String contains very useful method - String.Join(string, string[]). It creates a string from an array, separating each element of array with a symbol given. But general - it doesn't add a separator after the last element! I uses it for ASP.NET coding for separating with "<br />" or Environment.NewLine. So I want to add an empty row after each row in asp:Table. What method of IEnumerable<TableRow> can I use for the same functionality?

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