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• Alternative to c++ static virtual methods

  - by Jaime Pardos

  In C++ is not possible to declare a static virtual function, neither cast a non-static function to a C style function pointer. Now, I have a plain ol' C SDK that uses function pointers heavily. I have to fill a structure with several function pointers. I was planning to use an abstract class with a bunch of static pure virtual methods, and redefine them in derived classes and fill the structure with them. It wasn't until then that I realized that static virtual are not allowed in C++. Is there any good alternative? The best I can think of is defining some pure virtual methods GetFuncA(), GetFuncB(),... and some static members FuncA()/FuncB() in each derived class, which would be returned by the GetFuncX(). Then a function in the abstract class would call those functions to get the pointers and fill the structure.

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• Compiler doesn't find methods from base class

  - by Paul

  I am having a problem with my virtual methods in a derived class. Here are my (simplified) C++ classes. class Base virtual method accept( MyVisitor1* v ) { /*implementation is here*/ }; virtual method accept( MyVisitor2* v ) { /*implementation is here*/ }; virtual method accept( MyVisitor3* v ) { /*implementation is here*/ }; class DerivedClass virtual method accept( MyVisitor2* v ) { /*implementation is here*/ }; The following use causes VS 2005 to give: "error C2664: 'DerivedClass::accept' : cannot convert parameter 1 from 'Visitor1*' to 'Visitor2 *'". DerivedClass c; MyVisitor1 v1; c.accept(v1); I was expecting the compiler to find and call Base::accept(MyVisitor1) for my DerivedClass as well. Obviously this is not working, but I don't understand why. Any ideas? Thanks, Paul

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• Should I use implicit conversions to enforce preconditions?

  - by Malvolio

  It occurs to me that I could use use implicit conversions to both announce and enforce preconditions. Consider this: object NonNegativeDouble { implicit def int2nnd(d : Double) : NonNegativeDouble = new NonNegativeDouble(d) implicit def nnd2int(d : NonNegativeDouble) : Double = d.v def sqrt(n : NonNegativeDouble) : NonNegativeDouble = scala.math.sqrt(n) } class NonNegativeDouble(val v : Double ) { if (v < 0) { throw new IllegalArgumentException("negative value") } } object Test { def t1 = { val d : Double = NonNegativeDouble.sqrt(3.0); printf("%f\n", d); val n : Double = NonNegativeDouble.sqrt(-3.0); } } Ignore for the moment the actual vacuity of the example: my point is, the subclass NonNegativeDouble expresses the notion that a function only takes a subset of the entire range of the class's values. First is this: A good idea, a bad idea, or an obvious idea everybody else already knows about Second, this would be most useful with basic types, like Int and String. Those classes are final, of course, so is there a good way to not only use the restricted type in functions (that's what the second implicit is for) but also delegate to all methods on the underlying value (short of hand-implementing every delegation)?

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• flex/actionscript assignment failing?

  - by user346713

  I'm seeing something weird in my actionscript code I have two classes foo and bar, bar extends foo. In a model class I have a foo member variable, I assign an bar object to the foo variable. But after the assignment the foo variable is null. [Bindable] public var f:foo; public function someFunc(arr:ArrayCollection):void { if(arr.length > 0) { var tempBar:bar = arr.getItemAt(0) as bar; if(tempBar != null) { tempBar.someProp++; f = tempBar; // f is now null } } } Any ideas on what I could be doing wrong?

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• PHP APC - Why is loading cached array op codes slow?

  - by Aaron Kreider

  I'm using APC to reduce my loading time for my PHP files. My files load very fast, except for one file where I define more than 100 arrays. This 270 kb file takes 200 ms to load. The rest of the files are full of objects, methods, and functions. I'm wondering: does OP code caching not work as well for arrays? My APC cache should be big enough to handle all of my classes. Currently 40% of my cache is free. My hit rate is 99%. apc.shm_size=32 M apc.max_file_size = 1M apc.shm_segments= 1 APC 3.1.6 I'm using PHP 5.2, Apache 2, and Windows Vista.

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• Process for linking static ObjC libraries in XCode

  - by madmik3

  I'm trying to link to a static library and I keep getting linker errors. I've found a few sites that post examples but I have not been able to see what I am doing wrong. First I create a project that will link to my lib add existing files find my .xcodeproj file select "Copy items into destination groups folder"... Select my host project as Add To Targets. Then I add a direct dependency to my host app expand targets double click MyHost.app click + under direct dependencies select my lib Then I set build flags double click MyHost application icon in Groups and Files. click the build tab then I set the OtherLinerFlag to -ObjC then I set Header Search Paths to my header file location for my static library. I pass the compile stage but any classes in my static lib cause linker error: literal-pointer@_OBJC@_cls_refs@SomeClass in MyHost.o thanks!

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• Grails domain class initialization

  - by Don

  Hi, My Grails app has the following Spring bean defined in spring/resources.groovy calendarService(CalendarService) { bean -> bean.initMethod = "init" } This method looks something like: class CalendarService { void init() { User.findByEmail("[email protected]") } } When I call the dynamic finder findByEmail I get a MissingMethodException. My guess is that I'm trying to call this method too early, i.e. before the domain classes have had the dynamic finders added to their metaclass. One solution would be to call CalendarService.init() myself from Bootstrap.init, rather than instructing Spring to call it, but is there a better solution? Thanks, Don

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• E4X in ActionScript

  - by Brian Genisio

  Hey all, Looking at the E4X implementation in ActionScript, it occurs to me that they had to figure out how to do three things that I am not sure can be done within ActionScript regularly: Properties/Getters prefixed with @: var myAttribute = xmlPerson.@name; Nameless functions for filtering: xmlData.person.(/* predicate */) lambda syntax for predicates: xmlData.person.(@name == "Brian") So here is my question: Are these just one-off capabilities (much like Vector.<>) they put in just for E4X, therefore keeping out of reach for us? Or do we, as ActionScript developers, have access to these features? More specifically, I'd love to get access to the expression tree of that lambda predicate for my own code (not tied to the XML classes in any way). I figured out that this is called the "filter operator"... but I am not sure how to harness it. Not sure I can... since ActionScript does not allow for operator overloading :(

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• Generics and Exposing .Net Types For COM Consumers?

  - by IbrarMumtaz

  I remember seeing a question on my official MS 70-536 exam that talked about a simple class that was designed to be exposed for COM calling clients and etc. of all the members defined in the classes I chose the answer D. The one that used a generic. My question to you guys is this: If you were designing a .net custom type that was to be eventually consumed by a com caller or a com type .... of all the guidelines I have read on this subject. Generics is the one .Net topic I would not include in a class for this purpose I would omit such a data member or use something else? Am I right in thinking this. As soon as I saw this question I knew it was generics but I can't seem to prove it. Surely I did not make this up ... generics is a .net feature right?

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• C# Class Instantiation Overflow

  - by Goober

  Scenario I have a C# Win Forms App, where the Main Form contains a loop that creates 3000 Instances of another form (Form B). Inside Form B there are a large number of properties and fields and a bunch of methods that do a fair amount of processing. Question Will the creation of 3000 of these classes give me problems? I'm thinking along the lines of memory exceptions? I've had 1 or 2 already, and I've also had an exception that says something along the lines of "Something went bang and this is usually a sign of corrupt memory somewhere else". Setup I'm using a DevExpress Ribbon Form and I haven't implemented Dispose on anything....Do I need to? Help greatly appreciated.

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• What VS Projecttype for Model and Database?

  - by Tim

  Hello folks, i've just started a new asp.net project which could increase fastly(a small erp-system for our company). So i thought it would be a good idea to split at least the model from the view/controller(the asp.net project). Because it could be that i need to access some classes and the database from a windows app in future, i dicided to put the Model into its own Project. What Visual Studio 2005 Professional Projecttype is most suitable for this requirement and why? SqlServerProject (DB is MS Sql Server 2005 EP) Class Library Web Service Application Database project no separate Project/other(keep in mind VS 2005 has no ASP.NET MVC-Project) Thanks

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• Dynamic CSS class names in GWT

  - by Anupam Jain

  I am in the process of porting a simple CSS grid system to GWT. My CSS file currently has classes like .size1, .size2 etc., and I have a CSS resource that looks like - class MyResource extends CSSResource { @ClassName("size1") String size1(); @ClassName("size2") String size2(); // And so on } However what I really want, is to have a single function like the following - String size(int size); which will generate the appropriate class when passed the size as an integer at runtime. This is needed as I perform some calculations to determine the actual space available/needed for a widget in javascript and then attach the appropriate class name. Is this something that is even possible with GWT?

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• Problems adding static library QT project

  - by Smek

  I have problems adding a static library to my Qt project. I have two project one is my static library and the other one is a Qt GUI project. As I add all classes to my GUI project as c++ or header files everything works just fine but I want this to be in a separate library. When I select the option to add a library I check External library then I select the .a file I have build and the folder where my header files can be found because I am working on a Mac I select Mac as the target platform. Then I click continue and then done. macx: LIBS += -L$$PWD/../../MyLib/build-MyLib-Desktop_Qt_5_2_1_clang_64bit-Debug/ -lMyLib INCLUDEPATH += $$PWD/../../MyLib/build-MyLib-Desktop_Qt_5_2_1_clang_64bit-Debug/include DEPENDPATH += $$PWD/../../MyLib/build-MyLib-Desktop_Qt_5_2_1_clang_64bit-Debug/include macx: PRE_TARGETDEPS += $$PWD/../../MyLib/build-MyLib-Desktop_Qt_5_2_1_clang_64bit-Debug/libMyLib.a When I build my GUI project I get the following error: The process "/usr/bin/make" exited with code 2. Can anyone tell me what the problem can be and how to resolve the problem? Thanks

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• Ruby get inheriting class

  - by Brian D.

  I'm working on creating my first plugin for rails. I'm still pretty new to ruby and I was wondering if its possible to get the inheriting class? For example, I'm trying to create a plugin that will allow unit testing and functional testing when you are not using migrations. What I'm trying to do is initialize a class variable named controller to be initialized to the type of controller that is being tested. If I have a base class ControllerTest: class ControllerTest < Test::Unit::TestCase attr_accessor :controller def initialize super @controller = "call function that will find the inheriting classes name and create an instance of that controller type." end end So what I'm currently stuck on is getting the name of the inheriting class. Is this possible? And if not, does anyone know another way on how I could go about implementing this? Thanks in advance.

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• Maven: Multiple class with the same path implemented in different jar

  - by Phuong Nguyen de ManCity fan

  I'm running into trouble with having multiple class with the same path (i.e. same name, same package!!!). For some reason, gwt-dev comes with its own version of org.apache.xerces.jaxp.DocumentBuilderFactoryImpl and javax.xml.parsers.DocumentBuilderFactory. At the same time, spring also depends on these classes but from different jar. I don't know what should be, but look like xalan & xml-api are the two dependencies that spring depends on (these dependency are optional) Funny thing is that eclipse can run the same code (it's a unit test) without problem, but surefire cannot. So I guess the problem is due to the way each runner consider the priority of each jar. Now come to the question: How can I setup my POM so that I can sure that when ever any code running inside my app, then class from a jar will be selected over class from other jar? Thanks.

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• .NET ORM and Security

  - by Sphynx

  We're going to use an ORM tool with a .NET desktop application. The tool allows creation of persistent classes. It generates all database tables automatically. In addition to other data, our system needs to store user credentials, and deliver access control. The question is, is there any possibility of access control by means of ORM, without creating the database authentication mechanisms manually? Is there any product on the market which allows this? We thought of limiting the access in the program itself, but users can easily access the database directly, and bypass the program limitations. Thanks.

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• Declare 2 types inside using statement gives compile error?

  - by citronas

  I want to use this line of code: using (ADataContext _dc = new ADataContext(ConnectionString), BDataContext _dc2 = new BrDataContext(ConnectionString)){ // ...} This gives a compile error: Cannot use more than one type in a for, using, fixed or declartion statement. I thought this was possible? MSDN says it is: http://msdn.microsoft.com/en-us/library/yh598w02%28VS.80%29.aspx In the MSDN sample code Font is used, which is class and thereby a reference type as well as my two DataContext classes. What went wrong here? How does my attempt differ from the MSDN sample?

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• Deserialization on client side in Domain Service

  - by ankit

  I have 2 classes: Person and Contact. Person class has a property named ContactNumber which returns the Contact type, and this property is marked as a DataMember for serialization. I have marked Contact type as a DataContract. On the client side I am able to get the values, but when I try to insert a value and then do submit, I get the following exception: Failed to deserialize change-set. Failed to convert value of type 'Dictionary`2' to type 'Contact' Stack Trace is: at System.Web.Ria.DataServiceSubmitRequest.GetChangeSet(DomainService domainService) at System.Web.Ria.DataServiceSubmitRequest.Invoke(DomainService domainService) at System.Web.Ria.DataService.System.Web.IHttpHandler.ProcessRequest(HttpContext context) Can anyone give me the solution ?

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• Which langauge should i use for Artificial intelligence on web projects

  - by Mirage

  I have to do one project for my thesis involving Artificial intelligence, collaborative filtering and machine learning methods. I only know PHP/mysq/JS, and there is not much AI stuff examples in PHP. There are some books on AI on internet but they use Java , Python. Now I have to apply AI techniques on web application. Which language should i choose java or python. I searhed on internet that I can call java classes inside my php so that can help as as I am very good at php I have also seen that python can also be used with php as well So which way should I go and roughly how much it will take me to learn java I have done java basics but that was 6 years ago

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• Internet and Intellisense bad for your memory?

  - by Barry Jones

  Having programmed for a while now I have noticed that I am becoming more and more reliant on the internet and intellisense to do my job. But I was wondering how much that has effected my knowledge over the past year or so. But does this matter? For example I am more likely now to remember that when I need to program against objects I have no knowledge about, I will go to the System.Reflection namespace and a quick look down the list will provide me with enough detail to get going again. But if you was to ask me which classes etc are required I would struggle to name them all. This problem of remembering seems to manifest itself more when going for interviews when people seem to focus more on the minute detail of obscure areas of the .NET framework and not on the wide and varied knowledge and experience of the applicant. Anyway I digress. Does anyone else think that maybe its time to turn of the intellisense and try and find better ways to learn, then quick fixes and work arounds of the internet?

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• C++ method declaration, class definition problem

  - by John Fra.

  I have 2 classes: A and B. Some methods of class A need to use class B and the opposite(class B has methods that need to use class A). So I have: class A; class B { method1(A a) { } } class A { method1(B b) { } void foo() { } } and everything works fine. But when I try to call foo() of class A from B::method1 like this: class B { method1(A a) { a.foo(); } } I get as result compile errors of forward declaration and use of incomplete type. But why is this happening? (I have declared class A before using it?)

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• How to recognize the touch of a non regular sprite image ?

  - by srikanth rongali

  I have a sprite and if it is touched the touch should be recognized. I used the coordinates to do so. I took the coordinates (min x, min y, max x , max y)of the sprite image. But The sprite image is not a rectangular shape. So, even if I touch the coordinates outside the sprite and inside the rectangular bounds the sprite is recognized. But for my application I need only the sprite to be recognized. So, I have to take only the coordinates of the sprite, but it is not regular shape. I am using CCSprite in my program. So, what can I do to for only the sprite to be selected ? Which classes should use for this? Thank You.

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• C++/CLI Mixed Mode DLL Creation

  - by Adam Haile

  I've got a native C++ DLL that I would like to have a C++/CLI wrapper layer for. From what I understood, if you simple added a C++/CLI class to the project, VS would compile as mixed mode, but I was apparently wrong as VS doesn't seem to be even touching the managed code. So, given a pre-existing native code-base what exactly, step-by-step, do you need to do to create a mixed mode DLL, so that I can can link into that code from any .NET language? *I need to do this because my native code uses C++ classes that I cannot P/Invoke into.

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• C#: Problem trying to resolve a class when two namespaces are similar

  - by rally25rs

  I'm running into an issue where I can't make a reference to a class in a different namespace. I have 2 classes: namespace Foo { public class Class1 { ... } } namespace My.App.Foo { public class Class2 { public void SomeMethod() { var x = new Foo.Class1; // compile error! } } } The compile error is: The type or namespace name 'Class1' does not exist in the namespace 'My.App.Foo' In this situation, I can't seem to get Visual Studio to recognize that "Foo.Class1" refers to the first class. If I mouse-over "Foo", it shows that its trying to resolve that to "My.App.Foo.Class1" If I put the line: using Foo; at the top of the .cs file that contains Class2, then it also resolves that to "My.App.Foo". Is there some trick to referencing the right "Foo" namespace without just renaming the namespaces so they don't conflict? Both of these namespaces are in the same assembly.

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• Scala model-view-presenter, traits

  - by Ralph

  I am a fan of Martin Fowler's (deprecated) model-view-presenter pattern. I am writing a Scala view class containing several button classes. I would like to include methods to set the action properties of the buttons, to be called by the presenter. A typical code fragment looks like this: private val aButton = new JButton def setAButtonAction(action: Action): Unit = { aButton.setAction(action) } This code is repeated for each button. If Java/Scala had the C preprocessor, I would create a macro to generate this code, given the button name (no lectures on the evils of the C preprocessor, please). This code is obviously very verbose and repetitive. Is there any better way way to do this in Scala, perhaps using traits? Please hold the lectures about scala.swing. I looking for a general pattern here.

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