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• Why delegate types are derived from MulticastDelegate class why not it directly derive from Delegate class?

  - by Vijay

  I have a very basic question regarding delegate types. I compared the memebers of Delegate and MulticastDelegate classes in object browser and I couldn't find any new additional member present in MulticastDelegate. I also noticed that the Delegate class has GetInvocationList virtual method. So I assume that the Delegate class should have the capability to hold references to multiple methods. If my assumption is correct I wonder why not custom delegate types directly derive from the Delegate class instead of MulticastDelegate class. Not sure what I am missing here. Please help me understand the difference.

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• The pImpl idiom and Testability

  - by Rimo

  The pImpl idiom in c++ aims to hide the implementation details (=private members) of a class from the users of that class. However it also hides some of the dependencies of that class which is usually regarded bad from a testing point of view. For example if class A hides its implementation details in Class AImpl which is only accessible from A.cpp and AImpl depends on a lot of other classes, it becomes very difficult to unit test class A since the testing framework has no access to the methods of AImpl and also no way to inject dependency into AImpl. This has been a problem for me lately and I am beginning to think that the pImpl idiom and writing testable code don't mix well. Has anyone come across this problem before? and have you found a solution?

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• Objects with inheritance memory storage

  - by nikitas350

  Say that i have some classes like this example. class A { int k, m; public: A(int a, int b) { k = a; m = b; } }; class B { int k, m; public: B() { k = 2; m = 3; } }; class C : private A, private B { int k, m; public: C(int a, int b) : A(a, b) { k = b; m = a; } }; Now, in a class C object, are the variables stored in a specific way? I know what happens in a POD object, but this is not a POD object...

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• "Method name expected" error when trying add a handler method to a delegate - C#

  - by zakplayyy

  I keep getting the error "Method name expected" when trying add the a method to a delegate. I have a delegate which is invoked when ever my game ends. The function I'm trying to add to the delegate stops a countdown from flashing (the method is in a static class). I've searched about and I'm still unsure why its not working. Here is the line causing the error: LivesManager.gameEnded += new LivesManager.EndGame(CountdownManager.DisableFlashTimer(this)); The this passes the current form to the method so it can disable the timer flash on the form. I have added methods from static classes to the same delegate before and it works fine, the only difference is that I'm passing the form as a paramater and then it doesn't like it. Is there any way to pass the form to the method without the error? Thanks in advance :)

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• port an iOS (iPhone) app to mac?

  - by William Jockusch

  Is there a preferred way to go about this? The app in question is not too large . . . single-player game that I wrote over the course of a couple of months. EDIT: I should add that I have no experience with mac development . . . outside of what comes naturally with being an iOS developer. EDIT: Classes heavily used in the game: subclasses of NSObject, UIView, and UIViewController. I don't know much about NSView, but I'm pretty sure all the UIView stuff will work in that class. Also some use of UITableViewController. I do also have Game Center, but I can leave that part out for now. There is no multi-touch.

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• name of class that manipulates the entities

  - by cyberguest

  hi, i have a general question regarding naming convention. if I separate the data and operations into two separate classes. one has the data elements (entity), the other class manipulates the entity class. what do we usually call that class that manipulates the entity class? (the entity I am referring to has nothing to do with any kind of entity framework) manager? controller? operator? manipulator? thanks in advance

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• Coordinating 3 instances of Cycle on one page

  - by Wendy H

  I have 3 images, all same size, across top of page horizontally. I'd like to use Cycle to fade each instance very slowly, but I'd also like make sure the transitions do not start all at the same time, but are staggered. Is there somewhere this can be specified? If anyone can recommend a very slow fade rate, plus a way to prevent all 3 from fading/regenerating at the same time, I'd be very grateful! I assume I can run 3 instances of cycle using different classes for each container, and assure that no two photos are the same by "stacking" them in different orders within the divs ... yes? Thank you!

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• Linq to SQL DateTime values are local (Kind=Unspecified) - How do I make it UTC?

  - by ericsson007

  Isn't there a (simple) way to tell Linq To SQL classes that a particular DateTime property should be considered as UTC (i.e. having the Kind property of the DateTime type to be Utc by default), or is there a 'clean' workaround? The time zone on my app-server is not the same as the SQL 2005 Server (cannot change any), and none is UTC. When I persist a property of type DateTime to the dB I use the UTC value (so the value in the db column is UTC), but when I read the values back (using Linq To SQL) I get the .Kind property of the DateTime value to be 'Unspecified'. The problem is that when I 'convert' it to UTC it is 4 hours off. This also means that when it is serialized it it ends up on the client side with a 4 hour wrong offset (since it is serialized using the UTC).

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• Do I really need to return Type::size_type?

  - by dehmann

  I often have classes that are mostly just wrappers around some STL container, like this: class Foo { public: typedef std::vector<whatever> Vec; typedef Vec::size_type; const Vec& GetVec() { return vec_; } size_type size() { return vec_.size() } private: Vec vec_; }; I am not so sure about returning size_type. Often, some function will call size() and pass that value on to another function and that one will use it and maybe pass it on. Now everyone has to include that Foo header, although I'm really just passing some size value around, which should just be unsigned int anyway ...? What is the right thing to do here? Is it best practice to really use size_type everywhere?

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• Java inheritance question

  - by user247866

  So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = method-call();` // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void some-method(LIst<A> a) However, when I do: C c = new C(). c. some-method(b) I get an error that some-method is not applicable for the argument List, instead it's expecting to get List. Is there a good way to fix this problem? Many thanks!

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• Passing enum or object through an intent (the best solution)

  - by jax

  I have an activity that when started needs access to two different ArrayLists. Both Lists are different Objects I have created myself. Basically I need a way to pass these objects to the activity from an Intent. I can use addExtras() but this requires a Parceable compatible class. I could make my classes to be passed serializable but as I understand this slows down the program. What are my options? Can I pass an Enum? As an an aside: is there a way to pass parameters to an Activity Constructor from an Intent?

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• Checking variable from a different class in C#

  - by Josh

  Greetings- I have 2 classes. One is called "Programs" and the other is called "Logs". The class called Programs has public const string m_sEnviron = ""; near the top and I need to check what the m_sEnviron variable is set to through my class called Logs. The variable m_sEnviron will get set from a scheduler called Tidal so how can I check its value from a different class. If this is not the best to do this then please let me know what the better ways are. Thanks in advance. Regards,

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• Good JDBC pattern

  - by Java Developer

  What is the good practice for database operation in Java application? Do you construct the DML syntax in the Java code and send the statements to DB engine for execution, or you just collect the parameters and then make a call to stored procedure with the parameters via java code? or neither because that's just not how to do it? can anyone give an example of a full database utility classes to do database operations in Java app? also what about the transaction manager? My assignment is to make database operation that is modular in Java. Thanks

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• Is Java class initialized by the thread which use it for the first time?

  - by oo_olo_oo

  Lets assume following classes definition: public class A { public final static String SOME_VALUE; static { SOME_VALUE = "some.value"; } } public class B { private final String value = A.SOME_VALUE; } Assuming that the class A hasn't been loaded yet, what does happen when object of the class B is instantiated by some thread T? The class A has to be loaded and instantiated first. But my question is: if it's done in context of the thread T, or rather in context of some other (special) "classloader" thread?

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• Are static members of a generic class tied to the specific instance?

  - by mafutrct

  This is more of a documentation than a real question. I noticed the principle it is not described on SO yet (did I miss it?), so here goes: Imagine a generic class that contains a static member: class Foo<T> { public static int member; } Is there a new instance of the member for each specific class, or is there only a single instance for all Foo-type classes? It can easily be verified by code like this: Foo<int>.member = 1; Foo<string>.member = 2; Console.WriteLine (Foo<int>.member); What is the result, and where is this behavior documented?

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• Load custom class properly

  - by LinusAn

  I have a custom class which I want to "load" inside the firstViewController and then access it from other classes by segues. My Problem is, I can't even access and change the instance variable inside the firstViewController. Somehow I'm "loading" it wrong. Here is the code I used until now: inside viewController.h @property (strong, nonatomic) myClass *newClass; inside viewController.m @synthesize newClass; I then try to access it by: self.newClass.string = @"myString"; if(newClass.string == @"myString"){ NSLog(@"didn't work"); } Well, I get "didn't work". Why is that? When I write myClass *newClass = [myClass new]; It does work. But the class and its properties gets overwritten every time the ViewController loads again. What would you recommend? Thank you very much.

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• Why does String.Equals(Object obj) check to see if this == null?

  - by m-y

  // Determines whether two strings match. [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)] public override bool Equals(Object obj) { //this is necessary to guard against reverse-pinvokes and //other callers who do not use the callvirt instruction if (this == null) throw new NullReferenceException(); String str = obj as String; if (str == null) return false; if (Object.ReferenceEquals(this, obj)) return true; return EqualsHelper(this, str); } The part I don't understand is the fact that it is checking for the current instance, this, against null. The comment is a bit confusing, so I was wondering what does that comment actually mean? Can anyone give an example of how this could break if that check was not there, and does this mean that I should also place that check in my classes?

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• Localized database strings

  - by Steve

  I have a small Grails application that has the following domain: class Meal { String name String description String allergyNote } For localization purposes the three strings should now be available in multiple languages. For example, while an English user would see name="Steak", a Spanish user should see name="Filete" in the output. I was thinking of doing the following: class Language { String isoCode String languageName } class TranslatedString { Language language String translation } but I am not sure how to link the Meals with the TranslatedStrings as it is used for three members, also I would like to use it for other classes (not just Meal) as well (or do I need to have separated tables, i.e. a MealNameTranslated, MealDescriptionTranslated, etc tables?). I know this is probably a stupid question, but I am a beginner and have not been able to figure this out :-(

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• Help in restructuring a project

  - by mrblah

  I have a commerce application, asp.net mvc. I want it to be extensible in the sense others can create other payment providers, as long as they adhere to the interfaces. /blah.core /blah.web /blah.Authorize.net (Implementation of a payment provider using interfaces Ipaymentconfig and paymentdata class) Now the problem is this: /blah.core - PaymentData /blah.core.interfaces - IPaymentConfig where Payment Data looks like: using blah.core; public class PaymentData { public Order Order {get;set;} } IPayment data contains classes from blah.core like the Order class. Now I want to use the actual Authorize.net implementation, so when I tried to reference it in the blah.core project I got a circular dependency error. How could I solve this problem? Many have said to break out the interfaces into their own project, but the problem is PaymentData references entities that are found in blah.core also, so there doesn't seem to be a way around this (in my head anyhow). How can I redesign this?

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• When should methods be made private?

  - by AaronSzy

  There are lots of times where i'm not sure whether a particular method should be made private or not. For example, i'm building a class right now, which, is responsible for generating a report. This class has a buildReport method and several methods which collect the necessary data for buildReport. // single public method // uses a set of helper methods public buildReport() // helper methods private avgSurveyTime() private fetchVendors() private fetchSendCounts() private ... Im debating whether i should make these helper methods public. The only method i really plan on calling outside at the moment is buildReport. However, it might be useful to get just a list of the vendors with fetchVendors etc. I see two schools of thought on this: You can always expose as little as possible. (In which case, many of my classes would only have one public method) OR you can expose all you can that might be useful to the user of the class. Is there a good rule of thumb to use for deciding when methods should be made public/private?

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• Will [WithEvents = Nothing] RemoveHandlers in the derived class?

  - by serhio

  I use to set WithEvents variables to Nothing in Destuctor, because this will "Remove" all the Handlers associated with Handles keyword. Will this have the same effect for derivated classes? Class A Protected WithEvents _Foo as Button Private Sub _Foo_Click Handles _Foo.Click ' ... some Click action ' End Sub Public Sub Dispose(disposing as Boolean) If disposing then _Foo = Nothing ' remove handler _Foo_Click ' End Sub End Class Class B Inherits A Private Sub _Foo_Move Handles _Foo.Move ' ... some Move action ' End Sub ' ????? will or NOT remove OR handler _Foo_Move the base Dispose??' Public Overrides Sub Dispose(disposing as Boolean) 'If disposing then _Foo = Nothing ' MyBase.Dispose(disposing) End Sub End Class

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• Comparing Java enum members: == or equals() ?

  - by Bears will eat you

  I know that Java enums are compiled to classes with private constructors and a bunch of public static members. When comparing two members of a given enum, I've always used .equals(), e.g. public useEnums(SomeEnum a) { if(a.equals(SomeEnum.SOME_ENUM_VALUE)) { ... } ... } However, I just came across come code that uses the equals operator == instead: public useEnums2(SomeEnum a) { if(a == SomeEnum.SOME_ENUM_VALUE) { ... } ... } I've been programming in Java for 5+ years, and I thought I understood difference between the two - but I'm still scratching my head at which one is more correct. Which operator is the one I should be using?

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• Debug Mode for CodeIgniter?

  - by user350814

  Does CodeIgniter provide a Debug Mode, for example, when accessing an Invalid URL? Ruby on Rails does show debugging Messages when a incorrect URL has been given, and the controller is unable to resolve it using the routes map. How would I enable such debugging messages in CodeIgniter? The profiler ... $this->output->enable_profiler(TRUE); ... only affects single classes, but not all routes. So debugging without an actual debugger mode is a little... difficult. :-)

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• Why does do this code do if(sz !=sz2) sz = sz2 !?!

  - by acidzombie24

  For the first time i created a linq to sql classes. I decided to look at the class and found this. What... why is it doing if(sz !=sz2) { sz = sz2; }. I dont understand. Why isnt the set generated as this._Property1 = value? private string _Property1; [Column(Storage="_Property1", CanBeNull=false)] public string Property1 { get { return this._Property1; } set { if ((this._Property1 != value)) { this._Property1 = value; } } }

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• @MustOverride annotation?

  - by Harrypotter2k5

  In .NET, one can specify a "mustoverride" attribute to a method in a particular superclass to ensure that subclasses override that particular method. I was wondering whether anybody has a custom java annotation that could achieve the same effect. Essentially what i want is to push for subclasses to override a method in a superclass that itself has some logic that must be run-through. I dont want to use abstract methods or interfaces, because i want some common functionality to be run in the super method, but more-or-less produce a compiler warning/error denoting that derivative classes should override a given method.

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