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  • NSString inheritance

    - by Stef
    Hi, I'm doing an useless thing for my first step in Obj-C @interface String : NSString { int m_isnull; } - (id) init; - (int) isNull; @end @implementation String - (id) init { self = [super init]; m_isnull=1; return self; } - (int) isNull { return m_isnull; } @end test : String *a; a=@"ok"; Works fine, but just 2 little questions 1) When I'm compiling I have this warning warning: incompatible Objective-C types assigning 'struct NSString *', expected 'struct String *' I don't know how to avoid it !? 2) a=@"ok" is a fastest way to initialize a string, but when I'm debugging, I don't stop by at my init constructor why ?

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  • What's the difference between => , ()=>, and Unit=>

    - by Malvolio
    I'm trying to represent a function that takes no arguments and returns no value (I'm simulating the setTimeout function in JavaScript, if you must know.) case class Scheduled(time : Int, callback : => Unit) doesn't compile, saying " `val' parameters may not be call-by-name" case class Scheduled(time : Int, callback : () => Unit) compiles, but has to be invoked strangely, instead of Scheduled(40, { println("x") } ) I have to do this Scheduled(40, { () => println("x") } ) What also works is class Scheduled(time : Int, callback : Unit => Unit) but is invoked in an even-less-sensible way Scheduled(40, { x : Unit => println("x") } ) (What would a variable of type Unit be?) What I want of course is a constructor that can be invoke the way I would invoke it if it were an ordinary function: Scheduled(40, println("x") ) Give baby his bottle!

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  • WPF/C# - Sometimes my dropdowns/datepickers will stop functioning?

    - by BlargINC
    Q: Where should I check to track this down? Issue: Opening a view model in my application sometimes makes dropdowns/datepickers nonfunctional. ie. dropdown won't drop and the datepicker calendar won't come up I suspect a binding issue but don't see one. Dropdowns have normal things like strings, numbers. One drop has a list of mini views. Datepickers are bound to nullable dates set in the constructor of the viewmodel. Note: These same things work in other viewmodels/views. I can paste code, I'm just not sure what code is relevant here. Thank you for helping me :)

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  • Count function calls by name or signature. Gcc, C++

    - by MajesticRa
    I have some c++ written package. Linux, gcc. I can modify compilation process (change Makefile, flags, etc.), but can not change C++ source code. One runs the package with different parameters, it does a job and exits. How to count: 1) Number of calls of function with specific name? 2) Number of calls of functions with specific signature? 3) Number of calls of functions where one of the parameters is of specific type i.e. std::string (type is specified by signature)? 4) and extra Number of calls of functions of STL objects, i.e. std::string copy constructor? (I mean count a number of calls during the run. ) I thought to do it with GDB, but I found it very tough to do (1) and have not found how to do (2)-(4) at all. All acceptable answers I will write here for humanity.

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  • Sometimes my dropdowns/datepickers will stop functioning?

    - by BlargINC
    Q: Where should I check to track this down? Issue: Opening a view model in my application sometimes makes dropdowns/datepickers nonfunctional. ie. dropdown won't drop and the datepicker calendar won't come up I suspect a binding issue but don't see one. Dropdowns have normal things like strings, numbers. One drop has a list of mini views. Datepickers are bound to nullable dates set in the constructor of the viewmodel. Note: These same things work in other viewmodels/views. I can paste code, I'm just not sure what code is relevant here.

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  • any way to simplify this with a form of dynamic class instantiation?

    - by gnychis
    I have several child classes that extend a parent class, forced to have a uniform constructor. I have a queue which keeps a list of these classes, which must extend MergeHeuristic. The code that I currently have looks like the following: Class<? extends MergeHeuristic> heuristicRequest = _heuristicQueue.pop(); MergeHeuristic heuristic = null; if(heuristicRequest == AdjacentMACs.class) heuristic = new AdjacentMACs(_parent); if(heuristicRequest == SimilarInterfaceNames.class) heuristic = new SimilarInterfaceNames(_parent); if(heuristicRequest == SameMAC.class) heuristic = new SameMAC(_parent); Is there any way to simplify that to dynamically instantiate the class, something along the lines of: heuristic = new heuristicRequest.somethingSpecial(); That would flatten that block of if statements.

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  • Visual C++ CreateThread Parameter Problem

    - by Vanwaril
    I have a class that contains a function that calls create thread, and needs to pass itself (this) as a parameter: DWORD threadId; HANDLE h = CreateThread( NULL, 0, runThread, this, 0, &threadId); My runThread definition is as follows: DWORD WINAPI runThread(LPVOID args) { Obj *t = (Obj*)args; t->funct(); return 0; } Unfortunately, the object t that I get in runThread() gets garbage. My Obj class has a function pointer attribute. Could that be the problem? class Obj{ void(*funct)(); and in the constructor: Obj(void(*f)()) { funct = f; } where is my mistake? The function pointer, the createThread itself, or type-casting? I tried whatever I could think of.

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  • Is read-only auto-imlemented property possible?

    - by abatishchev
    Hello. I found a topic on MSDN that talks that yes, this is possible. I did a test that seems to break this statement: using System; namespace Test { class Program { static void Main(string[] args) { Foo f = new Foo("1"); Console.WriteLine(f.Bar); // prints 1 f.Test("2"); Console.WriteLine(f.Bar);// successfully prints 2 } } class Foo { public Foo(string b) { this.Bar = b; } public string Bar { get; private set; } public void Test(string b) { // this would be impossible for readonly field! // next error would be occur: CS0191 or CS0191 // A readonly field cannot be assigned to (except in a constructor or a variable initializer) this.Bar = b; } } } Where am I wrong?

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  • Converting C# class to JavaScript

    - by AgileMeansDoAsLittleAsPossible
    Take a look at this basic class: namespace AcmeWeb { public string FirstName { get; set; } public class Person { public Person(string firstName, string lastName) { if (String.IsNullOrEmpty(firstName)) { throw new ArgumentNullException(firstName); } this.FirstName = firstName; } } } What's the best translation of this into JavaScript? This is what I'm thinking: (function(namespace) { namespace.Person = function(firstName, lastName) { // Constructor (function() { if (!firstName) { throw "'firstName' argument cannot be null or empty"; } })(); // Private memberts var _ = { firstName: firstName }; // Public members this.firstName = function(value) { if (typeof(value) === "undefined") { return _.firstName; } else { _.firstName = value; return this; } }; }; })(AcmeWeb);

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  • .net: How do you feed a winform after clicking on a row of a datagridview of search form?

    - by odiseh
    I have a winform which is responsible for doing a search by some conditions that users enters and then selects the records from a Database. The search form has a data grid view which shows the result. After searching, user clikcs on a row of the datagridview and then another form (for example frmShowDetails) will be displayed. My question is when displaying frmShowDetails, what are your suggestions to send the id of selected row to frmShowDetails in order to feed it to show data in .net? Do you use form property or a private mariable which sets by only form constructor? Thank you

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  • Override existing AS3 classes

    - by purga
    For a custom derived class "Vector2" from flash.geom.Point, when trying to override the clone() method (similar to add(), subtract() methods that will return the type itself), it will always complain about incompatible overriding 'cuz the return type has been altered from "Point" to "Vector2". import flash.geom.Point; public class Vector2 extends Point { //Constructor is good public function Vector2(x:Number = 0, y:Number = 0) { super(x,y); } // Error: Incompatible overriding override public function clone():Vector2 //return type has to be "Point" { return new Vector2(this.x , this.y); } } How can we correctly reuse/override the methods provided by the super classes as supposed to create our own one (e.g. : a new clone1() method), or simply we just can't? Thanks.

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  • C# - Silverlight - Custom control or UserControl ?

    - by cmaduro
    I need a button that is visually completely customizable, but has custom logic to publish events and manage it's visual state based on events it has registered for. When I say visually customizable, I mean I should be able to both create the button in xaml and set it's style by binding to the supplied style. Or I can create an instance of the button and set the style by passing a parameter to an alternate constructor. Or by calling a method on the button class to set the style. I do not plan on substituting the controls template, it should be a button. Can anyone point me to some code samples of this?

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  • javascript - Google Chrome cluttering Array generated from .split()

    - by patrick
    Given the following string: var str = "one,two,three"; If I split the string on the commas, I normally get an array, as expected: var arr = str.split(/\s*,\s*/); Trouble is that in Google Chrome (for Mac), it appends extra properties to the array. Output from Chrome's debugger: arr: Array 0: one 1: two 2: three constructor: function Array() index: undefined input: undefined length: 3 So if I iterate over the array with a for/in loop, it iterates over the new properties. Specifically the input and index properties. Using hasOwnProperty doesn't seem to help. A fix would be to do a for loop based on the length of the Array. Still I'm wondering if anyone has insight into why Chrome behaves this way. Firefox and Safari don't have this issue.

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  • Subtle C++ mistake, can you spot it?

    - by aaa
    I ran into a subtle C++ gotcha, took me while to resolve it. Can you spot it? class synchronized_container { boost::mutex mutex_; std::vector <T> container_; void push_back(const T &value) { boost::scoped_lock(mutex_); // raii mutex lock container_.push_back(value); } ... }; scoped lock is a raii mutex lock, obtains lock on constructor, release lock in destructor. The program will work as expected in serial, but will may occasionally produce weird stuff with more than one thread.

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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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  • Why would you use a MyObject[] internally, but expose a List<MyObject>?

    - by timmyd
    I have come across a class that has an immutable property: MyObject[] allObjs The property is initialized like this: List<MyObject> objs = createAllMyObjects(); allObjs = objs.toArray(new MyObject[objs.size()]); When it is exposed through the accessor, it's done as a List: public List<MyObject> getAllMyObjects() { return Collections.unmodifiableList(Arrays.asList(allObjs)); } Why would a programmer do this? Is there a benefit that I don't know about? Performance is not a concern, as the array of objs will only ever number in a few dozen elements. It seems that we are going round and round in circles. The class is a sort of factory, so it's got a private constructor and exposes only static methods (not sure if this could be a reason for the madness).

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  • Are instance initializers good or bad?

    - by berry120
    I personally quite like instance initializers - I use them to assign default values to things such as collections so when writing constructors I don't have to remember to assign them the same default values each time. It seems quite elegant to me - avoids annoying NPE's popping up and avoids duplicate code. A private method doesn't seem as nice because a) it can't assign values to final fields, b) it could be run elsewhere in code and c) the method still needs to be explicitly called at the start of each constructor. However, the flip side with others I have spoken to is that they're confusing, some people reading the code might not understand what they do or when they're called and thus they could cause more problems than they solve. Are proper use of these initializers something to be encouraged or avoided? Or is it an "each to their own" case?

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  • How to initialize static const char array for ASCII codes [C++]

    - by Janney
    I want to initialize a static const char array with ASCII codes in a constructor, here's my code: class Card { public: Suit(void) { static const char *Suit[4] = {0x03, 0x04, 0x05, 0x06}; // here's the problem static const string *Rank[ 13 ] = {'A', '2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K'}; // and here. } However i got a whole lot of errors stating that 'initializing' : cannot convert from 'char' to 'const std::string *' 'initializing' : cannot convert from 'int' to 'const std::string *' please help me! Thank you so much.

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  • How to set value from other class

    - by Ram
    Its said that property should not be "Set" only and it should be "Get" as well. What should i do if I need to set value to a variable from some other class? The will keep changing so I cannot pass it through constructor. Shall I create a function for this as shown below? class A { public void SetValue() { b = new B(); b.SetTest(10); } } class B { int test; public void SetTest(int value) { test = value; } } What are the other alternatives?

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  • programming help

    - by user208639
    class Person holds personal data Its constructor receives 3 parameters, two Strings representing first and last names and an int representing age public Person(String firstName, String lastName, int age) { its method getName has no parameters and returns a String with format "Lastname, Firstname" its method getAge takes no parameters and returns an int representing the current age its method birthday increases age value by 1 and returns the new age value Create the class Person and paste the whole class into the textbox below public class Person { public Person(String first, String last, int age) { getName = "Lastname, Firstname"; System.out.print(last + first); getAge = age + 1; return getAge; System.out.print(getAge); birthday = age + 1; newAge = birthday; return newAge; } } im getting errors such as "cannot find symbol - variable getName" but when i declare a variable it still not working, i also wanted to ask if i am heading in the right direction or is it all totally wrong? im using a program called BlueJ to work on.

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  • Cannot create an array of LinkedLists in Java...?

    - by kchau
    I'm working on a sparse matrix class that needs to use an array of LinkedLists to store the values of a matrix. Each element of the array (i.e. each LinkedList) represents a row of the matrix. And, each element in the LinkedLists represents a column and the stored value. In my class, I have a declaration of the array as: private LinkedList<IntegerNode>[] myMatrix; And, in my constructor for the SparseMatrix, I try to define: myMatrix = new LinkedList<IntegerNode>[numRows]; The error I end up getting is "Cannot create a generic array of LinkedList<IntegerNode>." So, I have two issues with this, 1) What am I doing wrong, and 2) Why is the type acceptable in the declaration for the array if it can't be created? Edit: IntegerNode is a class that I have created. And, all of my class files are packaged together.

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  • Javascript Image object without instantiating

    - by user276027
    This question is about javascript performance. Consider 3 examples for illustration: function loadImgA() { new Image().src="http://example.com/image.gif" } function loadImgA1() { Image().src="http://example.com/image.gif" } function loadImgB() { var testImg = new Image(); testImg.src="http://example.com/image.gif" } Now the point is I don't really need to manipulate the the image object after it was created, hence loadImgA(). The question is, what happens if nothing is assigned to the return value of the new Image() constructor - in that case I can actually skip the 'new' keyword as in loadImgA1()? Does the object then live outside the function or somehow affects memory usage? Other implications, differences? I reckon not, as no real instance was actually created? To put this into perspective, I only need to get the http request for image through. No preloading or other advanced image manipulation. What would be the preferred method from the above?

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  • Question About Classic MVC

    - by kernix
    Hello, In classic MVC the model notifies the view about changes made on it. In C# this means I have to subclass the View I'm interested in and in the subclassed class register to the model's event. For example, if I were to implement MVC using C# and Winforms, I had to subclass TextBox class and then register inside the MyTextBox's constructor for the model events. Am I correct? How was this issued in Smalltalk? Does one also need to subclass every View in order to register the model's events, or is there some way to dynamically add events to the views on the fly? Thanks

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  • Dynamic memory allocation with default values

    - by viswanathan
    class A { private: int m_nValue; public: A() { m_nValue = 0; } A(int nValue) { m_nValue = nValue); ~A() {} } Now in main if i call A a(2);// 2 will be assigned for m_nValue of object A. Now how do we do this if i want to define an array of objects. Also how do we do this if i dynamically create objects using operator new like A *pA; pA = new A[5];// while creating the object i want the parameterised constructor to be //called I hope the question is clear. Do let me know if more explanation is needed

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  • ViewDidLoad not being called with my custom UIViewController

    - by user1060500
    I have created a custom UIViewController class that creates a ScrollView at runtime that it loads into the view. See code here in the constructor of my custom UIViewController. initControl(id, canEdit); _controllers = new NSMutableArray(0); //required to keep view controllers around _scrollView = new UIScrollView(); _scrollView.BackgroundColor = UIColor.Green; this.View = _scrollView; ViewDidAppear and ViewWillAppear are called normally. ViewDidLoad is not called which I am not sure why as the view is showing up on the screen just fine. Any ideas?

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