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Search found 3956 results on 159 pages for 'constructor overloading'.

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• C++ syntax of constructors " 'Object1 a (1, Object1(2))''

  - by osgx

  Hello I have a such syntax in program class Object1 : BaseClass { BaseClass *link; int i; public: Object1(int a){i=a;} Object1(int a, Object1 /*place1*/ o) {i=a; link= &o;} }; int main(){ Object1 a(1, /*place2*/ Object1(2)); ... } What do I need in place1? I want to save a link (pointer) to the second object in the first object. Should I use in place1 reference "&"? What type will have "Object1(2)" in place2? Is it a constructor of the anonymous object? Will it have a "auto" storage type?

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• Can't get a List(Of <my class>) from a Dictionary in .NET?

  - by magsto

  I have a Dictionary with key of type UInteger and the value is List(Of Session) where the (Public) class Session contains a couple of variables and a constructor (Public Sub New(...)). Some of the variables in my Session class is: Private count As Integer Private StartDate As Date Private Values As List(Of Integer) and a couple of methods like: Friend Sub Counter(ByVal c as Integer) count += c End Sub There is no problem to add values to the Dictionary: Dim Sessions As New List(Of Session) Dim dict As New Dictionary(Of Integer, Sessions) then some code to fill up a couple of Session objects in Sessions (not shown here) and then: dict.Add(17, Sessions) 'No problem Sessions.Clear() Sessions = dict(17) 'This doesn't return anything! The Sessions object is empty even if the code doesn't returned any error. Is my class Session to compex to be stored in a Dictionary?

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• WPF data binding issue .

  - by Praveen

  Hi All, I have a wpf app and there i simply have a dock panel and inside dock panel i have a textblock. I want to bind the text property of textblock to my custom objects property but that' not working. I think i am missing something here but don't know what. Here is the code snippet. <TextBlock Text="{Binding Source=myDataSource, Path=ColorName}"/> </DockPanel> My custom class. class MyData { public string ColorName { get; set; } } and main window constructor.. public partial class MainWindow : Window { MyData myDataSource; public MainWindow() { InitializeComponent(); myDataSource = new MyData { ColorName = "Red" }; } }

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• Why isn't the new() generic constraint satisfied by a class with optional parameters in the construc

  - by Joshua Flanagan

  The following code fails to compile, producing a "Widget must be a non-abstract type with a public parameterless constructor" error. I would think that the compiler has all of the information it needs. Is this a bug? An oversight? Or is there some scenario where this would not be valid? public class Factory<T> where T : new() { public T Build() { return new T(); } } public class Widget { public Widget(string name = "foo") { Name = name; } public string Name { get; set; } } public class Program { public static void Main() { var widget = new Widget(); // this is valid var factory = new Factory<Widget>(); // compiler error } }

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• getElementById does return null

  - by pbcoder

  I have following function: $('canvas').createWindow('xyz', 500, 600); And js-code behind is: var $ = function(element) { if (this.constructor !== $) { return new $(element); } alert(element); var windowObj = document.getElementById(element); this.createWindow = function(src, width, height) { if(width != "" && height != "") { windowWidth = windowObj.style.width = width + 'px'; windowHeight = windowObj.style.height = height + 'px'; } }; }; But the problem is that JS says windowObj is null, alert(element) works fine! Thanks for your help!

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• C++: use array of strings wrapped in namespace?

  - by John D.

  I got the following code, wishing to wrap a group of strings nicely in a namespace: namespace msgs { const int arr_sz = 3; const char *msg[arr_sz] = {"blank", "blank", "blank" }; msg[0] = "Welcome, lets start by getting a little info from you!\n"; msg[1] = "Alright, bla bla bla.."; msg[2] = "etc."; } The code inside works nicely inside a function, but I don't know how to return an array from it. The namespace idea LOOKS fine, but it returns on the last three lines: error: expected constructor, destructor, or type conversion before ‘=’ token Why can't I define the array inside a namespace, do I need to do something first? It's nice because I can call it like printf(msgs::msg[1]) etc. I want to do this I just can't wrap my head around what's wrong :(

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• Calling a method on an object a bunch of times versus constructing an object a bunch of times

  - by Ami

  I have a List called myData and I want to apply a particular method (someFunction) to every element in the List. Is calling a method through an object's constructor slower than calling the same method many times for one particular object instantiation? In other words, is this: for(int i = 0; i < myData.Count; i++) myClass someObject = new myClass(myData[i]); slower than this: myClass someObject = new myClass(); for(int i = 0; i < myData.Count; i++) someObject.someFunction(myData[i]); ? If so, how much slower?

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• Two phase Construction in C++

  - by tommieb75

  I have as part of assignment to look into a development kit that uses the "two-phase" construction for C++ classes: // Include Header class someFubar{ public: someFubar(); bool Construction(void); ~someFubar(); private: fooObject _fooObj; } In the source // someFubar.cpp someFubar::someFubar : _fooObj(null){ } bool someFubar::Construction(void){ bool rv = false; this->_fooObj = new fooObject(); if (this->_fooObj != null) rv = true; return rv; } someFubar::~someFubar(){ if (this->_fooObj != null) delete this->_fooObj; } Why would this "two-phase" be used and what benefits are there? Why not just instantiate the object initialization within the actual constructor?

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• StructureMap DI on Model Assembly

  - by Dan dot net

  I’m new to Dependency Injection and had a question/need guidance. I had an application that used the repository pattern for data access. I used StructureMap to get the correct repository and all worked well. I have since broken out my model (including the repository logic) into its own assembly and added a service layer. In the interest of DI the service layer class takes an IRepository in its constructor. This seems wrong to me as now all consumers of my model need to know about the repository (at least configure their DI to know which one to use). I feel like that is getting into the guts of the model. What sounds wrong with this?

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• Call an AsyncTask inside a Thread

  - by Arun

  I am working in an android application and I want to call an AsyncTask from my UI main thread. For that I want to call my AsyncTask from a thread. This is the method that I call from my main UI thread. This is working correctly CommonAysnk mobjCommonAysnk = new CommonAysnk(this, 1); mobjCommonAysnk.execute(); CommonAysnk is my AsyncTask class.I want to pass my activity and an integer parameter to the AsyncTask constructor. How can I call this from a thread as shown below method. Thread t = new Thread() { public void run() { try { CommonAysnk mobjCommonAysnk = new CommonAysnk(this, 1); mobjCommonAysnk.execute(); } catch (Exception ex) { }}}; t.start(); When I tried to call it from a Thread and I am not able to pass the activity parameter correctly. How can we sole this. Thanks

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• Best way to create a Unique ID field for an enum

  - by jax

  What is the best way to get a Unique ID from an ENUM that will stay consistent between repeated execution of the program? Currently I am doing this manually by passing an ID to the enum constructor. I don't really want to do this is I can help it. Another option would be to use a static field that gets incremented for each enum value. The problem is that if later I decide to move the enum fields around or delete some this will cause problems with my program as the ID will be saved into user preferences. The ID can be any basic type or a String.

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• C++ Static Array Initialization - Memory Issue

  - by donalmg

  Hi, I have a header file which contains a member variable declaration of a static char array: class ABC { public: static char newArray[4]; // other variables / functions private: void setArray(int i, char * ptr); } In the CPP file, I have the array initialized to NULL: char ABC::newArray[4] = {0}; In the ABC constructor, I need to overwrite this value with a value constructed at runtime, such as the encoding of an integer: ABC::ABC() { int i; //some int value defined at runtime memset(newArray, 0, 4); // not sure if this is necessary setArray(i,newArray); } ... void setArray(int i, char * value) { // encoding i to set value[0] ... value [3] } When I return from this function, and print the modified newArray value, it prints out many more characters than the 4 specified in the array declaration. Any ideas why this is the case. I just want to set the char array to 4 characters and nothing further. Thanks...

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• what is the purpose of numeric/boolean/string objects as opposed to primitive values?

  - by zespri

  In javascript you can call a function as a function or as a constructor. For example you can do : myObject = new Number(13); myPrimitiveValue = Number(13); or simply myPrimitiveValue = 13; I understand the difference between the results. Can you explain me under which reasonable circumstances creating a number, a boolean or a string as an object is desirable? For example, ability to set new properties (this is something you can do on objects but can't really do on primitive values) is almost always a bad idea for objects containing number/boolean/string. Why would I want a numeric/boolean/string object?

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• How to set a value from another 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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• Why does Generic class signature requires specifying new() if type T needs instantiation ?

  - by this. __curious_geek

  I'm writing a Generic class as following. public class Foo<T> : where T : Bar, new() { public void MethodInFoo() { T _t = new T(); } } As you can see the object(_t) of type T is instantiated at run-time. To support instantiation of generic type T, language forces me to put new() in the class signature. I'd agree to this if Bar is an abstract class but why does it need to be so if Bar standard non-abstract class with public parameter-less constructor. compiler prompts following message if new() is not found. Cannot create an instance of the variable type 'T' because it does not have the new() constraint

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• Getting Reference to Calling Activity from AsyncTask (NOT as an inner class)

  - by stormin986

  Is it at all possible, from within an AsyncTask that is NOT an inner class of the calling Activity class, to get a reference to the instance of Activity that initiated execution of the AsyncTask? I am aware of this thread, however it doesn't exactly address how to reference the calling Activity. Some suggest passing a reference to the Activity as a parameter to the AsyncTask constructor, however, it's reported that doing so will always result in a NullPointerException. So, I'm at a loss. My AsyncTask provides robust functionality, and I don't want to have to duplicate it as an inner class in every Activity that wants to use it. There must be an elegant solution.

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• jUnit same exception in different cases

  - by coubeatczech

  Hi, I'm writing a jUnit test for a constructor that parses a String and then check numerous things. When there's wrong data, for every thing, some IllegalArgumentException with different message is thrown. So I would like to write tests for it, but how can i recognize what error was thrown? This is how can I do it: @Test(expected=IllegalArgumentException.class) public void testRodneCisloRok(){ new RodneCislo("891415",dopocitej("891415")); } and this is how I would like to be, but I don't know if it is possible to write it somehow: @Test(expected=IllegalArgumentException.class("error1")) public void testRodneCisloRok(){ new RodneCislo("891415",dopocitej("891415")); }

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• Unable to use JAR in Eclipse

  - by Myn

  Hi guys, I have just created my first JAR in Eclipse, just a simple program with a single class Database.class. It is not in a package. public class Database { public Database() { int dbInit = 1; } } I have added it as an external JAR to the build path libraries for another project in Eclipse, but for some reason I cannot get Database db = new Database(), the default constructor, to work - it's as if the contents of the JAR are not being recognised. Could anyone please offer any advice on this? Thanks very much, M

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• WPF + MvvM + Prism

  - by 2Fast4YouBR

  Hi all, I am new in the Wpf & Mvvm world , but I have found a couple of examples and just found that there is some different way to instantiate the model. I would like to know the best/correct way to do it. both ways are using Unity What I've foud: var navigatorView = new MainView(); navigatorView.DataContext = m_Container.Resolve<INavigatorViewModel>(); m_RegionManager.Regions["NavigatorRegion"].Add(navigatorView); What I did: var navigatorView = m_Container.Resolve<MainView>; m_RegionManager.Regions["NavigatorRegion"].Add(navigatorView); and I changed the constructor to receive viewmodel so I can point the datacontext to it: public MainView(NavigatorViewModel navigatorViewModel) { this.DataContext = navigatorViewModel; } Other examples I've found another way like: ...vm = new viewmodel ...m = new model v.model = vm; get/set DataContext cheers

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• Silently binding a variable instance to a class in C++?

  - by gct

  So I've got a plugin-based system I'm writing. Users can create a child class of a Plugin class and then it will be loaded at runtime and integrated with the rest of the system. When a Plugin is run from the system, it's run in the context of a group of plugins, which I call a Session. My problem is that inside the user plugins, two streaming classes called pf_ostream and pf_istream can be used to read/write data to the system. I'd like to bind the plugin instance's session variable to pf_ostream and pf_istream somehow so that when the user instantiates those classes, it's already bound to the session for them (basically I don't want them to see the session internals) I could just do this with a macro, wrapping a call to the constructor like: #define MAKE_OSTREAM = pf_ostream_int(this->session) But I thought there might be a better way. I looked at using a nested class inside Plugin wrapping pf_ostream but it appears nested classes don't get access to the enclosing classes variables in a closure sort of way. Does anyone know of a neat way to do this?

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• C++11 initialize array with uniform value in constexpr function

  - by marack

  I have a class template which builds a simple array based on the template parameters as one of its members. I need to be able to initialize every element in the array to a single value in one of the constructors. Unfortunately this constructor must be constexpr. The relevant part boils down to: template <typename T, size_t N> class foo { T data[N]; constexpr foo(T val) { // initialize data with N copies of val } }; Using std::fill or a loop is incompatible with the constexpr requirement. Initializing with : data{val} only sets the first element of the array and zero-initializes the remainder. How can this be achieved? I feel like there should be a solution with variadic templates and tuples etc...

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• Pattern matching against Scala Map type

  - by Tom Morris

  Imagine I have a Map[String, String] in Scala. I want to match against the full set of key–value pairings in the map. Something like this ought to be possible val record = Map("amenity" -> "restaurant", "cuisine" -> "chinese", "name" -> "Golden Palace") record match { case Map("amenity" -> "restaurant", "cuisine" -> "chinese") => "a Chinese restaurant" case Map("amenity" -> "restaurant", "cuisine" -> "italian") => "an Italian restaurant" case Map("amenity" -> "restaurant") => "some other restaurant" case _ => "something else entirely" } The compiler complains thulsy: error: value Map is not a case class constructor, nor does it have an unapply/unapplySeq method What currently is the best way to pattern match for key–value combinations in a Map?

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• How do i get (is it possible to) a reference to the class that creates an instance of another class.

  - by Cadde

  Odd situation... I need to create a new instance of a class that needs a member of the calling class. But i can't pass a reference to the calling class through the constructor. The solution i am looking for is something like this: Public Class ChildClass Public Sub New(args) _MyMember = GetMemberFromCallingClass() ... ... End Sub End Class I want this to work without having to manually pass any references or variables from the calling class to the new instance of ChildClass. Is this possible and if so, what should i look at to make this part of my code.

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• How to Handle Console.log and error output in JavaScript.

  - by uber_n00b

  I have a constructor that has a series of classes and functions within it - in each function I check if the param is set to show the error and output if so. Like so using an inline if. The issue and question is short of keeping two versions is this approach not wise in that each IF has to be evaluated thus adding to the time it takes to perform? debugSlide = (bag.debug==1)? console.log("item id =" + bag.itemId) : 0; How do you do this? Any pointers on where I can find tips on this? Thanks in advance!

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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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