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A delegate is a form of type-safe function pointer used by the Common Language Infrastructure (CLI). Delegates specify a method to call and optionally an object to call the method on. Delegates are used, among other things, to implement callbacks and event listeners. A delegate object encapsulates a reference to a method.
In the delegate pattern, this is instead accomplished by explicitly passing the original object to the delegate, as an argument to a method. [1] " Delegation" is often used loosely to refer to the distinct concept of forwarding , where the sending object simply uses the corresponding member on the receiving object, evaluated in the context of ...
For instance, when the user clicks the close box, the window manager sends the delegate a windowShouldClose: call, and the delegate can delay the closing of the window, if there is unsaved data represented by the window's contents. Delegation can be characterized (and distinguished from forwarding) as late binding of self: [4]
C# provides type-safe object-oriented function pointers in the form of delegates. class Program { // Delegate type: delegate int Operation ( int a , int b ); static int Add ( int i1 , int i2 ) { return i1 + i2 ; } static int Sub ( int i1 , int i2 ) { return i1 - i2 ; } static void Main () { // Instantiate the delegate and assign the method to it.
CLI languages such as C# and VB.NET provide a type-safe encapsulating function reference known as delegate. Events and event handlers , as used in .NET languages, provide for callbacks. Functional languages generally support first-class functions , which can be passed as callbacks to other functions, stored as data or returned from functions.
C# 4.0 is a version of the C# programming language that was released on April 11, 2010. Microsoft released the 4.0 runtime and development environment Visual Studio 2010 . [ 1 ] The major focus of C# 4.0 is interoperability with partially or fully dynamically typed languages and frameworks, such as the Dynamic Language Runtime and COM .
Like the Qt framework's pseudo-C++ signal and slot, C# has semantics specifically surrounding publish-subscribe style events, though C# uses delegates to do so. C# offers Java-like synchronized method calls, via the attribute [MethodImpl(MethodImplOptions.Synchronized)], and has support for mutually-exclusive locks via the keyword lock.
Delegate (CLI), a form of type-safe function pointer used by the Common Language Infrastructure (CLI), specifying both a method to call and optionally an object to call the method on. See also [ edit ]