Delegates in C#

Delegates

• It is a reference type, holds address of a method.
• Allows to change reference to a method at runtime.
• Referring method should have the return type and function signature same as that of the delegate. 

•  The following are the steps for implementing Delegates

o   Declare a delegate

*  Syntax

[access modifier] delegate <return type> <delegate name> <parameter list>

*  E.g.

public delegate void MyDelegate();

*  This delegate can refer any method having no parameter with no return type.

o   Instantiate a delegate

*  MyDelegate delObj = new MyDelegate(staticMethod);

*  delObj is an object of type MyDelegate

*  delObj refers to staticMethod, by passing the name of method to the delegate constructor.

o   Invoke a delegate

*  Delegates are invoked using its object name and passing the parameters, if required, in a similar way of calling methods.

*  delObj();

• Types of Delegate

o   Single-cast Delegate

*  Refers to only one method at a time.

o   Multicast Delegate

*  A single delegate can refer to multiple methods.

*  Contains an invocation list of multiple methods.

*  Invokes multiple methods provided all methods have same return type and same function signature.

*  When invoked, executes the referenced methods in the calling order.

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