13 May 2013

Delegates in C#


Delegates in C#

-Delegates are just function pointers, That is, they hold references to functions.

A Delegate is a class. When you create an instance of it, you pass in the function name (as a parameter for the delegate's constructor) to which this delegate will refer.

Use a delegate when
- An eventing design pattern is used.
Easy composition is desired.
It is desirable to encapsulate a static method.

Every delegate has a signature. For example:
Delegate int SomeDelegate(string s, bool b);

is a delegate declaration. When I say this delegate has a signature, I mean that it returns an int type and takes two parameters of type string and bool.

Consider the following function:

private int SomeFunction(string str, bool bln){...}
You can pass this function to SomeDelegate's constructor, because of their similar signatures.


SomeDelegate sd = new SomeDelegate(SomeFunction);

Now, sd refers to SomeFunction, in other words, SomeFunction is registered to sd. If you call sd, SomeFunction will be invoked. Keep in mind what I mean by registered functions. Later, we will refer to registered functions.


sd("somestring", true);

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