Delegate. Give me scenario

Lalit Raghav

Dear All

Can you give me scenario when we should use Delegates in C#. i have read about delete and know that is hold reference of method .but i have not understand when should i use delegate .

3 Replies

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Nilesh Jadav11y ago
Accepted answer
Check this links sir !
http://www.codeproject.com/Articles/85296/important-uses-of-Delegates-and-Events

http://stackoverflow.com/questions/2019402/when-why-to-use-delegates

Use a delegate in the following circumstances:

An eventing design pattern is used.

It is desirable to encapsulate a static method.

The caller has no need to access other properties, methods, or interfaces on the object implementing the method.

Easy composition is desired.

A class may need more than one implementation of the method.

http://csharpindepth.com/Articles/chapter2/events.aspx

C# - What is Delegates in C# Example | Use of Delegates in C#

Thank you !
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Pankaj Kumar Choudhary11y ago
hello @Lalit

Delegates are a part of some well known design patterns. Delegates are used in events like button click etc. which belong to the Publisher/Subscriber pattern. Delegates are also used in asynchronous method invocation so the user does not have to wait for the completion of the operation.

You need a delegate when doing events or when you want to do asynchronous programming using asynchronous delegates, C# 3 expanded use of delegates to functional C# when you want to create higher order functions e.g currying, or when you want to pass a lambda expression as a parameter to a function.For functional composition in C# you will need to use delegates.

A delegate is a reference to a method. Whereas objects can easily be sent as parameters into methods, constructor or whatever, methods are a bit more tricky. But every once in a while you might feel the need to send a method as a parameter to another method, and that's when you'll need delegates.

When you want to provide a function, that will be executed on some event. You give to the event's Event handler a delegate of a function that is about to be executed. They are great when you do event driven programming.

Also when you have functions that have functions as arguments (LINQ expressions, predicates, map-functions, aggregate functions, etc). This functions are generally called higher level functions.

In addition you can wrap some functionality, when the caller has no need access other properties, methods, or interfaces on the object implementing the method. In this case it replaces inheritance, somehow.

+1
Rajeesh Menoth11y ago
Hi,

Delegate declaration determines the methods that can be referenced by the delegate. A delegate can refer to a method, which has the same signature as that of the delegate.

Ref this article in csharpcorner : http://www.c-sharpcorner.com/UploadFile/8911c4/simple-delegates-with-examples-in-C-Sharp/

Other ref :

1) http://www.codeproject.com/Articles/624575/Delegate-Tutorial-for-Beginners

2) http://stackoverflow.com/questions/2019402/when-why-to-use-delegates
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