Callback in C#

In computer programming, a callback is a reference to executable code, or a piece of executable code, that is passed as an argument to other code. This allows a lower-level software layer to call a subroutine (or function) defined in a higher-level layer.
Lets see how we can implement the same in C# using Action(function object).

In the below example we have a class called CallbackExample with a DoSomething() method which counts from 0 to 9 with a delay of 1 second. Within an application we can't wait for 10 seconds for the process to completed that why we implement a callback called Callback which takes an object as parameter and this been invoked once the for loop completes counting from 0-9.
There is an important check to see if the callback is not null before invoking it, this handles a situation when callback is not been registered in the other end.
The main method registered the Callaback to display a message into the console before it calls the DoSomething method.

	// Callback class example
	public class CallbackExample
	{
	//define the callback
	public Action<object> Callback;
	public void DoSomething()
	{
	//this task it taking too long call me once done
	for(int i=0;i<10;i++)
	{
	Console.WriteLine("Current counter is {0}",i);
	Thread.Sleep(1000);
	}
	//important to check
	if(Callback != null)
	Callback("Task Completed");
	}
	}
	//main
	void Main()
	{
	CallbackExample _cbe = new CallbackExample();
	_cbe.Callback = (o) => Console.WriteLine(o);
	_cbe.DoSomething();
	}
	//eof

view raw Callback.cs hosted with ❤ by GitHub