Uses of Action delegate in C# [closed]

I was working with the Action Delegates in C# in the hope of learning more about them and thinking where they might be useful.

Has anybody used the Action Delegate, and if so why? or could you give some examples where it might be useful?

Solution 1:

Here is a small example that shows the usefulness of the Action delegate

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        Action<String> print = new Action<String>(Program.Print);

        List<String> names = new List<String> { "andrew", "nicole" };

        names.ForEach(print);

        Console.Read();
    }

    static void Print(String s)
    {
        Console.WriteLine(s);
    }
}

Notice that the foreach method iterates the collection of names and executes the print method against each member of the collection. This a bit of a paradigm shift for us C# developers as we move towards a more functional style of programming. (For more info on the computer science behind it read this: http://en.wikipedia.org/wiki/Map_(higher-order_function).

Now if you are using C# 3 you can slick this up a bit with a lambda expression like so:

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<String> names = new List<String> { "andrew", "nicole" };

        names.ForEach(s => Console.WriteLine(s));

        Console.Read();
    }
}

Solution 2:

Well one thing you could do is if you have a switch:

switch(SomeEnum)
{
  case SomeEnum.One:
      DoThings(someUser);
      break;
  case SomeEnum.Two:
      DoSomethingElse(someUser);
      break;
}

And with the might power of actions you can turn that switch into a dictionary:

Dictionary<SomeEnum, Action<User>> methodList = 
    new Dictionary<SomeEnum, Action<User>>()

methodList.Add(SomeEnum.One, DoSomething);
methodList.Add(SomeEnum.Two, DoSomethingElse); 

...

methodList[SomeEnum](someUser);

Or you could take this farther:

SomeOtherMethod(Action<User> someMethodToUse, User someUser)
{
    someMethodToUse(someUser);
}  

....

var neededMethod = methodList[SomeEnum];
SomeOtherMethod(neededMethod, someUser);

Just a couple of examples. Of course the more obvious use would be Linq extension methods.