Storing a method as a member variable of a class

Question

I have this as one of my members of the class \'KeyEvent\':

private delegate void eventmethod();

And the constructor:

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Answer 1

public class KeyEvent
{
  private eventmethod hurr;
  public KeyEvent(eventmethod D)
  {
    hurr = D;
  }
  public void SomeOtherMethod()
  {
    hurr();
  }
}

Couple things... PascalCase types/delegates/etc (EventMethod) and camelCase arguments (d, dIsMyMethod). And reuse what the framework gives you: private Action hurr;

Answer 2

You pretty much have the code already. Just create a member field of the right delegate type and save the parameter to it just like you would with any other data type.

private eventmethod MySavedEvent;

public void KeyEvent(eventmethod D) {
    // Save the delegate
    MySavedEvent = D;
}

public void CallSavedEvent() {
    if (MySavedEvent != null) {
        MySavedEvent();
    }
}

Answer 3

the thing that you want is called "first class function" http://en.wikipedia.org/wiki/First-class_function

C#, since version 3, supports anonymous functions and lambda expressions.

So you can use Func<A,R> which represents a function taking an argument of type A and returning a value of type R

from wiki

static Func<double, double> MakeDerivative(Func<double, double> f, double deltaX)
  {
    return (x) => (f(x + deltaX) - f(x - deltaX)) / (2 * deltaX);
  }

Answer 4

You could do something like:

private Action CallBackFunction {get; set;}

public KeyEvent(Action callback) {
   CallBackFunction = callback;
}

Which can be instantiated by:

new KeyEvent(MyFunction);

Where MyFunction is the name of some function in that class

The KeyEvent class can then invoke that function with:

CallBackFunction();

The Action class also allows strongly typed parameters to be passed in and the Func class can be used for methods that return a result.