How can I pass a method name to another method and call it via a delegate variable?

Question

I have a method that contains a delegate variable that points at another class. I want to call a method in that class via this delegate, but pass the name of the method as a string to the method containing the delegate.

How can this be done? Using reflection? Func<T>?

Edit:

I understand now that reflection may not be the best solution.

This is what I have:

private static void MethodContainingDelegate(string methodNameInOtherClassAsString)
{
        _listOfSub.ForEach(delegate(Callback callback)
        {
            //Here the first works, but I want the method to be general and   
            //  therefore pass the method name as a string, not specfify it. 
            callback.MethodNameInOtherClass(); 
            //This below is what I am trying to get to work. 
             callback.MethodNameInOtherClassAsString();                  
          }
     });
}

So, basically, I am looking for a way to make my callback delegate "recognize" that my methodNameInOtherClassAsString is actually a method to execute in the other class.

Thanks!

Could you add some psuedocode? I can't quite understand what you're asking! — Nick, May 20 '11 at 08:58
What kind of references do you have? Is it a delegate reference, a string with the method name...? — BoltClock, May 20 '11 at 09:00

Andrei Sosnin · Accepted Answer · 2011-05-21T10:50:03.160

It's very simple:

public delegate void DelegateTypeWithParam(object param);
public delegate void DelegateTypeWithoutParam();

public void MethodWithCallbackParam(DelegateTypeWithParam callback, DelegateTypeWithoutParam callback2)
{
    callback(new object());
    Console.WriteLine(callback.Method.Name);
    callback2();
    Console.WriteLine(callback2.Method.Name);
}

// must conform to the delegate spec
public void MethodWithParam(object param) { }
public void MethodWithoutParam() { }

public void PassCallback()
{
   MethodWithCallbackParam(MethodWithParam, MethodWithoutParam);
}

It doesn't matter, what class does the delegate variable point to. It can be defined in another class -- there's not much difference.

I think you could even query the name of the original method from the delegate variable itself without reflection. Every delegate has a property called Method exactly for that.

Thanks for the answer. I've realized that maybe reflection is not the way to go, and looked into Action instead, since then I can pass the method as a method(action) and don't have to think about the conversion from string. — kakka47, May 20 '11 at 16:38

score 2 · Answer 2 · answered May 20 '11 at 09:04

You can do something like this:

var mi = typeof(Foo).GetMethods().Single(x => x.Name == "Bar");
mi.Invoke(foo, null);

Where Foo is your target class, Bar is the method you want to call. But you should note that reflection will have a great impact on your program's performance. Consider using strongly typed delegates instead.

score 0 · Answer 3 · answered May 20 '11 at 09:05

Assuming you have string representation of the method name:

var methodInfo = myObject.GetType().GetMethod(myString); //<- this can throw or return null
methodInfo.Invoke(myObject, new object[n]{parm1, pram2,...paramn});

you need to add some error checking to this obviously, and should use a more specific version of GetMethod if you can.

How can I pass a method name to another method and call it via a delegate variable?

3 Answers3

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