Question

How do I create and call a delegate Action<T> when at runtime I’m receiving the delegate as an object and I know type only at runtime?

For example, In Foo, I define my delegate and want to pass it to a method which receives an Action<int> as an object, along with the data to pass to the delegate. It’s contrived I know, but it’s to demonstrate my problem.

public void Foo()
{
    Action<int> handler = i => Console.WriteLine(i + 1);
    Process(handler,4)
}

public void Process(object myDelegate, object data)
{

}

and I’d like to call

myDelegate(data)

Answer 1

All the delegate types (Eg. Action<string>) Are actually types that have an Invoke(...) method.

You should look for that invoke method with reflection and call it, It is relatively slow – So watch out.

This should do it :

Action<string> action = s => Console.WriteLine("Hello " + s);
object obj = action;
// Invoking
obj.GetType ().GetMethod ("Invoke").Invoke (obj, new object[] {"World"});

This works too, I don’t know what is faster, you should check it out :

Action<string> action = s => Console.WriteLine("Hello " + s);
Delegate obj = action;
obj.DynamicInvoke(new [] { "World" });