Is it possible to use a method as the first parameter to an extension method?

Question

I tried to do this:

public static EventHandler ToEventHandler(this Action callback)
{...}

for some syntactic sugar when I want to pass a simple method like void x() to a method that's typed for an EventHandler.

But when I try to call this like so:

SomeMethod(x.ToEventHandler());

I get a compiler error:

x() is a 'method', which is not valid in the given context

Since methods are first class citizens in .NET, I can't see why this shouldn't be possible. Why doesn't it like this, and is there another way to accomplish what I'm trying to do?

check this link http://stackoverflow.com/questions/2082615/pass-method-as-parameter-using-c-sharp — rashfmnb, Mar 22 '16 at 20:00
Have you tried casting it to an `Action` first? It's a method group until the compiler knows otherwise. — Ian Mercer, Mar 22 '16 at 20:02

score 0 · Answer 1 · answered Mar 22 '16 at 20:12

You can't do this, because x is a method, and compiler won't magically turn a method by its identifier into a delegate when using extension methods (I believe it should be able to do so indeed...).

What you need is this: SomeMethod(new Action(x).ToEventHandler());

In the other hand, an EventHandler has two input parameters while you expect to use an Action (parameterless delegate...). I suspect that you're trying to this:

EventHandler handler = (sender, e) => callback();

...and then, if you're going this route, it's fine.

Is it possible to use a method as the first parameter to an extension method?

1 Answers1