How to convert delegate to identical delegate?

Question

There are two descriptions of the delegate: first, in a third-party assembly:

public delegate void ClickMenuItem (object sender, EventArgs e)

s

Answer 1

EDIT: There's a fourth option, i.e. to avoid all this nonsense and do what Jon Skeet suggests in his answer.

Something like this?

public static EventHandler ToEventHandler(this ClickMenuItem clickMenuItem)
{
    if (clickMenuItem == null)
        return null;

   return (sender, e) => clickMenuItem(sender, e);
}

and the reverse:

public static ClickMenuItem ToClickMenuItem(this EventHandler eventHandler)
{
   if (eventHandler == null)
       return null;

   return (sender, e) => eventHandler(sender, e);
}

Note that the compiler infers which delegate-types to convert the lamda-expressions to.

EDIT: If you prefer, you can use anonymous-delegates too.

EventHandler eventHandler =  delegate(object sender, EventArgs e)
                             { 
                                clickMenuItem(sender, e); 
                             };
return eventHandler; // can be inlined, type-inference works fine

The third alternative of course, is to write a closure-class yourself. I wouldn't really recommend this, but it gives you an idea of what the compiler does with the anonymous methods. Something like:

public static class ClickMenuItemExtensions
{
    public static EventHandler ToEventHandler(this ClickMenuItem clickMenuItem)
    {
        if (clickMenuItem == null)
            return null;

        // new EventHandler not required, included only for clarity 
        return new EventHandler(new Closure(clickMenuItem).Invoke);
    }

    private sealed class Closure
    {
        private readonly ClickMenuItem _clickMenuItem;

        public Closure(ClickMenuItem clickMenuItem)
        {
            _clickMenuItem = clickMenuItem;
        }

        public void Invoke(object sender, EventArgs e)
        {
            _clickMenuItem(sender, e);
        }
    }
}