anonymous delegates in C#

Question

I can't be the only one getting tired of defining and naming a delegate for just a single call to something that requires a delegate. For example, I wanted to call .Refresh() in a form from possibly other threads, so I wrote this code:

private void RefreshForm()
{
    if (InvokeRequired)
        Invoke(new InvokeDelegate(Refresh));
    else
        Refresh();
}

I'm not even sure I have to, I just read enough to be scared that it won't work at some later stage.
InvokeDelegate is actually declared in another file, but do I really need an entire delegate dedicated just for this? aren't there any generic delegates at all?
I mean, for example, there's a Pen class, but there's also Pens.pen-of-choice so you don't have to remake the whole thing. It's not the same, but I hope you understand what I mean.

Answer 1

Yes. In .NET 3.5 you can use Func and Action delegates. The Func delegates return a value, while Action delegates return void. Here is what the type names would look like:

System.Func<TReturn> // (no arg, with return value)
System.Func<T, TReturn> // (1 arg, with return value)
System.Func<T1, T2, TReturn> // (2 arg, with return value)
System.Func<T1, T2, T3, TReturn> // (3 arg, with return value)
System.Func<T1, T2, T3, T4, TReturn> // (4 arg, with return value)

System.Action // (no arg, no return value)
System.Action<T> // (1 arg, no return value)
System.Action<T1, T2> // (2 arg, no return value)
System.Action<T1, T2, T3> // (3 arg, no return value)
System.Action<T1, T2, T3, T4> // (4 arg, no return value)

I don't know why they stopped at 4 args each, but it has always been enough for me.