There's no difference between MyAction
and new Action(MyAction)
(when they're both valid) other than the former won't work in C# 1. This is an implicit method group conversion
. There are times that this isn't applicable, most notable when the compiler can't work out what kind of delegate you want, e.g.
Delegate foo = new Action(MyAction); // Fine
Delegate bar = MyAction; // Nope, can't tell target type
This comes into play in your question because both of the methods involved are overloaded. This leads to headaches, basically.
As for the generics side - it's interesting. Method groups don't get much love from C# 3 type inference - I'm not sure whether that's going to be improved in C# 4 or not. If you call a generic method and specify the type argument, type inference works fairly well - but if you try to do it the other way round, it fails:
using System;
class Test
{
static void Main()
{
// Valid - it infers Foo<int>
DoSomething<int>(Foo);
// Valid - both are specified
DoSomething<int>(Foo<int>);
// Invalid - type inference fails
DoSomething(Foo<int>);
// Invalid - mismatched types, basically
DoSomething<int>(Foo<string>);
}
static void Foo<T>(T input)
{
}
static void DoSomething<T>(Action<T> action)
{
Console.WriteLine(typeof(T));
}
}
Type inference in C# 3 is very complicated, and works well in most cases (in particular it's great for LINQ) but fails in a few others. In an ideal world, it would become easier to understand and more powerful in future versions... we'll see!