Question

Is it possible to overload the default function operator (the () operator) in C#? If so – how? If not, is there a workaround to create a similar affect?

EDIT:
I’m trying to give a class a default operator, something along the lines of:

class A {
    A(int myvalue) {/*save value*/}

    public static int operator() (A a) {return a.val;}
    ....
   }

...
A a = new A(5);
Console.Write(A());

EDIT 2:
I’ve read the spec and I understand there’s no straight forward way to do this. I was hoping there’s a workaround.

EDIT 3:
The motivation is to make a class, or an instance behave like a function, to make a convenient logging interface. By the way, this is doable and reasonable in C++.

Answer 1

No, () isn’t an operator so it cannot be overloaded. (This is incorrect, please see Eric Lippert’s comment below) The parentheses are part of C#’s syntax that are used to express a set of arguments that are passed to a method. () simply indicates that the method in question specified no formal parameters and therefore requires no arguments.

What are you trying to do? Perhaps if you gave a small example of the problem we would be able to help with a solution.

Edit: Okay I see what you are getting at now. You could always create a delegate that maps to the method on the instance like this (given that class A defines a method like this: public void Foo() { }):

Action action = someA.Foo;

Then you could invoke the delegate with a simple syntax like this:

action();

Unfortunately (or not, depending on your preference) this is pretty much as close as C# will let you get to this kind of syntax.