Representing void methods with generic delegates

Generics are cool. Learn about them.

I want to talk about a specific query that I had which right now I can only guess the answer.

To begin, here's the scenario.

You can create a Generic Delegate to point to a method you want to execute. For example this simple method :

 

void myMethod(int number)

 

you could create a generic delegate:

 

delegate void invokeDelegate<T>(T input)

 

can invoke it like this: invokeDelegate<int> invoker = myMethod;

(I'm using the new c# 2.0 syntax that allows me to create an "inferred delegate" instead of writing "new invokeDelegate<int>(myMethod)" )

 

it even cool if the method had a return type like this:

 

bool myMethod(int number)

 

you could create a generic delegate:

 

delegate RET invokeDelegate<T,RET>(T input)

and invoke it thusly:

invokeDelegate<int,bool> invoker = myMethod;

 

but how do you take the delegate I've just written and apply it to the *first* method which returns a void? Turns out you can't, at least from my poking around. The more I thought about it the more it makes sense.

If you allow a "void" type to be used as generic type parameter, it is implied that this parameter can be used not only as a return value but as a parameter to the generic function/delegate itself. Here's what someone *could* write if this was possible:

 

delegate void invokeDelegate<T,RET>(T input,RET moreinput)

 

assuming someone does this (if the compiler allowed it):

invokeDelegate<int,typeof(void)> invoker = myMethod;

it would have to implicitly mean that there's a method somewhere looking like this:

 

void myMethod(int number,void IhaveNoIdeaWhatThisIs)

 

which means, in essence, that to represent all method signatures you'd always need at least two generic delegates, one void and one with a generic return value.

That's just my line of thinking, but I'd love for someone from MS to comment on this.