How to cast a generic parameter?

Question

Here's what I am trying to write:

public void Foo<T>(T parameter) {
  otherObject.Bar<T>(parameter);
}

The signature of the Bar() method is:

public void Bar<T>(T parameter) where T: class 

So I get a compile error because the T in Foo's signature doesn't have the same constraint. Unfortunately I can't write:

public void Foo<T>(T parameter) where T: class {
  otherObject.Bar<T>(parameter);
}

because Foo is implementing a method defined in an external interface. Question is:

Can I somehow transpose the T within the method Foo before calling Bar. (Note, I can be sure that T always will be a class - I just need to get past the compiler).

The only way I have found is using reflection but I wonder if there is a simpler trick I'm missing.

Answer 1

You can use the dynamic keyword like this:

public void Foo<T>(T parameter)
{
    dynamic p = parameter

    otherObject.Bar(p);
}

What's happening is that the resolution of the call to otherObject.Bar is being made at run-time, because one of the parameters has a type of dynamic. Assuming that T is a reference type, the resolution will succeed.

Granted, this ultimately uses reflection (as you've indicated), but the syntax is probably better than what you're using.

Of course, this will give you a run-time error in the event that T is not a class.

Answer 2

public void Foo<T>(T parameter)
{
    otherObject.Bar<object>(parameter);
}