Defining bounded generic type parameter in C#

Question

In Java, it is possible to bind the type parameter of a generic type. It can be done like this:

class A<T extends B> {
    ...
}

So, the type parameter for this generic class of A should be B or a subclass of B.

I wonder if C# has a similar feature. I appreciate if somebody let me know.

Thanks

Decrepitude

class A<T> where T : B {...} I think. It's been awhile. – Fourdimensional

Answer 1

The same in C# is:

class A<T> where T : B
{

}

Also see "Constraints on Type Parameters" (msdn) for a great overview of constraints in general.

Scrim

Beat me by a few seconds while I was finishing mine, +1 for the MSDN link. – Hexavalent

Answer 2

Very similar:

public class A<T> where T : B
{
    // ...
}

This can be used to constrain T to be a sub-class or implementation of B (if B is an interface).

In addition, you can constrain T to be reference type, value type, or to require a default constructor:

where T : class     // T must be a reference type
where T : struct    // T must be a value type
where T : new()     // T must have a default constructor

Hexavalent

Answer 3

Of course you can:

class A<T> where T: B
{
    // ...
}

Monoplegia

Answer 4

Yes, you can do this, it's called type constraints. Here is an article that explains how:

http://msdn.microsoft.com/en-us/library/d5x73970.aspx

Rafa