Generics - Illustrated C# 2005 - page 444

Generic Interfaces
Generic interfaces allow you to write interfaces where the parameters and return types of inter-
face members are generic type parameters. Generic interface declarations are similar to
non-generic interface declarations, but have the type parameter list in angle brackets after
the interface name.
For example, the following code declares a generic interface called IMyIfc that declares a
single method.

Generic class Trivial implements the generic interface.

￿

￿ Main instantiates two objects of the generic class: one with type int , and the other with
type string .

Type parameter
↓
interface IMyIfc<T> // Generic interface
{
T ReturnIt(T inValue);
}
Type parameter Generic interface
↓ ↓
class Trivial<S> : IMyIfc<S> // Generic class
{
public S ReturnIt(S inValue) // Implement interface
{
return inValue;
}
}

class Program
{
static void Main()
{
Trivial<int> TrivInt = new Trivial<int>();
Trivial<string> TrivString = new Trivial<string>();

Console.WriteLine("{0}", TrivInt.ReturnIt(5));
Console.WriteLine("{0}", TrivString.ReturnIt("Hi there."));
}
}

The output of this code is the following:

5
Hi there.