Professional .NET 2.0 Generics

5.3. Apply Constraints

Anywhere you're allowed to create a generic type, you are also allowed to qualify that type with constraints. For a generic method, the application of constraints to the incoming type parameters is relatively simple. Chapter 7 looks at constraints in detail, but here's a quick peek at the mechanics of how constraints are applied to the type parameters of your generic methods:

[VB code]
Public Sub Foo(Of I As IComparable)(ByVal val1 As I)
End Sub

[C# code]
public void Foo<I>(I val1) where I : IComparable {}

As you can see, the syntax here leverages the same approach that you may have seen applied to generic classes. You simply add the interface qualifier for a given type parameter and that will allow you to treat any reference to that the type parameter as conforming to the supplied interface.