Overriding extension methods in C# 3.0

A language that properly supports modularity must deal with name collisions. In C# 3.0, extension methods allow us to dynamically add new methods to another class. So what happens when methods collide? If I add the same method signature (name + parameters) to a class, what will the compiler do?

• If I include two different namespaces, and both add the same method, the compiler warns that my method call is ambiguous. That’s good. But how can I explicitly specify which method I want?
• If the method exists in another namespace and I add the same method, the compiler does not report that I’ve modified an existing method. This means my program could change if anyone working in the same namespace accidently modifies another method. The compiler should warn that I’ve changed an existing method.

F# hits the big time

F# is moving out of research into a first-class language running on .NET. F# is a derivative of OCaml, a strongly-typed functional language with imperative and OO features. I’ve had the great fortune of working with Don Syme on Project 7 (a largely failed attempt to port “academic” languages to .NET) and at MSR Cambridge a long time ago. He’s a very sharp guy who also contributed to the design and implementation of generics in C# and the CLR. Who says nothing ever comes from research groups?