How can I use interface as a C# generic type constraint?

Question

Is there a way to get the following function declaration?

public bool Foo() where T : interface;

ie. where T is an interface type

Answer 1

The closest you can do (except for your base-interface approach) is "where T : class", meaning reference-type. There is no syntax to mean "any interface".

This ("where T : class") is used, for example, in WCF to limit clients to service contracts (interfaces).