Question

Do you use a global, catchall namespace for all of your extension methods, or do you put the extension methods in the same namespace as the class(es) they extend?

Or do you use some other method, like an application or library-specific namespace?

I ask because I have a need to extend System.Security.Principal.IIdentity, and putting the extension method in the System.Security.Principal namespace seems to make sense, but I’ve never seen it done this way.

Answer 1

I would recommend putting all your extension methods in a single namespace (incidentally this is also what Microsoft did with Linq by putting them in a single class ‘Extensions’ inside the ‘System.Linq’ namespace).

Since Visual Studio provides no clues as to how to locate an extension method that you want to use, it reduces confusion by only having to remember one namespace.