Namespace-only class visibility in C#/.NET?

Question

In C#, can you make a class visible only within its own namespace without living in a different assembly? This seems useful for typical helper classes that shouldn\'t be use

Answer 1

Not sure if it is directly possible, but a few good ways to fake it would be:

1) Have the classes that need this sort of stuff inherit from a single class which has the helper class as an internal class.

2) Use extension methods and then only reference the extension methods within the namespace.