why does my C# client that uses Library A need to have a using statement for Library B (which A uses)

Question

I have:

• Main Program Class - uses Library A
• Library A - has partial classes which mix in methods from Library B
• Library B - mix in methods &a

Answer 1

All you're using is the Node class from Library A, that's true. However, part of the definition of the Node class is the fact that it implements the INode interface from Library B.

The very fact of the existence of the Node class demands that you include a reference to Library B.