Question

I am working on some legacy code and have come across something that I’m not sure of. We have a class y that is declared inside of another class x. Class y is only ever used inside of class x but my question is why wouldn’t you create a separate class file and put class y in there instead of declaring it inside of class x? Isn’t this violating OOP’s or is it just a matter of style since it is only ever used inside of this class. I’m refactoring some of this code and my first reaction would be to separate class y out into it’s own file.

namespace Library {    public class x    {       // methods, properties, local members of class x        class y       {          // methods, properties, local members of class y       }    } } 

Answer 1

You create an inner class because it is only ever used within the scope of class x and it logically fits in the factoring/architecture of class x.

Class y might also be privy to implementation details of class x that are not meant to be known to the public.