When to use nested classes and classes nested in modules?

Question

I\'m pretty familiar with when to use subclasses and modules, but more recently I\'ve been seeing nested classes like this:

class Foo
  class Bar
    # do so         


        

Answer 1

In the addition to previous answers: Module in Ruby is a class

$ irb
> module Some end
=> nil
> Some.class
=> Module
> Module.superclass
=> Object