How to get the submodules of a ruby module

I needed to be able to find out what modules were defined inside a particular ruby module. Kinda like wanting to find out what child namespaces exist for a module. It’s probably more easily explained with an example. Given the following construct…

module A
  module B; end
  module C; end
  module D
    module E; end
  end
end

…I wanted to be able to ask A what submodules are defined within it and get the following answer:

[A::B, A::C, A::D]

(btw: I don’t want to see E in the list as it is not a direct child of A).

So… since the Module class doesn’t provide anything to support doing that, I wrote a method that does it for me. Here’s the monkey-patch:

class Module
  def submodules
    modules = []
    self.constants.each do |const|
      temp_const = self.const_get(const)
      modules << temp_const if temp_const.class == Module
    end
    modules
  end
end