I'd prefer the second way unless there's some weird Ruby reason why I shouldn't...

indentation_hell.rb

module My
  module Job
    class ReconcileAccounts
      # ...
    end
  end
end

namespace_ghost.rb

module My; end
module My::Job; end

class My::Job::ReconcileAccounts
  # ...
end

Job will be defined at the same level as My, so My::Job won't work...

But, you can do:

module My; module Job; end; end;

and define the class as you prefer in example 2.

I frequently see in gems where the module definitions are at the root lib/gemname.rb file, and all the classes within that module just defined as Gemname::ClassName in their respective files without repeating the explicit module definitions.

Second one should be

module My; end
module My::Job; end

But I'd recommend

My = Module.new
My::Job = Module.new

Because fuck semicolons. note: you can't do it my way in multiple files. You have to that globally.

Ahh nice, I always forget about Module/Class.new. Go with that.

@aniero duh. Forgot to namespace my modules. Thanks for the catch.