Calling selected methods of a module from another module

Given those modules:

Copymodule A
  def foo; end
  def bar; end
end

module B
end

When you want to call methods from A inside B you would normally just include A into B:

Copymodule B
  include A
end

Including exposes all of A's methods into B. If you do not want this to happen, use Ruby's module_function Show archive.org snapshot : it makes a module's method accessible from the outside. You could put the module_function calls into A but it would remain unclear to people looking at B's code.

A cleaner way would be like this:

Copymodule B
  module Outside
    include ::A
    module_function :foo
  end
end

This allows you to use B::Outside.foo or just define a method inside B which casts some magic itself and refers to Outside.foo eventually.