gistfile1.rb

module ALibrary
  class ABaseClass
    def quack
      puts "quack"
    end
  end
end


class ASpecificClass < ALibrary::ABaseClass
  def quack
    # overriden version that needs to call ALibrary::ABaseClass#quack
  end
end


# Same effect without barbarian monkey-patching:

module ABaseClassExtension
  def quack
    result = super

    puts "after quack"
    result
  end
end

class AnotherSpecificClass < ALibrary::ABaseClass
  include ABaseClassExtension
end

AnotherSpecificClass.new.quack