Module+monkeypatch (stripped back from http://stackoverflow.com/questions/3689736/rails-3-alias-method-chain-still-used )

gistfile1.rb

class A

  def a; "A#a" end

  module B
    def b; "B#b" end
  end

  include B
end

module PatchA
  def a; ["PatchedA#a", super].join ":" end

  def b; ["PatchedA#b", super].join ":" end
end

A.send(:include, PatchA)

puts A.new.a # calls unpatched A#a
puts A.new.b # calls PatchA#b