Redefine a method in a module

redefine-a-method-in-a-module.rb

module M1
  def hi
    puts "hi in M1"
  end
end

class A
  include M1

  def ha
    puts "ha"
  end
end

a = A.new
a.hi
# => hi in M1
a.ha
# => ha

module M2
  def hi
    puts "hi in M2"
    super
  end

  def ha
    puts "ha in M2"
  end
end

A.send :include, M2

a.hi
# => hi in M2
# => hi in M1
a.ha
# => ha