/ Ruby
/
method

extend

v1_8_7_72 - Show latest stable - Class: Object
extend(...)
public

Adds to obj the instance methods from each module given as a parameter. 

   module Mod
     def hello
       "Hello from Mod.\n"
     end
   end

   class Klass
     def hello
       "Hello from Klass.\n"
     end
   end

   k = Klass.new
   k.hello         #=> "Hello from Klass.\n"
   k.extend(Mod)   #=> #<Klass:0x401b3bc8>
   k.hello         #=> "Hello from Mod.\n"

1Note

extend adds class methods too

lazylester ยท Sep 9, 20091 thank

Because classes are objects. So for example:

module Ispeak
  def says
    "greetings aliens!"
  end
end

module Ieat
  def eats
    "spinach"
  end
end

module Inhabitant
  def says
    "I'm strong to the finish"
  end
end

class Human
  extend Ispeak # add class methods from Ispeak
  include Inhabitant # add instance methods from Inhabitant
end

Human.extend Ieat # add class methods from Ieat

puts Human.says # -> greetings aliens!
puts Human.eats # -> spinach


popeye = Human.new

puts popeye.says # -> I'm strong to the finish