Ruby: module, require and include

Question

I\'m trying to use Ruby modules (mixins).

I have test.rb:

#!/usr/bin/env ruby
require_relative \'lib/mymodule\'

class MyApp
  include MyModule
  sel         


        

Answer 1

class MyApp
  class << self
    include MyModule
  end
  self.hallo
end

is the same as

class MyApp
  extend MyModule
  self.hallo
end

extends just opens the class object and include the module methods. "hallo" becomes a class object aka. static method of class MyApp.

So "include" inject the methods to the instances of the receiver, in your case being "self" NOT to the object itself. "extend" inject the methods to the receiver in your case being "self".

self.include MyModule // inject the methods into the instances of self
self.extend MyModule // inject the methods into object self

At class level "self" will point to your class object which is MyApp.

Also remember that "include" and "extend" are just methods defined in module.rb. "include" is a class object method (static-method) and "extend" is an instance method.