Ruby on Rails module include module

Question

I want to include a module in a rails helper(is also a module).

The helper is:

module SportHelper 
  .....
end

And the module is:

module Formula
  def say()
    ....
  end
end

Now, I want to use the method say in SportHelper. What should I do?

If I write like this:

module SportHelper 
  def speak1()
    require 'formula'
    extend Formula
    say()
  end

  def speak2()
    require 'formula'
    extend Formula
    say()
  end
end

This will work, but I don't want to do so, I just want to add the methods on the helper module,not every methods.

Hi, which version of Ruby and Rails use your app? – hernanvicente Jan 03 '14 at 07:16 — hernanvicente, Jan 03 '14 at 07:16
why not every methods, and which are of them? – Малъ Скрылевъ Jan 03 '14 at 07:50 — Малъ Скрылевъ, Jan 03 '14 at 07:50

score 5 · Accepted Answer · edited May 23 '17 at 12:19

You need just to include this module in your helper:

require 'formula'

module SportHelper
  include Formula

  def speak1
    say
  end

  def speak2
    say
  end
end

Maybe you don't need this line require 'formula', if it's already in the load path. For check this you can inspect $LOAD_PATH variable. For more information see this answer.

Basic difference between extend and include is that include is for adding methods to an instance of a class and extend is for adding class methods.

module Foo
  def foo
    puts 'heyyyyoooo!'
  end
end

class Bar
  include Foo
end

Bar.new.foo # heyyyyoooo!
Bar.foo # NoMethodError: undefined method ‘foo’ for Bar:Class

class Baz
  extend Foo
end

Baz.foo # heyyyyoooo!
Baz.new.foo # NoMethodError: undefined method ‘foo’ for #<Baz:0x1e708>

And if you use extend inside the object method, it will adding methods to an instance of a class, but they would be available only inside this one method.

Might want to mention the need for a `require` or why it's not required (e.g. due to autoload in Rails), given the OP's apparent confusion about require vs. include vs. extend. — Peter Alfvin, Jan 03 '14 at 07:26

score 1 · Answer 2 · answered Jan 03 '14 at 07:28

I think directly include should work

 module SportHelper 
      include SportHelper
      .........
      end
    end

I tested like below:

module A
       def test
          puts "aaaa"
       end
end

module B
    include A
    def test1
        test
    end
end

class C
    include B
end

c = C.new()
c.test1  #=> aaaa

It should work.

Ruby on Rails module include module

2 Answers2