From: Zouplaz <user@...>
Date: 2008-10-10T17:02:39+09:00
Subject: Help me to better understand modules

Hello, I would like to use ruby modules for the first time. I understand 
theirs principle for a basic usage but get quite unsure for the present 
situation :

- I want to put some code in a library (railsapp/lib) to
    1) lighten the controller that will use it
    2) test unit the code on one side, and test unit the controller on 
the other side
- So, the lib is like this
    1) class BaseModule
    2) class SpecificModule < BaseModule
- The controller SomeController
    1) creates an instance sm = SpecificModule.new
    2) sm.doSomething

I don't like the idea of creating an instance - Because it seems (to me) 
  too much Java/C++ oriented

Instead I would like

module BaseModule
module SpecificModule
   include BaseModule

class SomeController
   include SpecificModule

Then, I could call doIt() from the controller


Hence, my question :
- is it 'good design' to use the modules like this ? May I have some 
(bad) surprises later ?
- are the modules 'motchable / stubbable' ?
- is it different to unit test modules compared to classes ?

I did few tries with modules (see above) and I have a question more : 
why did I need to use the 'self' keyword with self.my_stuff or 
self.method_payment ? (without self. the methods are unknow under 
SpecificPayment module)
I had a look to the rails code base and it seems that most methods 
defined in modules don't use it... In my case it seems that I should use 
'self' anywhere...

Any advice ?

Thank for the attention ;-)

module Payment

   @@attribut = "payment"

   def self.method_payment()
     p 'here again'
   end

end

module SpecificPayment

   include Payment

   @@attribut_specific = "foo"

   def self.my_stuff()
     p 'here'
     Payment.method_payment()
   end

end

class AClass
   include SpecificPayment

   def go()
     SpecificPayment.my_stuff()
     Payment.method_payment()
   end

end

a = AClass.new
a.go()