From: Ruby Admirer <ruby_admirer@...>
Date: 2007-03-01T07:47:38+09:00
Subject: Re: How to get modules included by a class/module (not those from the superclasses)

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Pit,

>Including a module in a class that already has been included by one of
>its superclasses doesn't change the inheritance hierarchy:
>
>module M
>end
>
   >class P
     >include M
   >end
>
   >class C < P
   >end
>
   >p C.ancestors  # => [C, P, M, Object, Kernel]
>
   >class C
     >include M
   >end
>
   >p C.ancestors  # => [C, P, M, Object, Kernel]
>
>The only way to create the situation you describe above would be to 
>include the module in the child class *before* including it in the 
>superclass.

You are absolutely right ! I did not catch this.
This seems to be a similar behaviour as for a class variable/method :

class B
@@var = "Hello"
end

class C < class B
end

The class variable @@var is shared/inherited in C. Similar as the case where there is only one include.

Conversely :

class B
end
 
 class C < class B
 @@var = "Hello"
  end
 
class B
 @@var = "Goodbye"
  end

The two class variables @@var are different. This is similar as the case where there is an include at each class.

I know that this behaviour for class variable/method will change with Ruby 2.0.
(A class variable/method will be static to the class)
Will it be the same for module inclusion ??


>class Class
     >def my_own_included_modules
       >ancestors.inject([]) { |acc, mod|
         >break acc if mod == superclass
         >acc << mod unless mod == self
         >acc
       >}
     >end
   >end

This is exactly what I need.

> Out of curiosity: why do you need this?

I just want to know/understand :
- the hierarchy (inheritance) between the Ruby classes
- which class really includes which module(s)

Thanks a lot.

Chauk-Mean.


 
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