From: Caleb Clausen <vikkous@...>
Date: 2010-03-24T07:45:51+09:00
Subject: Re: Module A extends Moudle B possible?

On 3/23/10, Robert Klemme <shortcutter@googlemail.com> wrote:
> On 03/23/2010 03:11 AM, Smart RoR wrote:
>> Can Modules extends within themselves?
>>
>> Like Class A < B is Valid, where B is another class
>> Module X < Y is invalid, where Y is another module?
>
> Not directly.  But you can use #included like this:
>
> irb(main):001:0> module A; end
> => nil
> irb(main):002:0> module B
> irb(main):003:1> def self.included(cl)
> irb(main):004:2> cl.class_eval { include A }
> irb(main):005:2> end
> irb(main):006:1> end
> => nil
> irb(main):007:0> class X
> irb(main):008:1> include B
> irb(main):009:1> end
> => X
> irb(main):010:0> X.ancestors
> => [X, A, B, Object, Kernel, BasicObject]
> irb(main):011:0>
>
> Note however that the inheritance order is reversed.  There are a number
> of other ways to achieve what you want.  The requirement does not seem
> to come up very frequently though.  So maybe it's not an issue as big as
> you think.

Am I missing something? Why not just include A from B? Like this:

irb(main):001:0> module A; end
=> nil
irb(main):002:0> module B include A end
=> B
irb(main):003:0> class X
irb(main):004:1> include B
irb(main):005:1> end
=> X
irb(main):006:0> X.ancestors
=> [X, B, A, Object, Kernel]
irb(main):007:0>