From: Quintus <quintus@...>
Date: 2012-05-09T20:45:00+09:00
Subject: Re: How to make a given klass to include a module

Am 09.05.2012 13:36, schrieb I��aki Baz Castillo:
> Hi, simple code:
> 
> ----------------------------
>   module M
>     def hello
>       "HELLO"
>     end
>   end
> 
>   class A
>   end
> 
> 
>   klass = A
> ----------------------------
> 
> Now I want to make an instance of klass (so an instance of A) but also
> need that klass includes module M.
> Note however that I cannot change class A definition since klass is
> given in runtime by the user.
> 
> NOTE: It must be efficient, I don't want to use eval and so.
> 
> Thanks a lot.
> 
> 

# ruby -v: ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-linux]
irb(main):001:0> module M
irb(main):002:1> def hello
irb(main):003:2> "HELLO"
irb(main):004:2> end
irb(main):005:1> end
=> nil
irb(main):006:0> class A
irb(main):007:1> end
=> nil
irb(main):008:0> klass = A
=> A
irb(main):009:0> klass.send(:include, M)
=> A
irb(main):010:0> a = klass.new
=> #<A:0x0000000202cfe0>
irb(main):011:0> a.hello
=> "HELLO"

Alternatively, if you don���t want to pollute the given class, use #extend
on the instances (which is also more clean as it doesn���t require #send).

Vale,
Marvin