From: Robert Klemme <shortcutter@...>
Date: 2006-05-06T05:48:45+09:00
Subject: Re: klass.include vs instance.extend question

2006/5/3, polypus <polypus@yahoo.com>:
>
> i want a few instance methods to be automatically defined for the user
> without any explicit coding on their part.
>
> in the below distillation of my code, i have two options (labelled), my
> question
> is whether one option is better in any way than the other, and why one
> would prefer one over the other. my suspicion is that option 1 is more
> space efficient, and option 2 more time efficient, is that correct?
>
> also i should note that for people to use my module M they must call
> (for other reasons) extend, foo, and init_m in the extended class
> regardless of which option i finally choose. also the method init_m must
> be defined in the manner below (define_method) regardless of the option
> i choose, also for other reasons. and so you should not take any of
> their having to be there or not into account in your assesment. thanks
> many.
>
> module InstanceMethods
>   # instance methods in here
> end
>
> module M
>   # option 1
>   def self.extend_object klass
>     klass.class_eval 'include InstanceMethods'
>     super
>   end
>   # option 2
>   def foo
>     define_method :init_m do
>       self.extend InstanceMethods
>     end
>   end
>
> end
>
> class X
>   extend M
>   foo
>   def intialize
>     init_m
>   end
> end

Why can't you just do

class X
  include InstanceMethods
end

Did I miss something?

robert


--
Have a look: http://www.flickr.com/photos/fussel-foto/