From: Robert Klemme <bob.news@...>
Date: 2003-04-07T16:47:25+09:00
Subject: Re: To inherit or to include? That is the question.


"Phil Tomson" <ptkwt@shell1.aracnet.com> schrieb im Newsbeitrag
news:b6kqiu0uka@enews4.newsguy.com...
> >The simples rule is that you have to use inheritance if you want to
reuse
> >state.  Modules can only provide methods.  So, if you have a set of
> >related methods that can be expected to be used in different classes,
put
> >them together in a module.
>
> But this isn't quite true.  You can create/manipulate instance variables
> withing a modules's methods:
>
> module Foo
>   def set_var(v)
>     @var = v
>   end
>   def get_var
>     @var
>   end
> end
>
> class Bar
>   include Foo
>   attr_accessor :var
> end
>
> b = Bar.new
> b.set_var(42)
> puts b.var #-> 42
>
>
> So, the module Foo was able to introduce some state into the class Bar.

Oops!  Something learned again.  Obviously I misread something.  Maybe the
difference then is that a module can't introduce state on initialization?

    robert