From: "David A. Black" <dblack@...>
Date: 2009-07-21T20:58:07+09:00
Subject: Re: Inheritance problem with dynamic methods

Hi --

On Tue, 21 Jul 2009, Stefano Grioni wrote:

> Hello,
>
> I'm tying to create a method which would allow me to get and set
> instance variables having the same name as the class. And this should be
> true even for classes inheriting it.
>
> For instance
>
> [code]
> class Mother
>         define_method(self.to_s.downcase){ instance_variable_get
> '@'<<self.class.to_s.downcase }
>         define_method((self.to_s.downcase+'=').to_sym){|nom|
> instance_variable_set '@'<<self.class.to_s.downcase, nom}
> end
> class Daughter < Mother
> end
> [/code]
>
> At the moment, this code creates "mother" and "mother=" instance methods
> for both Mother and Daughter's classes.
> Instead, what I'd like to have in a "mother" and "mother=" instance
> methods for Mother, and "daughter" and "daughter=" for Daughter.
>
> I think that there is some meta programming trick that I'm missing but I
> can't find which one.

One metaprogramming trick you could use is attr_accessor :-) Another
is the "inherited" hook. Try this:

class Mother
   def self.attr_eponymous(c=self)
     c.send(:attr_accessor, c.to_s.downcase)
   end

   def self.inherited(c)
     attr_eponymous(c)
   end

   attr_eponymous
end


David

-- 
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