From: Jean Helou <jean.helou@...>
Date: 2006-10-03T23:57:11+09:00
Subject: Re: Newbie: Question => How to do this with Classes ?

On 10/3/06, Eye Matz <matz@eyematz.com> wrote:
> Jean Helou wrote:
> > now for your example :
> > class Important
> >   def singleton_class
> >     #get the singleton class for this instance
> >     #A good explanation for the singleton class is available in the
> > pickaxe book
> >     #if i remember correctly it's in the duck typing section with a
> > diagram
> >     #which makes it all clear.
> >     class << self; self; end
> >   end
> >
> >   #define the class method which will be available as a dsl element.
> >   #this is only "syntactic sugar" for your dsl to make it nicer
> >   def self.set_this_value_method(value)
> >     define_attr_method :this_value_method, value
> >   end
> >
> >   #Then defines a new method called "name" in the singleton class of
> > the instance.
> >   #note that here the instance is a class thus it adds a class method
> >   def self.define_attr_method(name, value)
> >     singleton_class.class_eval do
> >      define_method(name) do
> >        value
> >      end
> >   end
> >
> > end
> >
> >
> > class SemiImportant < Important
> >   set_this_value_method :something_or_anything
> > end
> >
> > now you can call SemiImportant.this_value_method and it will return
> > :something_or_anything
> >
> > jean
>
> Hi Jean,
>
> Thanks you VERY much for making that example clearer !
>
> One minor error in it, though
> >   def singleton_class
> >     class << self; self; end
> >   end
>
> should be
>
> def self.singleton_class
>   class << self; self; end
> end
>
> And Yes, I do understand the concept of Singleton classes, just NOT very
> well in Ruby or in Ruby syntax. My problem is really more to do with the
> grammatical logic, ie: when should I use this or that, or how should I
> write this or that to get this or that result.
>
> I haven't found a clear and concise account of that, and therefore I am
> writing stuff like this [ Name are Matz I ] in Ruby, and things don't
> work so well then.
>
> Thank you for your help!
>
>
> --
> Posted via http://www.ruby-forum.com/.
>
>
Maybe this will help since he asked himself the exact same question :
http://wanderingbarque.com/ruby/DynamicRuby.html

he understood the how but not the why... hope this helps.

jean