From: "Christopher J. Bottaro" <cjbottaro@...>
Date: 2007-02-12T08:27:53+09:00
Subject: Re: creating/accessing class vars from modules being used as mixins?

Wow, thanks for the fast response.  Your solution worked perfectly.
On a side note, this should definitely be in a FAQ somewhere (if it
isn't already)... it's kind of a hard problem to figure out if you
don't know not to look at class variables.

Thanks again,
-- Christopher

On Feb 11, 5:16 pm, James Edward Gray II <j...@grayproductions.net>
wrote:
> On Feb 11, 2007, at 4:26 PM, Christopher J. Bottaro wrote:
>
> > I'm writing a module that is to be used as a mixin for classes.  I
> > cannot create or access class variables from within module methods.
> > Please look at this small pastie.  It contains the module definitions,
> > class definitions, and some sample code that demonstrates the errors
> > I'm receiving.
>
> Class variables have confusing inheritance rules, that I don't think
> are worth learning.  (They are changing in a future version of Ruby.)
>
> Instead, it's almost always easier to use instance variables on the
> class/module itself.  Your code could do this with changes like:
>
> module MyModule
>
>     def self.included base
>        base.extend ForBase
>     end # def self.included
>
>     module ForBase
>
>       def message
>        @message
>       end
>
>       def message=(message)
>        @message = message
>       end
>
>        def acts_as_whatever options = {}
>           include MyModule::InstanceMethods
>           extend MyModule::ClassMethods
>
>           if options.has_key? :message
>              self.message = options[:message]
>           else
>              self.message = "no message"
>           end
>        end # def acts_as_whatever
>
>     end # module ForBase
>
>     module InstanceMethods
>
>        def show_message
>           puts self.class.message
>        end
>
>     end # module InstanceMethods
>
>     module ClassMethods
>
>        def print_message
>           puts message
>        end
>
>     end # module ClassMethods
>
> end # module MyModule
>
> James Edward Gray II