From: Logan Capaldo <logancapaldo@...>
Date: 2006-05-03T01:51:05+09:00
Subject: Re: Mixin Syntax for Newbies


On May 2, 2006, at 12:40 PM, Nathan Olberding wrote:

> I'm trying to start using mixins and I'm having a little syntactual
> trouble, if that's a word.
>
> Here's my test code:
>
> ---------------
> module One
>         @one = "One!"
>         attr_reader :one
> end
>
> class Two
>         include One
>         def initialize
>                 puts @one
>         end
> end
>
> this = Two.new
> ----------------
>
> I have tried several variations on this, but Two.one always seems to
> come out as "nil". Is it possible to set it to "One!" by default?

First of all when you say
module One
    @one = "One!"
end

That sets the instance variable of the module One.

Second, this:

def initialize
   puts @one
end

defeats the whole purpose of using attr_reader

Finally, you may want to do something like:

module One
   def one
      @one ||= "One!" # sets @one to "One!" only if it's not already set
                      # or is nil or false
   end
end

class Two
   include One
   def initialize
     puts one
   end
end