From: "Simon Kröger" <SimonKroeger@...>
Date: 2006-05-23T06:43:21+09:00
Subject: Re: initializing instance variables in a module

Francis Cianfrocca wrote:
> Looks promising but what if you have to assign to the variable? This code
> throws an exception:

[...]

>  def inc_myvar
>    myvar += 1
>  end
> end

this is equivalent to

myvar = myvar + 1

which tries to initialize a *local* variable, thats not what you want.
try self.myvar += 1

this of course does only work if you define a setter for myvar.

module Mixin
 attr_writer :myvar

 def myvar
   @myvar ||= 100
   @myvar
 end

 def inc_myvar
   self.myvar += 1
 end
end

class Klass
 include Mixin
end

Klass.new.inc_myvar

cheers

Simon