From: Brian Candler <b.candler@...>
Date: 2010-02-09T22:47:16+09:00
Subject: Re: Mixin module with class variables and class methods

John Lane wrote:
> Can someone advise how this should be written so that a class method in
> a mixin can access a class variable created by the mixin ?

Class variables are a pain, for exactly this sort of reason. Instance 
variables of a class are much easier to handle and understand.

module TestMixin

  def self.included(base)
    p "TextMixin included in #{base}"
    base.class_eval {
      @name = "foobar"
    }
    base.extend ClassMethods
  end

  module ClassMethods

    def name
      @name
    end

    def name=(x)
      @name=(x)
    end

    def class_method(str)
      $stderr.puts "this is a class method in TestMixin #{str}"
      $stderr.puts "the class variable is #{name}"
    end

  end

  def name
    self.class.name
  end

  def name=(x)
    self.class.name=(x)
  end

  def instance_method
    $stderr.puts "this is an instance method in TextMixin"
    $stderr.puts "the class variable is #{name}"
  end

end

class Foo

  include TestMixin
  class_method "foo"
  def initialize
    instance_method
  end
end

Foo.new
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