From: Nikodemus Siivola <tsiivola@...>
Date: 2002-08-13T21:28:15+09:00
Subject: Re: Sibling rivalry and class variables


On Tue, 13 Aug 2002, Philip Mak wrote:

> What would you guys suggest I do if I want a variable set in the
> parent that the child may or may not override? So far, I've had to
> resort to using instance variables instead, like this:

This may or may not be what you are looking for, using class instance
variables. (The eval bit is just for conveninece.)


def class_attr_reader name
  eval <<-EOF
  def self.class_#{name}
    return @#{name}
  end
  EOF
end

class Parent
  class_attr_reader :info
  @info = "parent"
  def initialize
    puts "Parent 1: Initializing #{(self.class).class_info}"
    puts "Parent 2: in #{Parent.class_info}"
  end
end

class Daughter < Parent
  @info = "daughter"
  def initialize
    puts Daughter.class_info

    super
  end
end

class Son < Parent
  @info = "son"
  def initialize
    puts Son.class_info
    super
  end
end

Parent.new
puts "---"
Daughter.new
puts "---"
Son.new