From: John Maclean <info@...>
Date: 2006-01-21T07:12:26+09:00
Subject: Re: Basic Inheritance questions {noob alert:- pickaxe ed. 2,

Thanks for another fast response. Inheritance - I'm going to get this
-tonight-!

recap;
# the parent class
cat fx/ruby/chap3/class_Song.rb
#!/usr/bin/env ruby 
class Song
  def initialize(name, artist, duration)
    # define instance variables
    @name = name 
    @artist = artist 
    @duration = duration 
  end 

  def to_s 
    # method for displaying these instancess
  "Song: #@name--#@artist (#@duration)" 
  end 
end

# the child class

jayeola@tp20$ cat fx/ruby/chap3/class_KaraokeSong.rb
#!/usr/bin/env ruby 
require 'class_Song.rb'

# test if this class has been loaded correctly
Object.const_defined?(:Song)

class KaraokeSong < Song
  def initialize(name, artist, duration, lyrics)
    super(name, artist, duration) 
    @lyrics = lyrics 
  end

  def to_s
    super + " [#@lyrics]" 
  end 
end

#song = KaraokeSong.new("My Way", "Sinatra", 225, "And now, the...") 
#song = KaraokeSong.new("Sinatra", 225, "And now, the...") 
#song.to_s 
#song.inspect


How do we get KaraokeSong to acquire it's parent's attributes -without-
hadrcoding "def initialize(name, artist, duration, lyrics)", unless one
has to? From the book I get the impression that you can get away with
specifying the child's stuff and that it will take properties from it's
parent with the keyword super....


-- 
John Maclean
MSc (DIC)
07739 171 531