From: John Maclean <info@...>
Date: 2006-01-21T04:20:39+09:00
Subject: Basic Inheritance questions {noob alert:- pickaxe ed. 2, page 27}

Chaps,

Say you have a class Song. You'd make a file for that class with the
following;

#!/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
 
# test the class by creating a new object
#song = Song.new("Bicylops", "Fleck", 260) 
#song.inspect

Now it's time to make a "child" class....

jayeola@tp20$ cat class_KaraokeSong.rb 
#!/usr/bin/env ruby 
class KaraokeSong < Song
  def initialize(name, artist, duration, lyrics)
    super(name, artist, duration) 
    @lyrics = lyrics 
  end 

#  def to_s 
#    # method for displaying these instancess
#  "Song: #@name--#@artist (#@duration)" 
#  end 
end
 
When I created the parent it was simple to `irb` and then `require
class_Song.rb`. 

How would one use this child class? Not quite clear from the Pickaxe
book. Do I create a new file for KaraokeSong as I have done or have
both the "super" and "child" in the same file?

 -- 
John Maclean
MSc (DIC)
07739 171 531