From: chen li <chen_li3@...>
Date: 2006-12-30T10:28:39+09:00
Subject: With and without Song#to_s

Happy holiday for all!

I have two classes (most of them copied from Pickaxe
2)and they work fine. But I get the address for 
each object if I comment out method Song#to_s. How to
explain them?

Thanks,

Li





class Song  
  def initialize(name,artist,duration)
    @name=name
    @artist=artist
    @duration=duration
  end 
  attr_reader :name, :artist, :duration 
  
 def to_s
    "#@name\t#@artist\t#@duration"
 end
end


class Songlist
  def initialize
    @songs=Array.new
  end
  
 def append(song)
    @songs.push(song)
    #self 
  end
  
  def all_songs
    @songs.each{|song| song}  
  end  
end    

# populate the Songlist from a file
list=Songlist.new
File.open('song.txt').each_line do |line|
  if line=~/\w+/           #skip empty line
    name,artist,duration=line.split(',')  
    s=Song.new(name,artist,duration)
    list.append(s)
  end
end

puts" list all songs"
puts list.all_songs
puts

## define Song#to_s and the screen output
ist all songs
song1	 author1	20
song8	 author1	4
song5	 author2	6
song7	 author1	8
song2	 author5	1
song4	 author7	3
song6	 author3	5
song8	 author6	7


###comment out Song#to_s and the screen output
 list all songs
#<Song:0x28ab39c>
#<Song:0x28ab144>
#<Song:0x28ab090>
#<Song:0x28aade8>
#<Song:0x28aac44>
#<Song:0x28aaa8c>
#<Song:0x28aa9b0>
#<Song:0x28aa514>





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