# Newbie Alert **URL:** \ **Category:** Ruby\ **Created:** [September 13, 2006, 5:22am UTC](https://www.ruby-forum.com/t/newbie-alert/68499 "2006-09-13T05:22:52Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![johnlester](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e480ec/32.png) [@johnlester](https://www.ruby-forum.com/u/johnlester)\ **Post date:** [September 13, 2006, 5:22am UTC](https://www.ruby-forum.com/t/newbie-alert/68499/1 "2006-09-13T05:22:52Z")
I am a brand new Ruby beginner, and I have what is undoubtedly a painfully simple newbie question. I’m starting my learning by using the online “Programming Ruby, HTML Help Edition (v0.3a)”, and I’m having trouble getting one of the earliest code samples in the “Classes, Objects, and Variables” chapter to work. Here is my slightly modified version (with line numbers added) of the tutorial code that I’ve saved in a file called RubyTutorial.rb: 01 class Song 02 def initialize(name, artist, duration) 03 @name = name 04 @artist = artist 05 @duration = duration 06 end 07 def to\_s 08 puts “Song: #{@name}–#{@artist} (#{@duration})” 09 end 10 end 11 12 aSong = Song.new(“My Way”, “Sinatra”, 225) 13 print “aSong.to\_s ==\> " 14 aSong.to\_s 15 16 class KaraokeSong \< Song 17 def initialize(name, artist, duration, lyrics) 18 super(name, artist, duration) 19 @lyrics = lyrics 20 end 21 def to\_s 22 super + " [#{@lyrics}]” 23 end 24 end 25 26 kSong = KaraokeSong.new(“My Way”, “Sinatra”, 225, “And now, the…”) 27 print "kSong.to\_s ==\> " 28 kSong.to\_s When I try to run this from the Windows XP Command Prompt I get the following result: C:\Documents and Settings\jl2351\My Documents\Ruby\_Scripts\>ruby RubyTutorial.rb aSong.to\_s ==\> Song: My Way–Sinatra (225) kSong.to\_s ==\> Song: My Way–Sinatra (225) RubyTutorial.rb:22:in `to_s': undefined method`+’ for nil:NilClass (NoMethodError) from RubyTutorial.rb:28 C:\Documents and Settings\jl2351\My Documents\Ruby\_Scripts\> Obviously the “kSong.to\_s” call is supposed to be displaying the additional lyric information. Since I have no clue, can someone tell me how to correct this? And why is ‘+’ erroring out as an undefined method? And any other insights into this error that a rank beginner might find helpful? Thanks much. ---
**Author:** ![johnlester](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e480ec/32.png) [@johnlester](https://www.ruby-forum.com/u/johnlester)\ **Post date:** [September 13, 2006, 5:38am UTC](https://www.ruby-forum.com/t/newbie-alert/68499/2 "2006-09-13T05:38:09Z")
This is actually easy to fix. ‘+’ is an undefined method for nil:Nilclass, which means that the super on line 22 is returning nil. ‘super’ refers to the to\_s of the parent class which is, Song#to\_s: > 01 class Song > … > 07 def to\_s > 08 puts “Song: #{@name}–#{@artist} (#{@duration})” > 09 end > 10 end The problem is the ‘puts’. puts prints a string and a “\n” to standard out and returns nil. You actually don’t usually want to\_s to print anything, so if you change Song#to\_s to read def to\_s “Song: #{@name}–#{@artist} (#{@duration})” end That will fix the bug, but your program won’t print anything, because aSong.to\_s will just return a string (which is what you want). So you’ll need to change lines 13 and 14: > 13 print "aSong.to\_s ==\> " > 14 aSong.to\_s to print "aSong.to\_s ==\> " + aSong.to\_s + “\n” or puts “aSong.to\_s ==\> #{aSong.to\_s}” and do something similar with lines 26 and 27. ---
**Author:** ![johnlester](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e480ec/32.png) [@johnlester](https://www.ruby-forum.com/u/johnlester)\ **Post date:** [September 13, 2006, 5:38am UTC](https://www.ruby-forum.com/t/newbie-alert/68499/3 "2006-09-13T05:38:47Z")
John Legate wrote: > 01 class Song > 02 def initialize(name, artist, duration) > 03 @name = name > 04 @artist = artist > 05 @duration = duration > 06 end > 07 def to\_s > 08 puts “Song: #{@name}–#{@artist} (#{@duration})” Here is your problem. #puts prints out the String but it returns nil. > 09 end > 10 end > 11 > 12 aSong = Song.new(“My Way”, “Sinatra”, 225) > 13 print “aSong.to\_s ==\> " > 14 aSong.to\_s > 15 > 16 class KaraokeSong \< Song > 17 def initialize(name, artist, duration, lyrics) > 18 super(name, artist, duration) > 19 @lyrics = lyrics > 20 end > 21 def to\_s > 22 super + " [#{@lyrics}]” So here you have printed it out but have gotten a nil back, whence your error since nil does not respond to #+. > 23 end > 24 end > 25 > 26 kSong = KaraokeSong.new(“My Way”, “Sinatra”, 225, “And now, the…”) > 27 print "kSong.to\_s ==\> " > 28 kSong.to\_s ---
**Author:** ![johnlester](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e480ec/32.png) [@johnlester](https://www.ruby-forum.com/u/johnlester)\ **Post date:** [September 13, 2006, 5:50am UTC](https://www.ruby-forum.com/t/newbie-alert/68499/4 "2006-09-13T05:50:10Z")
On Sep 12, 2006, at 11:23 PM, John Legate wrote: > 08 puts “Song: #{@name}–#{@artist} (#{@duration})” This line is the culprit. You really don’t want ‘puts’ here – it writes to stdout and returns nil, which is why you’re getting the error. Try 08 “Song: #{@name}–#{@artist} (#{@duration})” Regards, Morton ---
**Author:** ![johnlester](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e480ec/32.png) [@johnlester](https://www.ruby-forum.com/u/johnlester)\ **Post date:** [September 13, 2006, 6:13am UTC](https://www.ruby-forum.com/t/newbie-alert/68499/5 "2006-09-13T06:13:10Z")
D’OH! I mean, thanks very much to all of you who helped me solve this problem. I’m also kind of new at searching for answers on a Help Forum like this, and I’m pleasantly surprised and impressed with how quickly the answer can be found in this venue. 1337p337 wrote: > This is actually easy to fix. ‘+’ is an undefined method for > nil:Nilclass, which means that the super on line 22 is returning nil. > ‘super’ refers to the to\_s of the parent class which is, Song#to\_s: > > > 01 class Song > > … > > 07 def to\_s > > 08 puts “Song: #{@name}–#{@artist} (#{@duration})” > > 09 end > > 10 end > > The problem is the ‘puts’. puts prints a string and a “\n” to > standard out and returns nil. You actually don’t usually want to\_s to > print anything, so if you change Song#to\_s to read > def to\_s > “Song: #{@name}–#{@artist} (#{@duration})” > end > That will fix the bug, but your program won’t print anything, because > aSong.to\_s will just return a string (which is what you want). So > you’ll need to change lines 13 and 14: > > > 13 print "aSong.to\_s ==\> " > > 14 aSong.to\_s > > to > print "aSong.to\_s ==\> " + aSong.to\_s + “\n” > or > puts “aSong.to\_s ==\> #{aSong.to\_s}” > and do something similar with lines 26 and 27.