From: Stefano Crocco <stefano.crocco@...>
Date: 2008-02-29T22:52:48+09:00
Subject: Re: HELP: NameError: uninitialized constant

Alle Friday 29 February 2008, Mac Flores ha scritto:
> OK.  I'm learning Ruby by going through the examples in Programming Ruby
> by Dave Thomas.  Somehow I'm stuck and I cannot progress further.  I
> have 3 files all in the same folder -- Song.rb, SongList.rb and
> TestSongList.rb. Code is as follows:
>
> ## Song.rb
> class Song
>     attr_reader :name, :artist, :duration
>     attr_writer :duration
>     @@plays=0
>     def initialize(name,artist,duration)
>         @name=name
>         @artist=artist
>         @duration=duration
>         @plays=0
>     end
> end
>
> ## SongList.rb
> def SongList
>     def initialize
>         @songs = Array.new
>     end
>
>     def append(song)
>         @songs.push(song)
>         self
>     end
> end
>
> ## TestSongList.rb
> require 'test/unit'
> class TestSongList < Test::Unit::TestCase
>     def test_delete
>         list = SongList.new
>         s1 = Song.new('title1','artist1',1)
>         s2 = Song.new('title2','artist2',2)
>         s3 = Song.new('title3','artist3',3)
>         s4 = Song.new('title4','artist4',4)
>         list.append(s1).append(s2).append(s3).append(s4)
>
>         assert_equal(s1, list[0])
>     end
> end
>
> So I run the test and I get this:
> [ookman@foorubyfiles]$ ruby ./TestSongList.rb
> Loaded suite ./TestSongList
> Started
> E
> Finished in 0.000414 seconds.
>
>   1) Error:
> test_delete(TestSongList):
> NameError: uninitialized constant TestSongList::SongList
>     ./TestSongList.rb:4:in `test_delete'
>
> 1 tests, 0 assertions, 0 failures, 1 errors
>
> Can anybody tell me why it's giving me the above error on this line?
> list = SongList.new
>
> I've tried to do:
> require 'SongList' at the top of TestSongList.rb but I get the same
> error. I've Googled this problem but I cannot find a resolution. I also
> tried to run the TestSongList code one line at a time in irb and it
> gives me the same error when it reaches line 4.
>
> Ruby version is:
>  ruby 1.8.6 (2007-03-13 patchlevel 0) [i686-linux]
>
> I appreciate any insight .... TIA!

There are two problems: you need to add

require 'SongList'

in TestSongList.rb. The second is you try to create the class SongList (in
SongList.rb) using 

def SongList

this creates a method called SongList, not a class. To create a class, you
need 

class SongList

(as you correctly used to create class Song).

I hope this helps

Stefano