HELP: NameError: uninitialized constant

ruby-talk
1

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!

···

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2

Can you verify you get *exactly* the same error when you require 'SongList'
at the top of your code?

Thanks!

Arlen

3

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

4

Arlen,

Thanks for your response. I get the same error when I do the require:

require 'test/unit'
require 'SongList'
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

[ookman@foo rubyfiles]$ ruby ./TestSongList.rb
Loaded suite ./TestSongList
Started
E
Finished in 0.000413 seconds.

  1) Error:
test_delete(TestSongList):
NameError: uninitialized constant TestSongList::SongList
    ./TestSongList.rb:7:in `test_delete'

1 tests, 0 assertions, 0 failures, 1 errors

Arlen Cuss wrote:

···

Can you verify you get *exactly* the same error when you require
'SongList'
at the top of your code?

Thanks!

Arlen

--
Posted via http://www.ruby-forum.com/\.

5

Hi,

···

On Sat, Mar 1, 2008 at 12:56 AM, Mac Flores <mac.flores@gmail.com> wrote:

Arlen,

Thanks for your response. I get the same error when I do the require:

Ah, see Stefano's answer. Use `class', not `def'. An accidental typo. :slight_smile:

But, I also think you'll find you need to require Song as well, otherwise
that won't exist either!

Arlen

6

Aarrgh! It's a typo!

Thanks, Arlen and Stefano! I've been looking at that code for so many
hours that I missed the 'class' declaration for SongList and was using
'def' instead like you observed. I changed that among other things. I
also added require 'Song' in the SongList class and require 'SongList'
in the TestSongList test class. The test runs now passes.

I appreciate your help and the extra set of eyes.

Arlen Cuss wrote:

···

Hi,

On Sat, Mar 1, 2008 at 12:56 AM, Mac Flores <mac.flores@gmail.com> > wrote:

Arlen,

Thanks for your response. I get the same error when I do the require:

Ah, see Stefano's answer. Use `class', not `def'. An accidental typo. :slight_smile:

But, I also think you'll find you need to require Song as well,
otherwise
that won't exist either!

Arlen

--
Posted via http://www.ruby-forum.com/\.