From: Chad Perrin <code@...>
Date: 2010-10-22T11:15:19+09:00
Subject: Re: Help needed with this code please

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On Fri, Oct 22, 2010 at 07:03:04AM +0900, Paul Roche wrote:
> class Song

[snip]

>
>   @@songs =3D [ ]

[snip]

>=20
>   def self.list
>     @@songs
>   end
>=20
>   def self.list_add=3D(val)
>     @@songs << val
>   end
>=20
> end

[snip]

>=20
> module Tuneuts
>   def self.fetch(item, out =3D [])
>     all =3D Song.list + Actor.list + Album.list + Library.list

[snip]

>   end
> end


>=20
> The problem is Song.list  (in the module Tuneuts)  is returning nothing.
> Am I missing something here?

Maybe I'm missing something obvious, but I think the parts I didn't snip
out are the relevant bits:

Are you, at any point before calling Song.list, assigning anything to the
@@songs variable?  From what I've seen, your @@songs variable is just an
empty list at the point you call Song.list in the Tuneuts module.  As
such, it should be returning "nothing", in that it returns nothing but an
empty list.

Note that in my irb examples, I've saved all the code that was included
inline in your email in a single file called song.rb, and commented out
the `require "predicate"` part -- and moved the Pred module definition
above the Song class definition so the class could actually take
advantage of the module.

    ~> irb
    irb(main):001:0> load 'song.rb'
    =3D> true
    irb(main):002:0> Song.list
    =3D> []
    irb(main):003:0> puts Song.list
    =3D> nil

If you assign something to it using your list_ad=3D method, however, you'll
then get something out of it:

    irb(main):004:0> Song.list_add =3D 'foo'
    =3D> "foo"
    irb(main):005:0> Song.list
    =3D> ["foo"]
    irb(main):006:0> puts Song.list
    foo
    =3D> nil

Is that perhaps where you're having a problem?

--=20
Chad Perrin [ original content licensed OWL: http://owl.apotheon.org ]

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