If you define a ruby program with only one model class like this:
class Order < ActiveRecord::Base
has_many :legs
end
and there are no other models defined shouldn''t the has_many cause a
compile error since there is no other model defined to which the
association can be applied?
Rick
--
Posted via http://www.ruby-forum.com/.
On Nov 19, 2005, at 11:26 AM, Rick wrote:> If you define a ruby program with only one model class like this: > > class Order < ActiveRecord::Base > has_many :legs > end > > and there are no other models defined shouldn''t the has_many cause a > compile error since there is no other model defined to which the > association can be applied?No, because if we checked at parse time, there would be no way to handle circular dependencies, like this: class Order < ActiveRecord::Base has_many :legs end class Leg < ActiveRecord::Base belongs_to :order end When the has_many instruction is parsed, the Leg class has not yet been seen. Thus, things have to be loaded lazily, such that errors caused by missing classes won''t be reported until an attempt to actually instantiate the class is made. - Jamis
Seems that a post-compile model check could be made.
OK, is this a bug? Compile this code:
require ''rubygems''
require_gem ''activerecord''
class Order < ActiveRecord::Base
has_many :legs
end
class Order < ActiveRecord::Base
has_many :legs
end
Shouldn''t the compiler at least detect the attempt to define the same
class a second time?
Rick
--
Posted via http://www.ruby-forum.com/.
Rick wrote:> Shouldn''t the compiler at least detect the attempt to define the same > class a second time? > > RickRuby has no problem about spcifyinbg the same class several times...many people actually considers this a feature ;-) -- Posted via http://www.ruby-forum.com/.
On 11/20/05, Rick <willirl-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> > Seems that a post-compile model check could be made. > > > > OK, is this a bug? Compile this code: > > > require ''rubygems'' > require_gem ''activerecord'' > > > class Order < ActiveRecord::Base > has_many :legs > end > > class Order < ActiveRecord::Base > has_many :legs > end > > > Shouldn''t the compiler at least detect the attempt to define the same > class a second time?Absolutely not, that''s one of the greatest features IMO of ruby - the fact that a class/object is never closed. I''m not sure what your level of ruby experience is - but you aren''t redefining your class in the example you quote - you are adding to the class definition. I''m not quite sure what happens under the covers with activerecord when you duplicate the has_many attribute but I would imagine it''s probably quite benign (hopefully a hash or something that wouldn''t have a problem with a duplicate member). You can modify a class from anywhere at all in your code. It means that if you wanted to add something to the String class you need not modify the core libraries - you can just add the method in your code and they will get added. There is the freeze method for objects which sort of prevents you from making modifications but for all real purposes ruby doesn''t lock down objects at all. While it may seem a little strange at first - boy does it get nice as you start to see the ways it can help you. -- John W Higgins wishdev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails