Rails - Mar 2007 - Tweak relationships & AR loading question

Hi,

Imagine you have a model Guy. Pick a guy from your table.
Maybe he is married and have children (single guys can''t have children,
can they?). So your are tempted to write:

class Guy < ActiveRecord::Base
  has_many :children
end

But if he is single, he can''t have children. So you wan''t to
write:

class Guy < ActiveRecord::Base
  if self.single
    has_many :children
  else
    has_one :child
  end
end

This could work: in fact has_* is just a macro for a bunch of specific
define_method. I am wrong?

But it doesn''t: the loading of the class fails claiming for
NoMethodError: undefined method `single''
I don''t understand: does AR loads relationships before defining
accessors? And if I force attr_accessor :single, assuming AR will
override it, I''ve got the same error. Does he parses the whole class
seeking for relationship first?

Thanks for your help,

-- 
,========================.
| Pierre-Alexandre Meyer |
| email : pam-1sEOgp2Wo8Qdnm+yROfE0A@public.gmane.org |
`========================'' 

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On Tue, Mar 20, 2007 at 11:57:32PM +0100, Pierre-Alexandre Meyer wrote
:
> But it doesn''t: the loading of the class fails claiming for
> NoMethodError: undefined method `single''
> I don''t understand: does AR loads relationships before defining
> accessors? And if I force attr_accessor :single, assuming AR will
> override it, I''ve got the same error. Does he parses the whole
class
> seeking for relationship first?
After going deeper in the source code, @attributes
attributes_from_column_definition is called in the initialize method of
ActiveRecord::Base.

Actually, during the loading of the class, there is first:

ActiveRecord::Base.class_eval do
  include ActiveRecord::Validations
	../..
  include ActiveRecord::Associations
	../..
end

@attributes is not initialized yet. 
I thought ActiveRecord::Validations could help me, to see how it handles
passed attributes, but I didn''t understand the validates_each method
(line 291). What''s the send method? :/

-- 
,========================.
| Pierre-Alexandre Meyer |
| email : pam-1sEOgp2Wo8Qdnm+yROfE0A@public.gmane.org |
`========================'' 

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