Validation schemes for model objects that are not yet saved

All,

I have a model object that I do a bunch of stuff to before I want to
save it to the database. Actually, to be more specific, I do a lot of
validation that is related to one attribute on this model. I would like
to do some validation on it but take advantage of something akin to
ActiveValidation.

I’ve read through this

http://www.ruby-forum.com/topic/1689#1210

which referenced this:

http://www.realityforge.org/articles/2005/12/02/validations-for-non-activerecord-model-objects

and I just wondered if anyone had come up with another scheme for
handling validation for “partially constructed” model objects that they
would be willing to share.

I think I can probably just create another non-database model object to
handle this validation (since the validation is fairly involved), it
seems fair to promote this stuff to first-class object status :).

Thanks,
Wes