[Hibernate-devel] New functionality in CVS

[Gavin_King/Cirrus%<CI...@ci...>]

(1) I implemented Validatable. It would be cool if people could try this
out and see if anything extra is required here.

(2) You may now use the <composite-id> declaration to specify properties of
the persistent class itself as the id properties. The form of the
declaration is:

<composite-id> <!-- name and class attibutes are missing -->
  <property name="foo"/>
  <property name="bar"/>
</composite-id>

to load() an instance, simply instantiate an instance of the class, set its
id properties and call:

session.load(object, object);

(3) After fielding so much user confusion over the semantics of cascade
="all", I found a way to extend the functionality consistent with the
current semantics and (hopefully) without any risk of breaking existing
code. I will need some feedback about the details here, though:

Essentially I have scrapped the notion of a cascaded update(). The
functionality performed by cascaded updates is now performed every time the
session is flushed.

This means that any lifecycle objects are automatically updated or saved as
soon as they are detected (in a collection or many-to-one association). The
choice of update() or save() is still made on the basis of wether or not
the id property is null.

There are still some remaining wrinkles here:

 * objects with primitive ids can't have null ids. Should we interpret 0 as
null?
 * the treatment of a transient object with a non-null id is different
between save() and flush(). A cascaded save() would cause the object to be
save()d whereas if discovered at flush-time, it would be update()d. Should
we tweak the semantics of cascaded saves? (Such a change has a fairly large
potential to break existing code.) Alternatively, should we reintroduce
cascaded update as a concept and tweak the new behaviour of flush() to be
consistent with save()? Or is the new behaviour actually fine?

Everyone should be aware that, even though this looks a lot like
"persistence by reachability", it still isn't because delete() remains a
manual process. I have very many misgivings about introducing any kind of
reference-counting scheme to solve the garbage collection problem...

Gavin

P.S. After this email, I will be recieving mail mainly at

  ga...@ap...

(thanks to Anton + to Christoph who also offered me use of a mail server)