[Zope-dev] ZODB: interface for walking object graph?

[Pavlos Christoforou]

On Thu, 23 Mar 2000, Andrew M. Kuchling wrote:

> I only see one way of doing this, by walking over the whole object
> graph starting from the ZODB's root objects.  Storage objects do this
> in their pack() method to determine reachability.  Problem: you'd have
> to copy the walking logic out of the pack() method into your own
> method.

Hmmm ... wouldn't that imply that you would need to change the stored
instances in place? Lets suppose there is such a function. What should 
it happen when you do find such an 'unreachable' object. Modify it and 
append it to the end of Data.fs? As part of which transaction? (I suppose
you can have one transaction that modifies all the objects of the given
type) What happens if that unreachable instance has a newer version? Then
if you modify both versions as part of different transactions (or even the
same) you still loose the Undo facility. Generally I can't see an easy
way of changing single instances that belong to a
multi-instance transaction and keeping that transaction set as a group.
Seems to me you would have the same problem even if you modify just the
reachable objcets. If I am right then you will loose the Undo facility
anyways so you might as well pack to 0 and modify all the reachable ones
in one transaction.


Pavlos