[Zope-CMF] Re: five.intid and DirectoryView

[Laurence Rowe]

Ross Patterson wrote:
> Tres Seaver <tseaver at palladion.com> writes:
> 
>> Martijn Pieters wrote:
>>> On Fri, Jun 27, 2008 at 6:53 PM, Ross Patterson <me at rpatterson.net> wrote:
>>>> "Martijn Pieters" <mj at zopatista.com> writes:
>>>>> But the code never does that. When cloning a file-based FSObject, a
>>>>> new instance is created and that is added to the ZODB. Noone else
>>>>> should do this either.
>>>> zope.app.keyreference does.  The persistence machinery doesn't add an
>>>> object to a connection until commit.  As such, an IPersistent and
>>>> IObjectAdded event handler, such as the one in zope.app.intid, that
>>>> needs the object to have a connection needs to add the object to a
>>>> connection.
>> Sounds like a bug in zope.app.intid to me:  it shouldn't be forcing
>> objects to have connections.
>>
>>> Why is the IObjectAdded event fired at all? Perhaps that's the bug here.
>>>
>>>> Shouldn't anything that implements IPersistent be able to be added to a
>>>> connection?  Wouldn't that be considered part of providing the
>>>> interface?  Where else is an object that provides IPersistent stored in
>>>> global state?
>>> I assume it was easier at the time to use just one class. Perhaps this
>>> should be reconsidered now. However, just providing the IPersistence
>>> interface does not mean the object expects to be added to a connection
>>> arbitrarily.
>> Exactly.  Nobody is supposed to add objects to a connection except their
>> already-persisted containers.
> 
> That sounds right to me especially given that an object's parent isn't
> necessarily "where" the object is persisted.  Shouldn't it be possible,
> for example, to have a container that looks up it's contained items from
> a utility that actually is stored in another ZODB.  Such a container's
> items would not share their parent's connection.
> 
> FWIW, this happens in zope.app.keyreference.  The reason it needs the
> object to have a connection is so that it can get the object's _p_oid.
> If this is a bug, how can zope.app.keyreference get _p_oid for an object
> added in the current, as yet uncommitted transaction?

Creating a savepoint seems to do the trick:

 >>> from persistent import Persistent
 >>> import transaction
 >>> app.pob = Persistent()
 >>> app.pob._p_oid is None
True
 >>> s = transaction.savepoint()
 >>> app.pob._p_oid
'\x00\x00\x00\x00\x00\x00E\xfa'

Laurence