Hello folks,
Introduction
============
I'm working to improve the reliability of ExternalStorage[1], an
Archetypes addon who provides a filesystem storage that can be
used (in theory) for any field.
The problem
===========
Some AT pieces rely in the presence of an attribute containing
the data it wants to access. This attribute should behave exactly
as calling the field accessor method (sorry for the AT specific
terminology). Normally, this kind of thing is a trivial task done
by ComputedAttribute, to mimics the results of an original method
call. When I try to use the ComputedAttribute trick, I make Zope
SEGFAULT... :-(
Details
=======
Considering a schema containing a field 'test', I need to create
an attribute 'test' on each instance which use the schema.
This new property should have the same value as when calling
'instance.getTest()', which is done by 'field.get()' as we are
playing with the 'test' field.
Segfaulting
===========
I'm setting the new property at field initialization time, as
we have all needed elements: self (the storage), instance (the
current object instance) and field (our 'test' field):
def initializeField(self, instance, field):
name = field.getName()
if not hasattr(aq_base(instance), name):
# This should create a 'test' attribute on the
# current instance, with the same value of a
# field.get method call
setattr(instance, name, ComputedAttribute(field.get, 1))
In fact, it seems to (almost) work as expected, because all the
'functional' (testFuncional.py, where I use 'self.publish()') tests
pass.
The SEGFAULTs happens when accessing the parent instance, or when
doing a copy/paste operation (reproducible at testCopy.py).
Probably I'm abusing of ComputedAttribute, but I can't think in
any other solution. Any thought is highly appreciated! :-)
Reproducing the error
=====================
You can reproduce the error with a current checkout from Archetypes
release-1_3-branch[2] and from ExternalStorage trunk[1], changing
initializeField method as above and running the tests.
I can provide any additional info on request.
Thanks for your attention.
[1]http://cvs.sf.net/viewcvs.py/collective/ExternalStorage
[2]http://svn.plone.org/archetypes/Archetypes/branches/release-1_3-branch
--
_____________________________________________________________________
Dorneles Treméa · Developer · Plone Solutions · Brazil
Consulting · Training · Development · http://www.plonesolutions.com
_____________________________________________________________________
Plone Foundation · http://plone.org/foundation · Protecting Plone
_______________________________________________
Zope-Coders mailing list
Zope-Coders@zope.org
http://mail.zope.org/mailman/listinfo/zope-coders
Introduction
============
I'm working to improve the reliability of ExternalStorage[1], an
Archetypes addon who provides a filesystem storage that can be
used (in theory) for any field.
The problem
===========
Some AT pieces rely in the presence of an attribute containing
the data it wants to access. This attribute should behave exactly
as calling the field accessor method (sorry for the AT specific
terminology). Normally, this kind of thing is a trivial task done
by ComputedAttribute, to mimics the results of an original method
call. When I try to use the ComputedAttribute trick, I make Zope
SEGFAULT... :-(
Details
=======
Considering a schema containing a field 'test', I need to create
an attribute 'test' on each instance which use the schema.
This new property should have the same value as when calling
'instance.getTest()', which is done by 'field.get()' as we are
playing with the 'test' field.
Segfaulting
===========
I'm setting the new property at field initialization time, as
we have all needed elements: self (the storage), instance (the
current object instance) and field (our 'test' field):
def initializeField(self, instance, field):
name = field.getName()
if not hasattr(aq_base(instance), name):
# This should create a 'test' attribute on the
# current instance, with the same value of a
# field.get method call
setattr(instance, name, ComputedAttribute(field.get, 1))
In fact, it seems to (almost) work as expected, because all the
'functional' (testFuncional.py, where I use 'self.publish()') tests
pass.
The SEGFAULTs happens when accessing the parent instance, or when
doing a copy/paste operation (reproducible at testCopy.py).
Probably I'm abusing of ComputedAttribute, but I can't think in
any other solution. Any thought is highly appreciated! :-)
Reproducing the error
=====================
You can reproduce the error with a current checkout from Archetypes
release-1_3-branch[2] and from ExternalStorage trunk[1], changing
initializeField method as above and running the tests.
I can provide any additional info on request.
Thanks for your attention.
[1]http://cvs.sf.net/viewcvs.py/collective/ExternalStorage
[2]http://svn.plone.org/archetypes/Archetypes/branches/release-1_3-branch
--
_____________________________________________________________________
Dorneles Treméa · Developer · Plone Solutions · Brazil
Consulting · Training · Development · http://www.plonesolutions.com
_____________________________________________________________________
Plone Foundation · http://plone.org/foundation · Protecting Plone
_______________________________________________
Zope-Coders mailing list
Zope-Coders@zope.org
http://mail.zope.org/mailman/listinfo/zope-coders
