Re: [Zope] [Zope-Annce] ZClasses resurrected
So...we are on 2.8.10 and our biggest app on our site is a ZClass based news object. How close will this provide functionality to just drop our data.fs into 2.12 and have those zclasses work? This is huge news! Thanks Dieter!!!! -Allen Dieter Maurer wrote:
The Zope developers have ripped out the ZClasses functionality from the Zope core in version 2.12.
As promised, I have collected the former code in a new package ("dm.zopepatches.zclasses" on PyPI). When imported, this package uses monkey patching to restore the ZClasses functionality. New tests verify the functionality as formerly described in the Zope book (2.7 edition).
To make "ZClasses" available again, the ZODB root database requires "dm.zopepatches.zclasses.ClassFactory" as "class-factory" option in the Zope configuration file. When this option is processed, the package is imported and the monkey patching takes place.
The current version does not yet restore the "distribution" functionality (of Zope products). Let me know when you need this functionality.
Allen Schmidt Sr. wrote at 2009-10-4 16:40 -0400:
So...we are on 2.8.10 and our biggest app on our site is a ZClass based news object. How close will this provide functionality to just drop our data.fs into 2.12 and have those zclasses work?
I do not know. "ZClasses" have quite vast functionality. My test, however, only covers that part documented in the former (2.7 edition) Zope book. Your "ZClasses" usage may use much more and there may still be problems therein. I tried to move on old "Data.fs" (from a Zope 2.8.1 on Python 2.4 with the "ZClass" created even earlier) to the new Zope (2.12.0 on Python 2.6) and got a ZODB problem (an "AccessControl.Permission.PermissionMapping.PM" could not be loaded). "PermissionMapping.PM" is used by "ZClasses" (to map general Zope permissions to "ZClass" specific permissions) but the problem seems not be directly related to the "ZClasses" code. Instead, it looks like a Python ("pickle/cPickle") bug I have encountered earlier when an object was pickled when it still was an instance of an old style Python class and should now be unpickled as an instance of a new style class. This fails because old style class pickling uses an optimization not recognized for new style classes. Because nothing changed between Zope 2.8 and Zope 2.12 with respect to the "PermissionMapping.PM" class type, I expect that the problem was already in the Zope 2.8 instance but the ZODB 3.4 (part of Zope 2.8) was less picky with respect to broken objects than the ZODB 3.9 used by Zope 2.12. I could successfully move a "Data.fs" with a "ZClass" created under Zope 2.11 to Zope 2.12. Thus, no garantee that you will not face problems. Try it out and report back. I am ready to sort out "ZClasses" related problems -- with the active help of people who observe such problems. -- Dieter
this is great, I never used ZClasses. But I really cherish that somebody did speak up and keeps on giving suport to parts of the zope ecosystem the rest of the community stopped to maintain. robert
Dieter Maurer wrote:
The Zope developers have ripped out the ZClasses functionality from the Zope core in version 2.12.
As promised, I have collected the former code in a new package ("dm.zopepatches.zclasses" on PyPI). When imported, this package uses monkey patching to restore the ZClasses functionality. New tests verify the functionality as formerly described in the Zope book (2.7 edition).
To make "ZClasses" available again, the ZODB root database requires "dm.zopepatches.zclasses.ClassFactory" as "class-factory" option in the Zope configuration file. When this option is processed, the package is imported and the monkey patching takes place.
The current version does not yet restore the "distribution" functionality (of Zope products). Let me know when you need this functionality.
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----- Original Message ----- From: "Allen Schmidt Sr." <aschmidt@fredericksburg.com> To: "Dieter Maurer" <dieter@handshake.de> Cc: "Zope Users" <zope@zope.org> Sent: Sunday, October 04, 2009 4:40 PM Subject: Re: [Zope] [Zope-Annce] ZClasses resurrected
So...we are on 2.8.10 and our biggest app on our site is a ZClass based news object. How close will this provide functionality to just drop our data.fs into 2.12 and have those zclasses work? This is huge news! Thanks Dieter!!!!
For long term stability and maintainability I would strongly recommend rewriting your application to remove ZClasses. Depending on your application(s) this can be a non-trivial task, but once it is done you can return to standard zope releases. This is a business risk/reward situation: how important are the ZClass apps to your business? Can you afford to have them stop working? Are willing to maintain your own ZClass patches (Dieter has provided a starting point, but what if Dieter "gets hit by a bus")? I have rewritten ZClass apps twice now, and it can be a serious PITA, but the peace-of-mind, ongoing product stability and maintainability was well worth it. Jonathan
participants (4)
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Allen Schmidt Sr. -
Dieter Maurer -
Jonathan (dev101) -
robert rottermann