python2_2

Using Python 2.2 with Zope 2.6

Introduction

Officially Zope 2 will not support python2.2 till the as yet unreleased, Zope 2.7. However, since the first python2.2 release in December 2001, many third party libraries have been created which require python 2.2. Using these libraries means running Zope w/ python 2.2.

Several people are currently running zope2.6 with python2.2 for development and production.

more information on new python2.2 features

http://python.org/doc/2.2.1/whatsnew/

Issue rundown

new style classes

in general new style classes aren't compatible with zope, in that they can't participate fully in the zope framework, and i would recommend not using them with zope infrastructure.

with that in mind, the next few sections explore some of the behavior of new-style classes within zope.

extension classes

new style classes and extension classes are not compatible. python will issue a type error if it sees a class definition which utilizes both new style classes and extension classes:

          class Foo(object, Persistent):
                pass

          TypeError: metatype conflict among bases

however python won't detect the conflict when extension classes are first in the base class list, though the resulting class is unuseable at runtime :

          class Bar(Implicit, object):
                pass

          bar = Bar()
          bar.a = 1

imo, the best practice here is, don't do that ;-). this places several restrictions on using new style classes with zope2, as the zope2 infrastructure is highly dependent on Extension Classes.

persistence

to be written.. explore new style class instances as attributes of persistent objects.

acquisition

to be written.. security interaction

properties

don't work with extension classes.

iterators

seem to work fine. stevea noted that were some issues with tales and iterators which he believed have been fixed.

generators

seem to work fine, very nice for making tree walkers.

nested scopes

work fine.

Unexplored

python scripts and python2.2 (restricted compiler)

Conclusion

Running zope2.6 with python2.2 is definitely possible...