--On 7. August 2005 19:02:51 +0200 Jan-Ole Esleben <[EMAIL PROTECTED]> wrote:


What do I need to do to derive a new base class for my products from
item that defines its own meta class? There's a whole mess of code in
the Zope source code that deals with meta classes, but nothing I can
actually identify as the thing to do.

I am deriving from SimpleItem at the moment. Currently, I use a meta
class derived from type, but this doesn't work:

  File "E:\Python23\lib\fliwas\ccitem.py", line 54, in ?
    class CCItem(SimpleItem):
  File "E:\Python23\lib\fliwas\ccmethods.py", line 38, in __new__
    return type.__new__(cls, name, bases, classdict)
TypeError: metaclass conflict: the metaclass of a derived class must be a
(non-s trict) subclass of the metaclasses of all its bases

I don't know much about meta-classes but I think you require new-style classes for working with meta-classes. This implies that you need at least Zope 2.8 since new-style classes conflict with Zope ExtensionClasses in pre-Zope 2.8 versions.


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