[Zope] outstanding zclass questions.

[Michel Pelletier]

chas wrote:
> 
> Maybe I'm getting tunnel vision after fudging about with
> zclasses for the better part of a week but can somebody
> pls enlighten me on the following (or better still offer
> pointers to the precise point in the documentation) :
> 
> 1. Once you've created a Zclass, how do you modify the base classes ?

Currently this can only be done in Python.

> 2. If you have a product containing several Zclasses within Zclasses,
>    why must all of the zope permissions for these Zclasses stay in the
>    root folder of the product ?

I didn't realize that was the behavior.  There may be a reason for it,
I'll ask Jim.
 
> 3. Are there are any caveats against renaming Zclasses ? I renamed a class
>    and the instances created with it broke (ie. methods failed). That's SNAFU
>    with Lotus Notes but I thought that Zope's Zclasses are truly OO and
>    can handle it.

I belive you can rename them as long as the class id is the same.  did
the class id change also?  This would break your instances.

> 4. Is it possible to 'lose' orphans within the ODB  (just like orphan
> documents
>    in Lotus Notes) ? ie. or should class-level changes propagate through to
>    all instances of the class including deletions ? (this is essentially
>    the same as question 3.)

Class level changes will propagate.  I think any orphan situation were
cleaned up when we added class ids.
 
> 5. Zclasses and Zcatalog : once items have been added to a ZCatalog, why
>    aren't there pulldowns or multiple select boxes under the MetaData Table
>    and Indexes tabs so that people can choose which properties or objects
>    are available ?  DC did this so consistently for all other management
>    screens in Zope that this omission makes me wonder if I'm missing
> something
>    here. (It seems that such a feature would ease use and reduce error.)

Because the Catalog assumes no forknowledge about the objects it can
catalog.  Any attribute of any set of object can be indexed.  There is
no way for the Catalog to know, in advance, what possible attributes can
be indexed.
 
> 6. As per previous email and post : what permissions need to be set in order
>    to create a product that has a zclass within a zclass ? Has anyone got this
>    working yet (other than Kevin Dangoor who didn't use the standard zope
>    permissions in KmNews) ?

This would need to be documented.  Even I'm unclear on the details. 
Isn't this the same as question number 2? ;)
 
> Thank you very much - sorry for so many questions but I've really been
> chasing my tail for the past 3 days - and run out of documentation.

Note that Zope 2.0 is the first system to have anything resembling
ZClasses.  They are sure to evolve over time, like all things.
 
-Michel