[Zope-dev] Re: Future of ZClasses

[Philipp von Weitershausen]

Dieter Maurer wrote:
> Philipp von Weitershausen wrote at 2006-9-29 01:35 +0200:
>> Dieter Maurer wrote:
>>> Philipp von Weitershausen wrote at 2006-9-28 14:23 +0200:
>>>> ...
>>>> Why not set marker interfaces directly on the objects? That whole "type" 
>>>> thing is unnecessary. Just use interfaces.
>>> Usually, a type is seen as a set of objects, its type instances.
>>>
>>> It is quite nice to be able to work on a object set meta level
>>> rather than on individual objects....
>> Sure, though I don't see how an interface can't represent this meta 
>> level. Perhaps I'm missing an important point here...
> 
> You want to stick this interface to individual objects,
> while Lennart proposed to stick it to a type and use
> some kind of inheritance to make it effective on all objects
> instantiated from this type.

But where does this type come from? Persistent classes are hard (hence 
ZClasses cannot be maintained by anyone except a few people).

> For me, Lennart's approach seems to be far more economic, as
> he does things on an abstract (the type) level rather than
> always work on the concrete (the individual object) level.

I don't see how introducing another concept (a type) would be more 
economic. It'd be one more thing to worry about wrt persistency etc.