[Zope3-dev] Containment constraints

[Jim Fulton]

Jim Fulton wrote:
> Roché Compaan wrote:
> 
>> The containment constraints are yummy. Just one thing I am concerned
>> about is that the current implementation (__setitem__.precondition on an
>> Interface) may lead to a lot of dead chickens. I seem to be ending up
>> with a lot of interfaces that only subclass IContainer and set
>> preconditions.
> 
> 
> Yes, and likewise for the __parent__ constraint.
> 
>> Add to that the class implementation and ZCML one has to
>> write for each interface and the dead chickens start to smell.
> 
> 
> The zcml one has to write?  I don't follow this.
> 
>> Should I just get used to it or am I missing some zen.
> 
> 
> Well, this is new. We need to get some experience.  I'm sure
> it can be improved.  I'll note that implementing containers is
> now *much* simpler than it used to be.
> 
> (In fact, I really need to update the slided, because, at the
>  Bangalore sprint a new zcml directive was added that vastly
>  simplifies defining the contents, add and index pages.)
> 
> I suspect that a zcml directive and/or Python api could automate
> certain aspects of defining these interfaces. Proposals are welcome.

I'll note that, eventually, there will be a TTW UI for defining
container types, much as there is in the CMF.

Jim

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