[Zope3-dev] IsarSprint topics - Zope 3 application components

[Jim Fulton]

Helmut Merz wrote:
> Am Mittwoch, 8. September 2004 12:17 schrieb Martijn 
> Faassen:
> 
>>Helmut Merz wrote:
>>
>>>- Reference Engine (this is my personal favorite here)
>>
>>I'm interested in this topic, but won't be at the
>>IsarSprint. 
> 
> 
> So I hope you will give us some remote support :-)
> 
> 
>>Could you tell me more about what you have in
>>mind for this?
> 
> 
> I'd like to implement something like this:
> 
> class Task(...):
> 
>     subtasks=[]
>     parenttasks=[]
> 
>     def assignSubtask(self, task):
>          self.subtasks.append(task)
>          task.parenttasks.append(self) # back reference
> 
> 
> Basic question: Will this work when the objects involved are 
> persistent?

Yes

> When all tasks are in the same container we could work with 
> the name field for referencing; or we could use the 
> uniqueid utility.

You could use the uniqueid utility in any case.  You could also
use IReference adapters.

> But one should also care for the cases when a referenced 
> object will be deleted - so we need some referential 
> constraints that are checked automatically...

Yup.

> Also often the references might carry additional information 
> (metadata / annotations), so they should be real objects.

Maybe. Depends on the application.

> And there might be some general ReferenceField schema 
> class...

Perhaps.

> That's the reason why the Archetypes developers have 
> invested considerable effort in developing a reference 
> implementation - and changed it two times.
> 
> I won't suggest any Zope 3 implementation for this 
> references stuff at the moment, but it would be fine if we 
> could start the discussion.

Yup

Jim

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