[Zope3-Users] Multiple containers in one object - how to implement in Zope3?

[Alek Kowalczyk]

Jeff Rush napisał(a):
> Alek Kowalczyk wrote:
>> Florian Lindner napisał(a):
>>
>>> Am Samstag, 1. April 2006 15:15 schrieb Alek Kowalczyk:
>>>  
>>>> I have a single object, which can contain many objects of 2 another
>>>> types (IType1, IType2). My intention is to have those objects 
>>>> contained
>>>> in separate collections (because they are very different 2 types of
>>>> objects and should not be mixed in one collection)
>>>> I'd like to have each collection editable like Zope folder, i.e each
>>>> collection to be IContainer/BTreeContainer.
>
>>> why don't just create two subfolders (of type zope.folder) in you 
>>> Container object, one for IType1, one for IType2?
>>>
>> Good idea, thanks! In the meantime I have made something similar, i.e 
>> defined two more container types (IObjects1, IObjects2) and created 
>> one IObjects1 and one IObjects2 in the IMasterObject's (which now is 
>> also a IContainer) constructor .
>>
>> But now the new question follows:  how to limit cardinality of items? 
>> I want now to have one and exactly one IObjects1 and IObjects2 
>> instance in IMasterObject. Is there some type of constraint defined, 
>> similar to ItemTypeConstraint, for limiting number of elements of 
>> specific type, or I should do it on my own by overriding __setitem__ 
>> and other methods?
>
> Alek, I do the same thing for a complex container with a fixed set of 
> member sub-containers.
>
>   IVenture("RUSH")
>     ILedgerSet, name "ledgers"
>        ILedgers
>        ...
>     IJournalSet, name "journals"
>        IJournals
>        ...
>
>   http://sample.com/ventures/RUSH/ledgers/CASH
>   http://sample.com/ventures/RUSH/journals/CHECKING
>
> The way to get what you want is to make IMasterObject *not* an 
> IContainer but an IReadContainer.
>
> There are IWriteContainer and IReadContainer which are sub-interfaces 
> of IContainer.
>
> This way no one can ever add/remove those sub-containers.  And 
> (presumeably you're doing it now) you add those the instances of 
> Objects1 and Objects2 at creation time of MasterObject, and then never 
> again need to manipulate them.
>
> You should also place Container/Containee constraints on the IObjects1 
> and IObjects2 so they cannot be created in inappropriate places, and 
> of course omit their menu entries from the ZMI so they are not 
> manually addable.
>
> -Jeff
>
Thanks Jeff! This is exactly what I wanted to :)

Warm Regards,
Alek