Re: How to remove an object and all its references ?

Yes that is helpful, thank you Jim for your answer.
I already do it at application level. I know about repoze.catalog but 
haven't used it yet.
I just wanted to know if there another standard way to do it, and you have 
answered me for this.

Have a nice day.

Le samedi 13 août 2016 14:44:53 UTC+2, Jim Fulton a écrit :
>
>
>
> On Fri, Aug 12, 2016 at 1:30 AM, <[email protected] <javascript:>> 
> wrote:
>
>> Good morning,
>>
>> I'm quite new to ZODB and I wonder if there is a way to remove a stored 
>> object with all its references ?
>> persistent weak ref seems a nice path, but objects are collected on pack 
>> operation only IIUC.
>>
>> What I'd like to do : create a persistent object, store it into the 
>> database and add it to a BTree. When I delete the original object stored in 
>> database, I'd like it removed from BTree too.
>>
>> If there is such a way, do I have to care about performance impact for 
>> collecting and removing all references ?
>>
>
> There are two levels at which to think about this question.
>
> In this context, you should think about ZODB as persistent memory in a 
> high-level language.  As with Python, objects are removed through garbage 
> collection. There's no way to explicitly deallocate/remove objects.
>
> At the application level, as with Python, you could arrange automation to 
> remove objects from collections, often some sort of master collection and 
> secondary collections (e.g. index).  How this is done seems to depend a lot 
> of application requirements and tradeoffs. As a result, there's more than 
> one way to do it.
>
> A very common pattern in the Zope community (including Plone, etc.) is to 
> use a "catalog" which is a collection of objects with indexes.  When object 
> lifecycle events happen, methods are called on the catalog to add, update, 
> or remove objects. Because Zope was designed to be wildly extensible, a 
> number of abstractions (base classes, event systems, special methods) are 
> used to automate this, which leads to some complexity.  I haven't used 
> Zope-based catalog machinery in a while, so I can't point to the current 
> best examples.
>
> Less ambitious applications can use simpler frameworks to do the same 
> thing.
>
>  
>
>> Thanks for your help.
>>
>
> I hope I was helpful.
>
> Jim
>
> -- 
> Jim Fulton
> http://jimfulton.info
>

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