[Zope3-Users] Re: Events

[Philipp von Weitershausen]

On 22 Feb 2007, at 13:37 , David Johnson wrote:
>> You're probably talking about dispatchToSublocations. This is the  
>> code that looks up a containers sublocations and dispatches the  
>> event to them.
>>
>> One way to prevent this behaviour for your container is to write a  
>> new ISublocations adapter for your container that simply returns  
>> an empty sequence:
>>
>>   class MyContainerSublocations(object):
>>       implements(zope.location.interfaces.ISublocations)
>>       adapts(...IMyContainer)
>>
>>       def __init__(self, context):
>>           self.context = context
>>
>>       def sublocations(self):
>>           return ()
> This is probably the approach I will follow, but what if I want my  
> container objects notified?

I thought you don't... ?

> Even if I don't it seems the default Folder implementation follows  
> this logic and so if you have a folder with several large images  
> for example, then you will pay a price whenever an event is  
> issued.  In general it seems that any change will result in the  
> entire ZODB being read for each event dispatch...if I still follow  
> the logic here.

That's not what I said. It will only happen on object moves, in  
particular, when a container is moved. It will also only happen for  
the subitems of that container, not "the whole ZODB", though arguably  
that can mean a lot of data.

I would personally like to see some form of disabling event handlers.