[Zope-CMF] [dev] content factories and events - a proposal

yuppie y.2007- at wcm-solutions.de
Wed Dec 26 13:21:26 EST 2007


We still have no easy way to use add views for CMF content. I tried to 
figure out what needs to be done to make CMF content creation more 
generic and to avoid duplicate notifyWorkflowCreated and (re)indexObject 

CMF uses two kinds of factories:

Oldstyle factories are used by FactoryTypeInformation if 'product' is 
specified and by ScriptableTypeInformation. They are black box factory 
methods that create unfinished content (no portal type set) and add it 
to the container.

Newstyle factories are used by FactoryTypeInformation if 'product' is 
not specified. They are zope 3 style factories. The code using these 
factories is responsible for setting the portal type and adding the 
content object to its container.

Both currently depend on the _finishConstruction() process that sets the 
portal type and calls notifyWorkflowCreated() and reindexObject().

Here are my assertions:

a) The right place for calling notifyWorkflowCreated() and indexObject() 
is the event handler for IObjectAddedEvent. _setObject() sends this 
event by default.

b) Oldstyle factory methods are not responsible for setting the portal 
type. They call _setObject() to early for sending IObjectAddedEvent 
because the portal type might be wrong at that moment.

Proposed changes:

1.) Let's get rid of _finishConstruction(): Using newstyle factories we 
should set the portal type *before* calling _setObject(). 
notifyWorkflowCreated() and reindexObject() should be called by the 
event handler.

2.) Fix *all* oldstyle factories: They don't finish content creation, so 
they should not send the events. Since ScriptableTypeInformation factory 
methods don't call _setObject() directly, this affects only file system 
     self._setObject(id, o)
Has to be replaced by:
     self._setObject(id, o, suppress_events=True)
In each factory of each third party content type. I don't like that, but 
it is the only solution I see that allows us to use the events correctly.

3.) For oldstyle factories, set the portal type after calling the 
factory and send events after that. Unfortunately We can't send the 
IObjectWillBeAddedEvent because we don't know the object before it is added.

4.) For newstyle factories, also set the portal type, but let 
_setObject() send the events.

5.) Modify handleContentishEvent(): Add the notifyWorkflowCreated() call 
for IObjectAddedEvent. indexObject() is already called.

Any comments? Questions? Objections?



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