[Zope-dev] add optional "folder" argument to ZClass.createInObjectManager() ?

[Toby Dickenson]

oops, forgot to cc the list.....

On Tue,  4 Apr 2000 18:26:53 -0700 (PDT), bruce@perens.com (Bruce
Perens) wrote:

>Currently, the ObjectManager in which an object is to be created is found
>through acquisition. This breaks when sub-objects are created in the
>constructor of their container object. For example: I have a Purchase object
>containing Item objects. In method PurchaseClass_add(), I create the Purchase
>object using PurchaseClass.createInObjectManager(). That goes fine. Then I
>create its contained objects using ItemClass().createInObjectManager().
>Instead of going inside of the PurchaseObject, they go in the folder that
>contains the PurchaseObject.
>
>No manipulation of name spaces by <dtml-with> will change this - the
>ObjectManager is found through acquisition, not the name space.

agreed

>1. Am I missing an easier or more elegant way to do this?

I wouldnt call it elegent, but the least ugly way to do this (afaik)
is to delay constructing the sub-objects until after the constructor
is complete, and the object is installed in it's context.

From a python product this is straightforward (and I use this alot):

def manage_addZCedarApp(self,id,title,REQUEST,RESPONSE):
        """ """
        c = MyObject(str(id),wstring(title))
        self._setObject(str(id),c)
        c.__of__(self)._after_create() # this creates the sub-objects
        if REQUEST is not None:
            return self.manage_main(self,REQUEST)


For a ZClass its a bit harder, since you need to find an appropriate
acquisition wrapper for the newly created object. Something like this
should do (untested)

<!--#with "whatever.createInObjectManager(REQUEST['id'], REQUEST)"-->
<!--#/with-->
<dtml-call "getattr(this(),REQUEST['id']).after_create()">

>I propose to add an optional argument to ZClass.createInObjectManager() that
>specifies the ObjectManager instance in which the newly-created object will
>reside.

That option is cleaner for this particular case, but doesn't solve the
more general problem. There are many resources that zope objects get
using acquisition, and most of them might be useful in a constructor. 

Toby Dickenson
tdickenson@geminidataloggers.com