RE: Dealloc Notification

[Gerrit Van Dyk]

Richard wrote:

>There is an NSObject method 'setDeallocNotificationsActive:' you can use.

This is an instance method that updates a global variable. What was the
intended purpose of this method? As you mentioned it is so that the _dealloc
method could return NO and then the object won't be dealloced. The method
name suggests to me that notifications should be sent when an object gets
deallocated. If I use this paradigm and add a category to NSObject
implementing _dealloc which sends notifications then all objects will send
this notification.

I have a suggestion. Could we add an ivar to the NSObject class that states
that a Dealloc notification should be sent when this object are being
deallocated. If this variable is set on an object then a GSObjectDidDealloc
notification would be posted in the dealloc method. This will enable any
object to subscribe to this notification. If an object is interested in a
notification then you could simply subscribe to the notification and set the
variable to true. In the DB library I need to know when a DB object gets
deallocated so that I can remove it from the uniqueing tables. I can set the
variable to true when I add the object to the tables and subscribe to the
notification, thus when it gets deallocated I can remove it from the tables.
I thought that we can implement this ivar in the same way the retained
variable is implemented ie adding it to the obj_layout structure of
NSObject, this will not influance other running applications as this
information is added to the end of the object's instance variables. We will
need to add a get and set method for this ivar as well.

If this is acceptable should I implement the changes in NSObject or will
somebody else do it.

Just a stupid question, why is there only one lock for all objects for
setting the retained count? Wouldn't this block to many objects
unnecessarily. I understand that creating a lock object for each object is
most probably more of an overhead.

Regards
Gerrit van Dyk
 
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