Question about garbage collection

[Frank Millman]

On 2024-01-17 3:01 AM, Greg Ewing via Python-list wrote:
> On 17/01/24 1:01 am, Frank Millman wrote:
>> I sometimes need to keep a reference from a transient object to a more 
>> permanent structure in my app. To save myself the extra step of 
>> removing all these references when the transient object is deleted, I 
>> make them weak references.
> 
> I don't see how weak references help here at all. If the transient
> object goes away, all references from it to the permanent objects also
> go away.
> 
> A weak reference would only be of use if the reference went the other
> way, i.e. from the permanent object to the transient object.
> 

You are right. I got my description above back-to-front. It is a pub/sub 
scenario. A transient object makes a request to the permanent object to 
be notified of any changes. The permanent object stores a reference to 
the transient object and executes a callback on each change. When the 
transient object goes away, the reference must be removed.

Frank