The joys of weakrefs... references to instance methods (callbacks)

[Magnus Lie Hetland]

In article <mailman.1013502171.782.python-list at python.org>, Mike C.
Fletcher wrote:
>Very nice module.  I just did a re-write of my watcher classes using 
>dispatcher.  Why did I keep the watcher pattern?  Well, it makes 
>creating pre-event processing possible (my one class needs to do some 
>processing to determine conflicts, and until 2.2 object-based-classes 
>(with properties) can live in ZODB, I'm stuck with that).
>
>Would be nice if there was a simple download somewhere (had to re-format 
>the code after Mozilla mangled it with cut-and-paste).  Should put an 
>explicit license in there (as ActiveState's legal policy says that the 
>license included with the contribution applies.
>
>Also looked at the References.py module in anygui.  Didn't spend much 
>time on it, as dispatcher is much closer to what I need.

Take a look at References.py and Events.py together -- Events.py is
the dispatcher part; References.py is just a set of utilities for
references that can be either weak or strong.

> Was one of 
>these modules based on the other (your comments on the ASPN site seem to 
>suggest there's some relationship)?

Yes, the dispatcher in Anygui is based on this and at least two other
similar dispatcher modules (but it is basically a full rewrite). There
was some lengthy discussion on the Anygui devel list about this sort
of dispatcher mechanism a while ago. (If you're interested, I could
probably find the other two modules as well :)

One advantage of the Anygui dispatcher is that it allows you to use
weak references for some handlers and strong references for others.
(Maybe Patrick has also added that now -- I'm not sure.)

>Good job all around. Thanks,
>Mike

--
Magnus Lie Hetland                                  The Anygui Project
http://hetland.org                                  http://anygui.org