instance creatiion as an "event"

[Aahz]

In article <mailman.1050117319.5102.python-list at python.org>,
Steven Taschuk  <staschuk at telusplanet.net> wrote:
>Quoth Simon Burton:
>> On Fri, 11 Apr 2003 17:15:32 -0400, Arthur wrote:
>>>
>>> The only thing I seem to be missing is some kind of "hook" to trigger a 
>>> general update cycle of all existing class instances upon the creation 
>>> of a new class instance at the interactive prompt
>> 
>> class Member:
>> 	members = []
>> 	def __init__(self):
>> 		for m in Member.members:
>> 			m.notify(self)
>> 		Member.members.append(self)
>> 	def notify(self,other):
>> 		print self,"a new member:",other
>
>Though you will probably want to use weak references in
>Member.members, unless you intend that all instances of the class
>live as long as the class does.

Blech.  It's essentially impossible to delete a class as long as
instances of it exist.
-- 
Aahz (aahz at pythoncraft.com)           <*>         http://www.pythoncraft.com/

This is Python.  We don't care much about theory, except where it intersects 
with useful practice.  --Aahz, c.l.py, 2/4/2002