Making immutable instances

[Mike Meyer]

bonono at gmail.com writes:
> I am puzzled, and could have read what you want wrong. Are you saying
> you want something like this :
>
> a={}
> a.something = "I want to hang my stuff here, outside the intended use
> of dict"

Exactly. For a use case, consider calling select.select on lists of
file objects. If the processing is simple enough, the clearest way to
associate a handler with each socket is just to add it as an
attribute. But that doesn't work - sockets are bulitin types. So you
consider less light-weight solutions, like subclassing socket (now
that that's possible), or a dictionary of handlers keyed by socket.

This works by default with classes written in Python. That it doesn't
work for builtins is inconsistent, non-orthogonal, and
incomplete. However, it's easy to work around, and the obvious fix -
adding a dictionary to every builtin - is rather costly. So we'll live
with it since practicality beats purity.

     <mike
-- 
Mike Meyer <mwm at mired.org>			http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.