Joe Strout <[EMAIL PROTECTED]> writes: > On Nov 13, 2008, at 3:23 PM, Arnaud Delobelle wrote: > >> Aaron Brady <[EMAIL PROTECTED]> writes: >> >>> One way around it, which I like the idea of but I'll be honest, I've >>> never used, is getting a function a 'self' parameter. You could make >>> it a dictionary or a blank container object, or just the function >>> itself. >>> ... >> Rummaging through my ~/python/junk/ I found the almost exact same: >> >> class NS(object): >> def __init__(self, dict): >> self.__dict__.update(dict) >> >> def static(**vars): >> ns = NS(vars) >> def deco(f): >> return lambda *args, **kwargs: f(ns, *args, **kwargs) >> return deco >> >> @static(ncalls=0, history=[]) >> def foo(ns, x): >> ns.ncalls += 1 >> ns.history.append(x) >> print "Number of calls: %s\nHistory:%s" % (ns.ncalls, ns.history) > > Thanks, Arnaud (and Aaron), that's really clever. I was thinking this > morning that something like this might be possible: a decorator that > adds the static storage with some standard name. I really like how > you've set this so that the static data is initialized right in the > decorator; that makes the intent very clear and hard to screw up. > > My only regret with this one is the need to add "ns" to the parameter > list. That makes it lok like part of the signature, when really (in > intent) it is not. If we have to add something to the parameter list, > we may as well do this: > > def foo(x, _ns=NS(ncalls=0, history=[])): > ... > > and skip the decorator. Then at least it's clear that this parameter > isn't really intended for callers. On the other hand, I guess the > decorator actually changes the signature as seen by the calling code, > which is a good thing. Rearranging the parameter order in the > decorator a bit, we could make this so that the intent is clear to the > reader, as well as enforced by the interpreter.
Check the wraps() function in the functools module. I think I wrote this decorator before it came into the standard library. -- Arnaud -- http://mail.python.org/mailman/listinfo/python-list
