On Apr 2, 2:38 pm, Ethan Furman <et...@stoneleaf.us> wrote: > Patrick Maupin wrote: > > On Apr 2, 1:21 pm, Ethan Furman <et...@stoneleaf.us> wrote: > >> For this type of situation, my preference would be: > > >> class spam(object): > >> def __call__(self, x, y, z): > >> try: > >> mongo = self.mongo > >> except AttributeError: > >> mongo = self.mongo = heavy_lifting_at_runtime() > >> return frobnicate(x, y, z, mongo) > >> spam = spam() > > >> No extra objects, out-of-place underscores, etc. > > >> ~Ethan~ > > > Well, I'm not a big fan of unnecessary try/except, so I would at least > > change it to: > > > class spam(object): > > def __getattr__(self, name): > > if name != 'mongo': > > raise AttributeError > > self.mongo = heavy_lifting_at_runtime() > > return self.mongo > > def __call__(self, x, y, z): > > return frobnicate(x, y, z, self.mongo) > > spam = spam() > > > Regards, > > Pat > > Sounds like a personal preference issue, rather than a necessary / > unnecessary issue -- after all, if you call that function a thousand > times, only once is mongo not defined... clearly the exception. ;) > > ~Ethan~
Well, I think the whole discussion has basically been about personal preference. OTOH, but if you call the function a few million times, you might find the cost of try/except to be something that you would rather not incur -- it might become a performance issue rather than a personal choice issue. On the other OTHER hand, if you call the function a few billion times, performance weighs more heavily in favor of the closure approach rather than the object approach, since local variable lookup is so much cheaper. Regards, Pat -- http://mail.python.org/mailman/listinfo/python-list
