* Wayne Werner <waynejwer...@gmail.com> [110315 17:29]: > On Tue, Mar 15, 2011 at 8:00 PM, Tim Johnson <t...@johnsons-web.com> wrote: > > > What is the difference between using > > hasattr(object, name) > > and > > name in dir(object) > > > > hasattr is basically > > try: > object.name > return True > except AttributeError: > return False > > while "name in dir(object)" is (AFAIK) more like: > > for attr in dir(object): > if name == attr: return True > return False Wayne, that is interesting to read. I'm glad I read it.
> However, rare is the occasion that you should use either of these. If you're > doing something like: > > if hasattr(myobj, 'something'): > myobj.something() > else: > print "blah blah blah" > > then what you really should be doing is: > > try: > myobj.something() > except AttributeError: > print "blah blah blah" > because 1) you avoid the overhead of an extra(?) try-except block, 2) in > Python it's EAFP - Easier to Ask Forgivness than Permission, 3) You > shouldn't inspect an object to find out what it can do, you should just try > it and then handle failures appropriately (at least that's what I've been > told). > > HTH, Yes it helps, including the distinction between the two try/except blocks. On another note, I made an error in the original posting. I did a 'reply' rather than a direct 'send' thus this thread is under the topic heading of a different thread. I will repost with your reply. thanks. -- Tim tim at johnsons-web dot com or akwebsoft dot com http://www.akwebsoft.com _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
