On Tue, Apr 8, 2008 at 10:21 PM, ian <[EMAIL PROTECTED]> wrote: > Ok, so what about 'hasattr' ?? > hasattr(myObject,'property') > seems equivalent to > 'property' in dir(myObject) > > I would suggest that using the 'in' is cleaner in this case also. Is > there a performance penalty here? Or is there reason why the two are > not actually the same?
>>> class HasAll(object): ... def __getattr__(self, name): pass ... >>> hasattr(HasAll(), 'spam') True >>> 'spam' in dir(HasAll()) False >From the docs: "Because dir() is supplied primarily as a convenience for use at an interactive prompt, it tries to supply an interesting set of names more than it tries to supply a rigorously or consistently defined set of names, and its detailed behavior may change across releases. ... [hasattr] is implemented by calling getattr(object, name) and seeing whether it raises an exception or not." http://docs.python.org/lib/built-in-funcs.html > Which style is preferred?? Don't test for the existence of the attribute if you're going to get it when it exists; just go ahead and get it. try: x = myObject.property except AttributeError: x = None - Miles -- http://mail.python.org/mailman/listinfo/python-list
