2010/8/23 Michael Foord email@example.com:
On 23/08/2010 23:55, Benjamin Peterson wrote:
2010/8/23 Raymond Hettingerraymond.firstname.lastname@example.org:
On Aug 23, 2010, at 1:13 PM, Benjamin Peterson wrote:
2010/8/23 Michael Foordfuzzyman@voidspace.org.uk:
To me hasattr *looks* like a passive introspection function, and the fact that it can trigger arbitrary code execution is unfortunate - especially because a full workaround is pretty arcane.
hasattr(x, "y") doesn't look any more passive to me the x.y.
One says "does this object have attribute y" the other fetches attribute y. I'm amazed they don't look different to you. Given Python's object model there is no reason that the first *should* fetch the attribute to determine that it is present, *except* for the dynamic attribute creation of __getattr__ and __getattribute__.
Actually, I'd say given Python's object model, you have to have the attribute in hand to determine that it is present.
For properties there is *no reason* why code should be executed merely in order to discover if the attribute exists or not.
Properties are allowed to raise AttributeError, so you technically have to execute it.