2010/8/23 Michael Foord fuzzyman@voidspace.org.uk:
Properties are allowed to do whatever the heck they want. That doesn't mean that you have to execute code to determine whether they exist or not.
I thought you were trying to determine whether the attribute exists not the property.
If fetching an attribute raises an AttributeError it doesn't mean that attribute doesn't exist (although I admit that at the moment this is exactly what hasattr uses to mean) it just means that fetching that attribute raised an AttributeError. Even if you allow other exceptions to propagate you are still left with the fact that an AttributeError raised as a bug will still be silenced and interpreted as meaning that hasattr should just return False.
Raised as a bug? Is this not a valid pattern?
@property def myprop(self): if not self.myprop_support: raise AttributeError("myprop")