Re: How can I determine the property attributes on a class or instance?
mrdylan wrote: class TestMe(object): def get(self): pass def set(self, v): pass p = property( get, set ) t = TestMe() type(t.p) #returns NoneType, what??? t.p.__str__ #returns method-wrapper object at XXX --- What is the best way to determine that the attribute t.p is actually a property object? Obviously I can test the __str__ or __repr__ attributes using substring comparison but there must be a more elegant idiom. Check the class instead of the instance: type(TestMe.p) type 'property' type(t.__class__.p) type 'property' isinstance(t.__class__.p, property) True --Ben -- http://mail.python.org/mailman/listinfo/python-list
Re: How can I determine the property attributes on a class or instance?
On Tue, 11 Apr 2006 19:11:46 -0700, mrdylan wrote: Given a class like so: --- class TestMe(object): def get(self): pass def set(self, v): pass p = property( get, set ) t = TestMe() type(t.p) #returns NoneType, what??? t.p calls t.get() which returns None. So t.p is None, and type(t.p) is NoneType. t.p.__str__ #returns method-wrapper object at XXX --- What is the best way to determine that the attribute t.p is actually a property object? Obviously I can test the __str__ or __repr__ attributes using substring comparison but there must be a more elegant idiom. If you want a general purpose solution for an object introspection tool, I must admit I'm as lost as you are. The only thing I have come up with is this nasty hack: t.p is None True dir(t.p) is dir(None) False for attr in dir(None): ... print attr, getattr(None, attr) is getattr(t.p, attr) ... __class__ True __delattr__ False __doc__ True __getattribute__ False __hash__ False __init__ False __new__ True __reduce__ False __reduce_ex__ False __repr__ False __setattr__ False __str__ False I don't even know if this hack generalises to any values of p, and I suspect it isn't of practical use. Why do you want to know if p is a property? -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: How can I determine the property attributes on a class or instance?
Replying to myself now... how sad. On Wed, 12 Apr 2006 15:19:17 +1000, Steven D'Aprano wrote: If you want a general purpose solution for an object introspection tool, I must admit I'm as lost as you are. The only thing I have come up with is this nasty hack: t.p is None True dir(t.p) is dir(None) False Scrub that. dir(t.p) is dir(t.p) False dir(None) is dir(None) False Which in hindsight is so obvious that I'll just slink off in embarrassment for having made the error in the first place. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
