On Thu, Dec 29, 2011 at 9:07 AM, Prim <uki...@gmail.com> wrote: > class C: > def x(self): > print 'x method' > def __getattr__(self, attr): > print 'in __getattr__ method' > return attr > c = C() > c.x --> print in __getattr__ method, then throw TypeError: 'str' > object is not callable > c.x() --> print in __getattr__ method, x method 2 lines > #Q2: why c.x would get a exception?
I'm not sure exactly what's going on there, but as a general rule you should use new-style classes, not classic classes, which are deprecated and have been removed in Python 3. In Python 2 if you define a class without any base classes, you get a classic class. To define C as a new-style class in Python 2, derive it from object (or another new-style class): >>> class C(object): ... def x(self): ... print 'x method' ... def __getattr__(self, attr): ... print 'in __getattr__ method' ... return attr ... >>> c = C() >>> c.x <bound method C.x of <__main__.C object at 0x00CB6150>> >>> c.x() x method Note that in this case __getattr__ never gets called because the name was found using the normal lookup mechanism. You would need to use __getattribute__ if you want it to be called unconditionally. > #Q4, if when I define the class use property too, then instance.name > look up order would be? You can't use properties in classic classes. In a new-style class, if you access a property, then any instance attribute with the same name is ignored and can't be set in the first place. -- http://mail.python.org/mailman/listinfo/python-list
