__new__ being static method allows a use-case when you create an instance of a subclass in it: return super(<currentclass>, cls).__new__(subcls, *args, **kwargs) If new is a class method then the above is written as: return super(<currentclass>, cls).new(*args, **kwargs) and there is no place to put subcls. I don’t really see when that would be a … Read more
Note: new-style classes are the default in Python 3. Subclassing object is unnecessary there. Read below for more information on usage with Python 2. In short, it sets free magical ponies. In long, Python 2.2 and earlier used “old style classes”. They were a particular implementation of classes, and they had a few limitations (for … Read more
This is an old question, but none of the answers seems to mention that. in the general case, it IS possible for a new-style class to have different values for type(instance) and instance.__class__: class ClassA(object): def display(self): print(“ClassA”) class ClassB(object): __class__ = ClassA def display(self): print(“ClassB”) instance = ClassB() print(type(instance)) print(instance.__class__) instance.display() Output: <class ‘__main__.ClassB’> … Read more
You seem to be using classic old-style classes in python 2. In order for properties to work correctly you need to use new-style classes instead (in python 2 you must inherit from object). Just declare your class as MyClass(object): class testDec(object): @property def x(self): print ‘called getter’ return self._x @x.setter def x(self, value): print ‘called … Read more
From New-style and classic classes: Up to Python 2.1, old-style classes were the only flavour available to the user. The concept of (old-style) class is unrelated to the concept of type: if x is an instance of an old-style class, then x.__class__ designates the class of x, but type(x) is always <type ‘instance’>. This reflects … Read more