new-style-class

All the Python built-ins are subclasses of object and I come across many user-defined classes which are too. Why? What is the purpose of the class object ? It's just an empty class, right? 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 example, you couldn't subclass builtin types). The fix for this was to create a new style of class. But, doing this would involve some backwards-incompatible changes. So, to make sure that code which is written for old style

What is the difference between type(obj) and obj.__class__ ? Is there ever a possibility of type(obj) is not obj.__class__ ? I want to write a function that works generically on the supplied objects, using a default value of 1 in the same type as another parameter. Which variation, #1 or #2 below, is going to do the right thing? def f(a, b=None): if b is None: b = type(a)(1) # #1 b = a.__class__(1) # #2 Mark Roddy type(obj) and type.__class__ do not behave the same for old style classes: >>> class a(object): ... pass ... >>> class b(a): ... pass ... >>> class c: ... pass ... >>> ai=a() >>> bi

So, I'm playing with decorators in Python 2.6, and I'm having some trouble getting them to work. Here is my class file: class testDec: @property def x(self): print 'called getter' return self._x @x.setter def x(self, value): print 'called setter' self._x = value What I thought this meant is to treat x like a property, but call these functions on get and set. So, I fired up IDLE and checked it: >>> from testDec import testDec from testDec import testDec >>> t = testDec() t = testDec() >>> t.x t.x called getter Traceback (most recent call last): File "<stdin>", line 1, in <module> File "testDec