What's the difference between 'class A:' and 'class A(object):' in Python?

Question

What's the difference between

class A:
    pass

and

class B(object):
    pass

? For some reason, in methods I can't use super(A, self) but super(B, self) works great. I guess there's no such peculiarity in Py3k :)

Answer 1

In 2.x, the latter creates a new-style class . In 3.x, both have the same effect since old-style classes have been removed.

Answer 2

The first is an old style class. The second is a new-style class. See http://docs.python.org/tutorial/classes.html#multiple-inheritance for a good discussion of the difference. super() only works with new-style classes. http://docs.python.org/library/functions.html#super

Answer 3

B类是一种新样式的类http://www.python.org/doc/newstyle/

Answer 4

As already said the second case creates a new-style class, while the first one creates an old-style class(deprecated!).

New-style classes where created to remove the limitation of the old-styles: old-style classes could not inherit from built-in types. With new-style classes you can inherit from built-in types; in fact all built-in types derive from "object":

>>> list.__mro__
(<type 'list'>, <type 'object'>)