Difference between class declarations

Question

I see some similar questions about this topic, but i wish to be sure, so i am asking...

What is the difference between:

class MyClass:
    pass

and

class MyClass():
    pass

Also, is there a difference between these two:

class MyClass():
    pass

class MyClass(object):
    pass

Answer 1

Class declarations of the type class MyClass(object) are New Style classes on Python 2.x

Guido writes about some of the thinking that brought about the new classes in the History of Python

Answer 2

There is no difference between the first two spellings.

In python 2.7, there is a huge difference between the latter two. Inheriting from object makes it a new-style class, changing the inheritance semantics and adding support for descriptors (@property, @classmethod, etc.). It's the default in Python 3.

New-style classes were introduced in Python 2.2 to unify types (such as int and list), and classes, and because several things change in backwards-incompatible ways, you need to 'opt in', explicitly inherit from object to enable the changes.

In Python 3, inheriting from object is no longer needed, classes are new-style, always.

Answer 3

There is no difference between class MyClass and class MyClass(). The second question is dependent on your python version. On python3.x, there is no difference -- On python2.x, the latter (where you inherit from object) creates a new-style class rather than an old-style class. In python3.x, ALL classes are new-style. New style classes are preferred these days -- As such, I always make sure that my classes inherit from object.