2.6. New and Old Style Class

Old Style classes - Not existing in Python 3
In Python 3 class will always produce new style class
The major motivation for introducing new-style classes is to provide a unified object model with a full meta-model
https://docs.python.org/dev/tutorial/classes.html

2.6.1. Old Style classes

Not existing in Python 3
Don't inherit from object
In Python 3, there are no old-style classes, and this code will produce new style class

2.6.2. New Style Class

Introduced in Python 2.2
In Python 3 this is the only way
Inherit from object or from another new style class
Ability to subclass most built-in types
super() added
MRO changed
descriptors added
new style class objects cannot be raised unless derived from Exception
__slots__ added

2.6.3. Definition

Old style classes are only in Python 2
New style classes works in Python 2 (when inherit from object)
In Python 3 all classes always inherit from object, hence they are new style classes

# Python 2.x
# old style class
# inherits from type

class MyClass:
    pass

# Python > 2.2
# new style class
# inherits from object

class MyClass(object):
    pass

# Python 3.x
# meta class
# inherits from type

class MyClass(metaclass=type):
    pass

# Python 3.x
# new style class
# inherits from object

class MyClass:
    pass

# Python 3.x
# new style class
# inherits from object

class MyClass(object):
    pass