In Python 2, not inheriting from
object will create an old-style class, which, amongst other effects, causes
type to give different results:
>>> class Foo: pass ... >>> type(Foo()) <type 'instance'>
>>> class Bar(object): pass ... >>> type(Bar()) <class '__main__.Bar'>
Also the rules for multiple inheritance are different in ways that I won't even try to summarize here. All good documentation that I've seen about MI describes new-style classes.
Finally, old-style classes have disappeared in Python 3, and inheritance from
object has become implicit. So, always prefer new style classes unless you need backward compat with old software.
In Python 3, classes extend
object implicitly, whether you say so yourself or not.
In Python 2, there's old-style and new-style classes. To signal a class is new-style, you have to inherit explicitly from
object. If not, the old-style implementation is used.
You generally want a new-style class. Inherit from
object explicitly. Note that this also applies to Python 3 code that aims to be compatible with Python 2.
In python 3 you can create a class in three different ways & internally they are all equal (see examples). It doesn't matter how you create a class, all classes in python 3 inherits from special class called object. The class object is fundamental class in python and provides lot of functionality like double-underscore methods, descriptors, super() method, property() method etc.
class MyClass: pass
class MyClass(): pass
class MyClass(object): pass
As other answers have covered, Python 3 inheritance from object is implicit. But they do not state what you should do and what is convention.
The Python 3 documentation examples all use the following style which is convention, so I suggest you follow this for any future code in Python 3.
class Foo: pass
Class objects support two kinds of operations: attribute references and instantiation.
Attribute references use the standard syntax used for all attribute references in Python: obj.name. Valid attribute names are all the names that were in the class’s namespace when the class object was created. So, if the class definition looked like this:
class MyClass: """A simple example class""" i = 12345 def f(self): return 'hello world'
Generally speaking, instance variables are for data unique to each instance and class variables are for attributes and methods shared by all instances of the class:
class Dog: kind = 'canine' # class variable shared by all instances def __init__(self, name): self.name = name # instance variable unique to each instance