some time i see some classes defined as subclass of object class, as
class my_class(object):
pass
how is if different from the simple definition as
class my_class():
pass
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4http://stackoverflow.com/questions/332255/difference-between-class-foo-and-class-fooobject-in-python – Ignacio Vazquez-Abrams Mar 10 '11 at 14:30
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1In older versions of Python, the latter is a syntax error. – Ignacio Vazquez-Abrams Mar 10 '11 at 14:30
5 Answers
8
This syntax declares a new-style class.
Björn Pollex
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3+∞: Oh look the question's already answered in the documentation. I wish folks would read more and ask less. – S.Lott Mar 10 '11 at 15:45
4
The first one is a new style class and the second is the old style class.
EDIT
In [1]: class A:
...: pass
...:
In [2]: class B(object):
...: pass
...:
In [3]: a = A()
In [4]: b = B()
In [5]: dir(a)
Out[5]: ['__doc__', '__module__']
In [6]: dir(b)
Out[6]:
['__class__',
'__delattr__',
'__dict__',
'__doc__',
'__format__',
'__getattribute__',
'__hash__',
'__init__',
'__module__',
'__new__',
'__reduce__',
'__reduce_ex__',
'__repr__',
'__setattr__',
'__sizeof__',
'__str__',
'__subclasshook__',
'__weakref__']
gruszczy
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1Does subclassing from object brings any inherited property to the class my_class ? – Stephane Rolland Mar 10 '11 at 14:30
3
For Python 3.x, there is no difference. In Python 2.x, deriving from object makes a class new-style, while providing no base classes will give you an old-style class.
Sven Marnach
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For new-style classes in Python 2.x, you MUST explicitly inherit from object. Not declaring that a class inherit from object gives you an old-style class. In Python 3.x, explicitly inheriting from object is no longer required, so you can just declare in Python 3.x with Python 2.x old-style class syntax class Klass: pass and get back a new-style (or just a class) class.
Y.H Wong
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