在Python中，“class name（object）：”和“class name（）：”之间有什么区别？

Question

What is the difference between the two classes below? Do you have some related information about this case? Thank you very much.

class test(object):
  def __init__(self, name):
     print name

class test():
  def __init__(self, name):
     print name

Answer 1

In python 2.x, the class that inherits from object will be a new-style class, while the other won't, while in python 3.x there'll be both new-style.

However, the differences between new and old are rather advanced, (for example, attribute search order) so a beginner shouldn't be too concerned about the incompatibilities.

See this answer for more information if you're interested, but it's rather a thing for library developers etc.

Answer 2

Mhmm ... this wiki-page explains the differences very illustratively: http://wiki.python.org/moin/NewClassVsClassicClass

And I saw some answeres with the information, that Old-(Classic)-Style and New-Style classes are the same in py3 -> that's not correct:

Old-style classes are removed in Python 3, leaving only the semantics of new-style classes

Besides this, the New-Style classes are quite available since Python 2.2. Up to 2.1 we have had to use the Classic style -> see here

Short summary about the differences/infos could be:

• New-Style classes are available since Python 2.2
• New-Style classes can use descriptors - Old Style classes cannot
• New Style classes can subclass most built-in types - Old Style classes cannot
• New Style classes supports a new meta-model (which affects eg the behaviour of the type() built-in massively)
• Old-Style classes will find an attribute on an instance before it looks in the hierarchy - New-Style classes will let the class definition win if it is a writeable descriptor
• Old-Style classes has been removed in Python 3

But in most way the introduction of the New-style classes has been affected within the comming up of python's Descriptors --> read more here .

Answer 3

在这种情况下，没有，因为第一个显式地从对象继承为基类，而第二个隐式地从对象继承。