CODEWITHSUNDEEP
pythonooppython-2.7
Parthiban Nagarajan
Parthiban Nagarajan

Reputation: 117

__new__ override does not work

May I know why myClass1 and myClass2 behaves differently in overriding the __new__() method? Which way is recommended to write a class and why? I think myClass1(): does not even call __new__(cls), am I right?

$ python
Python 2.7.5+ (default, Sep 19 2013, 13:49:51) 
[GCC 4.8.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> class myClass1():
...     def __new__(cls):
...             print cls.__name__
... 
>>> class myClass2(object):
...     def __new__(cls):
...             print cls.__name__
... 
>>> o1 = myClass1()
>>> o2 = myClass2()
myClass2
>>>

Upvotes: 1

Views: 72

Answers (1)

Martijn Pieters
Martijn Pieters

Reputation: 1123400

When you inherit from object you are creating a new-style class. Not inheriting from object makes it an old-style class.

Old-style classes don't support the __new__ constructor.

In Python 3, all classes are new-style and the object base class is implicit if there are no explicit base classes specified.

Upvotes: 5

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