Questions tagged [new-style-class]
47 questions
1124
votes
8 answers
What is the difference between old style and new style classes in Python?
What is the difference between old style and new style classes in Python? When should I use one or the other?
readonly
- 343,444
- 107
- 203
- 205
168
votes
4 answers
Why does @foo.setter in Python not work for me?
So, I'm playing with decorators in Python 2.6, and I'm having some trouble getting them to work. Here is my class file:
class testDec:
@property
def x(self):
print 'called getter'
return self._x
@x.setter
def…
TR.
- 2,205
- 3
- 16
- 15
83
votes
5 answers
Difference between type(obj) and obj.__class__
What is the difference between type(obj) and obj.__class__? Is there ever a possibility of type(obj) is not obj.__class__?
I want to write a function that works generically on the supplied objects, using a default value of 1 in the same type as…
Roger Pate
67
votes
6 answers
What is the purpose of subclassing the class "object" in Python?
All the Python built-ins are subclasses of object and I come across many user-defined classes which are too. Why? What is the purpose of the class object? It's just an empty class, right?
ignoramus
44
votes
1 answer
Why isn't __new__ in Python new-style classes a class method?
The Changelog for Python 2.2 (where new-style classes were introduced) says the following about the __new__ function:
__new__ is a static method, not a class method. I initially thought it would have to be a class method, and that's why I added the…
Dolda2000
- 25,216
- 4
- 51
- 92
29
votes
3 answers
Python: always use __new__ instead of __init__?
I understand how both __init__ and __new__ work.
I'm wondering if there is anything __init__ can do that __new__ cannot?
i.e. can use of __init__ be replaced by the following pattern:
class MySubclass(object):
def __new__(cls, *args, **kwargs):
…
EoghanM
- 25,161
- 23
- 90
- 123
29
votes
4 answers
Python 2.x super __init__ inheritance doesn't work when parent doesn't inherit from object
I have the following Python 2.7 code:
class Frame:
def __init__(self, image):
self.image = image
class Eye(Frame):
def __init__(self, image):
super(Eye, self).__init__()
self.some_other_defined_stuff()
I'm trying to…
cjm2671
- 18,348
- 31
- 102
- 161
26
votes
2 answers
Old-style and new-style classes in Python 2.7
Possible Duplicate:
Old style and new style classes in Python
What is the current state of affairs with new-style and old-style classes in Python 2.7?
I don't work with Python often, but I vaguely remember the issue. The documentation doesn't…
User
- 62,498
- 72
- 186
- 247
23
votes
3 answers
calling init for multiple parent classes with super?
Possible Duplicate:
Can Super deal with multiple inheritance?
Python inheritance? I have a class structure (below), and want the child class to call the __init__ of both parents. Is this possible to do in a 'super' way or is it just a terrible…
scruffyDog
- 721
- 3
- 7
- 17
11
votes
2 answers
TypeError: Error when calling the metaclass bases a new-style class can't have only classic bases
A collection of classes defined as:
class A():
@staticmethod
def call():
print('a')
class C(type):
def __repr__(self):
return 'somename'
class B(A):
__metaclass__ = C
@staticmethod
def call():
…
citronic
- 9,868
- 14
- 51
- 74
11
votes
2 answers
Python using derived class's method in parent class?
Can I force a parent class to call a derived class's version of a function?
class Base(object):
attr1 = ''
attr2 = ''
def virtual(self):
pass # doesn't do anything in the parent class
def func(self):
…
user35288
11
votes
4 answers
How to check if object is instance of new-style user-defined class?
Code:
import types
class C(object):
pass
c = C()
print(isinstance(c, types.InstanceType))
Output:
False
What correct way to check if object is instance of user-defined class for new-style classes?
UPD:
I want put additional emphasize on if…
Gill Bates
- 14,330
- 23
- 70
- 138
10
votes
1 answer
How do I call a property setter from __init__
I have the following chunk of python code:
import hashlib
class User:
def _set_password(self, value):
self._password = hashlib.sha1(value).hexdigest()
def _get_password(self):
return self._password
password =…
Chris Smith
- 251
- 2
- 6
8
votes
2 answers
Using a class instance as a class attribute, descriptors, and properties
I have recently stated trying to use the newer style of classes in Python (those derived from object). As an excersise to familiarise myself with them I am trying to define a class which has a number of class instances as attributes, with each of…
Chris
- 44,602
- 16
- 137
- 156
6
votes
3 answers
How to import object from builtins affecting just one class?
I am converting code from python2 to python3 for newstyle classes using future. My project is in Django 1.11
I have a class in forms.py as:
class Address:
...rest of code...
class AddressForm(Address, forms.ModelForm):
...rest of…
Deesha
- 538
- 8
- 27