Why don't have an object() instance a __dict__ attribute by default?
Létező
letezo at fw.hu
Tue Jan 30 18:31:26 EST 2007
I use Python 2.5, Win32 MSI release.
Setting attributes on an empty object does not work:
>>> a=object()
>>> a.x=1
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'object' object has no attribute 'x'
>>> setattr(a, 'x', 1)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'object' object has no attribute 'x'
>>> a.__setattr__('x', 1)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'object' object has no attribute 'x'
The dir(a) function indicates, that the object instance has no __dict__ attribute.
However using an empty new style class works fine:
>>> class C(object): pass
...
>>> c=C()
>>> setattr(c, 'x', 1)
>>>
The dir(c) function indicates, that the C instance has a __dict__ attribute.
Python 2.5 manual says:
"Return a new featureless object. object is a base for all new style classes. It has the methods that are common to all instances of new style classes."
Why don't have an object() instance a __dict__ attribute by default?
This may need some explanation in the Python manual.
Viktor
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