Re: Why don't have an object() instance a __dict__ attribute by default?

En Tue, 30 Jan 2007 20:31:26 -0300, Létező <letezo@xxxxx> escribió:

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'


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.

Why don't have an object() instance a __dict__ attribute by default?

Because it's not needed, and creating an empty dict has some cost. If you need a class with __dict__, just inherit from object as you already have noted.

This may need some explanation in the Python manual.

Maybe.

--
Gabriel Genellina

.

Relevant Pages

  • Re: When to clear a dictionary...
    ... Gabriel Genellina wrote: ... it to empty. ... dictionaries). ... iteration in Python code and is about 4x slower. ...
    (comp.lang.python)
  • Re: Checking list by using of exception
    ... (a list has a false boolean value when it is empty) ... except IndexError: ... But I would not reccomend it. ... Gabriel Genellina ...
    (comp.lang.python)
  • Re: Checking list by using of exception
    ... (a list has a false boolean value when it is empty) ... If you insist on using an exception (and assuming list_of_files is ... But I would not reccomend it. ... Gabriel Genellina ...
    (comp.lang.python)