En Wed, 20 Aug 2008 04:00:08 -0300, Dan Lenski <[EMAIL PROTECTED]>
escribi�:
On Mon, 18 Aug 2008 08:28:53 -0700, Dan Lenski wrote:
So is there a bug in the Python docs? Does __slots__ in fact work with
subclasses of tuple?
Anybody think that this may actually be a mistake in the Python docs?
It appears that __slots__ must be empty in those cases. Trying to use
anything non-empty raises a TypeError:
class xtuple(tuple):
... __slots__ = ('abc',)
...
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: nonempty __slots__ not supported for subtype of 'tuple'
So __slots__ partially works - it avoids creating an instance __dict__,
but you can't add additional instance attributes.
But there is a point I don't understand yet - by example, array.array
should fail too, same as tuple, AFAICT it is declared using
PyObject_VAR_HEAD. But __slots__ works fine with it:
from array import array
class xarray(array):
... __slots__ = ('foo','bar')
...
a = xarray('b', [1,2,3])
a
array('b', [1, 2, 3])
a.foo
Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: foo
(Note the short error message above: I guess it comes from the "foo" slot
containing NULL)
a.foo = 123
a.foo
123
a.xxx
Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: 'xarray' object has no attribute 'xxx'
a.xxx = 123
Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: 'xarray' object has no attribute 'xxx'
So I don't get *what* exactly makes a type reject __slots__ - it's not the
variable part alone as the docs imply (and I can't find the error message
anywhere to check the actual code)
Who
would I contact about getting them corrected?
I think you should report it at http://bugs.python.org/ -- best including
a documentation patch, if possible.
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
