On 12/23/2012 4:47 PM, Chris Jerdonek wrote:
On Sun, Dec 23, 2012 at 12:03 PM, Terry Reedy <tjre...@udel.edu> wrote:
+ # For example, PyPy 1.9.0 raised TypeError for these cases because it
+ # expects x to be a string if base is given.
+ @support.cpython_only
+ def test_base_arg_with_no_x_arg(self):
+ self.assertEquals(int(base=6), 0)
+ # Even invalid bases don't raise an exception.
+ self.assertEquals(int(base=1), 0)
+ self.assertEquals(int(base=1000), 0)
+ self.assertEquals(int(base='foo'), 0)
I think the above behavior is buggy and should be changed rather than frozen
into CPython with a test. According to the docs, PyPy does it right.
In any case, the discrepancy between doc and behavior is a bug and
should be fixed one way or the other way. Unlike int(), I do not see a
realistic use case for int(base=x) that would make it anything other
than a bug.
I support further discussion here. (I did draft the patch, but it was
a first version. I did not commit the patch.)
The current online doc gives the signature as
int(x=0)
int(x, base=10) <<where x is s string>>
The 3.3.0 docstring says
"When converting a string, use the optional base. It is an error to supply
a base when converting a non-string."
One way to partially explain CPython's behavior is that when base is
provided, the function behaves as if x defaults to '0' rather than 0.
That explanation does not work. int('0', base = invalid) and int(x='0',
base=invalid) raise TypeError or ValueError. If providing a value
explicit changes behavior, then that value is not the default. To make
'0' really be the base-present default, the doc and above behavior
should be changed. Or, make '' the default and have int('',
base=whatever) return 0 instead of raising. (This would be the actual
parallel to the str case.)
This is similar to the behavior of str(), which defaults to b'' when
encoding or errors is provided, but otherwise defaults to '':
This is different. Providing b'' explicitly has no effect.
str(encoding=x, errors=y) and str(b'', encoding=x, errors=y) act the
same. If x or y is not a string, both raise TypeError. (Unlike int and
base.) A bad encoding string is ignored because the encoding lookup is
not done unless there is something to encode. (This is why the
ignore-base base-default should be '', not '0'.) A bad error
specification is (I believe) ignored for any error-free bytes/encoding
pair because, again, the lookup is only done when needed.
http://docs.python.org/dev/library/stdtypes.html#str
Certainly, accepting any object as a base, violating "The allowed values are
0 and 2-36." just because giving a base is itself invalid is crazy.
For further background (and you can see this is the 2.7 commit),
int(base='foo') did raise TypeError in 2.7, but this particular case
was relaxed in Python 3.
Since the doc was not changed, that introduced a bug.
--
Terry Jan Reedy
_______________________________________________
Python-Dev mailing list
Python-Dev@python.org
http://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
