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integer subclass range behavior

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I was wondering what would happen, so I tried this out for the heck of

it with:

Python 3.0a2 (py3k:59572M, Dec 19 2007, 15:54:07) [MSC v.1500 32 bit

(Intel)] on win32

class a(int):
def __new__(cls,number):
return int.__new__(cls,number)

for x in range(0,a(5)):
print(x)

Which resulted in a:

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "a.py", line 5, in <module>
for x in range(0,a(5)):
SystemError: ..\Objects\longobject.c:400: bad argument to internal
function
[41030 refs]

It looks like the rangeobject performs a FitsInLong test on each of
the parameters to range, which uses the function
_PyLong_FitsInLong(PyObject *vv) within longobject.c. In tern, this
performs a typecheck: #define PyLong_CheckExact(op) (Py_TYPE(op) ==
&PyLong_Type) that fails.

Interesting!

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to pytho...@python.org

En Wed, 19 Dec 2007 18:11:49 -0300,

<

> escribió:

> I was wondering what would happen, so I tried this out for the heck of
> it with:
> Python 3.0a2 (py3k:59572M, Dec 19 2007, 15:54:07) [MSC v.1500 32 bit
> (Intel)] on win32
>
> class a(int):
> def __new__(cls,number):
> return int.__new__(cls,number)
>
> for x in range(0,a(5)):
> print(x)
>
>
> Which resulted in a:
>
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "a.py", line 5, in <module>
> for x in range(0,a(5)):

> SystemError: .\Objects\longobject.c:400: bad argument to internal
> function
>
> Interesting!

Yes. But much more interesting would be to report this on the bug tracker
http://bugs.python.org else it will fade away...

--
Gabriel Genellina

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On Dec 19, 7:42 pm, "Gabriel Genellina" <

>

wrote:

> En Wed, 19 Dec 2007 18:11:49 -0300,

> <

> escribió:

>
>
>
> > I was wondering what would happen, so I tried this out for the heck of
> > it with:
> > Python 3.0a2 (py3k:59572M, Dec 19 2007, 15:54:07) [MSC v.1500 32 bit
> > (Intel)] on win32
>
> > class a(int):
> > def __new__(cls,number):
> > return int.__new__(cls,number)
>
> > for x in range(0,a(5)):
> > print(x)
>
> > Which resulted in a:
>
> > Traceback (most recent call last):
> > File "<stdin>", line 1, in <module>
> > File "a.py", line 5, in <module>
> > for x in range(0,a(5)):
> > SystemError: .\Objects\longobject.c:400: bad argument to internal
> > function
>
> > Interesting!
>

> Yes. But much more interesting would be to report this on the bug tracker

it will fade away...

>

> --

> Gabriel Genellina

Gabriel,

I usually do that... But from what i've learned, most things i've
thought are bugs, turn out to be that way for a good reason. I was
playing it safe on this one :-)

Joseph Armbruster

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to pytho...@python.org

En Wed, 19 Dec 2007 22:20:17 -0300,

<

> escribió:

> On Dec 19, 7:42 pm, "Gabriel Genellina" <gagsl-...@yahoo.com.ar>
> wrote:
>> En Wed, 19 Dec 2007 18:11:49 -0300, josepharmbrus...@gmail.com
>> <josepharmbrus...@gmail.com> escribió:
>>
>> > I was wondering what would happen, so I tried this out for the heck of
>> > it with:
>> > Python 3.0a2 (py3k:59572M, Dec 19 2007, 15:54:07) [MSC v.1500 32 bit
>> > (Intel)] on win32
>>
>> > class a(int):
>> > def __new__(cls,number):
>> > return int.__new__(cls,number)
>>
>> > for x in range(0,a(5)):
>> > print(x)
>>
>> > Which resulted in a:
>>
>> > Traceback (most recent call last):
>> > File "<stdin>", line 1, in <module>
>> > File "a.py", line 5, in <module>
>> > for x in range(0,a(5)):
>> > SystemError: .\Objects\longobject.c:400: bad argument to internal
>> > function
>>
>> > Interesting!
>>
>> Yes. But much more interesting would be to report this on the bug

>> tracker http://bugs.python.org else it will fade away...
>>

> I usually do that... But from what i've learned, most things i've
> thought are bugs, turn out to be that way for a good reason. I was
> playing it safe on this one :-)

Well, it works on 2.5, and I don't see why it should not work on 3.0 too,
so IMHO this is a genuine bug. That means only that when some god or
demi-god explains the good reasons for this failure, we both will say a
big "Ahhhhh! That was it!" :)

--
Gabriel Genellina

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