How to avoid overflow errors

[Eduardo O. Padoan]

On 9/15/07, Carl Banks <pavlovevidence at gmail.com> wrote:
> On Fri, 14 Sep 2007 22:59:13 -0300, Eduardo O. Padoan wrote:
>
> > On 14 Sep 2007 18:08:00 -0700, Paul Rubin
> > <"http://phr.cx"@nospam.invalid> wrote:
> >> "Eduardo O. Padoan" <eduardo.padoan at gmail.com> writes:
> >> > Not totally unrelated, but in Py3k, as it seems, overflows are really
> >> > things of the past:
> >> >
> >> >
> >> > Python 3.0a1 (py3k:58061, Sep  9 2007, 13:18:37) [GCC 4.1.3 20070831
> >> > (prerelease) (Ubuntu 4.1.2-16ubuntu1)] on linux2 Type "help",
> >> > "copyright", "credits" or "license" for more information.
> >> > >>> class MyInt(int):
> >> > ...     pass
> >> > ...
> >> > >>> import sys
> >> > >>> MyInt(sys.maxint)
> >> > 2147483647
> >> > >>> MyInt(sys.maxint+1)
> >> > 2147483648
> >>
> >> I'd be interested in knowing what happens in 3.0a1 with
> >>
> >>   a = itertools.count(sys.maxint)
> >>   print a.next()
> >>   print a.next()
> >
> >
> >>>> print(next(a))
> > Traceback (most recent call last):
> >   File "<stdin>", line 1, in <module>
> > OverflowError: cannot count beyond PY_SSIZE_T_MAX
> >
> > Hum, you've got me there. it is the same as in 2.x. Maybe the message
> > should be less crypt, at least - nothing that googling for
> > PY_SSIZE_T_MAX cant help.
>
> This should demonstrate that OverflowError will not disappear entirely
> even in Python 3.

No one is denying that by now :)

> Even if we were to get rid of all OverflowErrors resulting from integer
> operations in Python, there are going to be some C extensions--including
> some in the Python standard library--that will store 32-bit integers.
> Modules such as array and struct will still raise it, and probably other
> modules were a long integer sometimes doesn't make sense (socket, for
> instance).  itertools.count() should work for arbitrary integers, though.

Agreed. I was lookind at itertoolsmodule.c, and even for my very
limited C knowlegment, it does not seem to be too hard.
Anyway: http://bugs.python.org/issue1165


> Carl Banks
> --
> http://mail.python.org/mailman/listinfo/python-list
>


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