[Python-Dev] Type of range object members
alexander.belopolsky at gmail.com
Tue Aug 15 04:08:19 CEST 2006
On Aug 14, 2006, at 7:32 PM, Guido van Rossum wrote:
> Methinks that as long as PyIntObject uses long (see intobject.h)
> there's no point in changing this to long.
I guess you meant "changing this to Py_ssize_t ". I don't understand
why the type used by PyIntObject is relevant here. Range object's
"start" is logically an index, but int object's "ob_ival" is not.
Since PyIntObject's is definition is exposed by Python.h, changing
the type of ob_ival will probably break a lot of code. This
reasoning does not apply to the range object.
Since on most platforms ssize_t is the same as long, the choice
between the two is just a matter of self-documenting code. Speaking
of which, I find it unfortunate that the name Py_ssize_t was selected
for the typedef. I would prefer Py_index_t. The first time I saw
Py_ssize_t, I did not notice the double 's' and thought it was an
unsigned type. On the second look, I've realized that it is signed
and started wondering why not ptrdiff_t. I understand that ssize_t
is defined by POSIX as the return type of functions such as "read"
that can return either size or -1 for error. I don't think POSIX
mandates sizeof(size_t) == sizeof(ssize_t), but I may be wrong. I
would agree that ptrdiff_t, although standard C, is not a very
intuitive name, but ssize_t is even less clear.
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