[Python-Dev] Py_ssize_t output parameters (Was: [Python-checkins] r41971 ...) (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Thu Jan 12 23:36:01 CET 2006

M.-A. Lemburg wrote:

What if x64 has a 64-bit value ? How do you catch and process the truncation error ?

We were both discussing a scenario where no sizes exceed 2**31, right?

Under such a scenario, this just won't happen.

OTOH, if you were discussing a scenario where sizes might exceed 2*31, then I don't see why you are worried about Py_ssize_t parameters alone: Even

PyString_Size()

might (of course!) return a value > 2**31 - so it is not just output parameters, but also return values.

For more information, please read "Conversion guidelines" in

http://www.python.org/peps/pep-0353.html

That is not necessary. Can you give in example of a module where you think it is necessary?

If you want to port the extension to Pyssizet, this is essentially the case. You might want to take the unicodeobject.c file as example.

unicodeobject.c is not an extension. We were discussing existing extension modules.

We could use the type flags for these. much like we do for the new style numbers.

Would you like to write a specification for that?

If you don't like the macro approach, why not simply leave the two separate sets of APIs visible.

To simplify the porting.

All Pyssizet aware and compatible extensions would use the new APIs instead. The old-style APIs should then take care of the proper down-casting and error reporting.

That is not possible. Some API does not support error reporting (like PyString_Size()). So callers don't expect it to fail.

Regards, Martin

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