Feature Requests item #1485576, was opened at 2006-05-10 15:28 Message generated for change (Comment added) made by loewis You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=355470&aid=1485576&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Extension Modules Group: None Status: Open Resolution: None Priority: 5 Submitted By: Konrad Hinsen (hinsen) Assigned to: Nobody/Anonymous (nobody) Summary: Backwards compatibility support for Py_ssize_t Initial Comment: PEP353 recommends to add the following code snippet to extension modules to ensure compatibility with pre-2.5 interpreters: #if PY_VERSION_HEX < 0x02050000 typedef int Py_ssize_t; #define PY_SSIZE_T_MAX INT_MAX #define PY_SSIZE_T_MIN INT_MIN #endif This is insufficient, because type definitions that use Py_ssize_t must also be added. Here is what works for me, though they may be more definitions to be included: #if PY_VERSION_HEX < 0x02050000 typedef int Py_ssize_t; #define PY_SSIZE_T_MAX INT_MAX #define PY_SSIZE_T_MIN INT_MIN typedef Py_ssize_t (*lenfunc)(PyObject *); typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t); typedef PyObject *(*ssizessizeargfunc)(PyObject *, Py_ssize_t, Py_ssize_t); typedef int(*ssizeobjargproc)(PyObject *, Py_ssize_t, PyObject *); typedef int(*ssizessizeobjargproc)(PyObject *, Py_ssize_t, Py_ssize_t, PyObject *); typedef Py_ssize_t (*readbufferproc)(PyObject *, Py_ssize_t, void **); typedef Py_ssize_t (*writebufferproc)(PyObject *, Py_ssize_t, void **); typedef Py_ssize_t (*segcountproc)(PyObject *, Py_ssize_t *); typedef Py_ssize_t (*charbufferproc)(PyObject *, Py_ssize_t, char **); #endif However, the main problem is elsewhere. Extension modules may well need to use Py_ssize_t in their own data types, and may furthermore with to make these data types available to yet other extension modules. In practice, this requires the inclusion of a code block such as the one shown above inside header files. However, this requires a mechanism for avoiding redefinitions, which at the moment does not seem to exist. My request is to add such a mechanism to Python 2.5 and recommend its consistent use in an update of PEP353. Concretely, I propose that Python 2.5 should define a macro PY_HAS_PY_SSIZE_T, and that PEP353 should recommend the inclusion of the code snippet #ifndef PY_HAS_PY_SSIZE_T #define PY_HAS_PY_SSIZE_T typedef int Py_ssize_t; /* add all the other definitions here */ #endif that contains an exhaustive set of definitions that depend on Py_ssize_t. ---------------------------------------------------------------------- >Comment By: Martin v. Löwis (loewis) Date: 2006-05-12 16:06 Message: Logged In: YES user_id=21627 Please re-read the section immediately following the #ifdef code in PEP 353. It explains how you should avoid these other typedefs. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=355470&aid=1485576&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
