[Python-Dev] Baffled by PyArg_ParseTupleAndKeywords modification (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Fri Feb 10 20:33:42 CET 2006

Tim Peters wrote:

Sigh. I don't see any way to avoid a warning in Jack's case.

Martin's turn ;-)

I see two options:

  1. Revert the change for the const char** keywords argument (but leave the change for everything else). C++ users should only see a problem if they have a const char* variable, not if they use literals (Jeremy's compiler's warning is insensate)

    For keyword arguments, people typically don't have char* variables; instead, they have an array of string literals.

  2. Only add the const in C++:

#ifdef __cplusplus #define Py_cxxconst const #else #define Py_cxxconst #endif

PyAPI_FUNC(int) PyArg_ParseTupleAndKeywords(PyObject *, PyObject *, const char *, Py_cxxconst char Py_cxxconst, ...);

This might look like it could break C/C++ interoperability on platforms that take an inventive interpretation of standard (e.g. if they would mangle even C symbols). However, I believe it won't make things worse: The C++ standard doesn't guarantee interoperability of C and C++ implementations at all, and the platforms I'm aware of support the above construct (since PA_PTAK is extern "C").

Regards, Martin

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