On Thu, Jul 15, 2010 at 11:07 AM, Robert Kern <[email protected]> wrote: > On 7/15/10 12:43 PM, Stefan Behnel wrote: >> Hi, note that this is a question for the cython-users mailing list. > > Sorry. Since I am also questioning the implementation, this seemed like a > reasonable place. :-) > >> Robert Kern, 15.07.2010 19:38: >>> What are the recommendations for the use of the "object" type versus >>> "PyObject >>> *"? Ondrej pointed out a potential bug in my line_profiler package: >>> >>> http://github.com/certik/line_profiler/commit/dc3ad198f8a810d34da5da71ffccf01c5e05a161 >>> >>> I have a cdef function that serves as the callback for the PyEval_SetTrace() >>> functionality. It has a PyObject* argument that is sometimes NULL. This >>> argument >>> happens to be unused. In the version of Cython I originally developed >>> line_profile under , no code referenced this argument. In the development >>> version of Cython that Ondrej used to compile line_profiler, a Py_INCREF is >>> apparently generated. When the argument is NULL, this obviously fails. >>> >>> Is this intentional? Should "object" be avoided when the argument could >>> possibly >>> be NULL? Or should the generated code use Py_XINCREF/Py_XDECREF instead to >>> avoid >>> failure? >> >> In Cython, object and PyObject* are not compatible. The first is an >> automatically ref-counted object, whereas the second is a plain pointer. >> For an argument that can be NULL, you cannot use object. > > Would using Py_XINCREF/Py_XDECREF allow the automatic refcounting to simply > ignore NULL pointers but still work for the usual case? Or would there be > other > issues?
There would be lots of other issues. An object is assumed to be an valid Python reference, ready for passing on to other functions, insertion into a list, assigning to variables, etc. - Robert _______________________________________________ Cython-dev mailing list [email protected] http://codespeak.net/mailman/listinfo/cython-dev
