I'm using Python 3.8 so I tried your second choice: pSents = PyObject_CallFunctionObjArgs(pSentMod, pListItem);
but pSents is 0x0. pSentMod and pListItem are valid pointers. Feb 9, 2022, 17:23 by songofaca...@gmail.com: > // https://docs.python.org/3/c-api/call.html#c.PyObject_CallNoArgs > // This function is only for one arg. Python >= 3.9 is required. > pSents = PyObject_CallOneArg(pSentMod, pListItem); > > Or > > // https://docs.python.org/3/c-api/call.html#c.PyObject_CallFunctionObjArgs > // This function can call function with multiple arguments. Can be > used with Python <3.9 too. > pSents = PyObject_CallFunctionObjArgs(pSentMod, pListItem); > > On Thu, Feb 10, 2022 at 10:15 AM Jen Kris <jenk...@tutanota.com> wrote: > >> >> Right you are. In that case should I use Py_BuildValue and convert to tuple >> (because it won't return a tuple for a one-arg), or should I just convert >> pListStr to tuple? Thanks for your help. >> >> >> Feb 9, 2022, 17:08 by songofaca...@gmail.com: >> >> On Thu, Feb 10, 2022 at 10:05 AM Jen Kris <jenk...@tutanota.com> wrote: >> >> >> Thanks for your reply. >> >> I eliminated the DECREF and now it doesn't segfault but it returns 0x0. Same >> when I substitute pListStrE for pListStr. pListStr contains the string >> representation of the fileid, so it seemed like the one to use. According to >> http://web.mit.edu/people/amliu/vrut/python/ext/buildValue.html, >> PyBuildValue "builds a tuple only if its format string contains two or more >> format units" and that doc contains examples. >> >> >> Yes, and PyObject_Call accept tuple, not str. >> >> >> https://docs.python.org/3/c-api/call.html#c.PyObject_Call >> >> >> Feb 9, 2022, 16:52 by songofaca...@gmail.com: >> >> On Thu, Feb 10, 2022 at 9:42 AM Jen Kris via Python-list >> <python-list@python.org> wrote: >> >> >> I have everything finished down to the last line (sentences = >> gutenberg.sents(fileid)) where I use PyObject_Call to call gutenberg.sents, >> but it segfaults. The fileid is a string -- the first fileid in this corpus >> is "austen-emma.txt." >> >> pName = PyUnicode_FromString("nltk.corpus"); >> pModule = PyImport_Import(pName); >> >> pSubMod = PyObject_GetAttrString(pModule, "gutenberg"); >> pFidMod = PyObject_GetAttrString(pSubMod, "fileids"); >> pSentMod = PyObject_GetAttrString(pSubMod, "sents"); >> >> pFileIds = PyObject_CallObject(pFidMod, 0); >> pListItem = PyList_GetItem(pFileIds, listIndex); >> pListStrE = PyUnicode_AsEncodedString(pListItem, "UTF-8", "strict"); >> pListStr = PyBytes_AS_STRING(pListStrE); >> Py_DECREF(pListStrE); >> >> >> HERE. >> PyBytes_AS_STRING() returns pointer in the pListStrE Object. >> So Py_DECREF(pListStrE) makes pListStr a dangling pointer. >> >> >> // sentences = gutenberg.sents(fileid) >> PyObject *c_args = Py_BuildValue("s", pListStr); >> >> >> Why do you encode&decode pListStrE? >> Why don't you use just pListStrE? >> >> PyObject *NullPtr = 0; >> pSents = PyObject_Call(pSentMod, c_args, NullPtr); >> >> >> c_args must tuple, but you passed a unicode object here. >> Read https://docs.python.org/3/c-api/arg.html#c.Py_BuildValue >> >> The final line segfaults: >> Program received signal SIGSEGV, Segmentation fault. >> 0x00007ffff6e4e8d5 in _PyEval_EvalCodeWithName () >> from /usr/lib/x86_64-linux-gnu/libpython3.8.so.1.0 >> >> My guess is the problem is in Py_BuildValue, which returns a pointer but it >> may not be constructed correctly. I also tried it with "O" and it doesn't >> segfault but it returns 0x0. >> >> I'm new to using the C API. Thanks for any help. >> >> Jen >> >> >> -- >> https://mail.python.org/mailman/listinfo/python-list >> >> >> Bests, >> >> -- >> Inada Naoki <songofaca...@gmail.com> >> >> >> >> -- >> Inada Naoki <songofaca...@gmail.com> >> > > > -- > Inada Naoki <songofaca...@gmail.com> > -- https://mail.python.org/mailman/listinfo/python-list
