// 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
