Can't get iterator in the C API

Tue Feb 8 21:10:51 EST 2022

On 2022年02月09日 01:12, Jen Kris via Python-list wrote:
> I am using the Python C API to load the Gutenberg corpus from the nltk library and iterate through the sentences.  The Python code I am trying to replicate is:
>> from nltk.corpus import gutenberg
> for i, fileid in enumerate(gutenberg.fileids()):
>         sentences = gutenberg.sents(fileid)
>         etc
>> where gutenberg.fileids is, of course, iterable.
>> I use the following C API code to import the module and get pointers:
>> int64_t Call_PyModule()
> {
>     PyObject *pModule, *pName, *pSubMod, *pFidMod, *pFidSeqIter,*pSentMod;
>>     pName = PyUnicode_FromString("nltk.corpus");
>     pModule = PyImport_Import(pName);
>>     if (pModule == 0x0){
>         PyErr_Print();
>         return 1; }
>>     pSubMod = PyObject_GetAttrString(pModule, "gutenberg");
>     pFidMod = PyObject_GetAttrString(pSubMod, "fileids");
>     pSentMod = PyObject_GetAttrString(pSubMod, "sents");
>>     pFidIter = PyObject_GetIter(pFidMod);
>     int ckseq_ok = PySeqIter_Check(pFidMod);
>     pFidSeqIter  = PySeqIter_New(pFidMod);
>>     return 0;
> }
>> pSubMod, pFidMod and pSentMod all return valid pointers, but the iterator lines return zero:
>> pFidIter = PyObject_GetIter(pFidMod);
> int ckseq_ok = PySeqIter_Check(pFidMod);
> pFidSeqIter  = PySeqIter_New(pFidMod);
>> So the C API thinks gutenberg.fileids is not iterable, but it is.  What am I doing wrong?
>Look at your Python code. You have "gutenberg.fileids()", so the 
'fileids' attribute is not an iterable itself, but a method that you 
need to call to get the iterable.