Alright, I managed to figure out what I wanted. Below is a fully working example of what I was trying to do. The answer is however not complete as there are quite a few error checking missing and more importantly a few Py_DECREF missing. I will try to catch them and update as I figure it out but if someone fluent in that sort of thing can help, that would be much appreciated. Here goes:
Python script: (testingoutput.py) This script receives a list of strings, For each string, it returns 3 random strings (from a provided list) and one random integer. Format is: [[sssi],]
import random
import string
def get_list_send_list(*input_list):
outer_list = []
for key in input_list:
inner_list = []
# from here, your program should produce the data you want to retrieve and insert it in a list
# for this example, a list comprised of 3 random strings and 1 random number is returned
for i in range (0, 3):
some_words = random.choice(["red", "orange", "yellow", "green", "blue", "purple", "white", "black"])
inner_list.append(some_words)
inner_list.append(random.randint(1,10))
outer_list.append(inner_list)
return outer_list
And this is the cpp file. Largely the same as the Python C API example but slightly modified to accomodate lists. I did not need this for my needs but I put a few type checking here and there for the benefit of anyone who might need that sort of thing.
#include <Python.h>
#include <iostream>
#include <vector>
int main(int argc, char *argv[])
{
PyObject *pName, *pModule, *pFunc;
PyObject *pArgs, *pValue;
PyObject *pList, *pListItem, *pyString;
char* strarray[] = {"apple", "banana", "orange", "pear"};
std::vector<std::string> strvector(strarray, strarray + 4);
std::string pyFile = "testingoutput";
std::string pyFunc = "get_list_send_list";
Py_Initialize();
pName = PyUnicode_FromString(pyFile.c_str());
/* Error checking of pName left out */
pModule = PyImport_Import(pName);
Py_DECREF(pName);
if (pModule != NULL)
{
pFunc = PyObject_GetAttrString(pModule, pyFunc.c_str());
/* pFunc is a new reference */
if (pFunc && PyCallable_Check(pFunc)) {
pArgs = PyTuple_New(strvector.size());
for (size_t i = 0; i < strvector.size(); ++i)
{
pValue = PyUnicode_FromString(strvector[i].c_str());
if (!pValue)
{
Py_DECREF(pArgs);
Py_DECREF(pModule);
fprintf(stderr, "Cannot convert argument\n");
return 1;
}
/* pValue reference stolen here: */
PyTuple_SetItem(pArgs, i, pValue);
}
pValue = PyObject_CallObject(pFunc, pArgs);
Py_DECREF(pArgs);
if (pValue != NULL)
{
int py_list_size = PyList_Size(pValue);
int sub_list_size = 0;
std::cout << "Retrieving content..."<< "\n";
for(Py_ssize_t i = 0; i < py_list_size; ++i)
{
pList = PyList_GetItem(pValue, i);
sub_list_size = PyList_Size(pList);
// verify if the subitem is also a list - if yes process it
if(PyList_Check(pList))
{
std::cout << "********** " << i << " **********\n";
for(Py_ssize_t j = 0; j < sub_list_size; ++j)
{
pListItem = PyList_GetItem(pList, j);
// verify if the item is a string or a number
if(PyUnicode_Check(pListItem))
{
// "Error ~" does nothing here but it should be defined to catch errors
pyString = PyUnicode_AsEncodedString(pListItem, "utf-8", "Error ~");
const char *tmpCstChar = PyBytes_AS_STRING(pyString);
std::cout << "Item " << j << ": " << tmpCstChar << "\n";
}
else if(PyLong_Check(pListItem))
{
int pyNumber = PyLong_AsLong(pListItem);
std::cout << "Item " << j << ": " << pyNumber << "\n";
}
}
}
else
{
std::cout << "This item is not a list\n";
}
}
Py_DECREF(pValue);
}
else
{
Py_DECREF(pFunc);
Py_DECREF(pModule);
PyErr_Print();
fprintf(stderr,"Call failed\n");
return 1;
}
}
else
{
if (PyErr_Occurred())
PyErr_Print();
fprintf(stderr, "Cannot find function \"%s\"\n", argv[2]);
}
Py_XDECREF(pFunc);
Py_DECREF(pModule);
}
else
{
PyErr_Print();
fprintf(stderr, "Failed to load \"%s\"\n", argv[1]);
return 1;
}
Py_Finalize();
return 0;
}
Again, there are a few error checks missing and significantly more important, a few Py_DECREFs missing. i.e. THIS PROGRAM IS LEAKING MEMORY. If you know how to fix this, your help would be appreciated.
