Compiling python functions on the fly & calling from C++

[Borse, Ganesh]

I want to call Python function which takes input arguments (parameters) from C++ program on the fly when program is running, as below:

def isSizeSmall(size,vol,ADV,prod):
if ( (size < 1000) & (vol < (0.001 * ADV)) & (prod=="Stock")): return 100
else: return 11

I tried following approaches for this but none worked.
1)Using PyEval_CallObject:- (After reading http://docs.python.org/ext/callingPython.html)
But for getting a ptr to Python function using PyObject_GetAttrString, a module has to be imported.
I cannot do so because I am generating the Python function source code at run time & so cannot create module of it.
So, I could not use this approach.

2)Using Py_CompileString & then using PyEval_EvalCode function:-
For this I passed above function source code to Py_CompileString, which compiled fine.
Then I packed the values for these parameters in Dictionary object, as below & passed that as 2nd input parameter to PyEval_EvalCode.


This function call also passed, but did not given any output.

Can someone please help me know following?
A) How can I compile a Python function at runtime (not by loading module from file) & then call it many times in the same program?
B) How to make sense out of the PyObject* returned by the PyEval_EvalCode function?

Thanks in advance for the help.

Warm Regards,
Ganesh

------------------
PyObject *glb, *loc;
glb = PyDict_New();
PyDict_SetItemString(glb, "__builtins__", PyEval_GetBuiltins());
loc = PyDict_New();
PyObject* val = 0;

val = PyInt_FromLong(ordval.size);
PyDict_SetItemString(loc,"size",val);

val = PyInt_FromLong(ordval.vol);
PyDict_SetItemString(loc,"vol",val);

val = PyInt_FromLong(ordval.ADV);
PyDict_SetItemString(loc,"ADV",val);

val = PyString_FromString(ordval.prod);
PyDict_SetItemString(loc,"prod",val);

/*** with stdin & Py_file_input ***/
PyObject* result = NULL;
result = Py_CompileString(szExpr,"<stdin>", Py_file_input);
if(result!=NULL){
printf("str compiled fine with stdin & Py_file_input, calling PyEval_EvalCode\n");
PyCodeObject *pyCo = (PyCodeObject *)result;
PyObject* evalret = NULL;
evalret = PyEval_EvalCode(pyCo,glb,loc);
if(!evalret || PyErr_Occurred())
PyErr_Print();
else
printf("ok [%d] size [%d]\n",PyObject_Print(evalret,stdout,0),PyObject_Size(evalret));
------------------
Output shows as below:
Expression to eval =
[def isSizeSmall(size,vol,ADV,prod):
if ( (size < 1000) & (vol < (0.001 * ADV)) & (prod=="Stock")): print "OK"; return 10
else: print "NOK"; return 11


]
str compiled fine with stdin & Py_file_input, calling PyEval_EvalCode
Noneok [0] size [-1]
------------------

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