Hi StephenThanks for examining and advise a solution. Before testing CPython I wanted to run this very simple think to send a tuple to a method of a python class.I have succeeded in sending a tuple (declared exactly the same way as I do in the code) to a method written in a python filebut as soon as you put the method in a class and try to send a tuple it doesn't work(get a run failed message)I don't send 3 arguments, it's a mistake from me to code that way,it leads to misunderstanding, it's 3 items in one tuple (declared args), 3 is just chosen by sample, it has to be dynamic later to send a series of data in a tuple.I modifed the code and try to do this thing: (again it works when the method doesn't belong to a class and this what is very "strange" for me) and it's still doesn't work // WE pass a tuple pTuple = PyTuple_New(10); if (pTuple == NULL) { Py_DECREF(pTuple); cout << "Can't build argument list for method call\n"; } PyObject *py_argument; for (int i = 0 ; i < 10 ; i++ ) { py_argument = PyFloat_FromDouble(5.*(double)i); PyTuple_SetItem(pTuple, i, py_argument); } args = Py_BuildValue("(O)", pTuple); if (args == NULL) { Py_DECREF(args); error("Can't build argument list for class instance"); } // Call our object method with arguments ret = PyEval_CallObject(method,args);
Message d'origine
De : [email protected]
À : [email protected]
Objet : C-API: Pass a tuple to a method of a class
Date : 10/01/2012 11:57:38 CET
HelloI am trying to pass a tuple to a method of a class from C++ to Python. I get a Run Failed from the execution. thanks for help/suggestionsthe code is the following:Python Code:class cVector: def __init__(self,msg): self.value = msg def ComputeNorm(self,vecData): #don't use vecData for instance result = 12. return(result)C++ Code ://instances. farenheit will hold our return value PyObject *ret, *mymod, *pclass, *method, *args, *object; float retValue; Py_Initialize(); //PySys_SetPath("/home/pascal/projPytCpp/proj1"); PySys_SetPath("."); // Module mymod = PyImport_ImportModule("mModule8"); if (mymod == NULL){ cout << "Can't Open a module:\n" ; Py_DECREF(mymod); } // Class pclass = PyObject_GetAttrString(mymod, "cVector"); if (pclass == NULL) { Py_DECREF(pclass); cout << "Can't find class\n"; } // Parameters/Values args = Py_BuildValue("(f)", 100.0); if (args == NULL) { Py_DECREF(args); cout << "Can't build argument list for class instance\n"; } // Object with parameter/value object = PyEval_CallObject(pclass, args); if (object == NULL) { Py_DECREF(object); cout << "Can't create object instance:\n"; } // Decrement the argument counter as we'll be using this again Py_DECREF(args); // Get the object method - note we use the object as the object // from which we access the attribute by name, not the class method = PyObject_GetAttrString(object, "ComputeNorm"); if (method == NULL) { Py_DECREF(method); cout << "Can't find method\n"; } // Decrement the counter for our object, since we now just need // the method reference Py_DECREF(object); // Build our argument list - an empty tuple because there aren't // any arguments cout << "Prepare the Tuple:\n" ; // WE pass a tuple args = PyTuple_New( 3 ); if (args == NULL) { Py_DECREF(args); cout << "Can't build argument list for method call\n"; } PyObject *py_argument; // 1st argument py_argument = PyFloat_FromDouble(5.); PyTuple_SetItem(args, 0, py_argument); // 2nd argument py_argument = PyFloat_FromDouble(10.); PyTuple_SetItem(args, 1, py_argument); // 3nd argument py_argument = PyFloat_FromDouble(15.); PyTuple_SetItem(args, 2, py_argument); cout << "Before the Exec:\n" ; // Call our object method with arguments //ret = PyEval_CallObject(method,args); ret = PyObject_CallObject(method,args); if (ret == NULL) { Py_DECREF(ret); cout << "Couldn't call method\n"; } // Convert the return value back into a C variable and display it PyArg_Parse(ret, "f", &retValue); printf("Farenheit: %f\n", retValue); // Kill the remaining objects we don't need Py_DECREF(method); Py_DECREF(ret); // Close off the interpreter and terminate Py_Finalize();
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