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c++ call python Class instantiation object to access member functions and members

One 、Python Add sample classes to

stay test.py Add a class to , Used to be C++ Call access ：

print('test.py')
class TypePy:
def __init__(self):
print("TypePy init")
def test(self):
print("TypePy test")

Two 、C++ Call the member function of the class in

 {

// Get class 
PyObject* TypePy = PyObject_GetAttrString(m, "TypePy");
if (!TypePy) {

throw exception("TypePy noe find!");
}
// Instantiate objects It is equivalent to calling the constructor __init__ Pass arguments to the constructor NULL
PyObject *obj = PyObject_CallObject(TypePy, NULL);
if (!obj) {

throw exception("obj not Create!");
}
// Calling class member functions 
PyObject_CallMethod(obj, "test", 0);
Py_XDECREF(obj);
Py_XDECREF(TypePy);
}

function ：

You can see that the desired string is output

3、 ... and 、 Calls to class functions with arguments

modify test.py Class in TypePy The function in test Parameters and return values of ：

class TypePy:
def __init__(self):
print("TypePy init")
def test(self, arg1, arg2):
print("TypePy test")
print("arg1 = ", arg1)
print("arg2 = ", arg2)
return 1003

C++ Add to single parameter Python Class

 // Calling class member functions i(int) s(string)
PyObject *re = PyObject_CallMethod(obj, "test", "is", 2001, "c Para2");
cout << "PyObject_CallMethod return" << PyLong_AsLong(re) << endl;
Py_XDECREF(re);

function ：

Four 、 Access to member variables

add to test.py Class member variables in

class TypePy:
id = 99
def __init__(self):
print("TypePy init")
def test(self, arg1, arg2):
print("TypePy test")
print("arg1 = ", arg1)
print("arg2 = ", arg2)
return 1003

C++ Add pair Python Access to class member variables

 // Access member variables 
PyObject* var = PyObject_GetAttrString(obj, "id");
cout << "TypePy.id=" << PyLong_AsLong(var) << endl;
Py_XDECREF(var);

function ：

complete C++ call Python Class code

#include <iostream>
#include <Python.h>
#include <exception>
using namespace std;
int main(int argc, char*argv[])
{

cout << "C++ call Python" << endl;
// Set up Python Of Home route 
Py_SetPythonHome(L"./");
// Python Initialize the interpreter 
Py_Initialize();
PyObject *m = NULL; // The main module 
try
{

int re = 0;
// perform Python Script 
re = PyRun_SimpleString("print('Hello world!')");
re = PyRun_SimpleString("print(\"__name__ = \", __name__)");
// perform Python file 
char* filename = "test.py";
FILE * fp = fopen(filename, "r");
if (!fp)
{

throw exception("open file failed");
}
PyRun_AnyFile(fp, filename);
if (re != 0)
{

PyErr_Print();
throw exception("PyRun_AnyFile failed");
}
// Get main module 
PyObject *key = PyUnicode_FromString("__main__");
m = PyImport_GetModule(key); // Do not clean parameters , It needs to be cleaned by hand 
Py_XDECREF(key);
// 2-1 call python The variable of python Make configuration file 
//con = {

// "width":1920,
// "heigth" : 1080,
// "title" : "C++ call Python"
//}
{

// Get objects by module and name （ Objects can be variables 、 Functions and classes ）
PyObject* conf = PyObject_GetAttrString(m, "conf");
if (!conf) {

throw exception("conf noe find!");
}
PyObject *key = PyUnicode_FromString("width");
int width = PyLong_AsLong(PyDict_GetItem(conf, key));
Py_XDECREF(key);
key = PyUnicode_FromString("height");
int height = PyLong_AsLong(PyDict_GetItem(conf, key));
Py_XDECREF(key);
key = PyUnicode_FromString("title");
wchar_t title[1024] = {
 0 };
int size = PyUnicode_AsWideChar(PyDict_GetItem(conf, key), title, 1023);
Py_XDECREF(key);
printf("width=%d height=%d \n", width, height);
wprintf(L"title=%s\n", title);
Py_XDECREF(conf);
}
{

// Get class 
PyObject* TypePy = PyObject_GetAttrString(m, "TypePy");
if (!TypePy) {

throw exception("TypePy noe find!");
}
// Instantiate objects It is equivalent to calling the constructor __init__ Pass arguments to the constructor NULL
PyObject *obj = PyObject_CallObject(TypePy, NULL);
if (!obj) {

throw exception("obj not Create!");
}
// Calling class member functions i(int) s(string)
PyObject *re = PyObject_CallMethod(obj, "test", "is", 2001, "c Para2");
cout << "PyObject_CallMethod return" << PyLong_AsLong(re) << endl;
Py_XDECREF(re);
// Access member variables 
PyObject* var = PyObject_GetAttrString(obj, "id");
cout << "TypePy.id=" << PyLong_AsLong(var) << endl;
Py_XDECREF(var);
Py_XDECREF(obj);
Py_XDECREF(TypePy);
}
Py_XDECREF(m);
// clear python
Py_Finalize();
}
catch (const std::exception&ex)
{

cout << ex.what() << endl;// clear python
Py_XDECREF(m);
Py_Finalize();
}
getchar();
return 0;
}

6、 ... and 、 summary

• This paper introduces c++ call python Class instantiation object to access member functions and members .
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