如何在 C++ 中访问 Python 模块？

Question

我正在尝试导入 C++ 中的模块；该模块位于一个包中，应该像这样访问：

from x.y import class1,func1, const1, etc

我在 Python 3.6 上，对于这个版本，到目前为止我发现的是使用 PyRun_SimpleString 进行导入，然后使用 PyImport_AddModuleObject 来处理我的模块。即：

PyRun_SimpleString("from PacKage1 import Module1 as Module1");
auto module = PyImport_AddModuleObject(PyUnicode_DecodeFSDefault("Module1"));

这样我以后就可以访问它的不同属性，如下所示：

auto args = Py_BuildValue("sOOOOONNiN", model_name, model_checkpoint_path, align_fn,
                          bank_folder_root, cache_folder, postfix, 
                          rebuild_cache, use_jit, threshold, device);

if (module != nullptr) {
    // dict is a borrowed reference.
    auto pdict = PyModule_GetDict(module);
    if (pdict == nullptr) {
        cout << "Fails to get the dictionary.\n";
        return 1;
    }
    //Py_DECREF(module);
    PyObject *pKeys = PyDict_Keys(pdict);
    PyObject *pValues = PyDict_Values(pdict);

    map<string, string> my_map;
    //cout << "size: " << PyDict_Size(pdict)<<endl;

    char* cstr_key = new char[100];
    char* cstr_value = new char[500];

    for (Py_ssize_t i = 0; i < PyDict_Size(pdict); ++i) {
        PyArg_Parse(PyList_GetItem(pKeys, i), "s", &cstr_key);
        PyArg_Parse(PyList_GetItem(pValues, i), "s", &cstr_value);
        //cout << cstr<< "  "<< cstr2 <<endl;
        my_map.emplace(cstr_key, cstr_value);
    }
    for (auto x : my_map)
    {
        cout << x.first << " : " << x.second << endl;
    }
    system("pause");

    // Builds the name of a callable class
    auto python_class = PyDict_GetItemString(pdict, "MyClass1");

    system("pause");
    if (python_class == nullptr) {
        cout << "Fails to get the Python class.\n";
        return 1;
    }
    //Py_DECREF(pdict);


    cout << python_class;
    PyObject* object;

    // Creates an instance of the class
    if (PyCallable_Check(python_class)) {
        object = PyObject_CallObject(python_class, args);
        Py_DECREF(python_class);
    }
    else {
        std::cout << "Cannot instantiate the Python class" << endl;
        Py_DECREF(python_class);
        return 1;
    }

    auto val = PyObject_CallMethod(object, "is_jit_model_available", NULL);
    if (!val)
        cout << "error!";

    cout << val;

当我尝试运行这段代码时，我得到了显示地图内容的输出：

size: 5
__doc__ : Module1
__loader__ : Module1
__name__ : Module1
__package__ : Module1
__spec__ : Module1

所以这是PyModule_GetDict(module);的结果但是，当涉及到从这个模块中提取class时，它失败了，即PyDict_GetItemString(pdict, "MyClass1"); returns null.

在我看来，模块处理程序本身不正确，这可能是因为它可能没有指向实际模块，这意味着我完全无法导入和获取该模块的句柄。

因此我想不出任何其他方法可以让我导入模块并像这样使用它。

我在这里错过了什么？

Answer 1

正如评论中指出的那样，我最初尝试导入该模块是完全错误的，我应该这样做：

auto module = PyImport_ImportModule("Package1.Module1");

所以我这样做了:

auto module = PyImport_ImportModule("FV.F_V");

这样做之后，现在我得到了更有意义的输出，如您所见：

module: 0000021306FF9B38
size: 30
FaceVerification: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
Image: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
Path: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
__builtins__: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
__cached__: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
__doc__: FV.F_V
__file__: C:\Users\Master\Anaconda3\Lib\site-packages\FV\F_V.py
__loader__: FV
__name__: FV.F_V
__package__: FV
__spec__: FV
__warningregistry__ : C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
align_face: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
cv2: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
data_transforms: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
get_central_face_attributes: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
math: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
nn: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
np: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
os: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
pickle: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
plt: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
resnet101: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
resnet18: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
resnet50: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
scipy: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
time: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
torch: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
tqdm: C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc
transforms : C:\Users\Master\Anaconda3\Lib\site-packages\FV\__pycache__\F_V.cpython-36.pyc

如何在 C++ 中访问 Python 模块？

How is it possible to access a Python module in C++?

c++

python

python-embedding