Question

我尝试从Python网站https://docs.python.org/3/extending/embedding.html编译示例代码。一切正常，除了以下几行：

 pName = PyUnicode_DecodeFSDefault(argv[1]);

我的MacOS El Captain上安装了Python 3.6。我的make文件如下所示：

call_function:     call_function.o        
    gcc -o call_function call_function.o -export-dynamic -L/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/config-3.6m-darwin -lpython3.6m -lpthread -lm -ldl -lutil


call_function.o:call_function.cpp    
    gcc -c call_function.cpp -I/Library/Frameworks/Python.framework/Versions/3.6/include/python3.6m

编译C ++代码时，出现以下错误：

gcc -c call_function.cpp -I/Library/Frameworks/Python.framework/Versions/3.6/include/python3.6m
call_function.cpp:16:13: error: use of undeclared identifier    'PyUnicode_DecodeFSDefault'
pName = PyUnicode_DecodeFSDefault(argv[1]);
        ^
1 error generated.

有谁知道如何解决上述错误？我非常感谢你的帮助。

以下是完整的示例代码：

#include <Python/Python.h>
#include <Python/unicodeobject.h>

int main(int argc, char *argv[])
{
PyObject *pName, *pModule, *pDict, *pFunc;
PyObject *pArgs, *pValue;
int i;

if (argc < 3) {
    fprintf(stderr,"Usage: call pythonfile funcname [args]\n");
    return 1;
}

Py_Initialize();
pName = PyUnicode_DecodeFSDefault(argv[1]);
// pName = PyUnicode_FromString(argv[1]);  <-- also gives me an error

/* Error checking of pName left out */

pModule = PyImport_Import(pName);
Py_DECREF(pName);

if (pModule != NULL) {
    pFunc = PyObject_GetAttrString(pModule, argv[2]);
    /* pFunc is a new reference */

    if (pFunc && PyCallable_Check(pFunc)) {
        pArgs = PyTuple_New(argc - 3);
        for (i = 0; i < argc - 3; ++i) {
            pValue = PyLong_FromLong(atoi(argv[i + 3]));
            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) {
            printf("Result of call: %ld\n", PyLong_AsLong(pValue));
            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;
}

Answer 1

我弄清楚问题是什么。包含<Python/Python.h>语句实际上链接到/System/Library/Frameworks/Python.framework/Versions/Current，目前是Python2.7。我在我的Mac上安装了Python 3.6，甚至在我的make文件中包含了/Library/Frameworks/Python.framework/Versions/3.6/include/python3.6m，它仍然被称为MacOS的Python 2.7文件夹中的Python.h文件。我试图将Current的符号链接更改为新的3.6文件夹，并且它不允许我进行更改。有没有人知道如何更改Python2.7当前文件夹的符号链接，所以我的gcc会查看Python.h的Python 3.6文件夹呢？

Answer 2

此问题发布已经很长时间了，但是我提出的解决方案如下，

char * full_cls_name = argv[1];
Py_Initialize();
pName = PyString_FromString(full_cls_name);

您还应该检查argv [1]是否存在？

未声明的标识符：PyUnicode_DecodeFSDefault

2 个答案: