我正在学习将c++代码包装到Python模块中,对于以下函数需要typemap int foo(int argc, char **argv); 例如,一个简单的c++代码可以

#include <iostream>

int foo(int argc, char** argv) {
    std::cout << "Have " << argc << " arguments:" << std::endl;
    for (int i = 0; i < argc; ++i) {
        std::cout << argv[i] << std::endl;
    }
    return 0;
}

然后我学习了SWIG教程 here (34.9.2)编写SWIG的接口文件:

%module Args
%{
extern int foo(int argc, char **argv);
%}

%typemap(in) (int argc, char **argv) {
  /* Check if is a list */
  if (PyList_Check($input)) {
    int i;
    $1 = PyList_Size($input);
    $2 = (char **) malloc(($1+1)*sizeof(char *));
    for (i = 0; i < $1; i++) {
      PyObject *o = PyList_GetItem($input,i);
      if (PyString_Check(o))
    $2[i] = PyString_AsString(PyList_GetItem($input,i));
      else {
    PyErr_SetString(PyExc_TypeError,"list must contain strings");
    free($2);
    return NULL;
      }
    }
    $2[i] = 0;
  } else {
    PyErr_SetString(PyExc_TypeError,"not a list");
    return NULL;
  }
}

%typemap(freearg) (int argc, char **argv) {
  free((char *) $2);
}

extern int foo(int argc, char **argv);

但是,在构建模块之后,Python中始终存在一个错误:

>>> import Args
>>> Args.foo(["foo","bar","spam","1"])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: list must contain strings

在typemap中似乎 $input 确实作为Python列表收到,但出现了一些问题 PyList_GetItem($input,i) . 我做错什么了吗?

提前感谢!