[C++-sig] Re: Problem with Extract conversion

[Dmitri Mouromtsev]

>> Hello all!
>> I am embedding Python in my application by using BOOST.PYTHON. I tried
>> to compile in MSVC 7.0 the example with extract<> conversion:
>>
>> boost::python::str test_str("test");
>> char const* c_str = extract<char const*>(test_str);
>>
>>  If I run this code an unhandled exception rise when the function
>> throw_no_lvalue_from_python compose error message "No registered
converter
>> was able to extract a C++...".
>>
>>  What I need to do and what is my mistake.
>
>Please post a small, complete program which reproduces your problem.

Here is test program reproducing my problem (or bug):
#include "Python.h"

#include "boost\python.hpp"

#include <iostream>

using namespace boost::python;

int main()

{

    Py_Initialize();

    boost::python::str test_str("test");

    char const* c_str = extract<char const*>(test_str);

    std::cout << c_str << '\n';

    return 0;

}

The exception rise in the same point as I describe blow.

If I use another conversoin:

char const* c_str = PyString_AsString(test_str.ptr());

it's all right.

And when I build this program I've got warning "'argument' : conversion from
'size_t' to 'int', possible loss of data" to line

BOOST_PYTHON_TO_PYTHON_BY_VALUE(std::string,
PyString_FromStringAndSize(x.c_str(),x.size()))

in the file builtin_converters.hpp.