id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
2781,Add python exception info extractor,macke@…,Dave Abrahams,"Something like this is useful when embedding python, and it took me almost an entire day to figure out how to do this. (Having not used boost::python before, I got many crashes when trying to extract data again.)

Example:
{{{
    try {
        boost::python::eval(...);
    } catch (boost::python::error_already_set&) {
        std::string msg = handle_pyerror();
        std::cerr << ""Error runnin python code: "" << msg;
    }
}}}

Implementation:

{{{
#!cpp
std::string handle_pyerror()
{
    using namespace boost::python;

    std::ostringstream os;
    os << ""Python error:\n  "" << std::flush;

    PyObject *type = 0, *val = 0, *tb = 0;
    PyErr_Fetch(&type, &val, &tb);
    handle<> e_val(val), e_type(type), e_tb(allow_null(tb));

    try {
        object t = extract<object>(e_type.get());
        object t_name = t.attr(""__name__"");
        std::string typestr = extract<std::string>(t_name);

        os << typestr << std::flush;
    } catch (error_already_set const &) {
        os << ""Internal error getting error type:\n"";
        PyErr_Print();
    }

    os << "": "";

    try {
        object v = extract<object>(e_val.get());
        std::string valuestr = extract<std::string>(v.attr(""__str__"")());
        os  << valuestr << std::flush;
    } catch (error_already_set const &) {
        os << ""Internal error getting value type:\n"";
        PyErr_Print();
    }

    if (tb) {
        try {
            object tb_list = import(""traceback"").attr(""format_tb"")(e_tb);
            object tb_str = str("""").attr(""join"")(tb_list);
            std::string str = extract<std::string>(tb_str);

            os << ""\nTraceback (recent call last):\n"" << str;
        } catch (error_already_set const &) {
            os << ""Internal error getting traceback:\n"";
            PyErr_Print();
        }
    } else {
        os << std::endl;
    }

    return os.str();
}
}}}

I'm sure it could be done better, but I'm sure this would help quite a bit.

A wrapper for all python calls that translated python errors into C++-exceptions with proper contents would be very nice, but I can live with this.",Patches,new,Boost 1.39.0,python USE GITHUB,Boost 1.38.0,Not Applicable,,,loonycyborg@…