[C++-sig] Re: The "return always existing pointer throws dangling error" problem

[Niall Douglas]

On 22 Oct 2003 at 19:05, Niall Douglas wrote:

> I'm thinking the best short-term stop-gap solution is an alternate
> call_method which basically disables the dangling pointer check. Then
> you can mark off functions in pyste which would fall foul of this
> particular problem on a case-by-case basis.

Just for reference for anyone searching the archives for a solution 
to this problem, mine was to add the following to call_method.hpp:

template <
    class R
    BOOST_PP_ENUM_TRAILING_PARAMS_Z(1, N, class A)
    >
typename detail::returnable<R>::type
call_method2(PyObject* self, char const* name
    BOOST_PP_COMMA_IF(N) BOOST_PP_ENUM_BINARY_PARAMS_Z(1, N, A, 
const& a)
    , boost::type<R>* = 0
    )
{
    PyObject* const result = 
        PyEval_CallMethod(
            self
            , const_cast<char*>(name)
            , const_cast<char*>("(" BOOST_PP_REPEAT_1ST(N, 
BOOST_PYTHON_FIXED, "O") ")")
            BOOST_PP_REPEAT_1ST(N, 
BOOST_PYTHON_FAST_ARG_TO_PYTHON_GET, nil)
            );

	object refincfix(handle<>(borrowed(result)));
    converter::return_from_python<R> converter;
    return converter(result);
}

Then you use call_method2<> instead of call_method when calling 
virtual overridable methods in python.

Cheers,
Niall




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