python/include/boost/python/return_arg.hpp at develop · boostorg/python · GitHub

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// Copyright David Abrahams and Nikolay Mladenov 2003.

// Distributed under the Boost Software License, Version 1.0. (See

// accompanying file LICENSE_1_0.txt or copy at

// http://www.boost.org/LICENSE_1_0.txt)

#ifndef RETURN_ARG_DWA2003719_HPP

# define RETURN_ARG_DWA2003719_HPP

# include <boost/python/default_call_policies.hpp>

# include <boost/python/detail/none.hpp>

# include <boost/python/detail/value_arg.hpp>

#ifndef BOOST_PYTHON_NO_PY_SIGNATURES

# include <boost/python/converter/pytype_function.hpp>

#endif

# include <boost/python/detail/type_traits.hpp>

# include <boost/mpl/int.hpp>

# include <boost/mpl/at.hpp>

# include <boost/static_assert.hpp>

# include <boost/python/refcount.hpp>

# include <cstddef>

namespace boost { namespace python {

namespace detail

{

template <std::size_t>

struct return_arg_pos_argument_must_be_positive

# if defined(__GNUC__) || defined(__EDG__)

{}

# endif

;

struct return_none

{

template <class T> struct apply

{

struct type

{

static bool convertible()

{

return true;

}

PyObject *operator()( typename value_arg<T>::type ) const

{

return none();

}

#ifndef BOOST_PYTHON_NO_PY_SIGNATURES

PyTypeObject const *get_pytype() const { return converter::expected_pytype_for_arg<T>::get_pytype() ; }

#endif

};

}

template <

std::size_t arg_pos=1

, class Base = default_call_policies

struct return_arg : Base

{

private:

BOOST_STATIC_CONSTANT(bool, legal = arg_pos > 0);

public:

typedef typename mpl::if_c<

legal

, detail::return_none

, detail::return_arg_pos_argument_must_be_positive<arg_pos>

// we could default to the base result_converter in case or

// arg_pos==0 since return arg 0 means return result, but I

// think it is better to issue an error instead, cause it can

// lead to confusions

>::type result_converter;

template <class ArgumentPackage>

static PyObject* postcall(ArgumentPackage const& args, PyObject* result)

{

// In case of arg_pos == 0 we could simply return Base::postcall,

// but this is redundant

BOOST_STATIC_ASSERT(arg_pos > 0);

result = Base::postcall(args,result);

if (!result)

return 0;

Py_DECREF(result);

return incref( detail::get(mpl::int_<arg_pos-1>(),args) );

}

template <class Sig>

struct extract_return_type : mpl::at_c<Sig, arg_pos>

{

};

template <

class Base = default_call_policies

struct return_self

: return_arg<1,Base>

{};

}} // namespace boost::python

#endif // RETURN_ARG_DWA2003719_HPP

python/include/boost/python/return_arg.hpp at develop · boostorg/python · GitHub

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