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implicit conversions
[SVN r13277]
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‎include/boost/python/converter/find_from_python.hpp‎

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BOOST_PYTHON_DECL rvalue_stage1_data find(
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PyObject* source, rvalue_from_python_registration const*);
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BOOST_PYTHON_DECL rvalue_from_python_registration const* find_chain(
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PyObject* source, rvalue_from_python_registration const*);
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}}} // namespace boost::python::converter
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#endif // FIND_FROM_PYTHON_DWA2002223_HPP

‎include/boost/python/converter/implicit.hpp‎

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// Copyright David Abrahams 2002. Permission to copy, use,
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// modify, sell and distribute this software is granted provided this
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// copyright notice appears in all copies. This software is provided
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// "as is" without express or implied warranty, and with no claim as
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// to its suitability for any purpose.
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#ifndef IMPLICIT_DWA2002326_HPP
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# define IMPLICIT_DWA2002326_HPP
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# include <boost/python/converter/from_python_data.hpp>
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# include <boost/python/converter/from_python_stage1_data.hpp>
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# include <boost/python/converter/registrations.hpp>
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namespace boost { namespace python { namespace converter {
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template <class Source, class Target>
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struct implicit
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{
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static void* convertible(PyObject* obj)
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{
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// Find a converter registration which can produce a Source
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// instance from obj
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return const_cast<rvalue_from_python_registration*>(
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find_chain(obj, rvalue_from_python_chain<Source>::value));
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}
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static void construct(PyObject* obj, rvalue_stage1_data* data)
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{
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// This is the registration we got from the convertible step
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rvalue_from_python_registration const* registration
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= static_cast<rvalue_from_python_registration*>(data->convertible);
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// Call the convertible function again
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rvalue_data<Source> intermediate_data(registration->convertible(obj));
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// Use the result to construct the source type if the first
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// converter was an rvalue converter.
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if (registration->construct != 0)
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registration->construct(obj, &intermediate_data.stage1);
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void* storage = ((rvalue_base_data<Target>*)data)->storage.bytes;
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new (storage) Target(*(Source*)intermediate_data.storage.bytes);
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// record successful construction
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data->convertible = storage;
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}
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};
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}}} // namespace boost::python::converter
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#endif // IMPLICIT_DWA2002326_HPP

‎include/boost/python/implicit.hpp‎

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// Copyright David Abrahams 2002. Permission to copy, use,
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// modify, sell and distribute this software is granted provided this
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// copyright notice appears in all copies. This software is provided
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// "as is" without express or implied warranty, and with no claim as
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// to its suitability for any purpose.
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#ifndef IMPLICIT_DWA2002325_HPP
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# define IMPLICIT_DWA2002325_HPP
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# include <boost/type.hpp>
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# include <boost/python/converter/implicit.hpp>
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# include <boost/python/converter/registry.hpp>
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# include <boost/python/converter/type_id.hpp>
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namespace boost { namespace python {
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template <class Source, class Target>
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void implicitly_convertible(boost::type<Source>* = 0, boost::type<Target>* = 0)
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{
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typedef converter::implicit<Source,Target> functions;
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converter::registry::insert(
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&functions::convertible
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, &functions::construct
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, converter::undecorated_type_id<Target>());
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}
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}} // namespace boost::python
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#endif // IMPLICIT_DWA2002325_HPP

‎include/boost/python/type_from_python.hpp‎

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}
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// A function generator whose static execute() function is an lvalue
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// from_python converter using the given Extractor. U is exepcted to
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// from_python converter using the given Extractor. U is expected to
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// be the actual type of the PyObject instance from which the result
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// is being extracted.
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template <class Extractor, class U>

‎src/converter/from_python.cpp‎

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return data;
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}
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BOOST_PYTHON_DECL rvalue_from_python_registration const* find_chain(
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PyObject* source
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, rvalue_from_python_registration const* chain)
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{
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for (;chain != 0; chain = chain->next)
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{
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if (chain->convertible(source))
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break;
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}
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return chain;
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}
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BOOST_PYTHON_DECL void* find(
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PyObject* source
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, lvalue_from_python_registration const* chain)

‎test/Jamfile‎

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bpl-test callbacks ;
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bpl-test virtual_functions ;
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bpl-test back_reference ;
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bpl-test implicit ;
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# --- unit tests of library components ---
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unit-test indirect_traits_test

‎test/implicit.cpp‎

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// Copyright David Abrahams 2002. Permission to copy, use,
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// modify, sell and distribute this software is granted provided this
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// copyright notice appears in all copies. This software is provided
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// "as is" without express or implied warranty, and with no claim as
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// to its suitability for any purpose.
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#include <boost/python/class.hpp>
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#include <boost/python/implicit.hpp>
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#include <boost/python/module.hpp>
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#include "test_class.hpp"
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// This test shows that a class can be wrapped "as itself" but also
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// acquire a back-reference iff has_back_reference<> is appropriately
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// specialized.
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using namespace boost::python;
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typedef test_class<> X;
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int x_value(X const& x)
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{
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return x.value();
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}
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BOOST_PYTHON_MODULE_INIT(implicit_ext)
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{
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implicitly_convertible<int,X>();
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module("implicit_ext")
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.def("x_value", x_value)
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.add(
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class_<X>("X")
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.def_init(args<int>())
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.def("value", &X::value)
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.def("set", &X::set)
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)
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;
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}
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#include "module_tail.cpp"

‎test/implicit.py‎

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'''
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>>> from implicit_ext import *
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>>> x_value(X(42))
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42
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>>> x_value(42)
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42
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'''
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def run(args = None):
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import sys
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import doctest
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if args is not None:
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sys.argv = args
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return doctest.testmod(sys.modules.get(__name__))
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if __name__ == '__main__':
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print "running..."
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import sys
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sys.exit(run()[0])

‎test/test_class.hpp‎

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// Copyright David Abrahams 2002. Permission to copy, use,
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// modify, sell and distribute this software is granted provided this
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// copyright notice appears in all copies. This software is provided
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// "as is" without express or implied warranty, and with no claim as
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// to its suitability for any purpose.
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#ifndef TEST_CLASS_DWA2002326_HPP
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# define TEST_CLASS_DWA2002326_HPP
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# include <cassert>
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template <int n = 0>
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struct test_class
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{
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explicit test_class(int x) : x(x), magic(7654321 + n) { ++counter; }
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test_class(test_class const& rhs) : x(rhs.x), magic(7654321 + n) { ++counter; }
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virtual ~test_class() { assert(magic == 7654321 + n); magic = 6666666; x = 9999; --counter; }
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void set(int x) { assert(magic == 7654321 + n); this->x = x; }
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int value() const { assert(magic == 7654321 + n); return x; }
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static int count() { return counter; }
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private:
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void operator=(test_class const&);
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private:
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int x;
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long magic;
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static int counter;
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};
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template <int n>
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int test_class<n>::counter;
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#endif // TEST_CLASS_DWA2002326_HPP

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