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dabrahamsdabrahams
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Object life support
[SVN r12662]
1 parent 0a9d5f6 commit 262396d

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5 files changed

+137
-7
lines changed

5 files changed

+137
-7
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‎Jamfile‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -20,6 +20,7 @@ PYTHON_PROPERTIES
2020
src/object/class.cpp
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src/object/function.cpp
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src/object/inheritance.cpp
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src/object/life_support.cpp
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src/errors.cpp
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src/module.cpp
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src/objects.cpp

‎include/boost/python/return_internal_reference.hpp‎

Lines changed: 28 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,10 @@
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# define RETURN_INTERNAL_REFERENCE_DWA2002131_HPP
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# include <boost/python/default_call_policies.hpp>
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# include <boost/python/object/life_support.hpp>
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# include <boost/type_traits/object_traits.hpp>
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# include <boost/python/reference_existing_object.hpp>
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# include <boost/python/to_python_indirect.hpp>
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namespace boost { namespace python {
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@@ -28,18 +31,39 @@ struct internal_reference_to_python_generator
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{
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typedef typename mpl::select_type<
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!is_object<T>::value
31-
, internal_reference_to_python<T>
32-
, detail::return_internal_reference_requires_a_pointer_or_reference_return_type
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, to_python_indirect<T, detail::make_reference_holder>
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, detail::return_internal_reference_requires_a_pointer_or_reference_return_type<T>
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>::type type;
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};
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};
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37-
template <std::size_t owner_arg, class Base = default_call_policies>
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template <std::size_t owner_arg = 1, class Base = default_call_policies>
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struct return_internal_reference : Base
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{
40-
typedef wrap_internal_reference<owner_arg> result_converter;
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typedef reference_existing_object result_converter;
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static PyObject* postcall(PyObject* args, PyObject* result);
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};
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template <std::size_t owner_arg, class Base>
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PyObject* return_internal_reference<owner_arg,Base>::postcall(PyObject* args_, PyObject* result)
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{
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PyObject* patient = PyTuple_GetItem(args_, owner_arg - 1);
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if (patient != 0) // Make sure the argument was in range.
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{
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result = Base::postcall(args_,result);
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if (result != 0)
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{
56+
if (python::objects::make_nurse_and_patient(result, patient) == 0)
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{
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return result;
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}
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}
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}
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Py_XDECREF(result);
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return 0;
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}
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}} // namespace boost::python
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#endif // RETURN_INTERNAL_REFERENCE_DWA2002131_HPP

‎src/object/life_support.cpp‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,99 @@
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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/object/life_support.hpp>
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#include <boost/python/detail/none.hpp>
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namespace boost { namespace python { namespace objects {
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struct life_support
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{
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PyObject_HEAD
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PyObject* patient;
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};
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extern "C"
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{
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static void
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life_support_dealloc(PyObject* self)
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{
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self->ob_type->tp_free(self);
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}
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static PyObject *
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life_support_call(PyObject *self, PyObject *arg, PyObject *kw)
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{
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// Let the patient die now
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Py_XDECREF(((life_support*)self)->patient);
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// Also let the weak reference die. This probably kills us.
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Py_XDECREF(PyTuple_GET_ITEM(arg, 0));
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return detail::none();
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}
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}
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PyTypeObject life_support_type = {
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PyObject_HEAD_INIT(&PyType_Type)
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0,
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"Boost.Python.life_support",
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sizeof(life_support),
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0,
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life_support_dealloc, /* tp_dealloc */
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0, /* tp_print */
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0, /* tp_getattr */
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0, /* tp_setattr */
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0, /* tp_compare */
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0, //(reprfunc)func_repr, /* tp_repr */
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0, /* tp_as_number */
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0, /* tp_as_sequence */
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0, /* tp_as_mapping */
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0, /* tp_hash */
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life_support_call, /* tp_call */
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0, /* tp_str */
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0, // PyObject_GenericGetAttr, /* tp_getattro */
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0, // PyObject_GenericSetAttr, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT /* | Py_TPFLAGS_HAVE_GC */,/* tp_flags */
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0, /* tp_doc */
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0, // (traverseproc)func_traverse, /* tp_traverse */
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0, /* tp_clear */
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0, /* tp_richcompare */
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0, //offsetof(PyLife_SupportObject, func_weakreflist), /* tp_weaklistoffset */
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0, /* tp_iter */
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0, /* tp_iternext */
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0, /* tp_methods */
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0, // func_memberlist, /* tp_members */
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0, //func_getsetlist, /* tp_getset */
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0, /* tp_base */
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0, /* tp_dict */
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0, /* tp_descr_get */
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0, /* tp_descr_set */
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0, //offsetof(PyLife_SupportObject, func_dict), /* tp_dictoffset */
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0, /* tp_init */
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0, /* tp_alloc */
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0,
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0 /* tp_new */
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};
78+
79+
int make_nurse_and_patient(PyObject* nurse, PyObject* patient)
80+
{
81+
life_support* system = PyObject_New(life_support, &life_support_type);
82+
if (!system)
83+
return -1;
84+
85+
// We're going to leak this reference, but don't worry; the
86+
// life_support system decrements it when the nurse dies.
87+
PyObject* weakref = PyWeakref_NewRef(nurse, (PyObject*)system);
88+
if (!weakref)
89+
{
90+
Py_XDECREF(system);
91+
return -1;
92+
}
93+
94+
system->patient = patient;
95+
Py_XINCREF(patient); // hang on to the patient until death
96+
return 0;
97+
}
98+
99+
}}} // namespace boost::python::objects

‎test/test_pointer_adoption.cpp‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
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#include <boost/python/module.hpp>
77
#include <boost/python/return_value_policy.hpp>
88
#include <boost/python/manage_new_object.hpp>
9-
#include <boost/python/reference_existing_object.hpp>
9+
#include <boost/python/return_internal_reference.hpp>
1010
#include <boost/python/class.hpp>
1111
#include <boost/mpl/type_list.hpp>
1212

@@ -75,7 +75,7 @@ BOOST_PYTHON_MODULE_INIT(test_pointer_adoption_ext)
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7676
class_<A>()
7777
.def("content", &A::content)
78-
.def("get_inner", &A::get_inner, return_value_policy<reference_existing_object>())
78+
.def("get_inner", &A::get_inner, return_internal_reference<>())
7979
)
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8181
.add(

‎test/test_pointer_adoption.py‎

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16,10 +16,16 @@
1616
>>> a.content()
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'with an exposed reference'
1818
19-
>>> innards = None
19+
# The a instance should be kept alive...
2020
>>> a = None
2121
>>> num_a_instances()
22+
1
23+
24+
# ...until we're done with its innards
25+
>>> innards = None
26+
>>> num_a_instances()
2227
0
28+
2329
"""
2430
def run(args = None):
2531
import sys

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