|
P: n/a
|
Hi, I'm trying to expose a C++ class' internals to python via
boost::python. I can do integer/boolean functions fine, but as soon
as I do a string get/set it craps out. - boost::python::class_<Entity, std::auto_ptr<pyEntity("Entity")
-
//publics
-
.def("isActive", &Entity::isActive) //bool
-
.def("activate", &Entity::activate) //bool
-
.def("deactivate", &Entity::deactivate) //bool
-
//...
-
.add_property("name", &Entity::getName) //compile error (1)
-
.def("getName", &Entity::getName,
-
boost::python::return_internal_reference<>()); //runtime error(2)
-
-
-
Compile error (1) shows this: C:/MinGW/include/boost/python/detail/
-
invoke.hpp: In function `PyObject*
-
boost::python::detail::invoke(boost::python::detail::invoke_tag_<
-
false, true>, const RC&, F&, TC&) [with RC =
-
boost::python::detail::specify_a_return_value_policy_to_wrap_functions_returning<const
-
std::string&>, F = const std::string&(rsblsb::Entity::*)() const, TC =
-
boost::python::arg_from_python<rsblsb::Entity&>]':
-
C:/MinGW/include/boost/python/detail/caller.hpp:199: instantiated
-
from `PyObject* boost::python::detail::caller_arity<1u>::impl<F,
-
Policies, Sig>::operator()(PyObject*, PyObject*) [with F = const
-
std::string&(rsblsb::Entity::*)() const, Policies =
-
boost::python::default_call_policies, Sig = boost::mpl::vector2<const
-
std::string&, rsblsb::Entity&>]'
-
C:/MinGW/include/boost/python/object/py_function.hpp:38:
-
instantiated from `PyObject*
-
boost::python::objects::caller_py_function_impl<Caller>::operator()
-
(PyObject*, PyObject*) [with Caller =
-
boost::python::detail::caller<const std::string&(rsblsb::Entity::*)()
-
const, boost::python::default_call_policies, boost::mpl::vector2<const
-
std::string&, rsblsb::Entity&]'
-
C:\Game\svn\Platform\Framework\Python\PyModuleSetup.cc:58:
-
instantiated from here
-
C:/MinGW/include/boost/python/detail/invoke.hpp:88: error: no match
-
for call to `(const
-
boost::python::detail::specify_a_return_value_policy_to_wrap_functions_returning<const
-
std::string&>) (const std::basic_string<char, std::char_traits<char>,
-
std::allocator<char&)'
Runtime error 2 just crashes whenever I try:
import modulename
I = modulename.Entity()
I.getName()
Anyone have any idea what I can try? thanks a lot!
-Shawn.
| |
Share this Question
|
P: n/a
|
I forgot to mention, getname is defined as:
const std::string &Entity::getName() const;
| |
|
P: n/a
|
On Mar 19, 12:00 pm, "Shawn McGrath" <shawn.mcgr...@gmail.comwrote:
I forgot to mention, getname is defined as:
const std::string &Entity::getName() const;
After more reading I found the copy_const_reference, and replaced:
boost::python::return_internal_reference<>());
with:
boost::python::return_value_policy<boost::python:: copy_const_reference>());
and it fixed my problem. Is there any downside to using
copy_const_reference over return_internal_reference?
Thanks,
Shawn. | |
|
P: n/a
|
On 19 Mar, 16:40, "Shawn McGrath" <shawn.mcgr...@gmail.comwrote:
On Mar 19, 12:00 pm, "Shawn McGrath" <shawn.mcgr...@gmail.comwrote:
I forgot to mention, getname is defined as:
const std::string &Entity::getName() const;
After more reading I found the copy_const_reference, and replaced:
boost::python::return_internal_reference<>());
with:
boost::python::return_value_policy<boost::python:: copy_const_reference>());
and it fixed my problem. Is there any downside to using
copy_const_reference over return_internal_reference?
You might get some answers here; if not, can I suggest http://mail.python.org/mailman/listinfo/c++-sig ? I think a lot of the
Boost.Python developers hang around on that list.
hth,
Jon. | |
|
P: n/a
|
On Mar 19, 12:49 pm, "Jon Clements" <jon...@googlemail.comwrote:
On 19 Mar, 16:40, "Shawn McGrath" <shawn.mcgr...@gmail.comwrote:
On Mar 19, 12:00 pm, "Shawn McGrath" <shawn.mcgr...@gmail.comwrote:
I forgot to mention, getname is defined as:
const std::string &Entity::getName() const;
After more reading I found the copy_const_reference, and replaced:
boost::python::return_internal_reference<>());
with:
boost::python::return_value_policy<boost::python:: copy_const_reference>());
and it fixed my problem. Is there any downside to using
copy_const_reference over return_internal_reference?
You might get some answers here; if not, can I suggesthttp://mail.python.org/mailman/listinfo/c++-sig? I think a lot of the
Boost.Python developers hang around on that list.
hth,
Jon.
Cool thanks a lot.
The problem is actually due to python's strings being immutable (I
knew this, but I thought returning const std::string& would do it).
return_internal_reference<works for other pointers/references, just
not strings.
(I just answered it so if it gets searched later on people will find
the solution)
-Shawn. | | This discussion thread is closed Replies have been disabled for this discussion. | |  Question stats - viewed: 3783
- replies: 4
- date asked: Mar 19 '07
|
