[C++-sig] Boost.Python: wrapping a method returning const std::string &

[Bilokon, Paul]

Hi Olaf,

Thanks a lot. This was certainly an informative error message.

As per your reply, the error was resolved by replacing

        .def("getName", &Ccy::getName)

with

        .def("getName", &Ccy::getName,
boost::python::return_value_policy<boost::python::copy_const_reference>(
)) 

Regards,
Paul

-----Original Message-----
From: c++-sig-bounces at python.org [mailto:c++-sig-bounces at python.org] On
Behalf Of Olaf Peter
Sent: Thursday, August 14, 2008 9:46 AM
To: Development of Python/C++ integration
Subject: Re: [C++-sig] Boost.Python: wrapping a method returning const
std::string &

Bilokon, Paul schrieb:
> Hi c++-sig,
> 
> Sorry if this is supposed to be glaringly obvious, but I thought 
> std::string types were pretty much fully supported in Boost.Python 
> (looking at Boost 1.35.0).
> 
> I'm trying to wrap a method
> 
>     const std::string& getName( ) const;
> 
> This should be straightforward, right?
> 
> I'm doing it like this:
> 
>     class_<Ccy>("Ccy", init<>())
>         .def("getName", &Ccy::getName)
>     ;
> 
> But in return I'm getting
> 
> Error	6	error C2027: use of undefined type
> 'boost::python::detail::specify_a_return_value_policy_to_wrap_function
> s_
> returning<T>'
> E:\dev\external\boost\boost_1_35_0\boost\python\detail\caller.hpp
> 223	
> 
> Is this because the string is returned by reference? Do I have to wrap

> the method? If so, I would be very much obliged if you could direct me

> to an example.

Cool compiler error, it says what he expected: see
http://www.boost.org/doc/libs/1_35_0/libs/python/doc/v2/copy_const_refer
ence.html. 
Please google, why this is you friend.


Regards,
Olaf

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