Python SWIG wrapper for C++ rvalue std::string &&

I'm trying to build a python wrapper for gnucash c++ parts. In QofBackend I encountered the method const std::string && get_message (). This returns <Swig Object of type 'std::string *' at 0x7f4a20f5c9f0> in my setting but I would like to access the string.

I didn't really find a simple explanation so I rebuilt an example setting and dug into c++ which I barely know. I managed to get the string into python but I'd like to know

• if this typemap(out) approach is correct (also in respect of memory and error handling).
• The conversion in set_s_workaround() is also just a workaround. I don't think that for gnucash the python code ever needs to set this value but for completeness sake it would be nice to also have a typemap(in) std::string&& and
• get rid of get_s_workaround.

/* example.hpp */
#include <string>

using namespace std;

struct struct1{
        string s;
        const std::string&& get_s();
        void set_s(string&&);
        void set_s_workaround(string);
        void init_s();
        void print_s();
};

string conv_rvalue_string(string);

/* example.cpp */
#include<iostream> 
#include"example.hpp"

using namespace std; 

void
struct1::set_s (std::string&& msg)
{
     s = msg;
}

std::string
conv_rvalue_string (std::string msg)
{
        return msg;
}

void
struct1::set_s_workaround(std::string msg)
{
        set_s ( conv_rvalue_string(msg) );
}

void
struct1::init_s ()
{
     set_s("Some content");
}

void
struct1::print_s ()
{
     cout<<get_s()<<endl;
}

const std::string&&
struct1::get_s ()
{
    return std::move(s);
}

/* example.i */
%module example

%include "std_string.i"

%typemap(out) std::string&& {
  std::string s = *$1;
  $result = SWIG_From_std_string(s);
}


%{
#include <string>
#include "example.hpp"
%}

%include "example.hpp"

#!/bin/bash
swig3.0 -c++ -shadow -python example.i
g++ -fpic -c example.hpp example.cpp example_wrap.cxx -I/usr/include/python3.7
g++ -shared example_wrap.o example.o -o _example.so 

# example.py
import example

s1 = example.struct1()
s1.set_s3('TEST')
s1.print_s()
print(s1.get_s())

Thanks for the help!