[C++-sig] using function objects as getters/setters for the properties

[Gennadiy Rozental]

Hi, 

I need to implement some translation in a getter and setter for particular 
field.

I am getting compile time errors, I am not sure how to fix. I am using 1.33.1.

Here is what I do:

template<typename T>
struct Getter {
    explicit Getter( MyClass T::* mem ) : m_member( mem ) {}

    bp::object  operator()( T const& obj ) const
    {
        return /* conversion here */;
    }

    MyClass T::* m_member;
};

template<typename T>
Getter<T>
make_getter( MyClass T::* mem )
{
    return Getter<T>( mem );
}

....

    bp::class_< MyClass >( "MyClass", bp::no_init )
        .add_property( "field", make_getter( &MyClass::field ) )

I see following errors:

..\..\3rdParty\boost-1.33.1\boost\python\class.hpp(441) : error C2784:
'boost::mpl::vector17<RT,most_derived<Target,ClassT>::type&,
T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14>
boost::python::detail::get_signature(RT (__thiscall ClassT::*
)(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) 
volatile const,Target *)' :
could not deduce template argument for 'T2 (__thiscall T3::*
)(T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,T15,T16,T17,T18) 
volatile const' from 'const Getter<T>'
        with
        [
            T=MyClass
        ]
        ..\..\3rdParty\boost-1.33.1\boost\python\signature.hpp(164):
see declaration of 'boost::python::detail::get_signature'
        ..\..\3rdParty\boost-1.33.1\boost\python\class.hpp(424):
see reference to function template instantiation
'boost::python::api::object boost::python::class_<W>::
make_fn_impl<W,F>(T *,const F &,boost::mpl::false_,void *,
boost::mpl::false_)' being compiled
        with
        [
            W=MyClass,
            F=Getter<MyClass>,
            T=MyClass
        ]
        ..\..\3rdParty\boost-1.33.1\boost\python\class.hpp(308):
see reference to function template instantiation 
'boost::python::api::object boost::python::class_<W>::
make_getter<Get>(F)' being compiled
        with
        [
            W=MyClass,
            Get=Getter<MyClass>,
            F=Getter<MyClass>
        ]
        src\export_riskmgr.cpp(157): see reference to 
function template instantiation 'boost::python::class_<W>::self
&boost::python::class_<W>::add_property<Getter<T>>
(const char *,Get,const char *)' being compiled
        with
        [
            W=MyClass,
            T=MyClass,
            Get=Getter<MyClass>
        ]
..\..\3rdParty\boost-1.33.1\boost\python\class.hpp(441):
error C2780: 
'boost::mpl::vector17<RT,ClassT&,
T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14>
boost::python::detail::get_signature(RT (__thiscall ClassT::*
)(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) 
volatile const)' : expects 1 arguments - 2 provided
        ..\..\3rdParty\boost-1.33.1\boost\python\signature.hpp(146) : 
see declaration of 'boost::python::detail::get_signature'
..\..\3rdParty\boost-1.33.1\boost\python\class.hpp(441):
 error C2784:
'boost::mpl::vector17<RT,most_derived<Target,ClassT>::type&,
T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14>
boost::python::detail::get_signature(
RT (__thiscall ClassT::* )
(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) 
volatile,Target *)' : could not deduce template argument for 
'T2 (__thiscall T3::* )
(T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,T15,T16,T17,T18) 
volatile' from 'const Getter<T>'
        with
        [
            T=MyClass        ]
  ..\..\3rdParty\boost-1.33.1\boost\python\signature.hpp(164) : 
see declaration of 'boost::python::detail::get_signature'

And lots more like this. I've tried to add make_function around. Did not help.

Any pointers? Thanks.

Gennadiy

_______________________________________________
Cplusplus-sig mailing list
Cplusplus-sig@python.org
http://mail.python.org/mailman/listinfo/cplusplus-sig