[Boost-users] [proto] transform with calling templates

Subject: [Boost-users] [proto] transform with calling templates
From: Felipe Magno de Almeida (felipe.m.almeida_at_[hidden])
Date: 2012-10-21 15:34:57

Hello,

I had the following transform and function object:

struct bind_functions_transform
  : proto::when
  <
    proto::terminal<binding::placeholder::method_value<proto::_,proto::_> >
  , bind_method_call(proto::_value, proto::_data, proto::_state)>
  >

struct bind_method_call : proto::callable
{
  template <typename T>
  struct result
  {
    typedef typename boost::function_types::parameter_types<T>::type
parameter_types;
    typedef typename boost::mpl::next
    <typename boost::remove_reference
     <typename boost::mpl::at_c<parameter_types, 2u>::type>::type>::type type;
  };

  template <typename Sig, typename F, std::size_t I, std::size_t N>
  boost::mpl::size_t<I+1>
  operator()(binding::placeholder::method_value<Sig, F>const& method
             , boost::fusion::vector<Class&, environment,
binding::virtual_table<N>&>& data
             , boost::mpl::size_t<I> v) const
  {
    ...
  }
};

So, I needed one more compile-time information which would be equal to
all calls and transforms,
so I made my transform into a template and also bind_method_call as follows:

template <typename T>
struct bind_functions_transform
  : proto::when
  <
    proto::terminal<binding::placeholder::method_value<proto::_,proto::_> >
  , bind_method_call<T>(proto::_value, proto::_data, proto::_state)>
  >

template <typename T>
struct bind_method_call : proto::callable [...]

And then I received the following error:

../boost_1_50_0/boost/proto/transform/detail/preprocessed/construct_funop.hpp:24:33:
error: no matching function for call to
‘jvb::binding::bind_method_call<hello_world>::bind_method_call(const
jvb::binding::placeholder::method_value<void(), void
(hello_world::*)()>&, boost::fusion::vector<jvb::class_&,
jvb::environment, jvb::binding::virtual_table<1ul>&,
boost::fusion::void_, boost::fusion::void_, boost::fusion::void_,
boost::fusion::void_, boost::fusion::void_, boost::fusion::void_,
boost::fusion::void_>&, const mpl_::size_t<0ul>&)’

I've remembered the workaround for msvc with proto::call. Because it
seemed that the transform was actually trying to construct instead of
calling bind_method_call, so I changed to:

template <typename PeerClass>
struct bind_functions_transform
  : proto::when
  <
    proto::terminal<binding::placeholder::method_value<proto::_,proto::_> >
  , proto::call<bind_method_call<PeerClass>(proto::_value,
proto::_data, proto::_state)>
  >

And it worked. Well, my question is: is this a known limitation? I
didn't find it in proto documentation.

I'm using GCC 4.7.1 and x86_64 with Linux

Regards,
-- 
Felipe Magno de Almeida