[Boost-users] [fusion] remove_if and as_vector with Placeholder Expression as predicate

Subject: [Boost-users] [fusion] remove_if and as_vector with Placeholder Expression as predicate
From: Felipe Magno de Almeida (felipe.m.almeida_at_[hidden])
Date: 2012-11-12 12:11:03

Hello,

I'm trying to remove_if a few elements from a fusion sequence. But it
is instantiating
my predicate with the placeholder from MPL later on. Including with as_vector.

The following code generates the error code I'm pasting by the end of
the message.
I'm using GCC 4.7.2 and Linux x86_64. If I wrap meta_func<mpl::_1> in
a mpl::lambda<>::type
then the errors following the first error messages is what I get. I'm
not sure if I'm doing
something wrong here. If anyone could please shed some light, I would
really appreciate it.

#include <boost/fusion/include/as_vector.hpp>
#include <boost/fusion/include/remove_if.hpp>

namespace mpl = boost::mpl;
namespace fusion = boost::fusion;

struct element
{
  typedef mpl::false_ type;
};

template <typename T>
struct meta_func
{
  typedef typename T::type type;
};

int main()
{
  fusion::vector<element, element> e;
  fusion::as_vector(fusion::remove_if<meta_func<mpl::_1> >(e));
}

--
main.cpp: In instantiation of ‘struct meta_func<mpl_::arg<1> >’:
../boost/boost_1_51_0/boost/mpl/aux_/nested_type_wknd.hpp:26:31:
required from ‘struct
boost::mpl::aux::nested_type_wknd<meta_func<mpl_::arg<1> > >’
../boost/boost_1_51_0/boost/mpl/not.hpp:39:8:   required from ‘struct
boost::mpl::not_<meta_func<mpl_::arg<1> > >’
../boost/boost_1_51_0/boost/fusion/container/vector/detail/preprocessed/as_vector10.hpp:48:36:
  required from ‘static typename
boost::fusion::detail::as_vector<2>::apply<I0>::type
boost::fusion::detail::as_vector<2>::call(const Iterator&) [with
Iterator = boost::fusion::filter_iterator<boost::fusion::forward_traversal_tag,
boost::fusion::vector_iterator<const boost::fusion::vector<element,
element>, 0>, boost::fusion::vector_iterator<const
boost::fusion::vector<element, element>, 2>,
boost::mpl::not_<meta_func<mpl_::arg<1> > > >; typename
boost::fusion::detail::as_vector<2>::apply<I0>::type =
boost::fusion::vector2<element, element>]’
../boost/boost_1_51_0/boost/fusion/container/vector/convert.hpp:43:44:
  required from ‘typename boost::fusion::result_of::as_vector<const
Sequence>::type boost::fusion::as_vector(const Sequence&) [with
Sequence = boost::fusion::filter_view<const
boost::fusion::vector<element, element>,
boost::mpl::not_<meta_func<mpl_::arg<1> > > >; typename
boost::fusion::result_of::as_vector<const Sequence>::type =
boost::fusion::vector2<element, element>]’
main.cpp:22:62:   required from here
main.cpp:16:28: error: no type named ‘type’ in ‘struct mpl_::arg<1>’
In file included from ../boost/boost_1_51_0/boost/mpl/is_sequence.hpp:17:0,
                 from
../boost/boost_1_51_0/boost/fusion/support/detail/is_mpl_sequence.hpp:12,
                 from ../boost/boost_1_51_0/boost/fusion/support/tag_of.hpp:13,
                 from ../boost/boost_1_51_0/boost/fusion/iterator/next.hpp:10,
                 from
../boost/boost_1_51_0/boost/fusion/container/vector/vector10.hpp:13,
                 from
../boost/boost_1_51_0/boost/fusion/container/vector/vector_fwd.hpp:14,
                 from
../boost/boost_1_51_0/boost/fusion/container/vector/vector.hpp:10,
                 from
../boost/boost_1_51_0/boost/fusion/container/vector/detail/as_vector.hpp:18,
                 from
../boost/boost_1_51_0/boost/fusion/container/vector/convert.hpp:10,
                 from
../boost/boost_1_51_0/boost/fusion/include/as_vector.hpp:10,
                 from main.cpp:2:
../boost/boost_1_51_0/boost/mpl/not.hpp: In instantiation of ‘struct
boost::mpl::not_<meta_func<mpl_::arg<1> > >’:
../boost/boost_1_51_0/boost/fusion/container/vector/detail/preprocessed/as_vector10.hpp:48:36:
  required from ‘static typename
boost::fusion::detail::as_vector<2>::apply<I0>::type
boost::fusion::detail::as_vector<2>::call(const Iterator&) [with
Iterator = boost::fusion::filter_iterator<boost::fusion::forward_traversal_tag,
boost::fusion::vector_iterator<const boost::fusion::vector<element,
element>, 0>, boost::fusion::vector_iterator<const
boost::fusion::vector<element, element>, 2>,
boost::mpl::not_<meta_func<mpl_::arg<1> > > >; typename
boost::fusion::detail::as_vector<2>::apply<I0>::type =
boost::fusion::vector2<element, element>]’
../boost/boost_1_51_0/boost/fusion/container/vector/convert.hpp:43:44:
  required from ‘typename boost::fusion::result_of::as_vector<const
Sequence>::type boost::fusion::as_vector(const Sequence&) [with
Sequence = boost::fusion::filter_view<const
boost::fusion::vector<element, element>,
boost::mpl::not_<meta_func<mpl_::arg<1> > > >; typename
boost::fusion::result_of::as_vector<const Sequence>::type =
boost::fusion::vector2<element, element>]’
main.cpp:22:62:   required from here
../boost/boost_1_51_0/boost/mpl/not.hpp:39:8: error: ‘value’ is not a
member of ‘boost::mpl::aux::nested_type_wknd<meta_func<mpl_::arg<1> >
>’
--
-*- mode: compilation; default-directory: "~/dev/test/" -*-
Compilation started at Mon Nov 12 15:09:15
bjam -q -j8
...patience...
...found 584 targets...
...updating 2 targets...
gcc.compile.c++ bin/gcc-4.7.2/debug/main.o
In file included from ../boost/boost_1_51_0/boost/mpl/is_sequence.hpp:17:0,
                 from
../boost/boost_1_51_0/boost/fusion/support/detail/is_mpl_sequence.hpp:12,
                 from ../boost/boost_1_51_0/boost/fusion/support/tag_of.hpp:13,
                 from ../boost/boost_1_51_0/boost/fusion/iterator/next.hpp:10,
                 from
../boost/boost_1_51_0/boost/fusion/container/vector/vector10.hpp:13,
                 from
../boost/boost_1_51_0/boost/fusion/container/vector/vector_fwd.hpp:14,
                 from
../boost/boost_1_51_0/boost/fusion/container/vector/vector.hpp:10,
                 from
../boost/boost_1_51_0/boost/fusion/container/vector/detail/as_vector.hpp:18,
                 from
../boost/boost_1_51_0/boost/fusion/container/vector/convert.hpp:10,
                 from
../boost/boost_1_51_0/boost/fusion/include/as_vector.hpp:10,
                 from main.cpp:2:
../boost/boost_1_51_0/boost/mpl/not.hpp: In instantiation of ‘struct
boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> >’:
../boost/boost_1_51_0/boost/mpl/aux_/preprocessed/gcc/apply_wrap.hpp:36:8:
  required from ‘struct
boost::mpl::apply_wrap1<boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> >, element>’
../boost/boost_1_51_0/boost/mpl/aux_/preprocessed/gcc/bind.hpp:144:21:
  required from ‘struct
boost::mpl::bind1<boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> >,
boost::mpl::bind1<boost::mpl::quote1<boost::fusion::result_of::value_of>,
mpl_::arg<1> > >::apply<boost::fusion::vector_iterator<const
boost::fusion::vector<element, element>, 0> >’
../boost/boost_1_51_0/boost/mpl/aux_/preprocessed/gcc/apply_wrap.hpp:36:8:
  required from ‘struct
boost::mpl::apply_wrap1<boost::mpl::bind1<boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> >,
boost::mpl::bind1<boost::mpl::quote1<boost::fusion::result_of::value_of>,
mpl_::arg<1> > >, boost::fusion::vector_iterator<const
boost::fusion::vector<element, element>, 0> >’
../boost/boost_1_51_0/boost/mpl/aux_/preprocessed/gcc/apply.hpp:42:8:
 required from ‘struct
boost::mpl::apply1<boost::mpl::bind1<boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> >,
boost::mpl::bind1<boost::mpl::quote1<boost::fusion::result_of::value_of>,
mpl_::arg<1> > >, boost::fusion::vector_iterator<const
boost::fusion::vector<element, element>, 0> >’
../boost/boost_1_51_0/boost/fusion/algorithm/query/detail/find_if.hpp:33:35:
  required from ‘struct
boost::fusion::detail::apply_filter<boost::fusion::vector_iterator<const
boost::fusion::vector<element, element>, 0>,
boost::mpl::bind1<boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> >,
boost::mpl::bind1<boost::mpl::quote1<boost::fusion::result_of::value_of>,
mpl_::arg<1> > > >’
../boost/boost_1_51_0/boost/mpl/if.hpp:67:11:   [ skipping 10
instantiation contexts ]
../boost/boost_1_51_0/boost/fusion/support/tag_of.hpp:69:16:
required from ‘struct
boost::fusion::traits::tag_of<boost::fusion::filter_iterator<boost::fusion::forward_traversal_tag,
boost::fusion::vector_iterator<const boost::fusion::vector<element,
element>, 0>, boost::fusion::vector_iterator<const
boost::fusion::vector<element, element>, 2>,
boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> > >, void>’
../boost/boost_1_51_0/boost/fusion/support/tag_of.hpp:77:16:
required from ‘struct
boost::fusion::detail::tag_of<boost::fusion::filter_iterator<boost::fusion::forward_traversal_tag,
boost::fusion::vector_iterator<const boost::fusion::vector<element,
element>, 0>, boost::fusion::vector_iterator<const
boost::fusion::vector<element, element>, 2>,
boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> > > >’
../boost/boost_1_51_0/boost/fusion/iterator/distance.hpp:60:16:
required from ‘struct
boost::fusion::result_of::distance<boost::fusion::filter_iterator<boost::fusion::forward_traversal_tag,
boost::fusion::vector_iterator<const boost::fusion::vector<element,
element>, 0>, boost::fusion::vector_iterator<const
boost::fusion::vector<element, element>, 2>,
boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> > >,
boost::fusion::filter_iterator<boost::fusion::forward_traversal_tag,
boost::fusion::vector_iterator<const boost::fusion::vector<element,
element>, 2>, boost::fusion::vector_iterator<const
boost::fusion::vector<element, element>, 2>,
boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> > > >’
../boost/boost_1_51_0/boost/fusion/view/filter_view/detail/size_impl.hpp:27:20:
  required from ‘struct
boost::fusion::extension::size_impl<boost::fusion::filter_view_tag>::apply<const
boost::fusion::filter_view<const boost::fusion::vector<element,
element>, boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> > > >’
../boost/boost_1_51_0/boost/fusion/sequence/intrinsic/size.hpp:68:16:
 required from ‘struct boost::fusion::result_of::size<const
boost::fusion::filter_view<const boost::fusion::vector<element,
element>, boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> > > >’
../boost/boost_1_51_0/boost/fusion/container/vector/convert.hpp:23:82:
  required from ‘struct boost::fusion::result_of::as_vector<const
boost::fusion::filter_view<const boost::fusion::vector<element,
element>, boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> > > >’
../boost/boost_1_51_0/boost/fusion/container/vector/convert.hpp:40:5:
 required by substitution of ‘template<class Sequence> typename
boost::fusion::result_of::as_vector<const Sequence>::type
boost::fusion::as_vector(const Sequence&) [with Sequence =
boost::fusion::filter_view<const boost::fusion::vector<element,
element>, boost::mpl::not_<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> > >]’
main.cpp:22:81:   required from here
../boost/boost_1_51_0/boost/mpl/not.hpp:39:8: error: ‘value’ is not a
member of ‘boost::mpl::aux::nested_type_wknd<boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<meta_func,
mpl_::void_>, mpl_::arg<1> >, 0> >’
Thanks in advance,
-- 
Felipe Magno de Almeida