[Boost-users] filter_iterator and bind

From: Nico Galoppo (nico_at_[hidden])
Date: 2006-02-21 08:42:23

Hi,

I'm having trouble getting make_filter_iterator and bind to work together nicely:

-------------------------------------------------------------------------------
   boost::function<bool (const node_type&)> is_constraint;
   is_constraint = boost::bind(&node_type::IsConstraint, _1);

   boost::make_filter_iterator(is_constraint, ab.begin(), ab.end()); // ERROR:
does not compile
   boost::make_filter_iterator(boost::bind(&node_type::IsConstraint, _1),
ab.begin(), ab.end()); // compiles
-------------------------------------------------------------------------------

Note that ab.begin()/ab.end() return iterators to containers of shared pointers.
See below for compiler errors.

What I would like to do, in the end, is something like this:

-------------------------------------------------------------------------------
   typedef boost::filter_iterator<boost::function<bool (const node_type&)>,
articulated_model_type::node_df_traversal_iterator> joint_iterator;

   joint_iterator first =
boost::make_filter_iterator(boost::bind(&node_type::IsConstraint, _1),
ab.begin(), ab.end());
-------------------------------------------------------------------------------

Unfortunately, this doesn't compile either. I want an explicit handle to the
interator (first), because I'd like to do a normal for loop like this:
for(joint_iterator joint = first; joint != last; ++joint)
{ ... }

Again, compile errors are below. Thanks for the help.

--nico

d:\dev\boost_1_33_1\boost\iterator\filter_iterator.hpp(100) : error C2664:
'boost::function1<R,T0,Allocator>::result_type
boost::function1<R,T0,Allocator>::operator ()(T0) const' : cannot convert
parameter 1 from 'Hybrid::Graph<node_traits>::const_node_ptr' to 'const
Hybrid::Node<graph_type_,node_traits> '
         with
         [
             R=bool,
             T0=const
Hybrid::Node<Hybrid::Graph<ArticulatedModelNodeTraits<MyTypes>>::graph_type,ArticulatedModelNodeTraits<MyTypes>> 

,
             Allocator=std::allocator<void>
         ]
         and
         [
             node_traits=ArticulatedModelNodeTraits<MyTypes>
         ]
         and
         [

graph_type_=Hybrid::Graph<ArticulatedModelNodeTraits<MyTypes>>::graph_type,
             node_traits=ArticulatedModelNodeTraits<MyTypes>
         ]
         Reason: cannot convert from
'Hybrid::Graph<node_traits>::const_node_ptr' to 'const node_type'
         with
         [
             node_traits=ArticulatedModelNodeTraits<MyTypes>
         ]
         No constructor could take the source type, or constructor overload
resolution was ambiguous
         d:\dev\boost_1_33_1\boost\iterator\filter_iterator.hpp(99) : while
compiling class-template member function 'void
boost::filter_iterator<Predicate,Iterator>::satisfy_predicate(void)'
         with
         [
             Predicate=boost::function<bool (const node_type &)>,

Iterator=Hybrid::Graph<ArticulatedModelNodeTraits<MyTypes>>::node_df_traversal_iterator
         ]
         d:\dev\Hybrid\Tests\Graph\main.cpp(645) : see reference to class
template instantiation 'boost::filter_iterator<Predicate,Iterator>' being compiled
         with
         [
             Predicate=boost::function<bool (const node_type &)>,

Iterator=Hybrid::Graph<ArticulatedModelNodeTraits<MyTypes>>::node_df_traversal_iterator
         ]

======================================================================================

:\dev\Hybrid\Tests\Graph\main.cpp(646) : error C2440: 'initializing' : cannot
convert from 'boost::filter_iterator<Predicate,Iterator>' to
'boost::filter_iterator<Predicate,Iterator>'
         with
         [

Predicate=boost::_bi::bind_t<bool,boost::_mfi::cmf0<bool,ConstraintNodeTraits>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,

Iterator=Hybrid::Graph<ArticulatedModelNodeTraits<MyTypes>>::node_df_traversal_iterator
         ]
         and
         [
             Predicate=boost::function<bool (const node_type &)>,

Iterator=Hybrid::Graph<ArticulatedModelNodeTraits<MyTypes>>::node_df_traversal_iterator
         ]
         No constructor could take the source type, or constructor overload
resolution was ambiguous

-- 
nico galoppo von borries     @  address: 105 creel st., chapel hill
comp. graphics phd. student  @           north carolina, 27516 USA
UNC, chapel hill             @  phone: [phone] (office)
                              @         [phone] (home)
                              @  email: nico at cs dot unc dot edu
                              @  homepage: http://www.cs.unc.edu/~nico
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