Re: [Boost-users] Comparing two mpl::vector types

On Fri, Feb 22, 2013 at 4:32 PM, Rodrigo Madera wrote:

Hello all,

Can anyone give me a hint on how to call a functor on the differences of two same size mpl::vector types?

For example, given:

typedef boost::mpl::vector v0_type; typedef boost::mpl::vector v1_type;

We can see that the second and third elements don't match, so I wish to call a functor twice, with the following signature:

struct SomeFunctor { template void operator()(T t, U u) const { // do something nice here } };

In this example, functor would be called twice: once with [T=char, U=int] and another with [T=short, U=std::string], along with their values.

Looks like using a zip_view [1] followed by a filter_view [2] followed by a for_each [3] will get you what you want. E.g., (untested) typedef mpl::zip_view< mpl::vector2< v0_type, v1_type > > zip_view_type; typedef mpl::filter_view< zip_view_type, mpl::not_< boost::is_same< mpl::_1, mpl::_2 > > > filter_view_type; mpl::for_each< filter_view_type >(SomeFunctor()); HTH, - Jeff [1] http://www.boost.org/doc/libs/1_53_0/libs/mpl/doc/refmanual/zip-view.html [2] http://www.boost.org/doc/libs/1_53_0/libs/mpl/doc/refmanual/filter-view.html [3] http://www.boost.org/doc/libs/1_53_0/libs/mpl/doc/refmanual/for-each.html