Eric Niebler wrote:
David Abrahams wrote:
Your patch gets everything all mixed up.
That's rather a bald and sweeping statement to make without any explanation. What do you really mean by "everything" in this case?
Everything, in this case, means the separate and orthogonal responsibilities of the three range metafunctions.
This is a potentially breaking change. Consider a range adaptor...
template<typename Range> struct some_adaptor { typedef typename range_iterator<Range>::type iterator; typedef typename range_const_iterator<Range>::type const_iterator; .... };
In this case, you really don't care about the const-ness of Range -- you just want the nested ::iterator type. And anyplace someone is using these metafunctions to perform type computations where const-ness doesn't matter will now be broken.
In the new version, this is how range_iterator is defined: namespace boost { template< typename C > struct range_iterator { typedef BOOST_RANGE_DEDUCED_TYPENAME mpl::if_< BOOST_DEDUCED_TYPENAME is_const<C>::type, BOOST_DEDUCED_TYPENAME range_const_iterator< BOOST_DEDUCED_TYPENAME remove_const<C>::type
::type, BOOST_DEDUCED_TYPENAME range_mutable_iterator<C>::type >:: type type; };
} // namespace boost -Thorsten