Re: [boost] [patch] first_iterator, second_iterator?

Sure, it can be implemented via transform_iterator too. And it is a trivial application. But it serves two purposes:

1) provides commonly-needed functionality with only a little additional code

Once a functor for selecting an elem of std::pair is available, wouldn't it also require little additional code to automate the creation of the associated transform_iterator? I illustrated this for fusion::map here: https://svn.boost.org/svn/boost/sandbox/statistics/detail/fusion/boost/stati... One small issue pertains to my post 10/5/09 11:01PM in the user's mailing list. In the same list I think I've already seen some posts about functors for std::pair and boost::tuple. HTH