"Brian Braatz" <brianb@rmtg.com> writes:
I am looking for a way to basically do this:
typedef vector<int,float,float,char,int,int,int,double> types; typedef vector<int,float,char, double> expected; typedef unique_all< types, is_same<_1,_2> >::type result;
BOOST_MPL_ASSERT(( equal< result,expected > ));
(note the examples I am using use integral types, in my situation I
am
not using integral types)
[David Abrahams Writes:]
If you don't need to preserve order, just stick them in an mpl::set<>. In fact, you might be able to use a set<> to begin with and just skip the vector<>.
Otherwise, I would write a little algorithm based on the implementation of remove_if (which you can find nicely described in the online reference manual). Instead of passing along a predicate at each stage of the fold<>, pass along a set<> that accumulates the elements you've already seen. When the next element is already in the set<>, skip it.
Try working that out for yourself; it'll be good for you ;-) If you get stuck, ask again!
[Brian Braatz Writes:] :) Thank you for the advice. There is a common mental pattern that occurs: "Hmm.. there SHOULD be a SIMPLE way to do X." (flip through MPL book, MPL ref manual, google boost archives, write sample code) "Hmm.. Ok I can see there maybe a way to do this COMPLETELY from scratch, but I am not totally certain I need to do that. I need to keep looking. There probably is a clever one liner to solve the problem".... Your advice was EXACLY what I needed. (i..e how to THINK about the solution) THANK YOU :) Brian