Kevin Sopp wrote:
Given a type T which is a model of MPL lambda expression, permute<T,
Args1,
..., ArgsN>::type is an MPL vector that contains all possible permutations of type T, where ArgsN is a model of an MPL forward sequence.
Example: template<class X, class Y> struct base{};
permute< base<_1,_2>, vector<int, float>, vector<double, bool>
::type types;
types is an MPL vector containing all possible permutations of base with the supplied argument lists: vector< base<int,double>, base<int,bool>, base<float,double>, base<float,bool>
(not necessarily in this order)
I'm sorry I'm not an MPL expert so I can't give you feedback about the usefulness of this class. It looks interesting though. What I would like to say is that you should choose a name different from "permute" because it is misleading. From the wikipedia: "The concept of a permutation expresses the idea that distinguishable objects may be arranged in various different orders." In other words "permute" conveys the concept that you already have a list of types and you provide a different re-ordering of such list (compare with std::next_permutation, std::last_permutation). In your case you are synthesizing a list of types based on a sort of "template" type and a set of sets of parameters. Moreover you say that the synthesized list has no particular order. This looks a very different operation to me. Just my opinion, Ganesh