Aleksey Gurtovoy writes:
Alexander Nasonov writes:
Good news, I can use mpl:find_if even though typeof isn't available!
This is how I do it:
1. define overload_set_iter class template that takes an overload set and an iterator for current position. (If it was ever possible, deref could return a signature of an overload the iterator refers to).
What if you define a "signature" as an (overload set, index) pair, declare it as a standard way to pass things around (within your library, that is), and make 'overload_set_iter' return that on dereference? Any reason why the approach you outline below is preferable?
Oh, I see it now: specializing 'iter_apply1' allows for intuitively obvious find_if< overloads, is_same<bool(int),_1> > while my suggestion would require something like find_if< overloads , overload_match< _1, is_same<bool(int),_1> > > That's indeed quite appealing. However, specializing 'iter_apply1' this way assumes that it's always invoked on a predicate metafunction, which, at least theoretically, does not hold. On the other hand, with 'typeof', dereferencing 'overload_set_iter' would simply return a corresponding function type and things would "just work" without any special effort on our side, and in that light 'iter_apply1' specialization for the compilers that need it is simply an implementation detail which I'm willing to close my eyes to ;). It's going to be interesting to see how many MPL algorithms can be made to work with overload sequences using this approach. -- Aleksey Gurtovoy MetaCommunications Engineering