on Fri Mar 13 2009, Roman Perepelitsa wrote:

I need a metafunction that returns true iif a type has a constructor with 2 arguments of a given type. Does mpl have it? If not, is it possible to implement?

template struct is_constructible_from;

struct foo { foo(int, int); }; struct bar { bar(int*, int); }; struct baz {};

int main() { assert(is_constructible_from::value); assert(is_constructible_from::value); assert(!is_constructible_from::value); assert(!is_constructible_from::value); };

I know of no way to do that. -- Dave Abrahams BoostPro Computing http://www.boostpro.com

Roman Perepelitsa wrote:

I need a metafunction that returns true iif a type has a constructor with 2 arguments of a given type. Does mpl have it? If not, is it possible to implement?

As has been explained it's impossible. However, if you change the construction syntax of your objects you could do it. If you made the constructors private or protected and provided a static function for building them you'd have something that can be tested with metaprogramming. Not saying this will help you, but it's an idea.