Re: [boost] [type_erasure] Downcasting is now possible

AMDG On 03/10/2015 11:24 AM, Mathias Gaunard wrote:

How about something like this:

any a; duck_visit(f, a);

with 'f' a polymorphic function object constrained with SFINAE.

This isn't quite going to work be itself. SFINAE doesn't actually matter as there's no way to make duck_visit work without calling register_() somewhere in the program (assuming that 'a' holds an int and F is the type of f).

if f(a) is callable for the dynamic type of a, then call it, otherwise raise an exception.

It's a start. Of course, there's no reason to limit it to one argument: any a, b, c; duck_visit(f, a, b, c); As a matter of fact, I already have a function named call which looks a lot like this, except that it dispatches using the arguments' vtables. The only real difficulty is how to integrate it into my existing framework. In Boost.TypeErasure, any is a class template. Handling the arguments isn't a problem, but what is the return type of duck_visit? In Christ, Steven Watanabe