[boost] Boost.Any and duck typing [was: 'Nother BoostBon Trip Report]

From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2007-07-22 09:44:36

Eric Niebler wrote:
> This one by Greg Colvin. (BoostCon had two tracks. So why not two trip 
> reports?) Enjoy! http://www.artima.com/cppsource

By following that link, I got on your own report.

I was surprised to see you considered boost.any to be a form of duck typing.
To me, it's not duck typing at all.

Duck typing would allow us to do stuff like this:

any a = string("hello world");
any b = a.substr(0, 5);
a = 4;
any c = a.substr(0, 5); // throws an exception, a has no member function 
'substr' with that signature.

boost.any does not allow that kind of thing at all.
boost.variant is a bit closer, but apart from the fact it is limited to 
a set of types it can neither do it because it would require some kind 
of compile-time reflection.