David Abrahams wrote:
on Mon Apr 28 2008, "Marco Costalba" <mcostalba-AT-gmail.com> wrote:
On Mon, Apr 28, 2008 at 6:48 PM, Steven Watanabe <watanabesj@gmail.com> wrote:
There's a page in the proto documentation that describes a solution.
If the page you refer to is: "Detecting the Arity of Function Objects"
under the link:
http://boost-sandbox.sourceforge.net/libs/proto/doc/html/boost_proto/appendi...
Then I have to say: WOW !!!!!! this is metaprogramming virtuosism to the highest level.
Isn't there the issue that passing non-PODs through ... is undefined behavior (note that the standard doesn't say you have to execute the code to cause the undefined behavior, and GCC will warn about it IIRC)? I avoided it for that reason in boost/detail/is_incrementable.hpp.
If it's in a non-evaluated context (e.g., sizeof expressions), GCC doesn't issue a warning. I think C++03 is silent on this matter, and I remember some discussion of the issue for C++0x, the result of which was that doing this in non-evaluated contexts was OK, but I could be misremembering. -- Eric Niebler Boost Consulting www.boost-consulting.com