Joel <joel@boost-consulting.com> writes:
Joel wrote:
Brian Braatz wrote:
Could it be as simple as missing the namespace on the is_sqeuence<> call? Have you tried it? If it was, I wouldn't have bothered the list ;-) Try replacing int_<0> with int.
I think the problem is the way mpl::is_sequence is implemented. It tries to detect the presence of a "tag" typedef and a "begin" typedef and concludes that a type is an mpl::sequence if it has both. I've complained a long time ago about this. I think this behavior is error prone. It's quite easy to come up with a situation where I have a type T with a "tag" and a "begin" but is not an MPL sequence. There must be a better way. MPL should not monopolize on the usage of "tag" and a "begin" in a type.
I never liked is_sequence in the first place. 1. Anything that makes structural checks is prone to masquerades like the one you cite. 2. Whenever you check if something is a sequence and do something different based on that fact, genericity is broken. We went through this discussion with boost::variant. Are you sure you want to be using even a perfect implementation of is_sequence? -- Dave Abrahams Boost Consulting www.boost-consulting.com