On 10/6/05, David Abrahams <dave@boost-consulting.com> wrote:
Geoffrey Romer <geoff.romer@gmail.com> writes:
If so, doesn't that mean Cromwell's fix is incorrect?
I'm afraid I've not seen his fix.
I'm also afraid I don't have time to look at it right now.
Fair enough. It's sort of a side issue anyway.
What I don't understand is when I should be saying "typename metafunc<args>::type" and when I should be using plain "metafunc<args>". This isn't a language-correctness issue, it's an MPL usage issue.
Oh. Maybe mapping into the runtime world will help. If you think of metafunc as a regular function, then "metafunc<args...>::type" is equivalent to a regular function call, and "metafunc<args...>" is equivalent to boost::bind(func, args...)
These are exact analogies, AFAICT.
OK, that's what I thought, but it seems not to apply to lambda-expressions. If I want to call foo<> on a placeholder, I seem to be required to write foo<_1>, and not typename foo<_1>::type, even though I want foo<> to actually be applied to the placeholder (after substitution). What am I missing?