On Sun, Oct 17, 2010 at 10:25 PM, David Abrahams <dave@boostpro.com> wrote:
But then, how would you return something that happens to have a nested ::type? Wrap it in identity?
Yes. Not that this would necessarily be a good idea, just throwing it out there. Ultimately I think it'd be best to leave it as result_type and lazy_result_type (or possibly explicit and lazy_explicit) to avoid such subtleties.
Can't you just detect whether "return" was used, and if not, sythesize the "end" internally?
No. The problem is that end is what closes off the return type (it closes off a decltype). With each ( requires stuff_here ) or similar, it adds more to the return type and then the last thing it does is specify the name of a macro. The next ( arguments_here ) applies that macro and does the same thing. At a return, everything is closed off and a definition is provided, which is why you don't need an end there, but you can't do that otherwise since it's possible that more arguments will be passed. The macro can't know in advance the next thing the user will pass -- it could be a semicolon, or it could be a return, or it could be a requires, or something else. -- -Matt Calabrese