Andrew Sutton <andrew.n.sut...@gmail.com> writes: | I presented that at C++Now, so I hope so :) It lets me write: | | template<typename T> | requires Input_iterator<T> // no parens! | void f(T x); | | Walter Brown also suggested this usage in his object alias paper. | | In concepts lite, a concept is essentially an expression. Thus far, | we've packaged those expressions in constexpr functions (using | "concept" as a declaration specifier to impose additional | restrictions). Variable templates fall easily into this same set of | restrictions. Plus, no overloading.
In this scenario, Input_iterator<T> (my prefered syntax!) is a constant expression (or will be a constant expression.) The real question is whether we need yet another way of declaring a constexpr variable template. I have not made up my mind on that, but I am leaning towards "no". So, we do need a comment in the code about this flag. -- Gaby
