[boost] Tick: Trait instrospection library for C++14

Subject: [boost] Tick: Trait instrospection library for C++14
From: paul Fultz (pfultz2_at_[hidden])
Date: 2014-05-22 12:23:22

Hi,

I developed a trait introspection library for C++14 based on Eric Niebler's
concept checking, here:

https://github.com/pfultz2/Tick

So you can build a simple `is_incrementable` trait like this:

    TICK_TRAIT(is_incrementable)
    {
        template<class T>
        auto requires(T&& x) -> TICK_VALID(
            x++,
            ++x
        );
    };

Then use it like this:

    static_assert(is_incrementable<T>(), "Not incrementable");

Also, you can validate the return of an expressions like this:

    TICK_TRAIT(is_equality_comparable)
    {
        template<class T, class U>
        auto requires(T&& x, U&& y) -> TICK_VALID(
            returns<bool>(x == y),
            returns<bool>(x != y)
        );
    };

You can also match against another trait using placeholder expressions:

    TICK_TRAIT(is_incrementable)
    {
        template<class T>
        auto requires(T&& x) -> TICK_VALID(
            return<std::is_integral<_>>(x++),
            return<std::is_integral<_>>(++x)
        );
    };

Any feedback would be appreciated. Also, I don't knw if there would be any
interest in incorporating this into boost.

Thanks,
Paul