Hello,

I would like to transliterate the following code, below, to D, but it seems to be more difficult than I expected.

I cannot find a keyword, like __COUNTER__, that would enable the construction of unique types each time UQ is used. Even if such a keyword did exist, I cannot find a way wrap it such that I can have statements like "auto c0 = UQ(3);".

Any suggestions would be appreciated.

(This question is related to https://forum.dlang.org/thread/gqzlchurxylkvwiirrxb@forum.dlang.org)


template<std::size_t ID, typename T>
struct Unique { T value; };

// Would prefer something like "__CPU_CLOCK_TICKS__"
// instead of __COUNTER__, if it were available
#define UQ(v) Unique<__COUNTER__, decltype(v)>{v}

int main()
{
  auto c0 = UQ(3);
  auto c1 = UQ(4);
  static_assert(!std::is_same<decltype(c0), decltype(c1)>::value);
}

(at: https://godbolt.org/z/O7lt5f)

On Friday, 30 November 2018 at 15:27:07 UTC, Dominic Jones wrote:
> Hello,
>
> I would like to transliterate the following code, below, to D, but it seems to be more difficult than I expected.
>
> I cannot find a keyword, like __COUNTER__, that would enable the construction of unique types each time UQ is used. Even if such a keyword did exist, I cannot find a way wrap it such that I can have statements like "auto c0 = UQ(3);".

You can use __FILE__ and __LINE__. The only limitation there is, obviously, one declaration per line.

struct Unique(T, string file, size_t line) {
    T value;
}

auto UQ(T, string file = __FILE__, size_t line = __LINE__)(auto ref T value) {
    return Unique!(T, file, line)(value);
}

void main() {
    auto c0 = UQ(3);
    auto c1 = UQ(4);
    static assert(!is(typeof(c0) == typeof(c1)));
}