PointerTarget

import automem.unique: Unique;
import automem.ref_counted: RefCounted;

static struct Point {
    int x;
    int y;
}

auto u = Unique!Point(2, 3);
static assert(is(Point == PointerTarget!(typeof(u))));

auto s = RefCounted!Point(2, 3);
static assert(is(Point == PointerTarget!(typeof(s))));

	import std.math : approxEqual;
    import automem.unique: Unique;
    import automem.ref_counted: RefCounted;

    static struct Point {
        int x;
        int y;
    }

    static double distance(T, U)(auto ref T p1, auto ref U p2)
        if (is(PointerTarget!T == Point) && 
            is(PointerTarget!U == Point))
    {
        import std.conv : to;
        import std.math : sqrt, pow;
        return((pow(p1.x - p2.x, 2) + pow(p1.y - p2.y, 2)).to!double.sqrt);
    }

    int x1 = 2;
    int y1 = 3;
    int x2 = x1 + 3;
    int y2 = y1 + 4;

    auto u_p1 = Unique!Point(x1, y1);
    auto u_p2 = Unique!Point(x2, y2);
    assert(approxEqual(distance(u_p1, u_p2), 5.0));

    auto rc_p1 = RefCounted!Point(x1, y1);
    auto rc_p2 = RefCounted!Point(x2, y2);
    assert(approxEqual(distance(rc_p1, rc_p2), 5.0));

    assert(approxEqual(distance(u_p1, rc_p2), 5.0));
    assert(approxEqual(distance(rc_p1, u_p2), 5.0));