refwrapper.d

struct Ref(T)
{
    T* ptr;

    ref inout(T) deref() inout
    {
        return *ptr;
    }
    alias deref this;
}

Ref!T byRef(T)(return ref T lvalue)
{
    return Ref!T(&lvalue);
}

auto forward(T)(return auto ref T value)
{
    static if (__traits(isRef, value))
        return value.byRef;
    else
        return value;
}

// Can't escape a reference to a local
unittest
{
    assert(!__traits(compiles, {
        int n = 123;
        return n.byRef;
    }));
}

// Can modify through a reference
unittest
{
    static void modify(Ref!int r)
    {
        r++;
    }

    int n = 123;
    modify(n.byRef);
    assert(n == 124);
}