On Wednesday, 10 May 2017 at 17:12:11 UTC, Carl Sturtivant wrote:
Here's the beginning of an interesting little experiment to simulate reference variables using `alias this` to disguise a pointer as a reference. Could add a destructor to set the pointer to null when a reference goes out of scope.
Here's a better version. Improvements? This can still behave as badly as a pointer, e.g. if returned from a function.
``` struct reference(T) { T* ptr; this(ref T x) { ptr = &x; } ~this() { ptr = null; } import std.exception : enforce; ref T cnvrt() @property { enforce( ptr !is null); return *ptr; } ref T cnvrt(T x) @property { enforce( ptr !is null); return *ptr = x; } ref reference!T opAssign(T t) { enforce( ptr !is null); *ptr = t; return this; } ref reference!T opAssign(ref reference!T r) { enforce( ptr !is null && r.ptr !is null); *ptr = *r.ptr; return this; } alias cnvrt this; } void main() { int i; auto ri = reference!int(i); auto ri2 = reference!int(ri); assert(ri.ptr==ri2.ptr); i = 99; assert(i==ri && i==ri2 && ri==ri2); ri = 100; assert(i==ri && i==ri2 && ri==ri2); ri2 = 101; assert(i==ri && i==ri2 && ri==ri2); int j = -1; auto rj = reference!int(j); ri = rj; assert(ri==rj); assert(ri.ptr!=rj.ptr); } ```