Linked variables

[via Digitalmars-d-learn]

Does the standard library have a way to create a forward link 
between two variables of the same type?
One variable is the source and the other is the sink.
When the source variable is changed, the sink variable is too.
Changing the sink variable has no effect on the source variable.

I have already implemented it using std.signals and class 
templates(https://github.com/TheBlu/lockd/blob/master/source/engine.d), but is there a better way, either in the standard library or a third party library?