why can't I call const methods on shared objects?

[Vlad Levenfeld via Digitalmars-d-learn]

@FreeSlave & John Colvin

Yes, I see your point. I could still get tearing on a read. So, 
in the case of methods that I believe are safe (e.g. 1-line 
@property getters) I'll just write a shared variadic function 
template that uses (cast()this).foo(args) to forward to the 
non-shared method... and in less-safe cases, I can just add some 
synchronization code to the shared version.
Or maybe its safer to do it the other way around, i.e. 
(cast(shared)this) and forward from non-shared to shared? There's 
not yet any established best practices for this, are there?