Re: RFC 178 (v1) Lightweight Threads

> There is a fundemental issue on how values are passed between
> threads. Does the value leave one thread and enter the other or are
> they shared.

> The idea tossed around -internals was that a value that crosses a thread
> boundary would have a wrapper/proxy attached to handle the mediation.

> The mediation would be activated only if the value is passed via a
> shared variable. In your case the shared variable is the argument
> being passed through the thread creation call.
[...]
> If we don't require a :shared on variable anything and everything
> has to have protection. If you want the variable to be shared
> declare it.
[...]
> Aha, I get it. -internals has been assuming that one _must_ specify
> the sharing. You want it to be infered.

> I think that's asking for too much DWIMery.


Question: Can the interpreter determine when a variable becomes
shared?

Answer: No. Then neglecting to put a :shared attribute on a shared
variable will crash the interpreter. This doesn't seem very Perlish.

Answer: Yes. Then the interpreter can take the opportunity to install
a mutex on the variable.


- SWM