Revamped concurrency API

[Sean Kelly]

Michel Fortin Wrote:

> On 2009-10-13 11:39:21 -0400, Sean Kelly <sean at invisibleduck.org> said:
> 
> > I disagree about poor performance though.  With unique references or 
> > move semantics, a copy of even complex data isn't necessary to ensure 
> > that a message is passed safely.
> 
> Yeah, but for unique reference to be usable you need lent semantics, 
> otherwise you can't make sure you're the unique holder once you call a 
> function to do something with your unique object.
> 
> Anything that use the reference could be storing it elsewhere:
> 
> 	unique!Object o = new Object;
> 	o.doSomething();
> 
> How in the example above can I enforce that doSomething() won't escape 
> the 'o' reference elsewhere? 'doSomething' could be made 'pure', but 
> that trick will only work for one-argument functions (in the case 
> above, the argument is the implicit 'this') because otherwise a pure 
> function could leak the reference through another argument.

I honestly don't know how to enforce this-- I simply mentioned it because people have suggested it.  Phobos already has assumeUnique() for converting to invariant, which is one option.  I was hoping someone could suggest alternatives.