On Jul 7, 2004, at 1:45 PM, Peter Dimov wrote:
My proposal (I'm not sure whether I should be credited for it; Howard posted locks that had these properties and I merely commented) can be made to break such code at compile time, simply by removing the nested TryMutex::scoped_try_lock typedef (as there is no longer a need for it, because ::scoped_lock is a TryLock or TimedLock, as appropriate).
Interesting... I hadn't thought about doing that. But I think I see where you're headed. A lock is just a lock, those parts of it you need, you instantiate and use. Those parts you don't, you ignore and they don't hurt anything (unless you try to explicitly instantiate your lock). If you try to use something the templated mutex doesn't support, you get a compile time error. Giving that some more thought... My intention with the read/write lock stuff was simply that these guys needed to at least support try locks. That is needed so that you can do assign-like locking between two objects: { lock_both<write_lock, read_lock> l(a.mut(), b.mut()); a = b; } Without try locks, lock_both can't be made to work without risking deadlock. -Howard