On Mar 26, 2007, at 2:04 PM, Peter Dimov wrote:
Howard Hinnant wrote:
Fair point. Perhaps we should go back to a more fundamental question:
std::thread t(f); ... t.cancel(); // Logically is this a const or non-const operation on the thread executing t/f?
I prefer to first ask "does it matter"? If you can't observe the cancelation state of t and if you are assured that t.cancel is valid no matter what else is going on with t, what difference does a const/non-const label make to the external observer?
(Internally there is a flag being set, of course.)
I believe it matters because other threads can detect whether the child thread has been canceled or not. Canceled may be a valid state. But it is a different and detectable state.
Perhaps shared_ptr/weak_ptr is a good analogy. I can have shared_ptr<int const>, and if this is the last reference to expire it'll delete the int (despite that mutable operations on the int are disallowed.) I can also have a weak_ptr<int const> to the same object, and I can detect the fact that it has been destroyed. Yet the object has no "destroyed" state. Emil Dotchevski