Stefan Seefeld <seefeld@sympatico.ca> writes:
I was looking for alternative ways to phrase the "Effects" (in particular to express the "joinable" concept, but ran into some issues:
* There doesn't appear to be any means to query a thread object's state.
A thread is either joinable() or not.
* I can (apparently) invalidate an existing thread object by detaching it.
Yes. Then the object ceases to refer to a thread, and thus joinable() returns false.
* I can construct a thread that doesn't refer to anything (default constructor).
Yes.
Of course there is 'joinable', but that doesn't let me distinguish between a default-constructed ("not-a-")thread, a detached thread, and a thread that has already been joined.
No, it doesn't. From the point of view of the thread object they are all the same: this thread object does not represent a thread, and therefore is not joinable(). In all three cases the thread::get_id() member function will return a default-constructed (not-a-thread) ID. Anthony -- Anthony Williams | Just Software Solutions Ltd Custom Software Development | http://www.justsoftwaresolutions.co.uk Registered in England, Company Number 5478976. Registered Office: 15 Carrallack Mews, St Just, Cornwall, TR19 7UL