On Mar 26, 2007, at 3:04 PM, Peter Dimov wrote:
I don't know if you remember it, but a while ago I tried to convince you that an N2178 handle is conceptually a lower level primitive than an N2184 thread.
Yeah, it was burned into my brain. :-) Just kidding around, really! :-)
This is extremely hard to sell to someone who has the implementations of both before his eyes and can plainly see that implementation-wise, N2184::thread is closer to pthread_t than N2178::handle.
But if you consider both on an abstract level, it's easier to accept. An N2184 thread can be built on top of an N2178::handle by just wrapping it and disabling copyability. And an N2178::handle is obviously more powerful and more unsafe, as opposed to N2184::thread which is simplified and safer.
This just leaves me with the feeling of implementing unique_ptr in terms of shared_ptr, at least on a pthreads platform. I understand that on a Windows platform one can get the opposite feeling. When it comes right down to it, we have two valid and reasonable OS threading models before us: 1. pthreads 2. Windows Which one do we model with std::thread (or std::thread::handle)? N2184 chose pthreads and N2178 chose Windows (to be fair, N2178 chose Windows with some pthreads mixed in). -Howard