Re: [boost] Re: Boost.Threads: Do we need all those mutexes?

From: Doug Gregor (dgregor_at_[hidden])
Date: 2004-06-29 08:15:07

On Tuesday 29 June 2004 8:00 am, Christopher Currie wrote:
> > The basic usages (covering about 80%) are:
> >
> > scoped_lock l(m); // Block until it locks.
> > scoped_try_lock l(m); // Try (!) to lock. I'll check the result.
>
> I disagree here, as well. Say I want to program generically...
>
> template <typename Mutex, typename Lock>
> class worker_class
> {
>    Mutex m_;
>
> public:
>    do_work()
>    {
>       Lock l(m_); // Does this call block?
>       // am I guarenteed to be locked here?
>    }
> }
>
> Yes, it's a contrived case,

I don't believe it is a contrived case. Certainly once we have read/write 
mutexes we're going to want to tell generic components which kind of lock 
they need to use.

> but the point is that all locks should have
> the same behavior in the 1-argument constructor case, and that is to
> block until this lock is obtained. The is the only way the user can use
> the lock in a generic way.

Absolutely. This is *extremely* important to keep in mind when discussing any 
kind of concept taxonomy. Refinements of a concept can only add restrictions, 
they cannot remove them.

        Doug