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Well, as you point out, try_lock is like a timed_lock with time = 0, and lock is like a timed_lock with time = infinity, so why not give timed_lock both lock() and try_lock() methods as shorthand notation for lock(m, t=0) and lock(m, t=infinity)?

[Batov, Vladimir] Because, in my view, it violates the fundamental (and I think widely accepted) OO design principle (guideline?) that in simple terms can be expressed as "one class, one responsibility". Names like Bertrand Meyer, Herb Sutter and many others immediately come to mind.

We can either achieve that by having a universal lock (with timed_lock as the basis) and shorthand notations in separate derived classes (lock, timed_lock and try_lock) or by keeping those three completely unrelated (probably at the expense of some code/functionality duplication). I am personally leaning towards latter, as even though technically all

I am thinking maybe technically it would be much easier and cleaner to implement one basic_lock (modeled on the current timed_lock) and then provide specializations (you see, I am avoiding "refinement" :-) ) of it to the user like: try_lock : public basic_lock { ... try_lock(mutex& m) : basic_lock(m, 0) {} } Then, 1. underlying implementation would be much simpler and without duplication as it'd always operate with basic_lock (good for maintainers/implementers); 2. average users would still have friendly and simple interface; 3. advanced users might do much more tricky stuff by simply cutting to the bone and using basic_lock. Just a thought. -----Original Message----- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Batov, Vladimir Sent: Friday, 2 July 2004 7:25 AM To: boost@lists.boost.org Subject: [boost] Re: Boost.Threads: Do we need all those mutexes? According to the current Boost.Threads documentation timed_wait() does not require timed_lock (cut and pasted from http://www.boost.org/libs/thread/doc/condition.html#class-condition): template <typename ScopedLock> bool timed_wait(ScopedLock& lock, const xtime& XT); Looking at the code it does appear to require timed_lock either: template <typename L> bool timed_wait(L& lock, const xtime& xt) { if (!lock) throw lock_error(); return do_timed_wait(lock.m_mutex, xt); } What am I missing? BTW. How can I get to have look at the development branch? I went to http://cvs.sourceforge.net/viewcvs.py/boost/boost/development/ but found nothing threads-related. Thanks, V. -----Original Message----- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Michael Glassford Sent: Friday, 2 July 2004 4:35 AM To: boost@lists.boost.org Subject: [boost] Re: Boost.Threads: Do we need all those mutexes? Batov, Vladimir wrote: three

concepts are related, from the user point of view they are distinct.

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The argument for try_lock not having a blocking lock() method, which you seem to stress more often, is much clearer; I'm much more inclined to agree with you there.

[Batov, Vladimir] Thank you. I feel that it is important that every class does what it promises to do. No more, no less.

For what it's worth, heres a use case I just ran across illustrating why timed_lock should have a blocking lock() method and/or a blocking locked constructor: condition c; void f(mutex m) { mutex::scoped_timed_lock l(m, locked); //always want the lock here for(;;) { //do stuff c.timed_wait(l, next_wakeup_time()); //timed_wait requires a timed_lock } } Mike _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost