From: Michael Glassford (glassfordm_at_[hidden])
Date: 2004-07-07 23:23:35
Eric Niebler wrote:
> Peter Dimov wrote:
>
>> compare:
>>
>> TryLock l( m, unlocked );
>>
>> if( l.try_lock() )
>> {
>> }
>>
>> with:
>>
>> TryLock l( m, non_blocking );
>>
>> if( l.locked() )
>> {
>> }
>>
>
> (Jumping late, forgive me if this has been discussed already.)
>
> How about:
>
> if( ScopedLock l = try_lock( m ) )
> {
> }
>
> where try_lock is function that returns a simple wrapper class:
>
> template< Mutex > struct try_locker
> {
> Mutex & m;
> ...
> };
>
> template< Mutex > try_locker< Mutex > try_lock( Mutex & m )
> {
> return try_locker< Mutex >( m );
> };
>
> and ScopedLock is some lockable type which has a constructor that
> accepts a try_locker. (It would also need a bool-ish conversion to allow
> the lock to be declared in the "if" statement, but that's not relevant
> to this discussion.)
Interesting idea. I suppose you could even do this:
if (ScopedLock l(m, locker()))
{
}
where locker() is a function object that defines
operator()(LockType& l)
which the lock calls in the constructor, passing *this. You could have
locker(), try_locker(), timed_locker(t), etc.
Mike