[boost] Re: Lock unification [move]

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2004-07-22 14:01:47

On Jul 22, 2004, at 1:16 PM, Eric Niebler wrote:

> Please no. The scoped_lock keeps track of whether it has locked the 
> mutext or not, so it kows whether or not to unlock the mutex in its 
> destructor. If you make the mutex interface public AND expose the 
> mutex of the lock, you break encapsulation:
>
> mutext m;
>
> {
>   scoped_lock l( m ); // locked
>   l.mutext()->unlock(); // unlocked
> } // unlocked again by l's destructor!

I just knew I was getting too much in the mood of:  Here's the rope, 
don't hang yourself! :-)

> It is for precisely this reason that I think you shouldn't be able to 
> get a pointer to the mutex from the scoped_lock. You should get back a 
> token or a void* that is useful only for comparison purposes.

I'll let you and Peter hammer that one out.  I could be happy with 
whatever you guys decide.

-Howard