[boost] Re: Moveable locks

From: Michael Glassford (glassfordm_at_[hidden])
Date: 2004-07-16 13:24:50

Christopher Currie wrote:

> Michael Glassford wrote:
> 
>> I believe there was (nearly?) consensus that we want to make locks 
>> movable at some point. My conclusion was that at that point this 
>> syntax becomes possible, too. I think Peter said or implied much the 
>> same thing, maybe before I did.
> 
> 
> I'm just going to be the voice of dissent here, again, and argue that 
> the scoped_locks, at least, should not be moveable, otherwise they're 
> not very scoped. The scoped lock serves a specific purpose in ensuring 
> that the mutex doesn't remain locked outside of block scope, just like 
> scoped_ptr ensures that a heap object has a specific lifetime.
> 
> If there's enough hew and cry for a movable lock, then we should create 
> a new class for it. That said, most of the arguments I could find on the 
> list archive for it are to support syntax changes in initializing a 
> scoped lock.

Did you see http://aspn.activestate.com/ASPN/Mail/Message/boost/1207226, 
and especially http://aspn.activestate.com/ASPN/Mail/Message/1209126?

 > I also saw an argument for storing locks in containers,
> which I can't quite fathom the need for, but I welcome the use cases.
> 
> As a compromise, we could create lock_transfer<> objects that wouldn't 
> lock a mutex, but would allow initialization syntax in places where the 
> language makes it difficult (this is just a quick sketch, there may be 
> errors):

[snip code example]

Mike