Re: [boost] Re: Re: Singleton

From: Jason Hise (chaos_at_[hidden])
Date: 2005-01-11 23:59:28

Pavel Vozenilek wrote:

>Maybe it could have threading policy, defaulting  to the
>same mechanism shared_ptr uses, other options being
>no-locking and user-locking.
>
To mirror another message I sent regarding aligned_storage, I like the 
idea of making this library a part of boost, but I don't like the idea 
of having countless dependencies upon boost.  Because a singleton 
doesn't do any multi threading itself, it shouldn't rely on a full 
fledged threading library at all.  The only thing really necessary is to 
make the singleton library thread safe when used in the context of 
multiple threads.  I would think this would be as simple as passing in a 
class which can be used as a mutex, locking upon creation and unlocking 
upon destruction.  If there are further safety issues of which I am 
unaware, I think it does make sense to provide *the interface* for them 
in a single-threaded safety policy (leaving empty definitions).  Any 
commonly used thread safety policies that require a specific major 
threading library (like boost's) could be provided in a separate 
header.  The main thing that I would like to know is what this thread 
safety *interface* should look like, if it should provide any features 
other than locking, and/or how specifically it should be used within the 
singleton itself (aka what operations need to be locked).

-Jason