Re: [boost] [singleton] Design questions

From: Peter Dimov (pdimov_at_[hidden])
Date: 2008-01-18 14:58:42

Tobias Schwinger:

> Peter Dimov wrote:
>> What is the reason to prefer the current instance/lease formulation 
>> instead
>> of
>>
>>     typedef ... instance_type;
>>     instance_type instance(); // automatically serves as a lease
>>
>> ?
>
> As we can't expose the instance when automatic locking is done, it is
> supposed to provide a means to not have to access the instance directly.

I'm not sure what this reformulation cannot do that the original can. An 
ordinary singleton can define instance_type as T*. A synchronized singleton 
can define instance_type as the moral equivalent of shared_ptr<T> (with a 
hidden unlocking deleter). What am I missing?