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Subject: Re: [boost] [Boost.utility]
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2010-01-26 16:05:30

GMan wrote:
> Take your best singleton class, but remove the bit where it
> intrudes and forces only a single instantiation. Call this
> "global", which provides the same thing as a singleton but
> allows other instantiations of the class.

OK, so it implicitly instantiates the object on first access, but the instance must be visible to any code interested in using it, right?

> My argument was that this class is more worth boost's time
> than the singleton class. The reason being, users of global
> could always re-introduce the single-instantiation behavior,
> but don't have to. This provides more flexibility.

Making a Singleton from a "global" implies somehow enforcing a single instance. Without help from the library, mistakes will happen. Indeed, if a UDT can be adorned in such a way as to prevent its use with anything but the Singleton library, user mistakes can be prevented by design.

I'd argue that one is a policy away from the other and that both are useful.

Rob Stewart robert.stewart_at_[hidden]
Software Engineer, Core Software using std::disclaimer;
Susquehanna International Group, LLP

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