Re: StateFull vs Stateless Singleton

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Mon, 5 Jul 2010 10:50:07 -0700 (PDT)
Message-ID:
<ade23776-548e-4e13-a30a-6f8f22d4db32@s9g2000yqd.googlegroups.com>
On Jul 5, 6:20 pm, =D6=F6 Tiib <oot...@hot.ee> wrote:

On 5 juuli, 19:57, James Kanze <james.ka...@gmail.com> wrote:

In the end, the only real arguments against singletons are that
1) they are often abused (but then, so are a lot of other
things), and 2) the usual syntax is excessively verbose (but
that's easy to fix---just use a lighter syntax).


Yes, exactly. Nothing suggests to use:

 SingletonFactory::instance().giveCordStringTyer().tie( cordString );

Use good syntax:

 tie( cordString );


You reduce coupling somewhat by grouping functions in classes.
(If nothing else, they don't invade global namespace.) Still,
something like:
    CommandLine::parse(argc, argv);
is still a lot less verbose than:
    CommandLine::instance().parse(argc, argv);

I've recently remodeled most of my singletons to use this
syntax. In some cases, there may be a more classical singleton
behind the scenes (in order to resolve order of initialization
issues, for example), but there's no point in burdening the
client code with such details.

I haven't worked out a way to do this with templates, and
I don't think I'm going to bother. While I don't have the
horror of singletons that some do, there's not something that
I use frequently enough to justify developing a complex template
for them.

--
James Kanze

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