[RFC][plugin]: make PluginObjectStore a singleton.

[Dr Andrew John Hughes]

On 15:32 Thu 31 Mar     , Deepak Bhole wrote:
> * Denis Lila <dlila at redhat.com> [2011-03-31 15:29]:
> > 
> > > I particularly like this comment ;) Do you have a source for this? I
> > > would prefer it if this was an actual class. It's not behaviourally an
> > > enum, so it should not be marked as such.
> > 
> > Effective Java, second edition.
> > I don't have the book with me, and I forget what Joshua Bloch's
> > arguments for enum singletons were (except for how much easier
> > the singleton property is to enfoce (which is more than enough
> > of a reason by itself, but there were others)), but they were
> > very good ones.
> > 
> 
> I've read this before too. The top things if I recall correctly are that
> an enum cannot be constructed, not even via reflection and it is 
> implicitly final.
> 

Being at home, I do have my copy with me and it says (in bold type):

'a single-element enum type is the best way to implement a singleton'.

What Deepak says is true, and there are also benefits for serialization too.

It initially seemed odd to me too, but I'm fine with it.  I would cite
the reference, which is:

Bloch, Joshua.  Effective Java, 2nd Edition.  Item 3, Chapter 2. ISBN: 0-321-35668-3.

> Cheers,
> Deepak
> 

-- 
Andrew :)

Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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