On Sep 24, 12:17 am, Gianni Mariani <gi3nos...@mariani.ws> wrote:
> Two issues here:

> a) What is the accepted definition of "observer pattern".
> While I can't point to anything specific, I do remember having
> issues with inconsistency in the definition.

I don't know if there is anything really formal, but I'd tend to
go with the description in the GoF book, if only because it
seems to be the most widespread.

> b) Generic observer design in C++. I have been pushing the Austria
> "Twin" interface for a while and more recently the multi threaded
> version of it "TwinMT" (see the 6129 alpha on sourceforge)

I'm not sure, but "Twin" sounds like you're managing a
one-to-one relationship. In my experience, it's almost always a
1->n relationship: each Observable will have many Observer.

> I am trying to distill the "fundamental" hard problems in
> software development, especially regarding C++ and I've seen
> too many issues relating to the observer pattern I think it is
> elevated to "fundamental".

> By fundamental issues I mean, "avoiding deadlock conditions",
> object lifetime management etc.

And persistency?

You're not the first. Back in the early 1990's, there was a lot
of discussion of "relationship management", with the hope of
finding some nice generic solution. As far as I know, there
were no real useful results, but the issue still seems to be
considered important---Java's hyping "container-managed
relations" in EJB.

--
James Kanze (GABI Software) email:james.kanze@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientierter Datenverarbeitung
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34