From: "Mauricio Fernández" <batsman.geo@...>
Date: 2003-03-27T17:43:03+09:00
Subject: Re: Conditionally make a method private?

On Thu, Mar 27, 2003 at 10:50:44AM +0900, Jeremy wrote:
> dblack@superlink.net wrote:
> Actually, if I understand what you are saying, this is EXACTLY what I want. 
> What I was trying to accomplish was having an attribute that wasn't quite
> global, but more accessable than just a normal class attribute.  I do want

But in a way it *is* global, as there's only one class attribute, it is
simply scoped into that class. Every pair of database/menu objects will
be using the same attribute.

If all you want is to share some part of the internal state, you can simply
externalize it as a separate object and keep as many references as needed.


> M1's view of the status to change when I change it in M2.  I think that the
> best way to think of it is like this:
> 
> I have two classes (a database class, and a menu class) that are different
> enough that it doesn't warrant doing inheritance from a single superclass,
> but I need any instances of the two classes to communicate directly.  I
> didn't really want to muck up global space with an attribute, because I
> don't want all things to be able to access it.  But I also didn't want to
> do a lot of hardcoding in each class to make them "aware" of each other.  I
> wanted this to kind of act like a community whiteboard.  Also, I needed
> something that could possibly "do more", such as formatting, or automatic
> message clearing, or things like that.  Using the above code was about the
> best that I could come up with for such a beast.  As stated in the message
> to John Johnson, the reasoning for the original posting was to see if I
> could have some of them to act only as senders of messages (the databases),
> and some as readers of messages (the menus).  I still would like to do
> something like that, but that will take a bit more thinking for me yet. 
> I'm still fresh meat in the ruby community, only having been using it for
> about 3 weeks now.

Now all this about writers and readers reminds me the Databus being used
by Freeride. In believe it probably what you want (esp. the "act like a
community whiteboard" part :)

http://www.rubyide.org/cgi-bin/wiki.pl?Databus 

"The FreeBASE Databus is the internal mechanism through which plugins
communicate with each other. It is a hierarchical publish/subscribe
system that combines the features of a data repository and a messaging
system. 

[...]

The Databus uses a publish/subscribe mechanism that allows you to use
the Databus as a messaging system. You can subscribe to any slot in the
Databus to receive notifications whenever that slot changes."

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