| Re: passing parameters from base to base [message #33020 is a reply to message #33004] |
Mon, 02 December 2002 12:19   |
JD Smith
Messages: 850
Registered: December 1999
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Senior Member |
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On Mon, 02 Dec 2002 10:05:50 -0700, Stein Vidar Hagfors Haugan wrote:
> JD Smith <jdsmith@as.arizona.edu> writes:
>
> [...]
>> Any suggestions much appreciated. Another option is to publish
>> "capabilities" or lists of potential messages sent in a common block of
>> some kind, but that gets complicated with many multiples of the same
>> type of object on the global stack.
>
> Ah, J.D., J.D.!
>
> I was about to send a very useful piece of code to build on for you, but
> then I discovered the file header:
>
> ;*********** Singleton Abstract Class -- must be inherited
> ;*******************************
> ;Written by J.D. Smith
> ;Added VARIANT code, S.V.H. Haugan
> ;Added methods ALL_SINGLETONS(), PICK_SINGLETON()
>
> You?!
>
As I recall, I wrote that not for any particular need but for
someone's query on the group. Like most such code, I write it quickly
and then forget it ;)
> Isn't what you need (to disguise the ugly common block ;-) exactly a
> singleton object which acts more or less like an Xmanager object?
This would help avoid a common block (though everyone would have to
know where that singleton Object Manager is somehow), but it doesn't
really help me, since I actually *need* all those objects to be
separately valid. The problem really isn't the common block, it's one
of developing a capabilities system that is flexible. The basic idea
is that widget events work in an "up-the-tree" manner, but for object
messages, I need to send messages to anyone at any time, i.e. totally
unconstrained. My solution is essentially to hand-craft the channels
of communication, which actually works more nicely than you'd expect,
except for run-time changes.
In an ideal system, ObjMsg objects would find each other and setup
their own intercommunication themselves. You get into lots of
chicken-and-egg dependency issues in this case though.
JD
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