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Re: How to keep two objects synchronized? [message #86105 is a reply to message #86103]

Fri, 04 October 2013 08:10

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Matthew Argall writes:

> I just had a look. This is a great idea -- much more straight-forward than what I had in mind. A couple of questions:
>
> Say I have a colorbar and an image object and I want them to listen to each other. I would still have to do something like this, right? It seems like there would be an infinite loop here...
>
> theColorbar -> RegisterForMessage, theImage, 'ChangeColor'
> theImage -> RegisterForMessage, theColorbar, 'ChangeColor"

In some cases, you do have to take care not to get in an infinite loop.
This is typically solved by adding a NOMESSAGE keyword, of something of
the sort, to the method that "changes colors". In other words, just do
this, but don't tell anyone about it. Such infinite loop cases are rare
in my experience.

> If I want to register more than one message, I cannot pass a string array. Instead, I have to register for again. Was there a reason for this?

The usual reasons: sloth and lack of foresight.

> Do you still develop the catalyst library? If not, do you know of any current widget features that are missing?

I keep the Library up-to-date, but I wouldn't say I am actively
developing it. I expect a new set of widgets ANY-DAY-NOW and presume
this Library will quickly become obsolete. Although given what I have
seen of how you have to program a Window() function, I would not bet on
simplicity as a feature of the new system when it arrives. :-)

One reason I haven't developed the Catalyst Library more is that even it
became overly complex over time, to the point where I was having trouble
teaching ordinary programmers how to work with it. Instead, I opted to
take some of its best ideas (e.g., simple image display, coordinate
objects, color and device independence) and incorporate them into the
Coyote Library in a way that was more understandable for everyone.

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")

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[Message index]

		How to keep two objects synchronized? By: Matthew Argall on Thu, 03 October 2013 05:49
		Re: How to keep two objects synchronized? By: David Fanning on Thu, 03 October 2013 06:20
		Re: How to keep two objects synchronized? By: Matthew Argall on Fri, 04 October 2013 07:48
		Re: How to keep two objects synchronized? By: David Fanning on Fri, 04 October 2013 08:10
		Re: How to keep two objects synchronized? By: David Fanning on Fri, 04 October 2013 08:44
		Re: How to keep two objects synchronized? By: David Fanning on Fri, 04 October 2013 09:05
		Re: How to keep two objects synchronized? By: lecacheux.alain on Thu, 03 October 2013 07:02
		Re: How to keep two objects synchronized? By: Matthew Argall on Fri, 04 October 2013 07:49

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