Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hplabsz!mayer
From: mayer@hplabsz.HPL.HP.COM (Niels Mayer)
Newsgroups: comp.windows.x
Subject: Re: Wish list for R5
Message-ID: <5821@hplabsz.HPL.HP.COM>
Date: 17 Aug 90 23:23:58 GMT
References: <9008161931.AA21572@erik.uucp>
Reply-To: mayer@hplabs.hp.com (Niels Mayer)
Organization: Hewlett-Packard Labs, Software & Systems Lab, Palo Alto, CA.
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In article <9008161931.AA21572@erik.uucp> randy@erik.UUCP (Randy Brown) writes:
>>Both of the aforementioned problems require more than a static description
>>of a widget hierarchy and resources as provided by UIL or WCL.
>
>Since WCL includes not only a string-to-widget converter but a string-to-
>callback converter, it's perhaps not quite as static as you might think,
>though I'm sure Niels has a point--there's a limit somewhere.

My point was that a UI prototyping/extension language requires more than
static layout, and static bindings to application code in order to handle
the dynamic aspects of user interfaces (e.g. the examples I gave of (1)
desensitizing UI components if input to them is not valid at a particular
application-state, and (2) handling the interactions between dialog and
presentation).

Having string-to-widget or string-to-callback converters is very useful
indeed, but it will not handle the things I'm thinking of. Basically, you
need a way of getting application state represented in the user-interface
language, and you need a way of sending messages relating application state
changes to widgets expressed in the UI prototyping/extension language. Now,
if all widgets in WCL or UIL could have a "constraint changed" callback,
then the string-to-callback mechanism might become useful for handling UI
dynamics. As far as I know, such constraint mechanisms only exist in
languages found in User-Interface Management Systems (UIMS) such as Serpent
or Open Dialog, and can also be implemented via a more traditional
extension-language mechanism in the UI prototyping/extension language,
WINTERP (see expo.lcs.mit.edu:contrib/winterp/winterp-<latestversion>.tar.Z)

-------------------------------------------------------------------------------
	    Niels Mayer -- hplabs!mayer -- mayer@hplabs.hp.com
		  Human-Computer Interaction Department
		       Hewlett-Packard Laboratories
			      Palo Alto, CA.
				   *