From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.4 required=5.0 tests=AC_FROM_MANY_DOTS,BAYES_00 autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,e429176c9adb07b X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-02-25 04:42:32 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!peernews-us.colt.net!newsfeed.news2me.com!newsfeed2.easynews.com!newsfeed1.easynews.com!easynews.com!easynews!newsfeed1.earthlink.net!newsfeed.earthlink.net!stamper.news.pas.earthlink.net!stamper.news.atl.earthlink.net!harp.news.atl.earthlink.net!not-for-mail From: "Marin David Condic" Newsgroups: comp.lang.ada Subject: Re: [OT] Best way to isolate a GUI? (The final concensous?) Date: Tue, 25 Feb 2003 07:41:37 -0500 Organization: MindSpring Enterprises Message-ID: References: <3E511C15.1040404@acm.org> <3E5121BD.4010200@cogeco.ca> <3E51A55A.3000101@cogeco.ca> <3E52A1BF.1020809@cogeco.ca> <3E53CE60.1030008@cogeco.ca> <3E55501D.9050006@cogeco.ca> <3E5669C8.30305@cogeco.ca> <3E5A5F1C.9040907@cogeco.ca> NNTP-Posting-Host: d1.56.ba.2d X-Server-Date: 25 Feb 2003 12:42:31 GMT X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2314.1300 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2314.1300 Xref: archiver1.google.com comp.lang.ada:34556 Date: 2003-02-25T12:42:31+00:00 List-Id: I understand your concerns - especially about returning data and potential indeterminism. A lot of that is why messaging systems get limited to a command/response protocol - so that you do have returned data and you force some serialization into the process. Some messaging systems include things like heartbeat counters or other numbering schemes to try to insure that things line up nicely and that failures are handled, specifically to try to get away from the problems you cite. Ultimately, it comes down to this: You want to design something, you'll have to pick some philosophy or approach. Having done that, you just eliminated all the other possible approaches. That means you'll always be able to stand there looking at the design you *did* pick and cast stones at it because it doesn't have the strengths of some other approach. If you do that enough, you never accomplish anything. So you try to pick the dog with the least number of fleas. In my little imaginary world of dreaming up a way to separate the GUI from the app, I tend to like a messaging scheme because it is loosely coupled and flexible enough that it could probably be mated to a number of GUIs and GUI builders as well as staying language neutral. I think if one went another route - that involving callbacks - one would likely lose the flexibility and find it difficult to make it line up with more than one GUI at a time. While callbacks are going to have certain advantages (forcing a certain amount of command/response protocol and returning results to the GUI) I think that careful design of a messaging system might be able to live without those advantages or synthesize them in some other way. So you pays your money and you takes your pick. :-) MDC -- ====================================================================== Marin David Condic I work for: http://www.belcan.com/ My project is: http://www.jsf.mil/ Send Replies To: m c o n d i c @ a c m . o r g "Going cold turkey isn't as delicious as it sounds." -- H. Simpson ====================================================================== Warren W. Gay VE3WWG wrote in message news:3E5A5F1C.9040907@cogeco.ca... > Unfortunately I have to be a bit brief in this reply (shortened > lunch today ;-) >