Re: Not intended for use in medical,

["Marin David Condic, 561.796.8997, M/S 731-93" <condicma@PWFL.COM>]

"John G. Volan" <johnvolan@SPRINTMAIL.COM> writes:
>Looks like I read too much into that article in Ada Letters.  I got the
>impression that there is still a significant constituency in the real
>time industry with serious reservations about OO-style inheritance.
>Hopefully, it's a dwindling minority. But, to do them justice, we can
>address their concerns thus:
>
>  Patient: "Doc, it hurts when I do this."
>  Doctor:  "Well, then don't do that!"
>
>In other words, tagged types and type derivation are useful tools that
>have their place, but they are not necessarily the right tool for every
>problem, and you are not necessarily forced to use them for everything.
>Make an informed engineering decision, weigh the trade-offs: If the
>overhead and dynamic dispatching and the indeterminacy of abstract types
>are unacceptable to a real-time application, just don't use those
>features.
>
    I'm almost with you here - except for one possible problem. If a
    given language feature poses too much runtime overhead to be
    useful *and* requires non-trivial space in its support in the
    runtime kernel (or otherwise causes "other" features to compile
    inefficiently because of dependency on the inefficient feature),
    then you've got a case for why it would be "bad" to include it in
    a realtime language.

    Tasking had (and still has, for some) this same problem. If I've
    got a tiny little microcontroller to do some specific job and I've
    maybe only got 64k of memory to work with and no need for anything
    more complex than a cyclic exec, dragging around the tasking
    support could make it difficult or impossible to use Ada. Try
    finding a nice, small SBC to use as a microcontroller that
    actually has Ada targeted to it - if you find one, let me know.
    I'm still shopping for one that doesn't involve me putting
    together a home-brewed, cobbled-up compiler port that may or may
    not work. (Or is really too big for the job and/or comes with it's
    own realtime version of DOS, etc., etc.) Tasking thus shut Ada out
    of a sizeable segment of the market that is now served almost
    exclusively by C or even C subsets.

    Don't get me wrong - I like the fact that tasking is there and
    have used it effectively in realtime systems. But it would be nice
    to see some (dare I say it?) subset of Ada available that was
    targeted to some of these really small machines.

    MDC

Marin David Condic, Senior Computer Engineer    ATT:        561.796.8997
Pratt & Whitney, GESP                           Fax:        561.796.4669
West Palm Beach, FL                             Internet:   CONDICMA@PWFL.COM
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