Re: Porting Experiences (was Ada and Pascal etc )

["Marin David Condic, 561.796.8997, M/S 731-96" <condicma@PWFL.COM>]

Craig Franck <clfranck@WORLDNET.ATT.NET> writes:
>What is it about Ada that makes it portable? I would say it is the
>types of applications being developed, as well as the platforms,
>and, perhaps, quality of implementation. Last time I was in Barnes
>& Noble I saw "Ada 95 for C and C++ Programmers" by Simon Johnston,
>from Add-Wes. I almost got it because it had a compiler from Aonix
>called "Objective Ada for Windows" on the accompanying CD. It would
>be interesting to see what that would be like. I just do not see
>how once I start throwing windows up on the screen and responding
>to messages, that that code is porting anywhere.
>
    I'd agree with the assessment about putting windows up on a
    screen. The only way this *might* be considered portable is that,
    for example, WinNT runs on more platforms than Pentium boxes, so
    sticking to the Win32api, your code will port. No such luck if you
    try to take it to a Motif box.

    I've had lots of success porting Ada code both from Ada83
    compilers to Ada95 compilers, between different vendors compilers
    for the same hardware and between dramatically different machine
    architectures. (Embedded M680x0 to Sun Unix & similar) Since I'm
    dealing primarily with embedded application code that does no I/O
    of its own, the ports have been very successful and mostly
    painless. (I had to modify some packages that had embedded
    assembler statements and eliminate a couple of calls to some
    vendor supplied code and that was about it.) Its always the I/O
    that gets you on a port because that's where the language has to
    interface to things beyond its control. Even with Text_IO as your
    only interface, you'll find variations in behavior across
    platforms - even with the same compiler vendor. (I've found some
    variance using GNAT between Sun/Unix and Pentium/WinNT concerning
    terminal I/O behavior and GNAT is a perfectly fine example of
    portable compiler technology.)

    I don't know that there will ever be a good answer to this issue.
    Certainly this is not a problem peculiar to Ada - C, C++, et alia
    are all going to be plagued with the same troubles so it would not
    be fair to say "Ada sucks because when I program I/O code, it
    doesn't port from Sun/Unix/Motif to IBM-370/MVS/Punchcards..." Yet
    all too often Ada (and other languages) are attacked for
    completely silly reasons - usually by inexperienced students who
    have not yet learned much about computers, operating systems and
    programming languages.

    MDC

Marin David Condic, Senior Computer Engineer     Voice:     561.796.8997
Pratt & Whitney GESP, M/S 731-96, P.O.B. 109600  Fax:       561.796.4669
West Palm Beach, FL, 33410-9600                  Internet:  CONDICMA@PWFL.COM
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