Re: Endianness independance

["Marin David Condic" <mcondic.auntie.spam@acm.org>]

I agree - solve it "by hand". That is to say, one establishes the
communications protocol and tests to make sure the programs involved work
with that protocol. But remember that the original notion was that somehow
Ada was invented to make sure that when a new device was plugged into some
big military system, you wouldn't have a case where it would misinterpret
the data and cause a failure. My contention was that A) it wasn't invented
for that purpose and B) the language can't really solve that problem. The
language can't check the representations of things that exist outside of the
language. If you have thousands of messages flying around through a system
you are always going to have some unusual cases generated by unusual needs
and it is not possible to anticipate all those circumstances from within a
language standard. You have to manually determine what the messages are
supposed to look like and test to be sure the software understands them.
Often there are corner cases or things that are difficult to test or unusual
enough that they get missed. Hence, the possibility of errors.

A language might *help* minimizing representation problems because if
everyone is using the same thing they are at least starting from a common
base. But the representation of data outside the language isn't defined by
the language and attempting to do so is only going to hamstring the language
& keep it from being usable in a large variety of circumstances. For
example, Ada's selection of ASCII for character representation pretty much
insured that it would not become a popular language on IBM mainframes where
EBCDIC ruled the roost. Had the standard gone further and tried to define
external representations for more things, they would have just kept ruling
out more and more architectures on which it would be difficult or impossible
to meet the standard. And none of this would result in more
interoperatbility because the problems tend to come up from inadequate
understanding on the part of the programmers about the data being dealt with
rather than some intrinsic data representations that the language can't
check anyway.

MDC
--
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Marin David Condic
I work for: http://www.belcan.com/
My project is: http://www.jsf.mil/

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    "Going cold turkey isn't as delicious as it sounds."
        -- H. Simpson
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Amir Yantimirov <amir@iae.nsk.su> wrote in message
news:5115eb96.0303020149.4d438e40@posting.google.com...
>
> We solves that by hand without much brain efforts so the task to
> automate it is not difficult by itself. Ideally we should only mark
> sertain types and interfaces that deals with communications as having
> particular endianess and thats all. But including notion of endianess
> (as kind of storage specifier) in existent Ada type system seems
> impossible to me.
>