Re: Do we need "Mission-Critical" software? Was: What to Do?

[Robert Dewar <robert_dewar@my-deja.com>]

In article <9343b1$3g5$1@nnrp1.deja.com>,
  n_brunot@my-deja.com wrote:
> Ada83 made the enormous mistake to lack a pragma export,
> denying the importance and justification of others languages.

A peculiar statement since

a) this is fixed in Ada 95

b) Ada 83 already went FAR further than other languages in
accomodating "the importance and justification of other[s]
languages". Someone once asked how to interface a COBOL and
C program (on comp.lang.ada) in a portable manner. I answered
that this could not be done directly (and that is still true
today). I added that the ONLY portable way to do this was to
write an Ada driver that would interface to COBOL and C using
the Ada features.

> May be one of the biggest problem of Ada95, is the work
> required to interface a simple C library.

> This should be made much more automatic by the language or by
> appropriate tools.

Hard to see how the language could make this more automatic,
and the demand for tools in this area has not materialized (in
our experience, for users of GNAT Professional, this is not the
"biggest problem" for most of them).

> This is not the case today.
> Take a C library, write a simple program to test it in Ada,
> and the same in C.

Well of course you have an easier time interfacing to a library
written in language X from language X.

Try another experiment, take a library written in Ada for use
by Ada programs, and try to interface to it from C. This is
in fact impossible, because C has no provision for interfacing
to foreign languages at all.

Now of course, since Ada has very good facilities in this area,
you can write your library (using pragma Export (C ...)) so
that it can be called by C, but all the burden on interlanguage
communication is assumed by Ada, since C is completely
incompetent in this area.

If any language here fails to recognize the importance of
other languages it is C, not Ada!




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