Ada -vs- GNAT

["Steve Doiel" <nospam_steved94@attbi.com>]

I've been using Ada for a several years now.  In my opinion one of the
greatest strengths of the language is in its portability.  I find it
reassuring that different vendors distribute the same reference manual for
the language.

Recently I did some work with XML/Ada and found a few pieces code dependent
on the GNAT specific attributes 'img and 'unrestricted_access.  I was able
to make the code work with ObjectAda (and any other Ada compiler) by making
a few small changes to the sources.

Personally I find the introduction of attributes and pragmas that are not
essential to be undesirable.

In a recent thread on the gcc mailing list, Robert Dewar describes how ACT
introduced the pragma "Unreferened" such that code that previously appeared
as:

  pragma Warnings (Off, entitiy)

could be replaced by

  pragma Unreferenced (entity)

because the latter is "neater, reads better, and is clearer why it is
there."

In the GCC context this type of change requires that GCC 3.2 be built with
GCC 3.1 and no earlier version.

In my opinion these extensions should only be added by revision to the
standard or as work-arounds when you come up against a brick wall.

Since I am not currently a supported customer of ACT, I have no grounds to
complain, but am interested in what other people think.

SteveD