Re: Calendar package

[Robert A Duff <bobduff@world.std.com>]

"singlespeeder" <singlespeeder@32sixteen.com> writes:

> "Robert A Duff" <bobduff@world.std.com> wrote in message
> news:<wcc7l1l4e95.fsf@world.std.com>...
> > Ada 9X was intended to be *very* compatible with Ada 83.  The only time
> > that was violated were for very good reasons (or so we thought).
> > Perhaps you can give some examples?
> >
> > - Bob
> 
> A trivial example of where I don't believe backward compatibility doesn't
> work as well as it could.
> 
> In package Text_IO there is a new enumeration File_Mode, Append_File.
> 
> We develop mainly in an Ada 95 (speedier toolset) with the compiler set to
> issue warning about Ada 83 incompatibilities - but it's not perfect. We have
> had instances where programmers (er, me) use the new File_Mode and break the
> code when we move it back to the Ada 83 environment. Yes this example was
> trivial and easy to fix but there are/have been worse cases.

What I meant was that Ada 95 was designed so that correct Ada 83
programs would be correct Ada 95 programs, with the same meaning, except
in rare circumstances.  You're complaining about the other direction:
moving Ada 95 code to Ada 83, which was not a goal of the Ada 9X
project.

It's almost impossible to implement "pragma Ada_83" exactly right.

- Bob