Re: How to exit an Ada program with (unix shell) error code?

[Adam Beneschan <adam@irvine.com>]

On May 7, 2:08 am, a...@anon.org (anon) wrote:
> There are basic three types of programs for computers.
>
>         The first, are the "Stand-Alone" programs aka OS types, which do not
>         return and have no needs for Ada.Command_Line routines.  In order
>         words, there are no links for the Ada.Command_Line package and the
>         Set_Exit_Status routine.
>
>         The second type are "Device Drivers" or "System/Kernel" installable
>         "Modules".  And the Ada.Command_Line package is not legal. But the
>         Kernel requires the "Module" to notify the kernel by using the
>         "exit status" so that the kernel can know if it should reclaim the
>         memory, etc, on errors. Using a "function" type of module install
>         program is the only way a "Module" can be written and have an
>         "exit status".
>
>         Note: Ada as a computer language should be allowed to create
>               these type of programs which means that Ada needs to
>               support main subprogram that are functions.

But you're ignoring a point I already made.  Since library-level
finalizations need to be done after the main subprogram is completed,
the Ada main subprogram cannot exit directly to the OS.  Therefore it
really doesn't matter whether Ada main subprograms can be functions or
not.  For an OS that expects its program to return a status in its
"function result" register, the requirement is that the code generated
by the compiler, that *does* exit back to the OS, has to put a status
in that register.  And there's no reason the compiler can't generate
code that generates this status based on the parameter to the last
Ada.Command_Line.Set_Exit_Status call (if any), whether or not the
main subprogram is a function.  If you still think that
Ada.Command_Line might not be available, read on.


>         And since there are times where the Ada.Command_Line package is
> not available

Ada.Command_Line is defined in Annex A.  Please read RM 1.1.2(2-6) and
1.1.2(17).  I'm surprised you'd say the above, since you're fond of
saying there are only a couple of Ada compilers out there since a
compiler that doesn't support all of the new Ada 2005 features is not
an Ada compiler---well, a compiler that doesn't support all of Annex A
(including Ada.Command_Line) is not an Ada compiler either, so why
would you be concerned about that?

                                 -- Adam