Re: Subprogram Renaming

["James A. Squire" <m193884@CSEHP3.MDC.COM>]

Robert A Duff <bobduff@WORLD.STD.COM> wrote:
> In article <316951C3.CE4@csehp3.mdc.com>,
> James A. Squire <m193884@CSEHP3.MDC.COM> wrote:
> >> package q is
> >>   procedure j;
> >> end q;
> >>
> >> package body q is
> >>    ...
> >>    procedure j renames k;
> >
> >which looks like a rename of a spec to me.  I can do this in Ada83.
>
> No, the above is illegal in Ada 83.  In Ada 83, you have two
> declarations of J, which are homographs, and therefore illegal.  And you
> have a missing body for the first J, which is also illegal.  The new

You are right about that.  That comment was my mistake.  However
(!!!)...

> thing in Ada 95 is that the renaming can act as the body of the first J.
> This is no big deal -- the renaming is just a short-hand notation for
> "procedure j is begin k; end;".  But it was illegal in Ada 83.

Still (!) Nobody has answered the $64,000.00 question:  WHY IS THIS SUCH
A GOOD THING?  In other words, why did they waste their time adding this
ability to rename a subprogram body.  Why should I do:

package q is
  procedure j;
end q;

package body q is
  procedure k;
  procedure j renames k;
end q;

when I can do:

package q is
  procedure k;
end q;

package body q is
  procedure k is ...
end q;

Now that I KNOW I can do in Ada83.  Since the parameter spec has to
match exactly, I see no point to doing a rename in the body and hiding
it from the user.  All you are changing is the name it goes by.  What's
the point?

> As Robert Dewar said, this has nothing to do with syntax rules -- the
> syntax for renamings is the same.  The difference is where they're
> allowed, and what they mean.  To find the rules, you have to look at the
> text under subprogram renamings (as opposed to just looking at the BNF
> syntax rules).

I read those - 8.5.4 and 6.3.1.  What does "subtype of the profile"
mean?
--
James Squire
MDA Avionics Tools & Processes
ja_squire@csehp3.mdc.com
"one of these days I'm going to better myself by going to Knight school"
"You'll be a web knight instead of a web page!"