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From: "Nick Roberts" <nickroberts@blueyonder.co.uk>
Newsgroups: comp.lang.ada
Subject: Expectation of Access Value Equality
Date: Fri, 5 Sep 2003 14:35:40 +0100
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Xref: archiver1.google.com comp.lang.ada:42174
Date: 2003-09-05T14:35:40+01:00
List-Id: <comp.lang.ada>

I'm asking for the help of Ada programmers of all levels of experience.

Given the following declarations:

   type A_String is access constant String;

   function "+" (S: String) return A_String is
   begin
      return new String'(S);
   end;

   type A_String_Array is array (Positive range <>) of String;

   procedure Print (A: in A_String_Array) is
      Sentinel: constant A_String := A(A'Last);
      Current: Positive := A'First;
   begin
      loop
         Put_Line( A(Current).all );
         exit when A(Current) = Sentinel;
         Current := Current + 1;
      end loop;
   end;

(a) Would you be surprised by:

   Print( (+"foo",+"bar",+"",+"") );

printing three lines?

(b) Would you be surprised by:

   Print( (+"foo",+"bar",+"hum",+"foo") );

printing one line?

(c) What would you think of an implementation that caused this behaviour?
(What would you think of an implementation that printed four lines in both
cases?)

(d) I'd be grateful for a very brief indication of your level and broad
area(s) of programming experience, in Ada and other languages.

I would be very grateful for as many people replying as possible, preferably
in this news group, but privately if you prefer. Thanks.

--
Nick Roberts
E-mail: nickroberts@blueyonder.co.uk
Jabber: debater@charente.de [ICQ: 159718630]