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From: Marius Amado Alves <amado.alves@netcabo.pt>
Newsgroups: comp.lang.ada
Subject: Re: array of strings in a function
Date: Thu, 16 Oct 2003 21:44:16 +0000
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Date: 2003-10-16T21:44:16+00:00

Craig Carey wrote: "Some of the other solutions seem worse."

Your array solution is probably the most "Adaist". But I liked Robert
Eachus's. I wrote a variant which allows a list of size 1 (something
Robert's doesn't), e.g.

   Show (+ "one");
   Show (+ "one" + "two");
   Show (+ "one" + "two" + "three");

Full source below. Vararg_Test outputs, as expected:

 1=>one
 
 1=>one
 2=>two
 
 1=>one
 2=>two
 3=>three
 
(Too much free time in our hands uh? :-)

with Vararg; use Vararg;
with Ada.Text_IO;

procedure Vararg_Test is
   L : List;
   procedure Show (L : List) is
      use Ada.Text_IO;
   begin
      for I in 1 .. Length (L) loop
         Put_Line (Integer'Image (I) & "=>" & Get (L, I));
      end loop;
      New_Line;
   end;
begin
   Show (+ "one");
   Show (+ "one" + "two");
   Show (+ "one" + "two" + "three");
end;


with Ada.Strings.Unbounded;

package Vararg is
   type List is private;
   function Length (L : List) return Natural;
   function Get (L : List; I : Positive) return String;
   function "+" (R : String) return List;
   function "+" (L : List; R : String) return List;
private
   type Store is array (1 ..1000) of
Ada.Strings.Unbounded.Unbounded_String;
   type List is record
      S : Store;
      N : Natural range 0 .. Store'Last := 0;
   end record;
end;

package body Vararg is

   function Length (L : List) return Natural is
   begin
      return L.N;
   end;

   use Ada.Strings.Unbounded;

   function Get (L : List; I : Positive) return String is
   begin
      return To_String (L.S (I));
   end;

   function "+" (R : String) return List is
      Y : List;
   begin
      Y.S (1) := To_Unbounded_String (R);
      Y.N := 1;
      return Y;
   end;

   function "+" (L : List; R : String) return List is
      Y : List;
   begin
      Y.S (1 .. Length (L)) := L.S (1 .. Length (L));
      Y.S (Length (L) + 1) := To_Unbounded_String (R);
      Y.N := Length (L) + 1;
      return Y;
   end;

end;