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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: basic questions on using Ada arrays
Date: Thu, 7 Oct 2010 19:04:00 -0500
Organization: Jacob Sparre Andersen
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Date: 2010-10-07T19:04:00-05:00
List-Id: <comp.lang.ada>

"Keith Thompson" <kst-u@mib.org> wrote in message 
news:ln8w2apy0u.fsf@nuthaus.mib.org...
...
> A more "generic" solution (though it doesn't use generics) is:

If you're using an Ada 2005, this solution is better using an anonymous 
access type, as in that case you can pass any matching subprogram, not just 
one from the same level. (If you don't do this, this will be annoyingly hard 
to use.) That is, change as follows:

> with Ada.Text_IO; use Ada.Text_IO;
> with Ada.Numerics; use Ada.Numerics;
> with Ada.Numerics.Elementary_Functions;
> use  Ada.Numerics.Elementary_Functions;
> with Ada.Float_Text_IO; use Ada.Float_Text_IO;
>
> procedure Test2 is
>   type Func_Ptr is access function(F: Float) return Float;

Delete this type.

>   type Float_Array is array(positive range <>) of Float;
>
>   function Apply(Func: Func_Ptr; Arr: Float_Array) return Float_Array is

Change this declaration to:

function Apply(Func: access function(F: Float) return Float; Arr: 
Float_Array) return Float_Array is

>      Result: Float_Array(Arr'Range);
>   begin
>      for I in Result'Range loop
>         Result(I) := Func(Arr(I));
>      end loop;
>      return Result;
>   end Apply;
>
>   function Init return Float_Array is
>      nPoints : constant := 100;
>      del : constant Float := 2.0*Pi/Float(nPoints-1);
>      Result: Float_Array(1 .. nPoints);
>   begin
>      for I in Result'Range loop
>         Result(I) := Float(I - 1) * del;
>      end loop;
>      return result;
>   end Init;
>
>   X: constant Float_Array := Init;
>   Y: constant Float_Array := Apply(sin'Access, X);
> begin
>   for I in X'Range loop
>      Put(X(I), Exp => 0);
>      Put(" => ");
>      Put(Y(I), Exp => 0);
>      New_Line;
>   end loop;
> end Test2;
>
> [...]


                       Randy.