Question

This post is a follow-up of a previous post:

Ada: Understanding private types and understanding packaging

I am trying to create an object named Configuration, print it on the screen so that I can see its contents and also try to access the components of this created object. It is the last part that is giving me trouble. The codes are given next:

First the package specification Rectangular_Method.ads:

package Rectangular_Method is
type Rectangular is private;

function Construct(Horz, Vert : Long_Float) return Rectangular;

procedure Print(Configuration: in Rectangular);

procedure Vector_Basis_r (A : in Long_Float; D : out Rectangular);

function Get_Horz (R : Rectangular) return Long_Float;
function Get_Vert (R : Rectangular) return Long_Float;

private
type Rectangular is
    record
         Horz, Vert: Long_Float;
    end record;

end Rectangular_Method;

Next, the package body Rectangular_Method.adb:

with Ada.Text_IO, Ada.Long_Float_Text_IO;
with Ada.Numerics.Long_Elementary_Functions;
use  Ada.Numerics.Long_Elementary_Functions;

package body Rectangular_Method is

function Construct(Horz, Vert : Long_Float) return Rectangular is
begin
  return(Horz, Vert);
end Construct;

procedure Print(Configuration: in Rectangular) is
use Ada.Text_IO, Ada.Long_Float_Text_IO;
  begin
Put("(");
Put(Configuration.Horz, Fore => 2, Aft => 2, Exp => 0); Put(", ");
Put(Configuration.Vert, Fore => 2, Aft => 2, Exp => 0);
Put_Line(")");
  end Print;

procedure Vector_Basis_r (A : in Long_Float; D : out Rectangular) is
begin
  D.Horz := Cos (A, Cycle => 360.0);
  D.Vert := Sin (A, Cycle => 360.0);
end Vector_Basis_R;

function Get_Horz (R : Rectangular) return Long_Float is
begin
  return R.Horz;
end Get_Horz;

function Get_Vert (R : Rectangular) return Long_Float is
begin
  return R.Vert;
end Get_Vert;
end Rectangular_Method;

And finally the test file test_rectangular_form.adb:

with Ada.Long_Float_Text_IO;
with Ada.Text_IO; use Ada.Text_IO;

with Rectangular_Form;
use type Rectangular_Form.Rectangular;
procedure Test_Rectangular_Form is

Theta                                 : Long_Float;
Basis_r                               : Rectangular_Form.Rectangular;

Configuration: Rectangular_Form.Rectangular;

begin
   Ada.Text_IO.Put("Enter the angle ");
   Ada.Long_Float_Text_IO.Get (Item => theta);

   --Vector basis
   Rectangular_Form.Vector_Basis_R (A => Theta, D => Basis_R);

   Configuration := Rectangular_Form.Construct(Rectangular_Form.Get_Horz (Basis_R),Rectangular_Form.Get_Vert (Basis_R));
   Ada.Text_IO.New_Line;
   Rectangular_Form.Print(Configuration);

end Test_Rectangular_Form;

Now the question (based on test_rectangular_form.adb):

I have created an object Configuration as shown above holding the horizontal and vertical components of Basis_R. If I want to access say the horizontal component of Configuration, the following doesn’t work:

aa := Rectangular_Form.Configuration.Rectangular.Horz;

(after defining aa to be of type Long_Float)

I have tried various expressions to access the components of the object Configuration but in vain.

Any help would be most appreciated.

Thanks…

Answer 1

The purpose of your Get_Horz and Get_Vert functions is to retrieve the components of your Rectangular object:

aa := Rectangular_Form.Get_Horz(Configuration);