Re: Question about reference types

[Martyn Pike <usenet@embeddedconsultinguk.com>]

On 27/10/2014 12:09, rkodinets@gmail.com wrote:
> with Ada.Text_IO; use Ada.Text_IO;
> with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
>
> procedure Ada_Test is
>
>     type Obj is record
>        A : aliased Integer;
>     end record;
>
>     type Obj_Access is access Obj;
>
>     type Accessor (Data : access constant Integer) is null record with

This is where the error is.  Data is constant.

>       Implicit_Dereference => Data;
>
>     function Get_Int (This : Obj_Access) return Accessor is
>     begin
>        return Accessor'(Data => This.A'Access);
>     end Get_Int;
>
>     X : Obj_Access := new Obj'(A => 22);
> begin
>     Get_Int(X).Data.all := 33; -- Error: left hand side of assignment must be a variable
>     Get_Int(X) := 33;          -- No error.
>     Put(X.A);                  -- This gives 33.
>     New_Line;
> end Ada_Test;