Re: Calling a record type's methods (functions or procedure) when record is in an array

[Simon Wright <simon@pushface.org>]

Mace Ayres <maceayres0@gmail.com> writes:

> To modify the item val in the trunk at array (5)(3) I code..
>
> ... my_truck_arrary(5)(3).val := trunks.post_val(N)
>
> rather than my_tunk_arrary(5)(3).val := N
>
> so I don't directly access the a_trunk record's value fields directly

? this code does indeed access the value fields directly!

> -- I have to add the private part too, to hide the inners of type
> a_trunk.

You're looking for an accessor (though accessors aren't always a good
idea; there might be checks needed, attributes may be related so you
need to deal with more than one at the same time, eg coordinates):

   package Mace is
      type Thing is private;
      procedure Set_Attribute (Into : in out Thing; Value : Integer);
      function Get_Attribute (From : Thing) return Integer;
   private
      type Thing is record
         Attribute : Integer;
      end record;
   end Mace;

   package body Mace is
      procedure Set_Attribute (Into : in out Thing; Value : Integer) is
      begin
         Into.Attribute := Value;
      end Set_Attribute;
      function Get_Attribute (From : Thing) return Integer
      is (From.Attribute);
   end Mace;