geometry.adb

来自「Ada 2005 Training Notes.」· ADB 代码 · 共 90 行

package body Geometry is


   function Distance (O: in Object) return Float is
   begin
      return Sqrt(O.Pos_X ** 2 + O.Pos_Y ** 2);
   end Distance;

   --
   -- Object does not have area
   -- abstract subprogram cannot have a body
   --
   -- function Area(O: in Object) return Float is
   -- begin
   --   return 0.0;
   -- end Area;

   --
   -- Its OK Distace2 to have class-wide parameter
   -- as Distance function is the same for type derived from
   -- Object.
   --
   function Distance2(OC: in Object'Class) return float is
   begin
      return Sqrt(OC.Pos_X ** 2 + OC.Pos_Y ** 2);
   end Distance2;


   function Area(C: in Circle) return Float is
   begin
      return Pi * C.Radius ** 2 * Pi;
   end Area;


   function Area(P: in Point) return Float is
   begin
     return 0.0;
   end;


   function Moment(OC: Object'Class) return Float is

   begin
      --

      --
      -- return OC.Pos_X * Area(OC);

      -- Prefixed notation
      return OC.Pos_X * OC.Area;

   end Moment;

   function MO(OC: in Object'Class) return Float is
   begin
      return MI(OC) + Area(OC) * Distance(OC) ** 2;
   end MO;

   function MI(C: in Circle) return Float is
   begin
      return Area(C) * Distance(C) ** 2 / 2.0;
   end MI;

   function MI(P: in Point) return Float is
   begin
      return 0.0;
   end MI;

   --
   -- Add any Object to the List
   --
   procedure Add_To_List (List: access Cell; OP: Pointer) is
      Local: access Cell := List;
   begin
      --
      -- Find the end of the list
      --
      loop
         if Local.Next = null then
            Local.Next.Element := OP;
            return;
         else
            Local := Local.Next;
         end if;
      end loop;
   end Add_To_List;

end Geometry;