Elegant 'realloc'?

[Lutz Donnerhacke <lutz@iks-jena.de>]

When dealing with dynamically allocated variable length arrays, the
allocated space might change. Is there a common idiom to simulate an
'realloc' (especially shrinking) other than, allocate, copy, free?

   declare
      procedure Free is new Unchecked_Deallocation(T_Array, T_Array_Access);
      oldp : constant T_Array_Access := current.field;
   begin
      current.field := new T_Array'(oldp(oldp'First .. current.last));
      Free(oldp);
   end;