main.adb

来自「Ada 2005 Training Notes.」· ADB 代码 · 共 45 行

with PrefixedNotation;

procedure Main is
   type T is record
      I: Integer;
   end record;

   type A1 is access all T;
   Ref1: A1;

   procedure P(Ptr: access T) is
      type A2 is access all T;
      Ref2: A2;
   begin
      -- raised PROGRAM_ERROR : main.adb:15 accessibility check failed
      -- Ptr's scope is in procedure P and Ref1's scope is longer then A1's.
      Ref1 := A1(Ptr);

      -- Ptr's scope is the same as A2's scope and has the same life duration
      Ref2 := A2(Ptr);
   end P;

X1: aliased T;
begin
   declare
      X2: aliased T;
   begin
      P(X1'Access);
      P(X2'Access);
   end;
end Main;

--procedure Main is
--   Var : PrefixedNotation.T;
--begin
--   -- Subprogram first
--   PrefixedNotation.P(X => Var);
--   -- Object first
--   Var.P;
--
--   Main;
--end Main;