Re: Calling through function pointer--syntax question

[Simon Wright <simon@pushface.org>]

adam@irvine.com (Adam Beneschan) writes:

>     type func_ptr is access function (param : integer) return integer;
>     function func (y : integer := 4) return func_ptr;
>     procedure P (x : in integer);
>     procedure P (x : in func_ptr);
> 
> and my question is about the procedure call:
> 
>     P (func (5));       

This has to be the second P. If you were meaning to call the first P,
you would write

    P (func.all (5));

  with Ada.Text_Io; use Ada.Text_Io;
  Procedure Q is
    type Func_Ptr is access function (Param : Integer) return Integer;
    function Actual (Param : Integer) return Integer is
    begin
      return 0;
    end Actual;
    function Func (Y : Integer := 4) return Func_Ptr is
    begin
      return Actual'Access;
    end Func;
    procedure P (X : in Integer) is
    begin
      Put_Line ("first interpretation");
    end P;
    procedure P (X : in Func_Ptr) is
   begin
      Put_Line ("second interpretation");
    end P;
  begin
    P (Func (5));
    P (Func.all (5));
  end Q;

results in

  second interpretation
  first interpretation

(GNAT 3.14a)