Re: Dynamic dispatch again

[tmoran@acm.org]

>OK, I'm still trying to figure out how to make one entry call wind up
>calling code in different units.
>...
>Essentially, I have a basic manager task doing I/O, distributing
>messages to "profiles". Each "profile" can get the same set of messages
>(start, stop, are you ready, here's a message), but each responds to the
>messages in different ways.

How about having a single "profile" task, and using tagged type "methods"
to respond in different ways, eg:

package profile is

  type changeable_content is abstract tagged limited null record;
  type changeable_content_pointer is access all changeable_content'class;

  procedure xlate_content(what_to_do : in changeable_content;
                          in_in : in integer; out_out : out integer)
      is abstract;

  task type general_task(content : changeable_content_pointer) is
    entry xlate(in_in : in integer; out_out : out integer);
  end general_task;
  type general_task_pointer is access general_task;

end profile;

package body profile is

    task body general_task is
    begin
        loop
            select
                accept xlate(in_in : in integer; out_out : out integer)
do
                    xlate_content(content.all, in_in, out_out);
                end xlate;
            or
                terminate;
            end select;
        end loop;
    end general_task;

end profile;



with profile;
package double is

  type content is new profile.changeable_content with null record;

  procedure xlate_content(what_to_do : in content;
                          in_in : in integer; out_out : out integer);

end double;

package body double is

  procedure xlate_content(what_to_do : in content;
                          in_in : in integer; out_out : out integer) is
  begin
      out_out := in_in + in_in;
  end xlate_content;

end double;




with profile;
package negate is

  type content is new profile.changeable_content with null record;

  procedure xlate_content(what_to_do : in content;
                          in_in : in integer; out_out : out integer);

end negate;

package body negate is

  procedure xlate_content(what_to_do : in content;
                          in_in : in integer; out_out : out integer) is
  begin
      out_out := - in_in;
  end xlate_content;

end negate;



with profile;
with double;
with negate;
with Ada.Text_IO;

procedure driver is
    type pat is array(1..2) of profile.general_task_pointer;
    pa : pat;
    i : integer;
    doubler : profile.changeable_content_pointer := new double.content;
    negater : profile.changeable_content_pointer := new negate.content;
begin
    pa(1) := new profile.general_task(doubler);
    pa(2) := new profile.general_task(negater);
    pa(1).xlate(100, i);
    Ada.Text_IO.Put_Line("First, " & Integer'Image(I));
    pa(2).xlate(100, i);
    Ada.Text_IO.Put_Line("Second, " & Integer'Image(I));
end driver;