Re: Tasks with discriminants

[Joh Harbaugh <john.s.harbaugh2@boeing.com>]

Larry Coon wrote:
> 
> I've been playing with discriminants for tasks and I
> can't get something to work.  I can declare a task
> such as the following:
> 
>      task type t (task_no: integer);
> 
> And later create actual tasks:
> 
>      t1: t (1);
>      t2: t (2);
>      t3: t (3);   -- etc...
> 
> But if I want to declare an array of tasks, I
> can't figure out how to supply values for the
> discriminants:
> 
>      type task_array is array (1..3) of t;
>      my_tasks: task_array;   -- ????
> 
> Can anybody tell me how the discriminants are
> supplied in this case?  Thanks in advance.
> 
> Larry Coon
> University of California
> larry@assist.org
> and lmcoom@home.com

A possibility is to create an array of dynamically allocated task:

   Task_Count : constant := 3;
   type Task_Ptrs is access all ADC;
   
-- Raises Program_Error with OA 7.1.105
--   Task_List : array(1..Task_Count) of Task_Ptrs :=
--	   (new T(25), new T(20), new T(T15));

Another approach is to use aliased objects:
    
   A : aliased T(25);
   B : aliased T(20);
   C : aliased T(15);
   
   Task_List : array(1..Task_Count) of T_Ptrs :=
      (A'access, B'access, C'access);

In any case, I have not found a way to create an array of static task
objects with discriminants.  Perhaps someone else has found a way.

Best regards,

	- John