Re: Generic Formal Parameter for a Task Type

[Tucker Taft <stt@averstar.com>]

"Robert C. Leif, Ph.D." wrote:
> 
> From: Bob Leif
> To: Tucker Taft et al.
> You wrote:
> "If you wanted to avoid generics, you could define an abstract limited
> tagged type (say "Has_Task") which had various (abstract) primitive
> operations, including  at least a "Task_ID" function.  You would then
> extend from this type by adding a component of the task type of interest
> (and of course override the abstract primitives as appropriate)."
> 
> Can you include the "Has_Task" in a generic package; or are the two
> approaches mutually exclusive for tasks?

As I mentioned, you can declare a formal derived type, such as
   generic
       type My_Task is new Has_Task with private;
   ...

and inside the generic use the My_Task type to create tasks and
query the information about instances of the type.

I wrote earlier:
> ...
> Why not have a formal function that returns the Task_ID, rather
> than 'Terminated?  That way, you can use the Ada.Task_Identification
> and Ada.Task_Attributes packages to get whatever else you need from the
> task, including task attributes...
> 
> If you wanted to avoid generics, you could define an abstract limited
> tagged type (say "Has_Task") which had various (abstract) primitive
> operations, including  at least a "Task_ID" function.  You would then
> extend from this type by adding a component of the task type of interest
> (and of course override the abstract primitives as appropriate).
> You could then manipulate objects of type Has_Task'Class, or references
> there-to, in a "Java"-like way ;-).  You could also pass in any
> extension of Has_Task to a generic with a formal tagged derived type
> of "type My_Task is new Has_Task with private;".
> 
> The possibilities are endless...

-- 
-Tucker Taft   stt@avercom.net   http://www.averstar.com/~stt/
Chief Technology Officer, AverCom Corporation (A Titan Company) 
Burlington, MA  USA (AverCom was formerly the Commercial Division of AverStar:
http://www.averstar.com/services/ebusiness_applications.html)