Re: Generic Formal Parameter for a Task Type

[James Rogers <jimmaureenrogers@worldnet.att.net>]

Yes, each of these is a possible way to create a system for monitoring
and controlling a set of tasks. 

I like your idea of the abstract limited tagged type containing a
"Task_ID" function. Unfortunately, this still adds a lot of 
overhead when all I want to do is monitor and control the creation
of tasks.

Note that the problem I am trying to solve does not require much
knowledge about the task, only the ability to create an instance,
and the ability to query a task attribute.

I fully realize the problem can be solved by building an elaborate
scaffold of data and code structure. I was hoping to achieve the
results simply and cleanly. I was hoping to avoid the additional
overhead of code bloat resulting from building tagged types and
associated subprograms.

Jim Rogers
Colorado Springs, Colorado USA

Tucker Taft wrote:
> 
> 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...