Re: Task discriminants

["Karen" <karen.nussbaum@blueyonder.co.uk>]

Or the obvious approach, to declare a access type to the task type.  Then
have an array of those access types, which are initialised using different
discriminants as you need.

(from a posting newbie, but an Ada Graybeard)
ian(dot)nussbaum(at)blueyonder.co.uk


"Nick Roberts" <nick.roberts@acm.org> wrote in message
news:2iceofFlgn4pU1@uni-berlin.de...
> "Dave Levy" <dlevy@mail.usyd.edu.au> wrote in message
> news:40ACC50E.9040406@mail.usyd.edu.au...
>
> > Suppose one has a task type with a discriminant:
> >
> >     task type A_Task( Id : integer);
> >
> > and one wishes to declare a set of tasks with initialised discriminants:
> >     t1 : A_Task(1);
> >     t2 : A_Task(2);
> >     t3 : A_Task(3);
> >
> > How could one declare them as an array of tasks with each one getting an
> > initialised discriminant? Perhaps something like:
> >
> >     The_Tasks: array (1..3) of A_Task( Id => 1,2,3 );
> >
> > Except I tried this with Gnat and it won't compile.
>
> It is a basic precept of Ada arrays that its components are all of the
same
> subtype. This means that they cannot have different discriminants. So this
> approach, as such, is doomed.
>
> You could use the 'old' technique:
>
>    type A_Task_Number is range 1..3;
>
>    task type A_Task is
>       entry Init (Num: in A_Task_Number);
>       ...
>    end;
>
>    The_Tasks: array (A_Task_Number) of A_Task;
>
>    ...
>       for i in A_Task_Number loop
>          The_Tasks(i).Init(i);
>       end loop;
>    ...
>
>    task body A_Task is
>       My_Num: A_Task_Number;
>       ...
>    begin
>       accept Init (Num: in A_Task_Number) do
>          My_Num := Num;
>       end;
>       ...
>    end A_Task;
>
> It's always worked for me!
>
> --
> Nick Roberts
>
>