Re: Task discriminants

[Dmitry A. Kazakov <mailbox@dmitry-kazakov.de>]

On Thu, 20 May 2004 19:30:57 +0200, Martin Krischik
<krischik@users.sourceforge.net> wrote:

>Dave Levy wrote:
>
>> 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 );

Ada does not have constructors with parameters, alas.

>> Except I tried this with Gnat and it won't compile.
>
>Of corse not! Tasks are indefinite type and can't be stored in arrays. You
>can store an access to a task in an array.
>
>With Regards
>
>Martin
>
>PS: I could not find anything in the RM: Does anybody know if task are also
>limited.

Task types are indeed limited. This does not prevent us from having
arrays of tasks. A task type as above with an integer discriminant
will be unconstrained not because it is a task, but because Id has no
default value. The solution Martin Dowie proposed shows it.

Though, why one should want an Id discriminant, if there is the
package Ada.Task_Identification?

--
Regards,
Dmitry Kazakov
www.dmitry-kazakov.de