Re: Idiom for a class and an object in Ada

["Matthew Heaney" <mheaney@on2.com>]

"Simon Wright" <simon@pushface.org> wrote in message 
news:x7v4qkqrlr1.fsf@smaug.pushface.org...
>
> package body ADC is
>
>   task type T is ...
>   type T_P is access T;
>   Converter_1 : T_P;
>
> begin
>
>   Converter_1 := new T (...);
>
> end ADC;

This doesn't buy you anything.  The rule is that the "task object" 
elaborates in linear order (the same as for any other declaration), but then 
the "task" itself "activates" when the begin statement is reached.

We can write your example as:

package body ADC is
   task type T;

   O : T;  -- this is the "task object"

   task body T is ... end;

end;

No explicit allocation is necessary.  Task object O elaborates in the normal 
way, and its associated task activates at the completion of elaboration of 
the package body.

The distinction between "task object" and "task", and between "elaboration" 
and "activation", is somewhat subtle.