Re: gnat: time-slicing

[dewar@gnat.com (Robert Dewar)]

Jan Prazak <janp9@gmx.net> wrote in message news:<pan.2002.07.15.10.24.43.431977.7868@gmx.net>...
> Hello,
> 
> I have seen this example program in a tutorial:
> 
> ------------
> with Ada.Text_IO; use Ada.Text_IO;
> 
> procedure Task_Demo is
>   task A;
>   task body A is
>   begin
>     Put_Line("b");
>     Put_Line("b");
>   end A;
> begin
>   Put_Line("a");
>   Put_Line("a");
> end Task_Demo;

This is a nonsense example, it is erroneous to do output
on the same file from two different tasks, since obviously
the file is a shared variable, and the program violates
rules about access to shared variables. You must always
properly control access of tasks to I/O. If the compiler
deleted your hard disk when you ran this program, you
could decide that it was an unpleasant compiler to use,
but not that it was an incorrect compiler (erroneous
programs have completely undefined semantics).

All the discussion about time slicing is besides the point
given this observation.