Re: time-slicing

["SteveD" <nospam_steved94@attbi.com>]

"Jan Prazak" <janp9@gmx.net> wrote in message
news:pan.2002.07.15.10.24.43.431977.7868@gmx.net...
[snip]
> But I want the output to be:
>
> ab
>
> ab
>

The following program gives the desired result by creating a task-safe
version of Put_Line (actually on W2K I get ba ba instead of ab ab).

There are no guarantees on how the run time system will behave with multiple
tasks sending output to the same file, but it's easy to use have multiple
task send the data to one task that exclusively accesses the file.


With Ada.Text_IO;

Procedure Task_Demo Is

  Task Safe_Io is
    Entry Put( ch : Character );
    Entry New_Line;
  end Safe_Io;

  Task Body Safe_Io is
    Out_Char : Character;
  begin
    loop
      select
        Accept Put( ch : Character ) do
          Out_Char := ch;
        end;
        Ada.Text_Io.Put( Out_Char );
      or
        Accept New_Line;
        Ada.Text_Io.New_Line;
      or
        terminate; -- quit when the main program has terminated
      end select;
    end loop;
  end Safe_Io;

  procedure Put_Line( Item : String ) is
  begin
    for index in Item'Range loop
      Safe_Io.Put( Item( index ) );
      Delay 0.0;  -- force a context switch
    end loop;
    Safe_Io.New_Line;
    Delay 0.0;
  end Put_Line;

  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;

> (the tutorial says that this is the output with enabled time-slicing)
>
> I have tried to use -gnatT100, and -gnatT1, and pragma
> Time_Slice(0.000001) etc., but none of this works.
> I have gnat for Linux.
>
> Jan
>