Re: redirecting the standard output

[Ted Dennison<dennison@telepath.com>]

In article <upuekpwjq.fsf@gsfc.nasa.gov>, Stephen Leake says...
>
>Backing up a bit, why do you want to do this? I can guess that you
>want to turn off some debugging output. It is _far_ better to define a
>Debug_IO package, with a Boolean or Integer debug enabled variable.
>Then have a style guide that says "Ada.Text_IO is _forbidden_ in
>delivered code; use Debug_IO if you need debug output".

We did something rather similar to this with our vxWorks program. We wrote a
"Log" package that takes in messages in a task-safe manner (using a queue to
prevent priority inversions), slaps a time stamp and severity level on them,
then outputs them to standard IO and to a log file. The standard IO part can be
turned off at runtime by tweaking a global variable (in vxWorks all exported
globals can be modified at the command line). Individual developers and
*strongly* discuraged from using Text_IO directly.

When using a RTOS, I'd expect everyone to develop something along these lines.
You can't deal with the random crashes and priority inversions that would be
caused by unrestrained IO calls in a real-time application.

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