[no subject]

CC: (BUG LISPM) at MIT-MC
    Date: Sat ,19 Apr 80 18:54:00 EDT
    From: HENRY at MIT-AI (Henry Lieberman)
    Subject:  errors
    To: (BUG LISPM) at MIT-AI

    What's a good way to divert error messages to a different 
    stream? The manual mentions an ERROR-OUTPUT stream, which 
    seems like a good idea, but seems not to be implemented.
    EH-SECOND-LEVEL binds STANDARD-OUTPUT to SYN-TERMINAL-IO, 
    binding that doesn't seem the way to go.
Well, ERROR-OUTPUT is supposed to work, but doesn't happen to.
Perhaps it will be fixed some day.  No one seems to have had a good
reason to use it yet.  Note that a reasonable thing to do is to
divert STANDARD-OUTPUT and or STANDARD-INPUT to be different from
TERMINAL-IO, which is supposed to be the stream over which all interaction
occurs.

There is also a global variable which you can use to divert error messages.
This is different from ERROR-OUTPUT in that it works for all processes rather
than being something a process can bind to affect just itself.  This variable
is called SI:ERROR-HANDLER-IO in the old window system and EH:ERROR-HANDLER-IO
in the new window system.  It takes effect if non-NIL.  Since this is for
all processes, it is normally used when debugging part of the system rather
than for "application" type use.