Re: Adding streams for standard out and standard err

[Eli Zaretskii <eliz@gnu.org>]

> From: phillip.lord@russet.org.uk (Phillip Lord)
> Cc: emacs-devel@gnu.org
> Date: Thu, 21 Jul 2016 21:13:26 +0100
> 
> > Maybe that's all we need: a small wrapper around append-to-file.
> 
> Actually, adding a new stream was your idea...
> 
> http://lists.gnu.org/archive/html/help-gnu-emacs/2016-06/msg00207.html

It said "IF you want more flexibility".  It's not clear to me what
additional flexibility is being gained by your suggestions.

> Yes, you are probably correct, that append-to-file could be used,
> without resorting to new C primitives. However, all the functionality
> that we need is already in the C layer. Also append-to-file (or rather
> write-region) would need updating to not send messages.

Nowadays avoiding the message just needs to bind inhibit-message to a
non-nil value.

Anyway, this is a minor issue.  If I'm the only one who thinks new
primitives are unnecessary, then I won't fight the addition.  However,
if we do add them, perhaps we need to test the file descriptor for
validity and/or being different from the terminal output device, and
provide some helpful diagnostics if it isn't, because I don't really
believe in people being aware of the pitfalls.  E.g., I many times
"rediscover" the problem when I need to debug a TTY session of Emacs.