🚀 go-pugleaf

In article <19880314183759.3.JRD@GRACKLE.SCRC.Symbolics.COM> jrd@STONY-BROOK.SCRC.SYMBOLICS.COM (John R. Dunning) writes:
>I'm looking for hints on the 'right' way to do character output to the
>screen.  (the real goal is to figure out what stuff wants to go in my C
>library).  I've tried Bconout and Cconout, but both have their problems.
>Cconout observes Xon/Xoff, but is confused by things that redirect file
>handle 1 (0?, 2?), such as Gulam.  Bconout takes a dev, thus avoiding
>the redirected handle problem, but doesn't observe Xon/Xoff, or
>control-C.  Neither of those behaviours is acceptable.  I've also
>considered doing Fwrite's, scanning the buffer for newlines on TTY
>devices, but that seems like a fairly excessive amount of work; there
>ought to be an easier way.  I guess it's also possible to build my own
>Xon/Xoff handler, but, again, it seems like there ought to be an easier
>way.  Anybody got any hints on how this is done elsewhere?

The Fwrite call using handle 1 (STDOUT) is my recomendation.  Why do you
need to scan for new-lines?   Cconout has a bug that causes it to not
work correctly with redirection (Fforce).  Fwrite does not have this
bug.  If you use Bconout() then your program will never work with redirection.

>On a related topic, what's a good way to discover whether a handle is
>actually connected to a disk file, as opposed to the screen?

If you can seek the handle it is a file.  If you can't seek, all you know
is that you can't seek, and it probably is a device and the output was not
redirected (but it could be a pipe with RTX).  But you don't know that
the output is the screen, because somebody might be using your program
from a terminal or (with RTX) on a custom installed device. You should
try to avoid making assumtions here, especially if you want your program
to be usable with multiuser systems like MT C-Shell.  Fwrite() should
work OK in all the cases anyway, so you shouldn't really have to worry.

If RTX is running, there is a better way with the Ftype() system call
which tells you whether the handle points to a file, device, or pipe.
-- 
David Beckemeyer			| "To understand ranch lingo all yuh
Beckemeyer Development Tools		| have to do is to know in advance what
478 Santa Clara Ave, Oakland, CA 94610	| the other feller means an' then pay
UUCP: ...!ihnp4!hoptoad!bdt!david 	| no attention to what he says"