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From: tchrist@convex.COM (Tom Christiansen)
Newsgroups: comp.lang.perl
Subject: Re: Perl keyboard processing
Message-ID: <1991May18.211524.24055@convex.com>
Date: 18 May 91 21:15:24 GMT
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Reply-To: tchrist@convex.COM (Tom Christiansen)
Organization: CONVEX Software Development, Richardson, TX
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From the keyboard of jukoff@imram.net.com (Steve Jukoff):
:This perl script is simply a loop to read and process keyboard input.
:Some tricky problems arise:
:
:1) I'd like a "read" routine to immediately process each character;
:   I don't want the user to be required to hit <return>. 

stty cbreak, or raw, or whatever sysV wants you to incant.

:2) I need to process all characters including:
:   1) Control chars, and

easy.

:   2) Special keyboard characters, i.e. UP-Arrow, HOME, etc.

not too easy.

:3) I need "immediate flush mode" for the user prompt.
:   (Something to do with select() but what I tried didn't work).

you have the wrong handle.

:# user_input is a "switch" to process keyboard input
:sub user_input {
:	open (TTY, "/dev/tty") || die "Can't open /dev/tty" ;
:
:	# Perl idiom to force a per-write flush on FILEHANDLE --  Doesn't 
:	# seem to work. 
:	select((select(TTY), $| = 1)[$[]) ;		
:
:	# Needed: immediately process single character input 
:
:	# Set "non-canonical mode": do not (pre-)interpret control chars
:	# system "stty raw"; 
:	# works but now I need to know how to match control chars.  

:	# And I need to catch signals in order to reset the terminal.
:
:	for (;;) {
:		print "Enter choice: " ;		# Needed: print *unbuffered*

you unbuffered TTY, not STDOUT.  make sure not to use the same handle
for both in and out though.  this idiom is open seen:

	open (TTYIN,  "</dev/tty") || die "Can't open /dev/tty" ;
	open (TTYOUT, ">/dev/tty") || die "Can't open /dev/tty" ;

and then unbuffer TTYOUT as before.

:		$char = getc(TTY) ;
:
:		# A Perl switch construct 
:		# Needed: capability to match control chars
:		# and special keyboard characters, i.e. DOWN-ARROW, END, etc.
:		$char =~ /\D+/ && do { print "non-digit entered\n" ; next ; } ;
:
:		$char =~ /\d+/ && do { print "digit entered\n" ; next ; } 
:
:# (?)	$char =~ /#Control-X#/ && do { print "Control-X entered\n" ; next ; }

Using octal escapes is probably easiest.

    char eq "\030" &&  do { print "Control-X entered\n" ; |

(You probably want equality not /pattern/ tests.)

:
:# (?)	$char =~ /#UP-ARROW#/ && do { print "Up-arrow entered\n" ; next ; }

Much harder.  These are multi-char sequences.  You should probably parse
the current termcap to figure out what "up" really is, since "\033OA"
is probably a bad assumption.

--tom
--
Tom Christiansen		tchrist@convex.com	convex!tchrist
		"So much mail, so little time."