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From: jukoff@imram.net.com (Steve Jukoff)
Newsgroups: comp.lang.perl
Subject: Perl keyboard processing
Message-ID: <1357@unet.UUCP>
Date: 17 May 91 01:08:52 GMT
Article-I.D.: unet.1357
Sender: news@unet.UUCP
Organization: NET
Lines: 57

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>. 
2) I need to process all characters including:
   1) Control chars, and
   2) Special keyboard characters, i.e. UP-Arrow, HOME, etc.
3) I need "immediate flush mode" for the user prompt.
   (Something to do with select() but what I tried didn't work).

Here is a first try at the code.


# 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*
		$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 ; }

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

	}
	system "stty -raw" ; 
}	


I know this code is a rough draft.  Any help would be appreciated.


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Steven Jukoff                 DDN:   jukoff@net.com       
Phone: 415-780-5819           uucp:  ...!ames!unet!jukoff     
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