I have a script that reads text files listed on the command line and slowly prints random paragraphs from them to stdout. I want to modify it so that instead of simply sleep, print, sleep until ctrl-break, it traps keystrokes and slows down or speeds up printing, turns on and off wrapping, quits, pauses, displays help, etc., based on the key pressed.

Theoretically Term::ReadKey should do this, from what I've read in various pages around the web and threads on this forum. However, this code and several variations I've tried are not working:

use Term::ReadKey;
use Time::HiRes qw(time);

#.......

sub slow_print {
    my $subscript = shift;
    my $para = $paras[ $subscript ];

    if ( $rewrap_margin ) {
    $para = &rewrap( $para );
    }

    my @lines = split /\n/, $para;
    foreach ( @lines ) {
    print $_ . "\n";
    my $thispause = $pause_len * length $_;

    ReadMode 3; # 'noecho';
    print STDERR "should be sleeping for $thispause secs\n"    if $deb
+ug;
    my $key;
    my $wait_until = time + $thispause;
    while ( time < $wait_until ) {
        $key = ReadKey( -1 );
        if ( defined $key ) {
        print STDERR "keystroke $key\t";
        &handle_keystroke( $key );
        }

    }
    }
    print "\n\n";
}

[download]

Whether I tap a key intermittently or hold something down indefinitely, $key never gets defined and handle_keystroke() never gets called; and echo isn't getting turned off, either, whether I pass 3 or 'noecho' to ReadMode. I'm using Perl v5.10.0 ("built for i486-linux-gnu-thread-multi") on Ubuntu 8.10 in a gnome-terminal (2.24.1) window.

I've tried several different things: doing a four-arg select to sleep before the call to ReadKey instead of a while loop checking highres time(); passing different mode values to ReadMode; passing 0 to ReadKey instead of -1; checking for 

while ( (not defined ($key = ReadKey( -1 ) ) ) and (time < $wait_until
+) ) 
{
}

[download]

as an empty loop... nothing seems to change its behavior, except for passing $this_pause to ReadKey, which theoretically should make ReadKey sleep that many seconds or until a key is pressed, but actually causes the script to scroll lines nonstop without a pause.

In reply to Problem with ReadKey by jimhenry

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