ch04.033_prob

Perl Best Practices the source code

##############################################################################
## Code fragment (NOT RECOMMENDED) from Chapter 4 of "Perl Best Practices"  ##
##     Copyright (c) O'Reilly & Associates, 2005. All Rights Reserved.      ##
##  See: http://www.oreilly.com/pub/a/oreilly/ask_tim/2001/codepolicy.html  ##
##############################################################################


# Standard modules...
use strict;
use warnings;
use IO::Prompt;
use Carp;
use English qw( -no_match_vars );
use Data::Alias;
use Readonly;

use constant VERBOSE => 1;

package Reveal;
sub desc { return 'reveal event' }

package Close;
sub desc  { return 'close event' }

package Quit;
sub desc   { return 'quit event' }

package main;

BEGIN {
    my @events = qw( Reveal Close Quit );

    sub get_next_event {
        return shift @events;
    }
}

EVENT:
while (1) {
    use constant EVENT => get_next_event();
    
    last EVENT if not defined EVENT;
    
    if (VERBOSE) {
        print EVENT->desc(), "\n";
    }
 
    # process event here...
}