ch11.024_best

Perl Best Practices the source code

##############################################################################
##   Code fragment (Recommended) from Chapter 11 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 List::Util qw( max );

{
    # Make variables "private" by declaring them in a limited scope
    my @buffer;
    my $next = -1;
 
    # Get the next element stored in our cyclic buffer...
    sub get_next_cyclic {
        $next++;                   # ...increment cursor
        $next %= @buffer;          # ...wrap around if at end of array
        return $buffer[$next];     # ...return next element
    }
 
    # Grow the cyclic buffer by inserting new element(s)...
    sub insert_cyclic {
        # At next pos (or zero): remove zero elems, then insert args...
        splice @buffer, max(0,$next), 0, @_;  
 
        return;
    }
 
    # etc.
}

insert_cyclic(1,2,3);
while (<>) {
    print "next: ", get_next_cyclic();
}