ch09.011_prob

Perl Best Practices the source code

##############################################################################
## Code fragment (NOT RECOMMENDED) from Chapter 9 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;

sub demo {
    use Fcntl ':flock'; # import LOCK_* constants

    my ($file, $text, $text_url);

    sub lock {
        my ($file) = @_; 
        return flock $file, LOCK_SH;
    }
    
    sub link {
        my ($text, $url) = @_;
        return qq{<a href="$url">$text</a>};
    }
    
    lock($file);                   # calls 'lock' subroutine; built-in 'lock' hidden
    print link($text, $text_url);  # calls built-in 'link'; 'link' subroutine hidden

}