ch07.016_best

Perl Best Practices the source code

##############################################################################
##   Code fragment (Recommended) from Chapter 7 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;

Readonly my $EMPTY_STR => q{};

my $raw;
my @perl5pats;

sub addarray_internal {
    my ($var_name, $needs_quotemeta) = @_;
 
    # Record original...
    $raw .= $var_name;
 
    # Build meta-quoting code, if required...
    my $quotemeta = $needs_quotemeta ? 'map {quotemeta $_}'
                                     : $EMPTY_STR
                                     ;
 
    # Expand elements of variable, conjoin with ORs...
    my $perl5pat 
        = qq{(??{join q{|}, $quotemeta \@{$var_name}})};
 
    # Insert debugging code if requested...
    my $type = length $quotemeta ? 'literal' : 'pattern';
    debug_now("Adding $var_name (as $type)");
    add_debug_mesg("Trying $var_name (as $type)");
 
    # Add back-translation...
    push @perl5pats, $perl5pat;
 
    return;
}