ch12.082_prob

Perl Best Practices the source code

##############################################################################
## Code fragment (NOT RECOMMENDED) from Chapter 12 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;

my $input = '314.15926e-2';

# Build a regex that matches floating point representations...
Readonly my $DIGITS    =>  q{ (?: \d+ (?: [.] \d*)? | [.] \d+   ) };
Readonly my $SIGN      =>  q{ (?: [+-]                          ) };
Readonly my $EXPONENT  => qq{ (?: [Ee] $SIGN? \\d+              ) };
Readonly my $NUMBER    => qr{ ( ($SIGN?) ($DIGITS) ($EXPONENT?) ) }xms;

# and later...
 
my ($number, $sign, $digits, $exponent) 
    = $input =~ $NUMBER;

use Data::Dumper 'Dumper';
warn Dumper [ $number, $sign, $digits, $exponent ];