ch12.083_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';

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


use Data::Dumper 'Dumper';
warn Dumper [ $number ];