ch12.105_prob

来自「Perl Best Practices the source code」· 105_PROB 代码 · 共 31 行

##############################################################################
## 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;

Readonly my $ITEM => qr/\d/xms;
my $str = '(1,2,3,4,5,6,7,8,9,';

croak 'oops!' if 

$str =~ m{ [(]               # A literal opening paren
           $ITEM             # At least one item
           (?:               # Followed by...
               ,             #     a comma
               $ITEM         #     and another item
           )*                #  as many times as possible (but none is okay too)
           [)]               # A literal closing paren
         }xms;