ch13.043_prob

来自「Perl Best Practices the source code」· 043_PROB 代码 · 共 47 行

##############################################################################
## Code fragment (NOT RECOMMENDED) from Chapter 13 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 get_number {
    Readonly my $MAX_ALLOWED_VALUE => 10;
    my $num = 17;

    croak( "Numeric value $num too big (must be $MAX_ALLOWED_VALUE or less)" )
        if $num > $MAX_ALLOWED_VALUE;
}


# Get the next number...
my $value = eval { get_number() };
 
# If the attempt fails...
if (defined $EVAL_ERROR) {
    # If the candidate was considered too big, go with the maximum allowed...
    if ($EVAL_ERROR =~ m{ \A Numeric [ ] value [ ] \S+ [ ] too [ ] big }xms) {
        ($value) = $EVAL_ERROR =~ m{ must [ ] be [ ] (\S+) [ ] or [ ] less }xms;
    }
    # If the candidate was deemed too small, try it anyway...
    elsif ($EVAL_ERROR =~ m{ \A Numeric [ ] value [ ] (\S+) [ ] too [ ] small }xms) {
        $value = $1;
    }
    # Otherwise, rethrow the exception...
    else {
        croak( $EVAL_ERROR );
    }
}

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