ch09.078_prob

来自「Perl Best Practices the source code」· 078_PROB 代码 · 共 67 行

##############################################################################
## Code fragment (NOT RECOMMENDED) from Chapter 9 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;




use Contextual::Return;
 
sub guesstimate {
    my ($criterion) = @_;
 
    my @estimates;
    my $failed = 1;
 
    # [Acquire data for specified criterion]

 
    if ($failed) {
        return (
            LIST   { ()    }
            SCALAR { undef }
        );
    }

 
    # [Do guesswork based on the acquired data]
 
    # Return all guesses in list context or average guess in scalar context...
    return (
        LIST   { @estimates if wantarray;    }
        SCALAR { sum(@estimates)/@estimates; }
    );
}


if (my @melt_rates = guesstimate('polar melting')) {
    my $model = Std::Climate::Model->new({ polar_melting => \@melt_rates });
 
    for my $interval (1,2,5,10,50,100,500) {
        print $model->predict({ year => $interval })
    }
}


package Std::Climate::Model;

sub new {
    my ($class, $arg_ref) = @_;
    print "Melt rate: ", @{$arg_ref->{polar_melting}}, "\n";
    return __PACKAGE__;
}

sub predict {}