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#!/usr/bin/perl
use strict;
use warnings;
use Test::More;
{
package Subject;
use Moose::Role;
has observers => (
traits => ['Array'],
is => 'ro',
isa => 'ArrayRef[Observer]',
auto_deref => 1,
default => sub { [] },
handles => {
'add_observer' => 'push',
'count_observers' => 'count',
},
);
sub notify {
my ($self) = @_;
foreach my $observer ( $self->observers() ) {
$observer->update($self);
}
}
}
{
package Observer;
use Moose::Role;
requires 'update';
}
{
package Counter;
use Moose;
with 'Subject';
has count => (
traits => ['Counter'],
is => 'ro',
isa => 'Int',
default => 0,
handles => {
inc_counter => 'inc',
dec_counter => 'dec',
},
);
after qw(inc_counter dec_counter) => sub {
my ($self) = @_;
$self->notify();
};
}
{
package Display;
use Test::More;
use Moose;
with 'Observer';
sub update {
my ( $self, $subject ) = @_;
like $subject->count, qr{^-?\d+$},
'Observed number ' . $subject->count;
}
}
package main;
my $count = Counter->new();
ok( $count->can('add_observer'), 'add_observer method added' );
ok( $count->can('count_observers'), 'count_observers method added' );
ok( $count->can('inc_counter'), 'inc_counter method added' );
ok( $count->can('dec_counter'), 'dec_counter method added' );
$count->add_observer( Display->new() );
is( $count->count_observers, 1, 'Only one observer' );
is( $count->count, 0, 'Default to zero' );
$count->inc_counter;
is( $count->count, 1, 'Increment to one ' );
$count->inc_counter for ( 1 .. 6 );
is( $count->count, 7, 'Increment up to seven' );
$count->dec_counter;
is( $count->count, 6, 'Decrement to 6' );
$count->dec_counter for ( 1 .. 5 );
is( $count->count, 1, 'Decrement to 1' );
$count->dec_counter for ( 1 .. 2 );
is( $count->count, -1, 'Negative numbers' );
$count->inc_counter;
is( $count->count, 0, 'Back to zero' );
done_testing;
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