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|
use strict;
use warnings;
use Test::More;
=pod
Some examples of triggers and how they can
be used to manage parent-child relationships.
=cut
{
package Parent;
use Moose;
has 'last_name' => (
is => 'rw',
isa => 'Str',
trigger => sub {
my $self = shift;
# if the parents last-name changes
# then so do all the childrens
foreach my $child ( @{ $self->children } ) {
$child->last_name( $self->last_name );
}
}
);
has 'children' =>
( is => 'rw', isa => 'ArrayRef', default => sub { [] } );
}
{
package Child;
use Moose;
has 'parent' => (
is => 'rw',
isa => 'Parent',
required => 1,
trigger => sub {
my $self = shift;
# if the parent is changed,..
# make sure we update
$self->last_name( $self->parent->last_name );
}
);
has 'last_name' => (
is => 'rw',
isa => 'Str',
lazy => 1,
default => sub { (shift)->parent->last_name }
);
}
my $parent = Parent->new( last_name => 'Smith' );
isa_ok( $parent, 'Parent' );
is( $parent->last_name, 'Smith',
'... the parent has the last name we expected' );
$parent->children( [ map { Child->new( parent => $parent ) } ( 0 .. 3 ) ] );
foreach my $child ( @{ $parent->children } ) {
is( $child->last_name, $parent->last_name,
'... parent and child have the same last name ('
. $parent->last_name
. ')' );
}
$parent->last_name('Jones');
is( $parent->last_name, 'Jones', '... the parent has the new last name' );
foreach my $child ( @{ $parent->children } ) {
is( $child->last_name, $parent->last_name,
'... parent and child have the same last name ('
. $parent->last_name
. ')' );
}
# make a new parent
my $parent2 = Parent->new( last_name => 'Brown' );
isa_ok( $parent2, 'Parent' );
# orphan the child
my $orphan = pop @{ $parent->children };
# and then the new parent adopts it
$orphan->parent($parent2);
foreach my $child ( @{ $parent->children } ) {
is( $child->last_name, $parent->last_name,
'... parent and child have the same last name ('
. $parent->last_name
. ')' );
}
isnt( $orphan->last_name, $parent->last_name,
'... the orphan child does not have the same last name anymore ('
. $parent2->last_name
. ')' );
is( $orphan->last_name, $parent2->last_name,
'... parent2 and orphan child have the same last name ('
. $parent2->last_name
. ')' );
# make sure that changes still will not propagate
$parent->last_name('Miller');
is( $parent->last_name, 'Miller',
'... the parent has the new last name (again)' );
foreach my $child ( @{ $parent->children } ) {
is( $child->last_name, $parent->last_name,
'... parent and child have the same last name ('
. $parent->last_name
. ')' );
}
isnt( $orphan->last_name, $parent->last_name,
'... the orphan child is not affected by changes in the parent anymore' );
is( $orphan->last_name, $parent2->last_name,
'... parent2 and orphan child have the same last name ('
. $parent2->last_name
. ')' );
done_testing;
|
