Perl: Recursive object instantiation with Moose - perl

Question

In the example code below, I am defining a class Person that can have child objects of the same class.
When I invoke the printTree method, I am expecting the following output
Sam Ram Geeta
What I see instead is
SamRamRamRamRamRamRamRamRamRamRamR.....
Any hints on what I am doing wrong and how to achieve my goal?
package Person;
use Moose;
has name => ( is => 'ro' );
my #kids;
sub addChild {
my ( $self, $name ) = #_;
my $k = Person->new( name => $name );
push #kids, $k;
return $k;
}
sub printTree {
my $self = shift;
print $self->name;
$_->printTree foreach ( #kids );
}
no Moose;
package main;
my $s = Person->new( name => "Sam" );
my $r = $s->addChild( "Ram" );
my $g = $s->addChild( "Geeta" );
$s->printTree;

Answer 1

The issue is that #Person::kids does not belong to any one instance, and you effectively end up with
#Person::kids = ($r, $g);
$s->printTree() loops through #Person::kids, calls
$r->printTree() loops through #Person::kids, calls
$r->printTree() loops through #Person::kids, calls
$r->printTree() loops through #Person::kids, calls
...
You need to make it an attribute, e.g.
has kids => (
isa => 'ArrayRef[Person]',
traits => ['Array'],
handles => {
all_kids => 'elements',
push_kids => 'push',
},
default => sub { [] },
);
sub addChild {
my ($self, $name) = #_;
my $k = Person->new(name => $name);
$self->push_kids($k);
return $k;
}
sub printTree {
my ($self) = #_;
print $self->name;
$_->printTree foreach $self->all_kids;
}
You can check perldoc Moose::Meta::Attribute::Native::Trait::Array for other useful handles from the Array trait.