Moose A postmodern metaclass-based object system for Perl 5

Manual new() method

No real attributes bless {}, __PACKAGE__; sub new { my ( $class, @args ) = @_; my $self = { @args }; # params bless $self, $class; return $self; } sub name { my ( $self, $name ) = @_; $name and $self->{'name'} = $name; return $self->{'name'}; }

Why would you want to use Moose? Moose package Person; use strict; use warnings; use Carp qw( confess ); use DateTime; use DateTime::Format::Natural; sub new { my $class = shift; my %p = ref $_[0] ? %{ $_[0] } : @_; exists $p{name} or confess 'name is a required attribute'; $class->_validate_name( $p{name} ); exists $p{birth_date} or confess 'birth_date is a required attribute'; $p{birth_date} = $class->_coerce_birth_date( $p{birth_date} ); $class->_validate_birth_date( $p{birth_date} ); $p{shirt_size} = 'l' unless exists $p{shirt_size}: $class->_validate_shirt_size( $p{shirt_size} ); return bless p, $class; } sub _validate_name { shift; my $name = shift; local $Carp::CarpLevel = $Carp::CarpLevel + 1; defined $name or confess 'name must be a string'; } Plain old Perl 5 package User; use Email::Valid; use Moose; use Moose::Util::TypeConstraints; extends 'Person'; subtype 'Email' => as 'Str' => where { Email::Valid->address($_) } => message { "$_ is not a valid email address" }; has email_address => ( is => 'rw', isa => 'Email', required => 1, );

Get it?

use warnings

An object!

new() method

A pon-.. err.. a moose! package User; use Moose; 1; You get:

You can set the getter or setter manually via reader / writer

I'll show more attribute options later on has name => ( is => 'rw', );

You can combine: ArrayRef[Str] , HashRef[ArrayRef[Int]]

They have inheritance: Int is a Num

Roll your own using subtype package User; use Moose; has name => ( is => 'rw', isa => 'Str', ); 1;

Methods are the same as before sub method { my $self = shift; ... $self->more(); }

after

around

inner

augment

Back to attributes options... has set => ( is => 'rw', isa => 'Set::Object', default => sub { Set::Object->new }, required => 1, lazy => 1, predicate => 'has_set', clearer => 'clear_set', builder => 'build_set', );

Attribute options default => 'kitteh', # string default => 3, # number default => sub { {} }, # HashRef default => sub { [] }, # ArrayRef default => sub { Object->new }, # an Object etc. etc. (if you need a more elaborate sub, use builder ) default

Attribute options required => 1, # required required => 0, # not required required

Attribute options lazy => 1, # make it lazy Class will not create the slot for this attribute unless it absolutely has to. That is defined by whether it is accessed at all. Wasn't accessed? You don't pay the penalty! :) lazy = good lazy

Attribute options builder => 'build_it', # subroutine name sub build_it { my $self = shift; # not a problem! return Some::Object->new( $self->more_opts, ); } # and, obviously... after build_it => sub { “they will come” }; (a builder sets the value of the attribute) builder

Attribute options clearer => 'clear_it', # subroutine name # you don't need to create the subroutine sub time_machine { my $self = shift; $self->clear_it; # 'it' never happened :) } (a clearer clears the attribute, not just the value) clearer

Attribute options predicate => 'has_it', # subroutine name # you don't need to create the subroutine sub try_to_do_it { my $self = shift; $self->has_it && $self->do_it(); } (a predicate checks an attribute exists) (even false values) (which is good!) predicate

Attribute options lazy_build => 1, # <3 # the same as: lazy => 1, builder => '_build_it', # private clearer => 'clear_it', predicate => 'has_it', ( lazy_build is recommended) lazy_build

It's clean

It's stable

It's here to stay

More control

Roles / Traits <3

Extensions OMGZ!

MooseX::POE

MooseX::Getopt

MooseX::Declare

MooseX::Storage

... sub { goto CPAN; }