Moose is an object framework for Perl that provides: 1) Full-featured object-oriented programming with attributes, inheritance, roles, and hooks 2) Powerful attribute features like types, defaults, builders, and more 3) A clean and stable API for defining and working with objects

1. Moose A postmodern metaclass-based object system for Perl 5

2. Objects in Perl 5 (a short intro) A blessed hashref

3. Manual new() method

4. 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'}; }

5. 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, );

6. Get it?

7. Defining an object in Moose use strict

8. use warnings

9. An object!

10. new() method

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

12. Full-Affordance accessors ' ro ' is also available for read-only attributes!

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

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

15. An attribute with type constraint Lots of types: Str , Int , ArrayRef , HashRef , CodeRef , Regexp

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

17. They have inheritance: Int is a Num

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

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

20. Inheritance is as easy as... Multiple inheritance is also possible, extends accepts an array package Punk; use Moose; extends 'Person'; 1; package Child; use Moose; extends qw/ Father Mother /; 1;