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

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?

8. use warnings

9. An object!

10. new() method

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

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', );

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(); }

23. after

24. around

25. inner

26. augment

27. 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', );

28. 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

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

30. 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

31. 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

32. 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

33. 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

34. 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

36. It's clean

37. It's stable

38. It's here to stay

40. More control

41. Roles / Traits <3

42. Extensions OMGZ!

43. MooseX::POE

44. MooseX::Getopt

45. MooseX::Declare

46. MooseX::Storage

47. ... sub { goto CPAN; }