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OO Perl with Moose Nelo Onyiah

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OO Perl with Moose What is Moose?

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OO Perl with Moose What is Moose? Moose is a postmodern object system for Perl 5 that takes the tedium out of writing object-oriented Perl. It borrows all the best features from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, while still keeping true to its Perl 5 roots.

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OO Perl with Moose Why Moose?

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OO Perl with Moose Why Moose? ● makes Perl 5 OO both simpler and more powerful

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OO Perl with Moose Why Moose? ● makes Perl 5 OO both simpler and more powerful ● define your class declaratively

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OO Perl with Moose Why Moose? ● makes Perl 5 OO both simpler and more powerful ● define your class declaratively ● offers "sugar" for object construction, attributes, e.t.c

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OO Perl with Moose Why Moose? ● makes Perl 5 OO both simpler and more powerful ● define your class declaratively ● offers "sugar" for object construction, attributes, e.t.c ● don't need to care how they are implemented

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OO Perl with Moose Why Moose? ● makes Perl 5 OO both simpler and more powerful ● define your class declaratively ● offers "sugar" for object construction, attributes, e.t.c ● don't need to care how they are implemented ● concentrate on the logical structure of your classes

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OO Perl with Moose Why Moose? ● makes Perl 5 OO both simpler and more powerful ● define your class declaratively ● offers "sugar" for object construction, attributes, e.t.c ● don't need to care how they are implemented ● concentrate on the logical structure of your classes ● don't need to be a wizard to use it

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OO Perl with Moose Why Moose? ● makes Perl 5 OO both simpler and more powerful ● define your class declaratively ● offers "sugar" for object construction, attributes, e.t.c ● don't need to care how they are implemented ● concentrate on the logical structure of your classes ● don't need to be a wizard to use it ● but if you are, lets you dig about in the guts and extend it

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OO Perl with Moose package Person; 1; To make a class you start with a package

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OO Perl with Moose package Person; use Moose; 1; To make a class you start with a package and just use Moose

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OO Perl with Moose package Person; use Moose; 1; This is a complete class definition

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OO Perl with Moose package Person; use Moose; 1; This is a complete class definition not terribly useful though

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OO Perl with Moose package Person; use Moose; 1; Under the hood Moose is doing a lot

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OO Perl with Moose package Person; use Moose; 1; Under the hood Moose is doing a lot (won't go into that though)

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OO Perl with Moose package Person; use Moose; 1; Classes have zero or more attributes

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OO Perl with Moose package Person; use Moose; has 'birth_date' => ( ); 1; Attributes are declared using the has function

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OO Perl with Moose package Person; use Moose; has 'birth_date' => ( ); 1; Attributes are declared using the has function Attributes have properties

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OO Perl with Moose package Person; use Moose; has 'birth_date' => ( ); 1; Attributes are declared using the has function Attributes have properties probably the most powerful feature of Moose

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OO Perl with Moose package Person; use Moose; has 'birth_date' => ( ); 1; Can be provided with accessors

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OO Perl with Moose package Person; use Moose; has 'birth_date' => ( is => 'rw', ); 1; Can be provided with accessors by stating that attribute is read-writeable

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OO Perl with Moose package Person; use Moose; has 'birth_date' => ( is => 'ro', ); 1; or read-only

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OO Perl with Moose package Person; use Moose; has 'birth_date' => ( is => 'ro', writer => '_set_birth_date', ); 1; or you can provide your own reader and/or writer

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OO Perl with Moose package Person; use Moose; has 'birth_date' => ( is => 'ro', isa => 'Str', ); 1; You can specify a type for your attribute

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OO Perl with Moose package Person; use Moose; has 'birth_date' => ( is => 'ro', isa => 'Str', ); 1; Only values that pass the type check will be accepted for the attribute

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OO Perl with Moose package Person; use Moose; has 'birth_date' => ( is => 'ro', isa => 'Str', ); 1; Built in types include: ● Str ● Num ● ArrayRef ● CodeRef ● Any ● more ...

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OO Perl with Moose package Person; use Moose; use DateTime; has 'birth_date' => ( is => 'ro', isa => 'DateTime', ); 1; Class names are treated as types

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OO Perl with Moose package Person; use Moose; use Moose::Util::TypeConstraints; use DateTime; subtype 'ModernDateTime' has 'birth_date' => ( is => 'ro', isa => 'DateTime', ); 1; You can create your own types

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OO Perl with Moose package Person; use Moose; use Moose::Util::TypeConstraints; use DateTime; subtype 'ModernDateTime' => as 'DateTime' has 'birth_date' => ( is => 'ro', isa => 'DateTime', ); 1; You can create your own types from existing types

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OO Perl with Moose package Person; use Moose; use Moose::Util::TypeConstraints; use DateTime; subtype 'ModernDateTime' => as 'DateTime' => where { $_->year >= 2000 }; has 'birth_date' => ( is => 'ro', isa => 'DateTime', ); 1; You can create your own types from existing types and apply your own constraints on them

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OO Perl with Moose package Person; use Moose; use Moose::Util::TypeConstraints; use DateTime; subtype 'ModernDateTime' => as 'DateTime' => where { $_->year >= 2000 }; has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', ); 1; You can create your own types from existing types and apply your own constraints on them and use them

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OO Perl with Moose package Person; use Moose; use Moose::Util::TypeConstraints; use DateTime; subtype 'ModernDateTime' => as 'DateTime' => where { $_->year >= 2000 }; has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', ); 1; You can also coerce one type into another

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OO Perl with Moose package Person; use Moose; use Moose::Util::TypeConstraints; use DateTime; subtype 'ModernDateTime' => as 'DateTime' => where { $_->year >= 2000 }; has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', ); 1; See Moose::Manual::Types for more details

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OO Perl with Moose package Person; use Moose; use Moose::Util::TypeConstraints; use DateTime; subtype 'ModernDateTime' => as 'DateTime' => where { $_->year >= 2000 }; has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', ); 1; A person with no birth date seems odd

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OO Perl with Moose package Person; use Moose; use Moose::Util::TypeConstraints; use DateTime; subtype 'ModernDateTime' => as 'DateTime' => where { $_->year >= 2000 }; has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', required => 1, ); 1; A person with no birth date seems odd so it can be made compulsary with the required flag

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OO Perl with Moose package Person; use Moose; use Moose::Util::TypeConstraints; use DateTime; subtype 'ModernDateTime' => as 'DateTime' => where { $_->year >= 2000 }; has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', required => 1, default => '2000-01-01', ); 1; You can also set default values for the attribute

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OO Perl with Moose package Person; use Moose; use Moose::Util::TypeConstraints; use DateTime; subtype 'ModernDateTime' => as 'DateTime' => where { $_->year >= 2000 }; has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', required => 1, default => sub { DateTime->now }, ); 1; Complex defaults need to be set in a sub ref

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OO Perl with Moose package Person; use Moose; # subtype ... has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', required => 1, builder => '_build_birth_date', ); sub _build_birth_date { DateTime->now; } 1; or you could write a separate builder method

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OO Perl with Moose package Person; use Moose; # subtype ... has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', required => 1, builder => '_build_birth_date', lazy => 1, ); sub _build_birth_date { DateTime->now; } 1; and make it lazy

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OO Perl with Moose package Person; use Moose; # subtype ... has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', required => 1, lazy_build => 1, ); sub _build_birth_date { DateTime->now; } 1; or in one step

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OO Perl with Moose package Person; use Moose; # subtype ... has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', required => 1, lazy_build => 1, handles => { birth_year => 'year' }, ); sub _build_birth_date { DateTime->now; } 1; Attributes handle delegation

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OO Perl with Moose package Person; use Moose; # subtype ... has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', required => 1, lazy_build => 1, handles => { birth_year => 'year' }, ); sub _build_birth_date { DateTime->now; } 1; Attributes handle delegation Calling $person- >birth_year delegates to $person->birth_date->year

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OO Perl with Moose package Person; use Moose; # subtype ... has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', required => 1, lazy_build => 1, handles => { birth_year => 'year' }, ); sub _build_birth_date { DateTime->now; } 1; Delegation is one option to inheritance

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OO Perl with Moose package Person; use Moose; # subtype ... has 'birth_date' => ( is => 'ro', isa => 'ModernDateTime', required => 1, lazy_build => 1, handles => { birth_year => 'year' }, ); sub _build_birth_date { DateTime->now; } 1; Delegation is one option to inheritance Especially when inheriting from non-Moose based classes

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OO Perl with Moose package Employee; use Moose; extends qw( Person ); 1; Inheritance is achieved with the extends function

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OO Perl with Moose package Employee; use Moose; extends qw( Person ); 1; Inheritance is achieved with the extends function Moose supports multiple inheritance

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OO Perl with Moose package Employee; use Moose; extends qw( Person ); 1; Inheritance is achieved with the extends function Moose supports multiple inheritance just pass more class names to extends

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OO Perl with Moose package Employee; use Moose; extends qw( Person ); override '_build_birth_date' => sub { # ... } 1; Override parent methods with the override function

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OO Perl with Moose package Employee; use Moose; extends qw( Person ); override '_build_birth_date' => sub { # ... super(); } 1; Call the parent method with the super function

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OO Perl with Moose package Employee; use Moose; extends qw( Person ); has '+birth_date' => ( # ... ); 1; You can also override attributes

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OO Perl with Moose package Employee; use Moose; extends qw( Person ); has '+birth_date' => ( # ... ); 1; You can also override attributes (carefully)

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OO Perl with Moose package Science; 1; Moose also has a concept of roles

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OO Perl with Moose package Science; use Moose::Role; 1; Moose also has a concept of roles Declared by using Moose:: Role

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OO Perl with Moose package Science; use Moose::Role; 1; Similar to Smalltalk traits, Ruby Mixins and Java interfaces

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OO Perl with Moose package Science; use Moose::Role; 1; Similar to Smalltalk traits, Ruby Mixins and Java interfaces Most similar to Perl 6 Roles

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OO Perl with Moose package Science; use Moose::Role; 1; A collection of reusable traits (attributes)

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OO Perl with Moose package Science; use Moose::Role; has 'speciality' => ( # ... ); 1; A collection of reusable traits (attributes)

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OO Perl with Moose package Science; use Moose::Role; has 'speciality' => ( # ... ); sub research { # ... } 1; A collection of reusable traits (attributes) and behaviour (methods)

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OO Perl with Moose package Science; use Moose::Role; has 'speciality' => ( # ... ); sub research { # ... } 1; Roles are not classes

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OO Perl with Moose package Science; use Moose::Role; has 'speciality' => ( # ... ); sub research { # ... } 1; Roles are not classes ● cannot instantiate a role

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OO Perl with Moose package Science; use Moose::Role; has 'speciality' => ( # ... ); sub research { # ... } 1; Roles are not classes ● cannot instantiate a role ● cannot inherit from a role

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OO Perl with Moose package Science; use Moose::Role; has 'speciality' => ( # ... ); sub research { # ... } 1; Roles are another option to inheritance

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OO Perl with Moose package Science; use Moose::Role; has 'speciality' => ( # ... ); sub research { # ... } 1; Roles are composed into consuming classes/roles

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OO Perl with Moose package Science; use Moose::Role; has 'speciality' => ( # ... ); sub research { # ... } 1; Roles are composed into consuming classes/roles Attributes and methods from role are flattened into consuming class/role

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OO Perl with Moose package Science; use Moose::Role; has 'speciality' => ( # ... ); sub research { # ... } 1; Roles can insist that consuming classes implement certain methods

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OO Perl with Moose package Science; use Moose::Role; requires qw( research ); has 'speciality' => ( # ... ); 1; Roles can insist that consuming classes implement certain methods Use the requires function

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OO Perl with Moose package Science; use Moose::Role; requires qw( research ); has 'speciality' => ( # ... ); 1; Roles can insist that consuming classes implement certain methods Use the requires function Consuming classes must now implement the research function

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } 1; Roles are consumed into classes by using the with keyword

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } 1; Roles are consumed into classes by using the with keyword More than one role can be consumed into a class

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } 1; Roles are consumed into classes by using the with keyword More than one role can be consumed into a class just pass more roles to with

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } 1; Class methods and attributes are prioritized

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } 1; Class methods and attributes are prioritized Conflicts are resolved at compile time

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } 1; See Moose::Manual::Roles for details

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } 1; Moose is not perfect

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } 1; Moose is not perfect Biggest caveat is start up time

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } 1; Moose is not perfect Biggest caveat is start up time Actively being worked on

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } 1; Moose is not perfect Biggest caveat is start up time Actively being worked on But you can help

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } __PACKAGE__->meta->make_immutable(); 1; Make your classes immutable

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } __PACKAGE__->meta->make_immutable(); 1; Make your classes immutable This lets Moose create an inline constructor for your class

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } __PACKAGE__->meta->make_immutable(); 1; Make your classes immutable This lets Moose create an inline constructor for your class Greatly speeding up start up time

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } __PACKAGE__ ->meta->make_immutable(); 1; Also you are adviced to clean up after your class i.e remove all Moose sugar from packages using your classes

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OO Perl with Moose package Scientist; use Moose; extends qw( Person ); with qw( Science ); sub research { ... } __PACKAGE__ ->meta->make_immutable(); no Moose; 1; Also you are adviced to clean up after your class i.e remove all Moose sugar from packages using your classes

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OO Perl with Moose package Scientist; use Moose; use namespace::clean -except => [qw( meta )]; extends qw( Person ); with qw( Science ); sub research { ... } __PACKAGE__ ->meta->make_immutable(); 1; Also you are adviced to clean up after your class i.e remove all Moose sugar from packages using your classes Alternatively

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OO Perl with Moose ● Moose is also extensible

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OO Perl with Moose ● Moose is also extensible ● Done by manipulating metaclass objects

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OO Perl with Moose ● Moose is also extensible ● Done by manipulating metaclass objects ● This is where the wizards roam free

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OO Perl with Moose ● Moose is also extensible ● Done by manipulating metaclass objects ● This is where the wizards roam free ● A lot of extensions exist in the MooseX:: namespace

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OO Perl with Moose ● Moose is also extensible ● Done by manipulating metaclass objects ● This is where the wizards roam free ● A lot of extensions exist in the MooseX:: namespace ● New ideas usually start life here

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OO Perl with Moose ● Moose is also extensible ● Done by manipulating metaclass objects ● This is where the wizards roam free ● A lot of extensions exist in the MooseX:: namespace ● New ideas usually start life here ● Good ones get incorporated into Moose

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OO Perl with Moose ● Moose is also extensible ● Done by manipulating metaclass objects ● This is where the wizards roam free ● A lot of extensions exist in the MooseX:: namespace ● New ideas usually start life here ● Good ones get incorporated into Moose ● An example is MooseX::AttributeHelpers

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OO Perl with Moose ● Moose is also extensible ● Done by manipulating metaclass objects ● This is where the wizards roam free ● A lot of extensions exist in the MooseX:: namespace ● New ideas usually start life here ● Good ones get incorporated into Moose ● An example is MooseX::AttributeHelpers ● These were incorporated in the Moose::Meta::Attribute:: Native namespace

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OO Perl with Moose package Person; use Moose; use namespace::clean -except => [qw( meta )]; # attributes and methods __PACKAGE__->meta->make_immutable(); 1; Lastly you will note that Moose introduces its own boiler plate code

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OO Perl with Moose package Person; use Moose; use namespace::clean -except => [qw( meta )]; # attributes and methods __PACKAGE__->meta->make_immutable(); 1; Lastly you will note that Moose introduces its own boiler plate code There is an extension that reduces this

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OO Perl with Moose package Person; use Moose; use namespace::clean -except => [qw( meta )]; # attributes and methods __PACKAGE__->meta->make_immutable(); 1; Lastly you will note that Moose introduces its own boiler plate code There is an extension that reduces this MooseX::Declare

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OO Perl with Moose use MooseX::Declare; class Person { # attributes and methods } Declaring classes becomes even more declarative

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OO Perl with Moose use MooseX::Declare; class Person { # attributes and methods } Combines the power of Moose with Devel::Declare to produce keywords for Perl 5 written in Perl 5

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OO Perl with Moose use MooseX::Declare; class Person { # attributes and methods method research() { ... } } Combines the power of Moose with Devel::Declare to produce keywords for Perl 5 written in Perl 5 Keywords include class, role, method

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OO Perl with Moose use MooseX::Declare; class Person { # attributes and methods method research() { ... } } Combines the power of Moose with Devel::Declare to produce keywords for Perl 5 written in Perl 5 Keywords include class, role, method Note that the methods have signatures complete with type checking

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OO Perl with Moose use MooseX::Declare; class Person { # attributes and methods method research() { ... } } Combines the power of Moose with Devel::Declare to produce keywords for Perl 5 written in Perl 5 Keywords include class, role, method Note that the methods have signatures complete with type checking So using MooseX::Declare the Scientist class example could look like the following:

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OO Perl with Moose use MooseX::Declare; class Scientist extends Person with Science { use Duration; # fictional class one could write has 'funding' => ( is => 'rw', isa => 'Num', lazy_build => 1, ); method research( Duration $contract_duration ) { unless ( $self->has_funding ) { confess 'need funding to work'; } while ( not $contract_duration->expired ) { # do your research ... } } }

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Thank you Questions?