Mojo::Base - Minimal base class for Mojo projects


package Cat;
use Mojo::Base -base;

has name => 'Nyan';
has ['age', 'weight'] => 4;

package Tiger;
use Mojo::Base 'Cat';

has friend  => sub { Cat->new };
has stripes => 42;

package main;
use Mojo::Base -strict;

my $mew = Cat->new(name => 'Longcat');
say $mew->age;
say $mew->age(3)->weight(5)->age;

my $rawr = Tiger->new(stripes => 38, weight => 250);
say $rawr->tap(sub { $_->friend->name('Tacgnol') })->weight;


Mojo::Base is a simple base class for Mojo projects with fluent interfaces.

# Automatically enables "strict", "warnings", "utf8" and Perl 5.10 features
use Mojo::Base -strict;
use Mojo::Base -base;
use Mojo::Base 'SomeBaseClass';

All three forms save a lot of typing.

# use Mojo::Base -strict;
use strict;
use warnings;
use utf8;
use feature ':5.10';
use IO::Handle ();

# use Mojo::Base -base;
use strict;
use warnings;
use utf8;
use feature ':5.10';
use IO::Handle ();
push @ISA, 'Mojo::Base';
sub has { Mojo::Base::attr(__PACKAGE__, @_) }

# use Mojo::Base 'SomeBaseClass';
use strict;
use warnings;
use utf8;
use feature ':5.10';
use IO::Handle ();
require SomeBaseClass;
push @ISA, 'SomeBaseClass';
sub has { Mojo::Base::attr(__PACKAGE__, @_) }


Mojo::Base implements the following functions, which can be imported with the -base flag or by setting a base class.


has 'name';
has ['name1', 'name2', 'name3'];
has name => 'foo';
has name => sub {...};
has ['name1', 'name2', 'name3'] => 'foo';
has ['name1', 'name2', 'name3'] => sub {...};

Create attributes for hash-based objects, just like the "attr" method.


Mojo::Base implements the following methods.


SubClass->attr(['name1', 'name2', 'name3']);
SubClass->attr(name => 'foo');
SubClass->attr(name => sub {...});
SubClass->attr(['name1', 'name2', 'name3'] => 'foo');
SubClass->attr(['name1', 'name2', 'name3'] => sub {...});

Create attribute accessors for hash-based objects, an array reference can be used to create more than one at a time. Pass an optional second argument to set a default value, it should be a constant or a callback. The callback will be executed at accessor read time if there's no set value, and gets passed the current instance of the object as first argument. Accessors can be chained, that means they return their invocant when they are called with an argument.


my $object = SubClass->new;
my $object = SubClass->new(name => 'value');
my $object = SubClass->new({name => 'value'});

This base class provides a basic constructor for hash-based objects. You can pass it either a hash or a hash reference with attribute values.


$object = $object->tap(sub {...});
$object = $object->tap('some_method');
$object = $object->tap('some_method', @args);

Tap into a method chain to perform operations on an object within the chain (also known as a K combinator or Kestrel). The object will be the first argument passed to the callback, and is also available as $_. The callback's return value will be ignored; instead, the object (the callback's first argument) will be the return value. In this way, arbitrary code can be used within (i.e., spliced or tapped into) a chained set of object method calls.

# Longer version
$object = $object->tap(sub { $_->some_method(@args) });

# Inject side effects into a method chain
$object->foo('A')->tap(sub { say $_->foo })->foo('B');


my $new_class = SubClass->with_roles('SubClass::Role::One');
my $new_class = SubClass->with_roles('+One', '+Two');
$object       = $object->with_roles('+One', '+Two');

Create a new class with one or more Role::Tiny roles. If called on a class returns the new class, or if called on an object reblesses the object into the new class. For roles following the naming scheme MyClass::Role::RoleName you can use the shorthand +RoleName. Note that role support depends on Role::Tiny (2.000001+).

# Create a new class with the role "SubClass::Role::Foo" and instantiate it
my $new_class = SubClass->with_roles('+Foo');
my $object    = $new_class->new;


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