The Perl Toolchain Summit needs more sponsors. If your company depends on Perl, please support this very important event.


Mojo::Base::Tiny - Minimal base class for !Mojo projects


  package Cat;
  use Mojo::Base::Tiny -base;

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

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

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

  package main;
  use Mojo::Base::Tiny -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::Tiny is a simple base class for Perl projects with fluent interfaces.

It is nothing else than Mojo::Base in a single file without dependencies outside the core modules (or to be correct, on Perl 5.20 and older you need Sub::Util 1.41). You can copy it directly to your project in all the "I can't (or don't want to) install Mojolicious" cases.

  # Automatically enables "strict", "warnings", "utf8" and Perl 5.16 features
  use Mojo::Base::Tiny -strict;
  use Mojo::Base::Tiny -base;
  use Mojo::Base::Tiny 'SomeBaseClass';
  use Mojo::Base::Tiny -role;

All four forms save a lot of typing. Note that role support depends on Role::Tiny (2.000001+).

  # use Mojo::Base::Tiny -strict;
  use strict;
  use warnings;
  use utf8;
  use feature ':5.16';
  use mro;

  # use Mojo::Base::Tiny -base;
  use strict;
  use warnings;
  use utf8;
  use feature ':5.16';
  use mro;
  push @ISA, 'Mojo::Base::Tiny';
  sub has { Mojo::Base::Tiny::attr(__PACKAGE__, @_) }

  # use Mojo::Base::Tiny 'SomeBaseClass';
  use strict;
  use warnings;
  use utf8;
  use feature ':5.16';
  use mro;
  require SomeBaseClass;
  push @ISA, 'SomeBaseClass';
  sub has { Mojo::Base::Tiny::attr(__PACKAGE__, @_) }

  # use Mojo::Base::Tiny -role;
  use strict;
  use warnings;
  use utf8;
  use feature ':5.16';
  use mro;
  use Role::Tiny;
  sub has { Mojo::Base::Tiny::attr(__PACKAGE__, @_) }

On Perl 5.20+ you can also use the -signatures flag with all four forms and enable support for subroutine signatures.

  # Also enable signatures
  use Mojo::Base::Tiny -strict, -signatures;
  use Mojo::Base::Tiny -base, -signatures;
  use Mojo::Base::Tiny 'SomeBaseClass', -signatures;
  use Mojo::Base::Tiny -role, -signatures;

If you want to activate the async and await keywords to deal much more efficiently with promises, it is finally time to move to a full Mojolicious installation and to use Mojo::Base.

  # async/await not available
  use Mojo::Base::Tiny -strict, -async_await;  # throws an error

This will also disable experimental warnings on versions of Perl where this feature was still experimental.


Fluent interfaces are a way to design object-oriented APIs around method chaining to create domain-specific languages, with the goal of making the readability of the source code close to written prose.

  package Duck;
  use Mojo::Base::Tiny -base;

  has 'name';

  sub quack {
    my $self = shift;
    my $name = $self->name;
    say "$name: Quack!"

Mojo::Base::Tiny will help you with this by having all attribute accessors created with "has" (or "attr") return their invocant ($self) whenever they are used to assign a new attribute value.


In this case the name attribute accessor is called on the object created by Duck->new. It assigns a new attribute value and then returns the Duck object, so the quack method can be called on it afterwards. These method chains can continue until one of the methods called does not return the Duck object.


Mojo::Base::Tiny 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 {...};
  has name => sub {...}, weak => 1;
  has name => undef, weak => 1;
  has ['name1', 'name2', 'name3'] => sub {...}, weak => 1;

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


Mojo::Base::Tiny 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 {...});
  SubClass->attr(name => sub {...}, weak => 1);
  SubClass->attr(name => undef, weak => 1);
  SubClass->attr(['name1', 'name2', 'name3'] => sub {...}, weak => 1);

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.

These options are currently available:

  weak => $bool

Weaken attribute reference to avoid circular references and memory leaks.


  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;


Mojo::Base, Mojolicious.


Sebastian Riedel -

William Lindley -

Maxim Vuets -

Joel Berger -

Jan Henning Thorsen -

Dan Book -

Elmar S. Heeb -

Dotan Dimet -

Zoffix Znet -

Ask Bjørn Hansen -

Tekki (Rolf Stöckli) -

Mohammad S Anwar -


© 2008–2019 Sebastian Riedel and others.

© 2019–2020 Tekki (Rolf Stöckli).

This program is free software, you can redistribute it and/or modify it under the terms of the Artistic License version 2.0.