Mojo::Base(3) User Contributed Perl Documentation Mojo::Base(3)
NAME
Mojo::Base - Minimal base class for Mojo projects
SYNOPSIS
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;
DESCRIPTION
Mojo::Base is a simple base class for Mojo projects with fluent
interfaces.
# Automatically enables "strict", "warnings", "utf8" and Perl 5.16 features
use Mojo::Base -strict;
use Mojo::Base -base;
use Mojo::Base 'SomeBaseClass';
use Mojo::Base -role;
All four forms save a lot of typing. Note that role support depends on
Role::Tiny (2.000001+).
# use Mojo::Base -strict;
use strict;
use warnings;
use utf8;
use feature ':5.16';
use mro;
# use Mojo::Base -base;
use strict;
use warnings;
use utf8;
use feature ':5.16';
use mro;
push @ISA, 'Mojo::Base';
sub has { Mojo::Base::attr(__PACKAGE__, @_) }
# use Mojo::Base 'SomeBaseClass';
use strict;
use warnings;
use utf8;
use feature ':5.16';
use mro;
require SomeBaseClass;
push @ISA, 'SomeBaseClass';
sub has { Mojo::Base::attr(__PACKAGE__, @_) }
# use Mojo::Base -role;
use strict;
use warnings;
use utf8;
use feature ':5.16';
use mro;
use Role::Tiny;
sub has { Mojo::Base::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 -strict, -signatures;
use Mojo::Base -base, -signatures;
use Mojo::Base 'SomeBaseClass', -signatures;
use Mojo::Base -role, -signatures;
If you have Future::AsyncAwait 0.52+ installed you can also use the
"-async_await" flag to activate the "async" and "await" keywords to
deal much more efficiently with promises. Note that this feature is
EXPERIMENTAL and might change without warning!
# Also enable async/await
use Mojo::Base -strict, -async_await;
use Mojo::Base -base, -signatures, -async_await;
This will also disable experimental warnings on versions of Perl where
this feature was still experimental.
FLUENT INTERFACES
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 -base, -signatures;
has 'name';
sub quack ($self) {
my $name = $self->name;
say "$name: Quack!"
}
Mojo::Base 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.
Duck->new->name('Donald')->quack;
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.
FUNCTIONS
Mojo::Base implements the following functions, which can be imported
with the "-base" flag or by setting a base class.
has
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.
METHODS
Mojo::Base implements the following methods.
attr
$object->attr('name');
SubClass->attr('name');
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
weak => $bool
Weaken attribute reference to avoid circular references and memory
leaks.
new
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.
tap
$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');
with_roles
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;
SEE ALSO
Mojolicious(3), Mojolicious::Guides(3), <https://mojolicious.org>.
perl v5.32.1 2021-12-08 Mojo::Base(3)
mojolicious 9.260.0 - Generated Thu Jun 2 16:05:24 CDT 2022