MixinFactory::NEXT(3pm) User Contributed Perl Documentation MixinFactory::NEXT(3pm)NAME
Class::MixinFactory::NEXT - Superclass method redispatch for mixins
SYNOPSIS
use Class::MixinFactory::NEXT;
package My::BaseClass;
sub foo { return "Foo Bar" }
package My::Logging;
sub foo { warn "Calling foo"; (shift)->NEXT('foo', @_) }
package My::MixedClass;
@ISA = ( 'My::Logging', 'My::BaseClass', 'Class::MixinFactory::NEXT'; );
package main;
print My::MixedClass->foo();
DESCRIPTION
Enhanced superclass method dispatch for use inside mixin class methods. Allows mixin classes to redispatch to other classes in the
inheritance tree without themselves inheriting from anything.
Public Methods
This package defines one method, named NEXT.
$callee->NEXT( $method, @args );
Searches the inheritance tree of the callee until it finds the package from which NEXT is being called, and then continues searching until
the next class which can perform the named method.
Unlike SUPER, this method will backtrack down the inheritance tree to find implementations later in the search path even if they are on a
separate branch.
SEE ALSO
This class is automatically included by Class::MixinFactory.
This is similar to the functionality provided by NEXT::ACTUAL, but without using AUTOLOAD; for a more generalized approach to this issue
see NEXT.
For distribution, installation, support, copyright and license information, see Class::MixinFactory::ReadMe.
perl v5.10.1 2009-12-10 MixinFactory::NEXT(3pm)
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MixinFactory(3pm) User Contributed Perl Documentation MixinFactory(3pm)NAME
Class::MixinFactory - Class Factory with Selection of Mixins
SYNOPSIS
package MyClass;
use Class::MixinFactory -hasafactory;
sub new { ... }
sub foo { return "Foo Bar" }
package MyClass::Logging;
sub foo { warn "Calling foo"; (shift)->NEXT('foo', @_) }
package MyClass::UpperCase;
sub foo { uc( (shift)->NEXT('foo', @_) ) }
package main;
my $class = MyClass->class( 'Logging', 'UpperCase' );
print $class->new()->foo();
# Calls MyClass::Logging::foo, MyClass::UpperCase::foo, MyClass::foo
DESCRIPTION
This distribution facilitates the run-time generation of classes which inherit from a base class and some optional selection of mixin
classes.
A factory is provided to generate the mixed classes with multiple inheritance. A NEXT method allows method redispatch up the inheritance
chain.
USAGE
The Class::MixinFactory package is just a facade that loads the necessary classes and provides a few import options for compile-time
convenience.
Factory Interface
To generate an object with some combination of mixins, you first pass the names of the mixin classes to a class factory which will generate
a mixed class. (Or return the name of the already generated class, if there has been a previous request with the same combination of
mixins.)
You can add a factory method to your base class, create a separate factory object, or inherit to produce a factory class.
Factory Method
To add a factory method to a base class, inherit from the Class::MixinFactory::HasAFactory class, or use the "-hasafactory" import
option:
package MyClass;
use Class::MixinFactory -hasafactory;
package main;
my $class = MyClass->class( 'Logging', 'UpperCase' );
print $class->new()->foo();
Factory Class
To create a new class which will act as a factory for another base class, inherit from the Class::MixinFactory::Factory class, or use
the "-isafactory" import option:
package MyClass::Factory;
use Class::MixinFactory -isafactory;
MyClass::Factory->base_class( "MyClass" );
package main;
my $class = MyClass::Factory->class( 'Logging', 'UpperCase' );
print $class->new()->foo();
Factory Object
To create an object which will act as a factory, create a Class::MixinFactory::Factory instance by calling the new() method:
use Class::MixinFactory;
my $factory = Class::MixinFactory->new();
$factory->base_class( "MyClass" );
my $class = $factory->class( 'Logging', 'UpperCase' );
print $class->new()->foo();
Inheriting from a Mixed Class
Inheriting with a Factory Method or Factory Object
A subclass can inherit from a mixed class:
package MyClass::CustomWidget;
@ISA = MyClass->class( 'Logging', 'UpperCase' );
sub foo { local $_ = (shift)->NEXT('foo', @_); tr[a-z][z-a]; $_ }
package main;
print MyClass::CustomWidget->new()->foo();
Inheriting with a Factory Class
A subclass can use a factory class to define its own inheritance:
package MyClass::CustomWidget;
use Class::MixinFactory -isasubclass,
MyClass::Factory => 'Logging', 'UpperCase';
sub foo { local $_ = (shift)->NEXT('foo', @_); tr[a-z][z-a]; $_ }
package main;
print MyClass::CustomWidget->new()->foo();
Configuring a Factory
Factories support methods that control which classes they will use.
The base class will be inherited from by all mixed classes.
$factory->base_class( "HelloWorld" );
The mixin prefix is prepended to the mixin names passed to the class() method. Mixin names that contain a "::" are assumed to be fully
qualified and are not changed. If empty, the base_class is used.
$factory->mixin_prefix( 'HelloFeature' );
The mixed prefix is at the start of all generated class names. If empty, the base_class is used, or the factory's class name.
$factory->mixed_prefix( 'HelloClass' );
Writing a Mixin Class
Writing a mixin class is almost the same as writing a subclass, except where methods need to redispatch to the base-class implementation.
(The SUPER::method syntax will only search for classes that the mixin itself inherits from; to search back up the inheritance tree and
explore other branches, another redispatch mechanism is needed.)
A method named NEXT is provided to continue the search through to the next class which provides a given method. The order in which mixins
are stacked is significant, so the caller should understand how their behaviors interact. (See Class::MixinFactory::NEXT.)
SEE ALSO
For distribution, installation, support, copyright and license information, see Class::MixinFactory::ReadMe.
perl v5.10.1 2009-12-10 MixinFactory(3pm)