|Aspect::Library::Singleton(3pm)||User Contributed Perl Documentation||Aspect::Library::Singleton(3pm)|
Aspect::Library::Singleton - A singleton aspect
use Aspect; use Aspect::Singleton; aspect Singleton => 'Foo::new'; my $f1 = Foo->new; my $f2 = Foo->new; # Both $f1 and $f2 refer to the same object
A reusable aspect that forces singleton behavior on a constructor. The constructor is defined by a pointcut spec: a string. regexp, or code ref.
It is slightly different from "Class::Singleton" (<http://search.cpan.org/~abw/Class-Singleton/Singleton.pm>):
- No specific name requirement on the constructor for the external interface, or for the implementation ("Class::Singleton" requires clients use "instance()", and that subclasses override "_new_instance()"). With aspects, you can change the cardinality of your objects without changing the clients, or the objects themselves.
- No need to inherit from anything- use pointcuts to specify the constructors you want to memoize. Instead of pulling singleton behavior from a base class, you are pushing it in, using the aspect.
- No package variable or method is added to the callers namespace
Note that this is just a special case of memoizing.
Adam Kennedy <email@example.com>
Marcel Grünauer <firstname.lastname@example.org>
Ran Eilam <email@example.com>
Copyright 2001 by Marcel Grünauer
Some parts copyright 2009 - 2013 Adam Kennedy.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.