Aspect::Library::Singleton (3pm)

  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 \*(C`Class::Singleton\*(C' (http://search.cpan.org/~abw/Class-Singleton/Singleton.pm <http://search.cpan.org/~abw/Class-Singleton/Singleton.pm>):

• No specific name requirement on the constructor for the external interface, or for the implementation (\*(C`Class::Singleton\*(C' requires clients use \*(C`instance()\*(C', and that subclasses override \*(C`_new_instance()\*(C'). 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 protected]>

Marcel Gru\*:nauer <[email protected]>

Ran Eilam <[email protected]>

Copyright 2001 by Marcel Gru\*:nauer

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.