---
name: "Aspect::Library::Singleton"
section: "3pm"
platform: "linux"
package: "libaspect-perl"
version: "1.04-3"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Aspect::Library::Singleton"
---

# Aspect::Library::Singleton(3pm)

A singleton aspect

## NAME

Aspect::Library::Singleton - A singleton aspect

## SYNOPSIS

```
  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
```

## DESCRIPTION

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.

## AUTHORS

Adam Kennedy \<adamk@cpan.org\>

Marcel Grünauer \<marcel@cpan.org\>

Ran Eilam \<eilara@cpan.org\>

## COPYRIGHT

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.