Aspect::Library::Singleton - A singleton aspect
use Aspect::Singleton; aspect Singleton => 'Foo::new'; my $f1 = Foo->new; my $f2 = Foo->new; # now $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
No specific name requirement on the constructor for the external interface, or for the implementation (
Class::Singletonrequires 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.
See the Aspect pods for a guide to the Aspect module.
You can find an example comparing the OO and AOP solutions in the
examples/ directory of the distribution.