How can I implement a singleton class in perl?

Question

What's the best practice for implementing Singletons in Perl?

Answer 1

You can use the Class::Singleton module.

A "Singleton" class can also be easily implemented using either my or state variable (the latter is available since Perl 5.10). But see the @Michael's comment below.

package MySingletonClass;
use strict;
use warnings;
use feature 'state';

sub new {
    my ($class) = @_;
    state $instance;

    if (! defined $instance) {
        $instance = bless {}, $class;
    }
    return $instance;
}