/usr/share/perl5/Aspect/Library/Singleton.pm is in libaspect-perl 1.04-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 | package Aspect::Library::Singleton;
use strict;
use Aspect::Modular ();
use Aspect::Advice::Before ();
use Aspect::Pointcut::Call ();
our $VERSION = '1.04';
our @ISA = 'Aspect::Modular';
my %CACHE = ();
sub get_advice {
my $self = shift;
Aspect::Advice::Around->new(
lexical => $self->lexical,
pointcut => Aspect::Pointcut::Call->new(shift),
code => sub {
my $class = $_->self;
$class = ref $class || $class;
if ( exists $CACHE{$class} ) {
$_->return_value($CACHE{$class});
} else {
$_->proceed;
$CACHE{$class} = $_->return_value;
}
},
);
}
1;
__END__
=pod
=head1 NAME
Aspect::Library::Singleton - A singleton aspect
=head1 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
=head1 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 C<Class::Singleton>
(L<http://search.cpan.org/~abw/Class-Singleton/Singleton.pm>):
=over
=item *
No specific name requirement on the constructor for the external
interface, or for the implementation (C<Class::Singleton> requires
clients use C<instance()>, and that subclasses override
C<_new_instance()>). With aspects, you can change the cardinality of
your objects without changing the clients, or the objects themselves.
=item *
No need to inherit from anything- use pointcuts to specify the
constructors you want to memoize. Instead of I<pulling> singleton
behavior from a base class, you are I<pushing> it in, using the aspect.
=item *
No package variable or method is added to the callers namespace
=back
Note that this is just a special case of memoizing.
=head1 AUTHORS
Adam Kennedy E<lt>adamk@cpan.orgE<gt>
Marcel GrE<uuml>nauer E<lt>marcel@cpan.orgE<gt>
Ran Eilam E<lt>eilara@cpan.orgE<gt>
=head1 COPYRIGHT
Copyright 2001 by Marcel GrE<uuml>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.
=cut
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