--- /dev/null
+package experimental;
+$experimental::VERSION = '0.007';
+use strict;
+use warnings;
+
+use feature ();
+use Carp qw/croak carp/;
+
+my %warnings = map { $_ => 1 } grep { /^experimental::/ } keys %warnings::Offsets;
+my %features = map { $_ => 1 } keys %feature::feature;
+
+my %min_version = (
+ array_base => 5,
+ autoderef => 5.014000,
+ lexical_topic => 5.010000,
+ regex_sets => 5.018000,
+ smartmatch => 5.010001,
+ signatures => 5.019009, # change to 5.20.0 someday? -- rjbs, 2014-02-08
+);
+
+my %additional = (
+ postderef => ['postderef_qq'],
+ switch => ['smartmatch'],
+);
+
+sub _enable {
+ my $pragma = shift;
+ if ($warnings{"experimental::$pragma"}) {
+ warnings->unimport("experimental::$pragma");
+ feature->import($pragma) if exists $features{$pragma};
+ _enable(@{ $additional{$pragma} }) if $additional{$pragma};
+ }
+ elsif ($features{$pragma}) {
+ feature->import($pragma);
+ _enable(@{ $additional{$pragma} }) if $additional{$pragma};
+ }
+ elsif (not exists $min_version{$pragma}) {
+ croak "Can't enable unknown feature $pragma";
+ }
+ elsif ($min_version{$pragma} > $]) {
+ croak "Need perl version $min_version{$pragma} or later for feature $pragma";
+ }
+}
+
+sub import {
+ my ($self, @pragmas) = @_;
+
+ for my $pragma (@pragmas) {
+ _enable($pragma);
+ }
+ return;
+}
+
+sub _disable {
+ my $pragma = shift;
+ if ($warnings{"experimental::$pragma"}) {
+ warnings->import("experimental::$pragma");
+ feature->unimport($pragma) if exists $features{$pragma};
+ _disable(@{ $additional{$pragma} }) if $additional{$pragma};
+ }
+ elsif ($features{$pragma}) {
+ feature->unimport($pragma);
+ _disable(@{ $additional{$pragma} }) if $additional{$pragma};
+ }
+ elsif (not exists $min_version{$pragma}) {
+ carp "Can't disable unknown feature $pragma, ignoring";
+ }
+}
+
+sub unimport {
+ my ($self, @pragmas) = @_;
+
+ for my $pragma (@pragmas) {
+ _disable($pragma);
+ }
+ return;
+}
+
+1;
+
+#ABSTRACT: Experimental features made easy
+
+__END__
+
+=pod
+
+=encoding UTF-8
+
+=head1 NAME
+
+experimental - Experimental features made easy
+
+=head1 VERSION
+
+version 0.007
+
+=head1 SYNOPSIS
+
+ use experimental 'lexical_subs', 'smartmatch';
+ my sub foo { $_[0] ~~ 1 }
+
+=head1 DESCRIPTION
+
+This pragma provides an easy and convenient way to enable or disable
+experimental features.
+
+Every version of perl has some number of features present but considered
+"experimental." For much of the life of Perl 5, this was only a designation
+found in the documentation. Starting in Perl v5.10.0, and more aggressively in
+v5.18.0, experimental features were placed behind pragmata used to enable the
+feature and disable associated warnings.
+
+The C<experimental> pragma exists to combine the required incantations into a
+single interface stable across releases of perl. For every experimental
+feature, this should enable the feature and silence warnings for the enclosing
+lexical scope:
+
+ use experimental 'feature-name';
+
+To disable the feature and, if applicable, re-enable any warnings, use:
+
+ no experimental 'feature-name';
+
+The supported features, documented further below, are:
+
+ array_base - allow the use of $[ to change the starting index of @array
+ autoderef - allow push, each, keys, and other built-ins on references
+ lexical_topic - allow the use of lexical $_ via "my $_"
+ postderef - allow the use of postfix dereferencing expressions, including
+ in interpolating strings
+ regex_sets - allow extended bracketed character classes in regexps
+ signatures - allow subroutine signatures (for named arguments)
+ smartmatch - allow the use of ~~, given, and when
+
+=head2 Disclaimer
+
+Because of the nature of the features it enables, forward compatibility can not
+be guaranteed in any way.
+
+=head1 AUTHOR
+
+Leon Timmermans <leont@cpan.org>
+
+=head1 COPYRIGHT AND LICENSE
+
+This software is copyright (c) 2013 by Leon Timmermans.
+
+This is free software; you can redistribute it and/or modify it under
+the same terms as the Perl 5 programming language system itself.
+
+=cut
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