add useful tool

tools/lib/JSON/backportPP/Boolean.pm

@@ -0,0 +1,44 @@
+package # This is JSON::backportPP
+    JSON::PP::Boolean;
+
+use strict;
+require overload;
+local $^W;
+overload::unimport('overload', qw(0+ ++ -- fallback));
+overload::import('overload',
+    "0+"     => sub { ${$_[0]} },
+    "++"     => sub { $_[0] = ${$_[0]} + 1 },
+    "--"     => sub { $_[0] = ${$_[0]} - 1 },
+    fallback => 1,
+);
+
+$JSON::backportPP::Boolean::VERSION = '4.12';
+
+1;
+
+__END__
+
+=head1 NAME
+
+JSON::PP::Boolean - dummy module providing JSON::PP::Boolean
+
+=head1 SYNOPSIS
+
+ # do not "use" yourself
+
+=head1 DESCRIPTION
+
+This module exists only to provide overload resolution for Storable and similar modules. See
+L<JSON::PP> for more info about this class.
+
+=head1 AUTHOR
+
+This idea is from L<JSON::XS::Boolean> written by Marc Lehmann <schmorp[at]schmorp.de>
+
+=head1 LICENSE
+
+This library is free software; you can redistribute it and/or modify
+it under the same terms as Perl itself.
+
+=cut
+