import UNIVERSAL-isa 0.03 from CPAN

git-cpan-module:   UNIVERSAL-isa
git-cpan-version:  0.03
git-cpan-authorid: NUFFIN
git-cpan-file:     authors/id/N/NU/NUFFIN/UNIVERSAL-isa-0.03.tar.gz

META.yml

@@ -1,6 +1,6 @@
 ---
 name: UNIVERSAL-isa
-version: 0.02
+version: 0.03
 author: ~
 abstract: |-
   Hack around stupid module authors using UNIVERSAL::isa as a
@@ -12,5 +12,5 @@ requires:
 provides:
   UNIVERSAL::isa:
     file: lib/UNIVERSAL/isa.pm
-    version: 0.02
+    version: 0.03
 generated_by: Module::Build version 0.2611

Makefile.PL

@@ -2,12 +2,12 @@
 use ExtUtils::MakeMaker;
 WriteMakefile
 (
-          'PL_FILES' => {},
-          'INSTALLDIRS' => 'site',
           'NAME' => 'UNIVERSAL::isa',
           'VERSION_FROM' => 'lib/UNIVERSAL/isa.pm',
           'PREREQ_PM' => {
-                           'Scalar::Util' => 0
-                         }
+                           'Scalar::Util' => '0'
+                         },
+          'INSTALLDIRS' => 'site',
+          'PL_FILES' => {}
         )
 ;

SIGNATURE

@@ -1,5 +1,5 @@
 This file contains message digests of all files listed in MANIFEST,
-signed via the Module::Signature module, version 0.44.
+signed via the Module::Signature module, version 0.50.
 
 To verify the content in this distribution, first make sure you have
 Module::Signature installed, then type:
@@ -16,15 +16,15 @@ Hash: SHA1
 
 SHA1 c90c2476bc82d060488d8ae50896dcda8ee4221f Build.PL
 SHA1 cb3ff2dc987a0b6708a4760215065b3c08d4388e MANIFEST
-SHA1 97221bde9191e7c4b54203aef1f5478cd2bea595 META.yml
-SHA1 348c8145f3fdb3342ef6ab634db519745b781a51 Makefile.PL
-SHA1 0c453919f49aec6fc5e5b689fd44d35de6351aa0 lib/UNIVERSAL/isa.pm
-SHA1 6bba987abb95183f6373079eacc852ff060d8c39 t/basic.t
-SHA1 c25e7e58bb5cb6c36f960be4fb4468ba2f16a1e8 t/bugs.t
+SHA1 bf0b31daaabbf62e52c9b9f9d76253f2ae6e03e8 META.yml
+SHA1 5cf0c1336517270a31f2b893775bb284130b672e Makefile.PL
+SHA1 51acd043352dc970d0df6c9700cf7593c6d01ff2 lib/UNIVERSAL/isa.pm
+SHA1 8497ba6abe4951ce5358a9bf4b57e908da7c37de t/basic.t
+SHA1 49e60190b6d966c78a3a52b8fd55d0a312468c02 t/bugs.t
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1.4.1 (Darwin)
 
-iD8DBQFCx+jQVCwRwOvSdBgRAsXVAJ9DQc0HHhWZM5BGLLSiljKKF/TYRwCgrUMd
-GlpBh7KgLJoY5+gnt/rQBxE=
-=/jQg
+iD8DBQFDHEr1VCwRwOvSdBgRAqD1AJ0dIjNN73SpjeDJHGn7Z0b8Plq8nQCeMuoc
+naUdFHFHIi325FKoEG1hjXk=
+=rEL/
 -----END PGP SIGNATURE-----

lib/UNIVERSAL/isa.pm

@@ -1,14 +1,16 @@
-#!/usr/bin/perl
+#!/usr/bin/perl -w
 
 package UNIVERSAL::isa;
 
 use strict;
-use warnings;
+use vars qw/$VERSION $recursing/;
+
 use UNIVERSAL ();
 
 use Scalar::Util qw/blessed/;
+use warnings::register;
 
-our $VERSION = "0.02";
+$VERSION = "0.03";
 
 my $orig;
 BEGIN { $orig = \&UNIVERSAL::isa };
@@ -21,6 +23,7 @@ sub import {
 }
 
 sub UNIVERSAL::isa {
+	goto &$orig unless defined $_[0];
 
 	# not an object or a class name, we can skip
 	unless ( blessed($_[0]) )
@@ -47,13 +50,19 @@ sub UNIVERSAL::isa {
 
 	# if we've been called from an overridden isa, we are either SUPER:: or explicitly called.
 	# in both cases the original ISA behavior is expected.
-	our $recursing;
 	goto &$orig if $recursing;
 
 	# the last possible case is that 'isa' is overridden
 	local $recursing = 1;
 	my $obj = shift;
-	return $obj->isa(@_);	
+
+	if (warnings::enabled()) {
+		my $calling_sub  = ( caller( 1 ) )[3] || '';
+		warnings::warn( "Called UNIVERSAL::isa() as a function, not a method" )
+			if $calling_sub !~ /::isa$/;
+	}
+
+	return $obj->isa(@_);
 }
 
 __PACKAGE__;
@@ -84,6 +93,20 @@ called on those objects as a method.
 
 In all other cases the real C<UNIVERSAL::isa> is just called directly.
 
+=head1 WARNINGS
+
+If the lexical warnings pragma is available, a warning will be emitted for each
+naughty invocation of C<UNIVERSAL::isa>. These warnings can be silenced by
+saying:
+
+	no warnings 'UNIVERSAL::isa';
+
+in the lexical scope of the naughty code.
+
+=head1 SEE ALSO
+
+L<UNIVERSAL::can> for a more mature discussion of the problem at hand.
+
 =head1 AUTHORS
 
 Autrijus Tang <autrijus@autrijus.org>

t/basic.t

@@ -1,12 +1,13 @@
-#!/usr/bin/perl
+#!/usr/bin/perl -w
 
 use strict;
-use warnings;
 
 use Test::More tests => 12;
 
 BEGIN { use_ok("UNIVERSAL::isa", "isa") };
 
+no warnings "UNIVERSAL::isa";
+
 {
 	package Foo;
 

t/bugs.t

@@ -1,12 +1,13 @@
-#!/usr/bin/perl
+#!/usr/bin/perl -w
 
 use strict;
-use warnings;
 
-use Test::More tests => 4;
+use Test::More tests => 5;
 
 BEGIN { use_ok('UNIVERSAL::isa', 'isa') };
 
+no warnings 'UNIVERSAL::isa';
+
 # class method
 
 {
@@ -67,3 +68,5 @@ my $quux = Quux->new();
 ok(   isa( 'Bar', 'Foo' ), 'isa() should work on class methods too'    );
 ok( ! isa( 'Baz', 'Foo' ), '... but not for non-existant classes'      );
 ok(   isa( $quux, 'Foo' ), '... and should work on delegated wrappers' );
+
+is( scalar(isa(undef, 'Foo')), undef, 'isa on undef returns undef');