From: Karen Etheridge <ether@cpan.org>
Date: Tue, 3 Oct 2017 00:49:48 +0000 (-0700)
Subject: preserve list context for the sub being called by $_call_if_can
X-Git-Tag: v1.000008~2
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?p=p5sagit%2FSafe-Isa.git;a=commitdiff_plain;h=2e029f319a43f444105ec4ea2587103980a2b7e7

preserve list context for the sub being called by $_call_if_can

also add some additional tests to demonstrate behaviour in list context
(some of which failed before the fix)
---

diff --git a/Changes b/Changes
index e09ce96..71a2409 100644
--- a/Changes
+++ b/Changes
@@ -1,5 +1,7 @@
 Revision history for Safe-Isa
 
+  - fix scalar/list context handling for $_call_if_can
+
 1.000007 - 2017-09-22
   - added new interface: $obj->$_call_if_can
 
diff --git a/lib/Safe/Isa.pm b/lib/Safe/Isa.pm
index e7a1337..01933ab 100644
--- a/lib/Safe/Isa.pm
+++ b/lib/Safe/Isa.pm
@@ -26,7 +26,8 @@ our ($_isa, $_can, $_does, $_DOES) = map {
 
 our $_call_if_can = sub {
   my ($obj, $method) = (shift, shift);
-  $obj->$_call_if_object(can => $method) && $obj->$method(@_);
+  return unless $obj->$_call_if_object(can => $method);
+  return $obj->$method(@_);
 };
 
 1;
@@ -123,6 +124,9 @@ class names that you might not want to treat as one (like say "Matt") - the
 C<is_module_name> function from L<Module::Runtime> is a good way to check for
 something you might be able to call methods on if you want to do that.
 
+We are careful to make sure that scalar/list context is preserved for the
+method that is eventually called.
+
 =head1 EXPORTS
 
 =head2 $_isa
diff --git a/t/safe_isa.t b/t/safe_isa.t
index 6657722..d650af1 100644
--- a/t/safe_isa.t
+++ b/t/safe_isa.t
@@ -1,9 +1,9 @@
 use strict;
 use warnings;
-use Test::More tests => 38;
+use Test::More tests => 68;
 
 { package Foo; sub new { bless({}, $_[0]) } }
-{ package Bar; our @ISA = qw(Foo); sub bar { $_[1] } }
+{ package Bar; our @ISA = qw(Foo); sub bar { wantarray ? ( 5, 6 ) : $_[1] } }
 
 my $foo = Foo->new;
 my $bar = Bar->new;
@@ -25,6 +25,8 @@ ok(!eval { $undef->can('bar'); 1 }, 'undef goes poof');
 
 use Safe::Isa;
 
+note 'scalar context..';
+
 ok($foo->$_isa('Foo'), 'foo $_isa Foo');
 ok($bar->$_isa('Foo'), 'bar $_isa Foo');
 ok(eval { is($blam->$_isa('Foo'), undef, 'blam isn\'t Foo'); 1 }, 'no boom today');
@@ -49,3 +51,64 @@ is($bar->$_call_if_can(bar => ), undef, 'bar $_call_if_can(bar => )');
 is($bar->$_call_if_can(bar => 2), 2, 'bar $_call_if_can(bar => 2)');
 ok(eval { is($blam->$_call_if_can(isa => 'Foo'), undef, 'blam can\'t call anything'); 1 }, 'no boom today');
 ok(eval { is($undef->$_call_if_can(isa => 'Foo'), undef, 'undef can\'t call anything'); 1 }, 'and no boom tomorrow either');
+
+
+note 'list context..';
+
+# isa always returns true/false
+is_deeply([ $foo->$_isa('Foo') ], [ 1 ], 'foo $_isa Foo');
+is_deeply([ $bar->$_isa('Foo') ], [ 1 ], 'bar $_isa Foo');
+ok(
+    eval { is_deeply([ $blam->$_isa('Foo') ], [], 'blam isn\'t Foo'); 1 },
+    'no boom today',
+);
+ok(
+    eval { is_deeply([ $undef->$_isa('Foo') ], [], 'undef isn\'t Foo either'); 1 },
+    'and no boom tomorrow either',
+);
+
+# can returns ref/undef if it ran, or false if not an object.
+is_deeply([ $foo->$_can('bar') ], [ undef ], 'foo !$_can bar');
+is_deeply([ $bar->$_can('bar') ], [ \&Bar::bar ], 'bar $_can bar');
+ok(
+    eval { is_deeply([ $blam->$_can('bar') ], [], 'blam can\'t bar'); 1 },
+    'no boom today',
+);
+ok(
+    eval { is_deeply([ $undef->$_can('bar') ], [], 'undef can\'t bar either'); 1 },
+    'and no boom tomorrow either',
+);
+
+# _call_if_object has the same behaviour as the method it is calling and
+# propagates context.
+is_deeply([ $foo->$_call_if_object(isa => 'Foo') ], [ 1 ], 'foo $_call_if_object(isa => Foo)');
+is_deeply([ $bar->$_call_if_object(isa => 'Foo') ], [ 1 ], 'bar $_call_if_object(isa => Foo)');
+is_deeply([ $bar->$_call_if_object(bar => ) ], [ 5, 6 ], 'bar $_call_if_object(bar => undef): wantarray is true');
+is_deeply([ $bar->$_call_if_object(bar => 2) ], [ 5, 6 ], 'bar $_call_if_object(bar => 2): wantarray is true');
+ok(
+    eval { is_deeply([ $blam->$_call_if_object(isa => 'Foo') ], [], 'blam can\'t call anything'); 1 },
+    'no boom today',
+);
+ok(
+    eval { is_deeply([ $undef->$_call_if_object(isa => 'Foo') ], [], 'undef can\'t call anything'); 1 },
+    'and no boom tomorrow either',
+);
+
+# _call_if_can has the same behaviour as the method it is calling and
+# propagates context.
+is_deeply([ $foo->$_call_if_can(isa => 'Foo') ], [ 1 ], 'foo $_call_if_can(isa => Foo)');
+is_deeply([ $bar->$_call_if_can(isa => 'Foo') ], [ 1 ], 'bar $_call_if_can(isa => Foo)');
+ok(
+    eval { is_deeply([ $foo->$_call_if_can(bar => ) ], [], 'foo can\'t call bar'); 1 },
+    'no boom today',
+);
+is_deeply([ $bar->$_call_if_can(bar => ) ], [ 5, 6 ], 'bar $_call_if_can(bar => ): wantarray is true');
+is_deeply([ $bar->$_call_if_can(bar => 2) ], [ 5, 6 ], 'bar $_call_if_can(bar => 2): wantarray is true');
+ok(
+    eval { is_deeply([ $blam->$_call_if_can(isa => 'Foo') ], [], 'blam can\'t call anything'); 1 },
+    'no boom today',
+);
+ok(
+    eval { is_deeply([ $undef->$_call_if_can(isa => 'Foo') ], [], 'undef can\'t call anything'); 1 },
+    'and no boom tomorrow either',
+);