comment about why we explicitly clear @ISA

[gitmo/Moose.git] / lib / Class / MOP / Package.pm

diff --git a/lib/Class/MOP/Package.pm b/lib/Class/MOP/Package.pm
index cca1cb6..ad2202c 100644 (file)
--- a/lib/Class/MOP/Package.pm
+++ b/lib/Class/MOP/Package.pm
@@ -22,8 +22,7 @@ sub initialize {
     my $package_name = delete $options{package};
 
 
-    # we hand-construct the class 
-    # until we can bootstrap it
+    # we hand-construct the class until we can bootstrap it
     if ( my $meta = Class::MOP::get_metaclass_by_name($package_name) ) {
         return $meta;
     } else {
@@ -96,6 +95,7 @@ sub create {
         my ($class, %options) = @_;
 
         my $cache_ok = delete $options{cache};
+        $options{weaken} = !$cache_ok unless exists $options{weaken};
 
         my $cache_key;
         if ($cache_ok) {
@@ -109,8 +109,6 @@ sub create {
             }
         }
 
-        $options{weaken} = !$cache_ok unless exists $options{weaken};
-
         my $package_name = $class->_anon_package_prefix . ++$ANON_SERIAL;
 
         my $meta = $class->create($package_name, %options);
@@ -142,14 +140,24 @@ sub create {
         # class when fixing metaclass incompatibility. In that case,
         # we don't want to clean out the namespace now. We can detect
         # that because Moose will explicitly update the singleton
-        # cache in Class::MOP.
-        no warnings 'uninitialized';
+        # cache in Class::MOP using store_metaclass_by_name, which
+        # means that the new metaclass will already exist in the cache
+        # by this point.
+        # The other options here are that $current_meta can be undef if
+        # remove_metaclass_by_name is called explicitly (since the hash
+        # entry is removed first, and then this destructor is called),
+        # or that $current_meta can be the same as $self, which happens
+        # when the metaclass goes out of scope (since the weak reference
+        # in the metaclass cache won't be freed until after this
+        # destructor runs).
         my $current_meta = Class::MOP::get_metaclass_by_name($name);
-        return if $current_meta ne $self;
+        return if defined($current_meta) && $current_meta ne $self;
 
         my ($first_fragments, $last_fragment) = ($name =~ /^(.*)::(.*)$/);
 
         no strict 'refs';
+        # clear @ISA first, to avoid a memory leak
+        # see https://rt.perl.org/rt3/Public/Bug/Display.html?id=92708
         @{$name . '::ISA'} = ();
         %{$name . '::'}    = ();
         delete ${$first_fragments . '::'}{$last_fragment . '::'};
@@ -188,7 +196,7 @@ sub _new {
 # Attributes
 
 # NOTE:
-# all these attribute readers will be bootstrapped 
+# all these attribute readers will be bootstrapped
 # away in the Class::MOP bootstrap section
 
 sub _package_stash {