Class::MOP

• Traditional MOP only has class metaclasses
• Moose uses metaclasses for other things
• Method metaclass describes a method
• Attribute metaclass describes an attribute
• Instance metaclass describes how to interact with an instance
• (this is where, bless, $self->{attribute} = $new_value happen)
• default is hash, but others have written InsideOut and GlobRef instance metaclasses