Contravariant Argument Types
<?php
class 🐖pig {}
class 🐗boar extends 🐖 {}
class Asterix
{
public function hunt(🐖pig $animal) {}
}
class Gauls extends Asterix
{
public function hunt(🐗boar $animal) {}
}
?>
Warning: Declaration of Gauls::hunt(🐗boar $animal) should be compatible with Asterix::hunt(🐖pig $animal)
Arguments types are *contra-variant*:
~they can *not* accept a narrower type~