Pure Intersection Types
To enforce a value is both %Traversable% and %Countable%:
traversable =& $this->both;
$this->countable =& $this->both;
$this->both = $countableIterator;
}
}
]]>
In PHP 8.1:
countableIterator = $countableIterator;
}
public function getIterator(): *Traversable&Countable* {
return $this->countableIterator;
}
}
]]>
Only for class and interface names
Variance rules are respected, but they are complicated