在setter php中输入Hinting vs Type Casting

Question

In php, I'm wondering if the following are functionally equivalent?

class Foo  {
    public $bar;
    ...
    public function setBar($bar)  {
        $this->bar = (array)$bar;
    }
}


class Foo  {
    public $bar;
    ...
    public function setBar(array $bar)  {
        $this->bar = $bar;
    }
}

Which of the two is considered best practice? Does it make sense to do both?:

class Foo  {
    public $bar;
    ...
    public function setBar(array $bar)  {
        $this->bar = (array)$bar;
    }
}

Answer 1

They are NOT functionally equivalent.

Type Hinting: You are dictating what type must be passed. If the given value is of the incorrect type, then an error is generated. This does not cast or "convert" the passed value into a specific type.

Type Casting: Regardless of what value is passed, you are "converting" it into the correct type. If your function "needs" an array, then why let a boolean be passed and then cast it to an array?

Also, type hinting allows you to specify an object instance of a specific class. In the following, $bar must be an instance of class Bar or else an error is generated:

public function setBar(Bar $bar)

You can not type cast a variable to an object of a specific class.