PHP - How does constructor parse data when inheriting?

Question

I have 2 classes, one extends the other:

class Human {
    const PERKS = 'none';
    public function __construct() {
        echo self::PERKS;
    }
}

class King extends Human {
    const PERKS = 'crown';
}

Ignore the silly example. However, no matter whom I initialize I get printed 'none'.

How exactly does the constructor work?
How can I get around this?

Thank you.

Read there - php.net/manual/en/language.oop5.late-static-bindings.php — splash58
– splash58, Commented Feb 20, 2018 at 19:48

iainn · Accepted Answer · 2018-02-20 19:51:51Z

4

self always refers to exact class in which it's used. From the manual:

Static references to the current class like self:: or CLASS are resolved using the class in which the function belongs, as in where it was defined.

To work around this, you can use the static class resolution operator, which is resolved at runtime instead, e.g.

class Human {
    const PERKS = 'none';
    public function __construct() {
        echo static::PERKS;
    }
}

class King extends Human {
    const PERKS = 'crown';
}

new King;
// crown

new Human;
// none

See https://eval.in/959784

answered Feb 20, 2018 at 19:51

iainn

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