PHP: What if I call a static method in non-static way

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As Baba already pointed out, it results in an E_STRICT depending on your configuration.

But even if that’s no problem for you, I think it’s worth mentioning some of the pitfalls which may result from calling static methods in a non-static way.

If you have a class hierarchy like

class A {
    public static function sayHello() {
        echo "Hello from A!\n";
    }

    public function sayHelloNonStaticWithSelf() {
        return self::sayHello();
    }

    public function sayHelloNonStaticWithStatic() {
        return static::sayHello();
    }
}

class B extends A {
    public static function sayHello() {
        echo "Hello from B!\n";
    }

    public function callHelloInMultipleDifferentWays() {
        A::sayHello();
        B::sayHello();
        $this->sayHelloNonStaticWithSelf();
        $this->sayHelloNonStaticWithStatic();
        $this->sayHello();
    }
}

$b = new B();
$b->callHelloInMultipleDifferentWays();

This produces the following output:

Hello from A!
// A::sayHello() - obvious

Hello from B!
// B::sayHello() - obvious

Hello from A!
// $this->sayHelloNonStaticWithSelf()
// self alweays refers to the class it is used in

Hello from B!
// $this->sayHelloNonStaticWithStatic()
// static always refers to the class it is called from at runtime

Hello from B!
// $this->sayHello() - obvious

As you can see, it’s easy to achieve unexpected behaviour when mixing static and non-static method calls and techniques.

Therefore, my advice also is:
Use Class::method to explicitly call the static method you mean to call.
Or even better don’t use static methods at all because they make your code untestable.

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