Oddity of static:: calling a method that contains $this

Question

In this example I get the fatal error "Fatal error: Using $this when not in object context" as expected

class ctis_parent{
    public function objFunc(){
        var_dump('Called succes');
    }

    public static function call(){

        $this->objFunc(); 
    }

    public function __construct(){
        self::call();
    }

}

new ctis_parent();

But if remove static keyword from definition of call() method all work fine, why?

class ctis_parent{
    public function objFunc(){
        var_dump('Called succes');
    }

    public  function call(){
        $this->objFunc();
    }

    public function __construct(){
        self::call();
    }

}

new ctis_parent(); 

//string 'Called succes' (length=13)

Answer 1

A static function, by definition doesn't need the class being instantiated, so it doesn't have access to the $this-> reference, which points to the current instance. If an instance doesn't exist, it can't be pointed to. Makes sense.

Answer 2

Because you're using $this when you're not in an object. Well, you're not REALLY, but with the static declaration, people could do:

ctis_parent::call();

Where, $this would be illegal.

See the docs for static.