PHP 7.2：如何检查是否处于静态模式

Situation:

Class A{
    public function F(){
        var_dump($this);
    }
}

A::F();

When doing this I get PHP Fatal error:Uncaught Error: Using $this when not in object context.

1. Shouldn't I get a NULL or something, instead of the error?
2. How do I check (in PHP 7.2!!!) if in object context?

Thx!

$this is not available in static calls, you need to use self:: but keep in mind these are not interchangeable equivalents.