从类实例访问静态变量

Question

I would like to use this line of code:

$this->ClassInstance::$StaticVariable;

Where this is the basic setup:

Class foo{
   public static $StaticVariable;
}

$this->ClassInstance = new foo();

What is the reasoning behind this being a parse error?

When this:

$ClassInstance = $this->ClassInstance;
$ClassInstance::$StaticVariable;

Is perfectly valid.

Answer 1

In PHP docs

Declaring class properties or methods as static makes them accessible without needing an instantiation of the class. A property declared as static can not be accessed with an instantiated class object (though a static method can).

source http://php.net/manual/en/language.oop5.static.php