using self instead of this variable [duplicate]

Question

I'm reading a book of php and found this code:

class Employee {
        static public $NextID = 1;
        public $ID;

        public function _ _construct( ) {
                $this->ID = self::$NextID++;
        }

        public function NextID( ) {
                return self::$NextID;
        }
}

why here is used self::$NextID++; can I use like this:

$this-ID = $this->$NextID++;

Community · Accepted Answer · 2017-05-23 12:14:22Z

1

Because in php you have to reference static functions with self.

There was also an explanation on stackoverflow already: see here

edited May 23, 2017 at 12:14

CommunityBot

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answered Nov 13, 2013 at 8:31

sHentschel

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1 Comment

Petah Over a year ago

Also note that it is valid to call static methods with $this in the same class.

Damien Overeem · Accepted Answer · 2013-11-13 08:52:49Z

0

When a class is called statically ie. ClassName::someMethod(), there is no "instance" of the class.

Since $this refers to the instance of the class, $this will not exist when your class is used statically. (so $this will only be available when you created an object of your class by using $var = new ClassName())

self refers to the class (not the object) so in static classes you can use self::.. to refer to properties or methods within the class.

edited Nov 13, 2013 at 8:52

answered Nov 13, 2013 at 8:38

Damien Overeem

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1 Comment

Petah Over a year ago

Its not $self is just self, or static

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