using self instead of this variable

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++;

score 1 · Answer 1 · edited May 23 '17 at 12:14

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 '17 at 12:14

Community

1
1

answered Nov 13 '13 at 08:31

sHentschel

155
6

Also note that it is valid to call static methods with `$this` in the same class. – Petah Nov 13 '13 at 08:38

Damien Overeem · Accepted Answer · 2013-11-13T08:52:49.923

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 '13 at 08:52

answered Nov 13 '13 at 08:38

Damien Overeem

4,487
4
36
55

1

Its not `$self` is just `self`, or `static` – Petah Nov 13 '13 at 08:39

using self instead of this variable

2 Answers2