Usage of $this and self in object oriented PHP

Question

I know that inside a class, $this is used to refer to the current object and self is used to refer to the current class. For example:

class My_Class {

    function start1() {
        $var = self::hello();

        echo $var;
    }

    function start2() {

        $var = $this->hello();

        echo $var;
    }

    function hello() {
        return 'Hello';
    }
}

$obj = new My_Class;
$obj->start1(); // Hello
$obj->start2(); // Hello

In my example, both $this->hello() and self::hello() appear to do the exact same thing. Can anyone give an example of when I should use $this and when I should use self?

@Rizier123 that is not accurate, for static the better is to use the word static, self is only helpful to avoid overwrites of methods. http://php.net/manual/en/language.oop5.static.php — Daniel Aranda, Feb 25 '15 at 15:52
Do yourself a favor and use `error_reporting(E_ALL|E_STRICT);` — chelmertz, Feb 25 '15 at 16:09
dpue: http://stackoverflow.com/q/3754786/3933332 | http://stackoverflow.com/q/151969/3933332 ? — Rizier123, Feb 25 '15 at 16:20

Carlos M. Meyer · Answer 1 · 2015-02-25T16:07:51.330

$this cannot be used on static functions.

And $this needs an instantiated object.

class example
{
    public static $mystring ;
    public $anotherString;

    //non-static functions (calling static and non-static variables)
    public function regularFunction() { echo $this->anotherString; } 
    public function regularFnUsingStaticVar() { echo self::$mystring ; }

    //static functions (calling static functions and variables)
    public static function anotherStatFn() { self::staticFunction(); }
    public static function staticFunction() { echo self::$mystring ; }
}

// using static vars and functions
example::$mystring = "Hello World!";
example::staticFunction();           /* Hello World! */

// using non-static vars and functions
$obj = new example();
$obj->anotherString = "Hello World!";
$obj->regularFunction();             /* Hello World! */

That should be an comment – Utkarsh Dixit Feb 25 '15 at 16:04 — Utkarsh Dixit, Feb 25 '15 at 16:04

Usage of $this and self in object oriented PHP

1 Answers1