Use Self

December 18, 2014 ยท View on GitHub

self is a PHP keyword that represent the current class. Thus, the following are all identical :

<?php

namespace x\y;

class theClass {
	const a = 1;
	
	public function y() {
		echo self::a."\n";	
		echo theClass::a."\n";	
		echo \x\y\theClass::a."\n";	
	}
}

$z = new z();
$z->y();

?>

Of course, full namespaced name is both longer to write and harder to read. The class name is usually longer than self (though not all the time, of course).

self keyword will be solved by the PHP interpreter at compile time, with little penalty on processing speed. It will also be handy when refactoring, as there is no more need to change the hardcoded name of the class in the code.

There are some edge cases where the name of the class will have a different behavior than the self keyword : the former will propagate the calling class name, while the class name will actually replace it with itself.

<?php
class A {
    static function foo() {
        echo get_called_class();
    }
}
class B extends A {
    static function bar() {
        self::foo();
    }
    static function baz() {
        B::foo();
    }
}
class C extends B {}

C::bar(); //C
C::baz(); //B
?>

// example quoted from Artefacto

Rule Details

The following are considered a warning :

<?php

class theClass {
	const a = 1;
	
	public function y() {
		echo theClass::a."\n";	
		echo \x\y\theClass::a."\n";	
	}
}


?>

The following pattern is considered OK :

<?php

class theClass {
	const a = 1;
	
	public function y() {
		echo self::a."\n";	
	}
}

?>

Further Reading