Using $this, self::, parent:: for code readability

Question

I would like to know if it is acceptable/preferred to use self::method() and parent::method() when working in php classes.

You can use $this->method() but $this-> can al

Answer 1

Controllers are not static in Kohana, although they can contain static member variables / methods or constants.

self:: is a shorthand way of writing ClassName:: i.e

class Animal
{
    public static $arms = 0;
}

class Dog extends Animal
{
    public static $leg = 0;
    const NAME = 'dog';

    public static function bark()
    {
        echo 'Woof';
    }
}

To call static functions or get constants from a class we use the scope resolution operator ::. Static functions are per class not per object. Saying :: refers to static instances of a class is wrong, it is just a way to access the static methods - there isn't an object instance that has these methods.

so:

Dog::bark(),
Dog::$leg, 
Dog::NAME, 

we can also use

Animal::$arms

Inside the class Dog we can use self:: and parent:: so that we do not need to type the full class name (as it could be very long!)

In answer to your question though: No - self:: is not deprecated and no it is not bad practice to use it. The reason it is not used in kohana core is for a very different reason.... (transparent class extensions with eval read below for more info...).

p.s calling non-static methods statically is wrong and shouldn't be allowed- if you set error_reporting(E_ALL | E_STRICT) (like you should during development) you will see an error being raised.

Basically what happens is:

Core has a file called:

class Controller_Core { 
    public function someMethod(){}
}

You create:

// We can use someMethod of Controller_Core
Index_Controller extends Controller {}

This is really extending Controller_Core UNLESS you have created MY_Controller.php which would be class Controller extends Controller_Core.

//MY_Controller.php
class Controller extends Controller_Core
{
      // overloads Controller_Core::someMethod without us having to change the core file
      public function someMethod(){}
}