PHP Can static:: replace self::?

Question

I am a little confused with this matter. I am designing an ORM class that tries to behave very similarly to ActiveRecord in ruby on rails, but that\'s beside the point.

Answer 1

try to use the code bellow to see the difference between self and static:

<?php
class Parent_{
    protected static $x = "parent";
    public static function makeTest(){
        echo "self => ".self::$x."<br>";
        echo "static => ".static::$x;       
    }
}

class Child_ extends Parent_{
    protected static $x = "child";
}

echo "<h4>using the Parent_ class</h4>";
Parent_::makeTest();

echo "<br><h4>using the Child_ class</h4>";
Child_::makeTest();
?>

and you get this result:

using the Parent_ class

• self => parent
• static => parent

using the Child_ class

• self => parent
• static => child

Answer 2

You have to ask yourself: "Am I targeting the problem with the adequated approach?"

self:: and static:: do two different things. For instance self:: or __CLASS__ are references to the current class, so defined in certain scope it will NOT suffice the need of static calling on forward.

What will happen on inheritance?

class A {
    public static function className(){
        echo __CLASS__;
    }

    public static function test(){
        self::className();
    }
}

class B extends A{
    public static function className(){
        echo __CLASS__;
    }
}

B::test();

This will print

A

In the other hand with static:: It has the expected behaviour

class A {
    public static function className(){
        echo __CLASS__;
    }

    public static function test(){
        static::className();
    }
}

class B extends A{
    public static function className(){
        echo __CLASS__;
    }
}


B::test();

This will print

B

That is called late static binding in PHP 5.3.0. It solves the limitation of calling the class that was referenced at runtime.

With that in mind I think you can now see and solve the problem adequately. If you are inheriting several static members and need access to the parent and child members self:: will not suffice.