Chaining Static Methods in PHP?

Question

Is it possible to chain static methods together using a static class? Say I wanted to do something like this:

$value = TestClass::toValue(5)::add(3)::subtract(2)::add(8)::result(); 

. . . and obviously I would want $value to be assigned the number 14. Is this possible?

Update: It doesn't work (you can't return "self" - it's not an instance!), but this is where my thoughts have taken me:

class TestClass {     public static $currentValue;      public static function toValue($value) {         self::$currentValue = $value;     }      public static function add($value) {         self::$currentValue = self::$currentValue + $value;         return self;     }      public static function subtract($value) {         self::$currentValue = self::$currentValue - $value;         return self;     }      public static function result() {         return self::$value;     } } 

After working that out, I think it would just make more sense to simply work with a class instance rather than trying to chain static function calls (which doesn't look possible, unless the above example could be tweaked somehow).

Answer 1

I like the solution provided by Camilo above, essentially since all you're doing is altering the value of a static member, and since you do want chaining (even though it's only syntatic sugar), then instantiating TestClass is probably the best way to go.

I'd suggest a Singleton pattern if you want to restrict instantiation of the class:

class TestClass {        public static $currentValue;      private static $_instance = null;      private function __construct () { }      public static function getInstance ()     {         if (self::$_instance === null) {             self::$_instance = new self;         }          return self::$_instance;     }      public function toValue($value) {         self::$currentValue = $value;         return $this;     }      public function add($value) {         self::$currentValue = self::$currentValue + $value;         return $this;     }      public function subtract($value) {         self::$currentValue = self::$currentValue - $value;         return $this;     }      public function result() {         return self::$currentValue;     } }  // Example Usage: $result = TestClass::getInstance ()     ->toValue(5)     ->add(3)     ->subtract(2)     ->add(8)     ->result();