“Overloading” in PHP5 and magic methods

PHP doesn’t support constructor / methods overloading with the classical syntax !

Overloading” in PHP5 is realized via the magic method
__call($functionName, $argumentsArray)

Dynamic creation of PROPERTIES
Let’s consider a class X (without content) and one its instance
class X {}
$x = new X();
Now, If we try to read the inexistent property “m1” of the class, that is:
print $->m1;
we have
  • if the class X contains the definition of the method
    public function __get($name) { … }
    this method will be invoked passing “m1” in the 1st argument (no errors or notice will be generated)
  • if the class doesn’t contain that method, php will generate a notice (Undefined property)
__get()” is a “magic method”, that php invokes when we access a variabile of the class.
There are other magic methods for each class we create:
  • __set($name, $value) : called when we assign a value to a member
    $x->m1 = “val”; // equivalent to $x->__set(“m1″,”val”);
  • __isset($name): called when we call isset() //since php 5.1.0
    isset($x->m1); // equivalent to $x->__isset(“m1”);
  • __unset($name): called when we call unset() //since php 5.1.0
    unset($x->m1); // equivalent to $x->__unset(“m1”);
note: magic methods work with each visibility public/protected/private !
note: if we access to “m1” and the class X already contains a member called “m1”:
  • if accessible: php accesses to the value of the existend member “m1”
  • if non accessible: php invoke __get()
Dynamic creation of METHODS
A similar feature is available for methods:
  • __call( string $name , array $arguments )
    $x->method1(1,”val”); // equivalent to $x->__call(“method1”, array(1, “val”) );
  • __callStatic( string $name , array $arguments ) //since php 5.3.0
    $x::method2(2,”val2″); // equivalent to $x->__call(“method1”, array(1, “val”) );