able to extend more than one class at once. For this we can fake multiple inheritance in php using some
class and object functions provided by php.
I came across the problem where i had to extend more than once class using a single class, and for that
after some research came to a solution that can be used to make php support multiple inheritance, if i can say that.
//this is the Abatract class that implements fake multiple inheritance in php
//not allowed to create instance of this class
Abstract class MultipleExtension {
public $_this;
private $_extension = array(); //contains extended classes
//constructor function that passes $this to our private variable $_this
function __construct(){
$_this = $this;
}
//function to add the extended class objects
public function addExtension($obj) {
$this->_extension[]=$obj;
}
//overloading the members with getter function
public function __get($name) {
foreach($this->_extension as $ext) {
//check if the property defined as $name exists in the class $ext
if(property_exists($ext,$name))
return $ext->$name;
}
}
//member overloading using setter function
public function __set($name, $value) {
foreach($this->_extension as $ext) {
//check if the property $name exists in class $ext
//and if it does assign the value in $value to $name property of $ext class
if(isset($ext->$name)) {
$ext->$name = $value;
}
}
}
public function __call($method,$arguments) {
foreach($this->_extension as $ext) {
//check if function exists defined in method variable for the extended class
if(method_exists($ext,$method)) {
//call the user defined function with method and parameters
return call_user_func_array(array($ext, $method) ,$arguments);
}
}
}
}
And below is the implementation of above abstract class that supports multiple inheritance
//this is the first class that sets firstname of a user
class First {
private $_firstName;
public function setName($firstname){
$this->_firstName = $firstname;
}
public function getName(){
return $this->_firstName;
}
}
//this is the second class that sets location of a user
class Second {
private $_locationName;
public function setLocation($location){
$this->_locationName = $location;
}
public function getLocation(){
return $this->_locationName;
}
}
//this is a test class that extends multipleExtension class that fakes multiple inheritance
class Test extends MultipleExtension {
function __construct() {
//call the function that stores all the objects of classes as shown below
parent::addExtension(new First());
parent::addExtension(new Second());
}
public function __toString() {
return $this->getName().' located in: '.$this->getLocation();
}
}
//now create object of Test class and do as follows
$obj = new Test();
$obj->setName("Sudhir");
$obj->setLocation("Nepal");
echo $obj;
//This will output Sudhir located in: Nepal.
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