Wednesday, 1 July 2015

PHP Magic Function

PHP Magic Function

The "magic" methods are ones with special names, starting with two underscores, which denote methods which will be triggered in response to particular PHP events. magic functions will never directly be called by the programmer – actually, PHP will call the function ‘behind the scenes’.

List of List of Magic Methods in PHP
__construct: This magic methods is called when someone create object of your class. Usually this is used for creating constructor in php5.
__destruct: This magic method is called when object of your class is unset. This is just opposite of __construct.
__get: This method called when your object attempt to read property or variable of the class which is inaccessible or unavailable.
__set: This method called when object of your class attempts to set value of the property which is really inaccessible or unavailable in your class.
__isset:  This magic methods trigger when isset() function is applied on any property of the class which isinaccessible or unavailable.
__unset:  __unset is something opposite of isset method. This method triggers when unset() function called on inaccessible or unavailable property of the class.
__call:  __call magic method trigger when you are attempting to call method or function of the class which is either inaccessible or unavailable.
__callstatic: __callstatic execture when inaccessible or unavailable method is in static context.
__sleep:  __sleep methods trigger when you are going to serialize your class object.
__wakeup:  __wakeup executes when you are un serializing any class object.
__toString: __toString executes when you are using echo on your object.
__invoke:  __invoke called when you are using object of your class as function

Accessing __get() methods

<?php
class newClass {
    public function __get($name)
    {
        return $name;
    }
}

$c = new newClass();
$c->persone = "shidhu047@gmail.com";
echo $c->persone;
 ?>

Output: shidhu047@gmail.com

Accessing __set() methods

class newClass {
public function __set($name, $value)
    {
        echo "$name = $value<br>";
    }
}

$c = new newClass();
$c->name = "Sudhir Pandey";
$c->email = "shidhu047@gmail.com";

output:
name = Sudhir Pandey
email = shidhu047@gmail.com

Notes: 
It works perfectly and not generate error. This is due to the two magic methods __get() and __set() in php.The purpose of these methods will be to run when you try to access a variable which has not been declared.If you try to set a variable like '$c->email = "shidhu047@gmail.com"' PHP will run the __set() method or when it tries to get a variable that is not set it will run the __get() method.

It is possible to stop this behavior of PHP to assign values to undefined issues.
The solution is that you raise an exception from within __set() method.
public function __set($name, $value) {
throw new Exception(“Cannot assign values to undefined variables”,1);
}

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