PHP oops - Magic Method

What is Magic Method in php?

Magic methods are special methods that are used to perform certain tasks in PHP. Magic methods are started with double underscore (__) as prefix.

• Magic methods is called automatically and does not require any function call to execute the code inside these functions in php.
• The function  __construct(), __destruct(), __call(), __callStatic(), __get(), __set(), __isset(), __unset(), __sleep(), __wakeup(), __serialize(), __unserialize(), __toString(), __invoke(), __set_state(), __clone() and __debugInfo() are called as Magic Methods in php
• Magic method in a class must be declared public.

List of Magic Methods in PHP

1. __construct()
   
   __construct() method is called when object is created.
   
   PHP Example:
   <?php class Aryatechno {
       public function __construct()
       {
           echo "construct is called when object is created.";
       }
    }
    
   $obj=new Aryatechno();
   ?>
   Output:
   construct is called when object is created.
    
2. __destruct()
   __destruct() method is called when object is destroyed.
   
   PHP Example:
   <?php class Aryatechno {
       public function __destruct()
       {
           echo "Destructor is called  when object is destroyed.";
       }
    }
    
   $obj=new Aryatechno();
   ?>
   Output:
   Destructor is called when object is destroyed.
    
3. __call($function_name, $argument)
   __call() is triggered when trying to access inaccessible methods in an object context.

   PHP Code Example:

   <?php
      //code by aryatechno for Method Overloading
      class Aryatechno {
        
         function __call($name,$arg){
            
            echo "<br/> Magic method __call is triggered when trying to accees non-existing method course()";
            echo "<br/> Method Name :".$name;
            echo "<br/> Passes Argument in array:".$arg[0];
      }
   }
      $obj = new Aryatechno();
      $obj->course("php");
   ?>

   Output:
   Magic method __call is triggered when trying to accees non-existing method course()
   Method Name :course
   Passes Argument in array:php

4. __callStatic($function_name, $argument)
   __callStatic() is triggered when trying to access inaccessible methods in a static context.
   
   PHP Code Example:
   <?php
   class Aryatechno
   {
    
    public static function __callStatic($fun, $arg) {
        echo "<br/>Method that does not exist：" . $fun . " ";
        echo "<br/>parameter list of method that does not exist:"; print_r($arg);
    }
    }
    $obj = new Aryatechno();
    $obj::course("PHP"); // If the method does not exist is called within the object in static manner, then the __callStatic() method will be called automatically.
   ?>
   Output:
   Method that does not exist：course
   parameter list of method that does not exist:Array ( [0] => PHP )
    
5. __get($property_name)
   __get() is called when reading data from inaccessible (like  protected or private) or non-existing properties.

   PHP Example:
   <?php
   //code by aryatechno for Method Overloading
   class Aryatechno
   {
       
       function __get($name)
       {
           
           echo "<br/> __get magic method is called when reading inaccessiable property";    
           echo "<br/> Inaccessiable variable Name :".$name;
           
       }
       
   }

   $obj = new Aryatechno;
   echo $obj->j; //variable j is not available
   ?>

   Output:
   __get magic method is called when reading inaccessiable property
   Inaccessiable variable Name :j

   
    
6. __set($property_name, $value)
   __set() is triggered when writing data to inaccessible (like protected or private) or undefined properties.

   PHP Example:
   <?php
   //code by aryatechno for Method Overloading

   class Aryatechno
   {
       function __set($name,$val)
       {
           echo "<br/> __set magic method is called when writing value into inaccessiable property";    
           echo "<br/> Inaccessiable variable Name :".$name;
           echo "<br/> variable value :".$val;
           
       }   
       
   }

   $obj = new Aryatechno;
   $obj->i=100; ////variable i is not available
   ?>
   
   Output:
   __set magic method is called when writing value into inaccessiable property
   Inaccessiable variable Name :i
   variable value :100

7. __isset($property_name)
   __isset() is triggered when isset() or empty() is called on inaccessible (like protected or private) or non-existing properties.
    
8. __unset($property_name)
   __unset() is triggered when unset() is called on inaccessible (like protected or private) or non-existing properties.
   
   PHP Example:

   <?php
   //code by aryatechno for Method Overloading

   class Aryatechno
   {
       
       function __isset($name)
       {
           echo "<br/> __isset magic method is called when isset() method is called for inaccessiable property";    
           echo "<br/> variable Name :".$name;
       }
       
       function __unset($name)
       {
           echo "<br/> __unset magic method is called when unset() method is called for inaccessiable property";    
           echo "<br/> Inaccessiable variable Name :".$name;
       }
       
       
   }

   $obj = new Aryatechno;
   isset($obj->p); //variable p is not available
   unset($obj->p);

   ?>

   Output:
   __isset magic method is called when isset() method is called for inaccessiable property
   variable Name :p
   __unset magic method is called when unset() method is called for inaccessiable property
   Inaccessiable variable Name :p

9. __sleep()
   __sleep() method is called first while executing serialize(). It returns the object’s property array on cleaning PHP class objects before serialization.

   PHP Example:
   <?php
   //code by aryatechno for Method Overloading

   class Aryatechno
   {
       
       public function __construct($val)
       {
           $this->name = $val;
       }
       
       
       public function __sleep()
       {
           echo "<br/>It is called when the serialize() method is called outside the class.";
           return array('name');
       }
       
   }

   $obj = new Aryatechno("PHP");
   echo serialize($obj);

   ?>

   Output:
   It is called when the serialize() method is called outside the class.O:10:"Aryatechno":1:{s:4:"name";s:3:"PHP";}

10. __wakeup()
    __wakeup() method is called while deserialization() is executed. It would reverse work to restore objects properties and resources on invoking deserialization().

    PHP Example:
    <?php
    //code by aryatechno for Method Overloading

    class Aryatechno
    {
        
        public function __construct($val)
        {
            $this->name = $val;
        }
        
        
        public function __sleep()
        {
            echo "<br/>It is called when the serialize() method is called outside the class.";
            return array('name');
        }
        
        public function __wakeup()
        {
            echo "It is called when the unserialize() method is called outside the class.
    ";
            $this->name = "java";
            
            
        }
        
    }

    $obj = new Aryatechno("PHP");
    echo serialize($obj);
    print_r(unserialize(serialize($obj)));
    ?>

    Output:
    It is called when the serialize() method is called outside the class.O:10:"Aryatechno":1:{s:4:"name";s:3:"PHP";}
    It is called when the serialize() method is called outside the class.It is called when the unserialize() method is called outside the class. Aryatechno Object ( [name] => java )

11. __toString()
    __toString() method will be called while using echo method to print an object directly. It is expected to return a string value while using class instances with PHP printing statements.
12. __invoke()
    __invoke() method is called while trying to call an object in a way of calling function.
13. __set_state($array)
    __set_state method is triggered while calling var_export(). It is a static method invoked while exporting objects property array and expects such array variable as its argument.
14. __clone()
    __clone() method is triggered when the object is copied.

    PHP Example:
    <?php
    //code by aryatechno for Method Overloading

    class Aryatechno
    {
        
       public function __clone()
        {
            echo " You are cloning the object.".__METHOD__;
        }
        
    }

    $obj = new Aryatechno();
    $obj2 = clone $obj;
    ?>

    Output:
    You are cloning the object. Aryatechno::__clone

15. __debugInfo()
    __debugInfo() method is called when using var_dump()
    
    PHP Example:
    <?php class Aryatechno {
        public function __construct()
        {
        }
     
        public function __debugInfo()
        {
            echo "<br/> Debug info.";
        }
    }
    var_dump(new Aryatechno());
    ?>
    Output:
    Debug info.object(Aryatechno)#1 (0) { }