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) { }

 

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