php - How can I restrict user to only created limited numbers of objects -

<?php class book {  var $name;    function setname($name){           $this->name = $name;    }    function getname(){          return $this->name ;    } } $objectfirst = new book; $objectfirst->setname('english'); echo $objectfirst->getname(); $objectsecond = new book; $objectsecond->setname('science'); echo $objectsecond->getname(); ?> 

how can restrict user created limited numbers of objects. above example if create 1 more object throw error.

add static counter variable class, add constructor , destructor increase , decrease it. check value in constructor:

<?php class book {     var $name;    private static $counter=0;     function __construct()    {      self::$counter++;      if(self::$counter > 2)        throw new exception('limit exceeded');    }     function __destruct()    {      self::$counter--;    }     function setname($name){           $this->name = $name;    }     function getname(){          return $this->name ;    } }  $objectfirst = new book; $objectfirst->setname('english'); echo $objectfirst->getname(); $objectsecond = new book; $objectsecond->setname('science'); echo $objectsecond->getname();  $objectthird = new book; $objectthird->setname('test'); echo $objectthird->getname(); 

script output:

englishscience fatal error: uncaught exception 'exception' message 'limit exceeded' in sandbox/scriptname.php:12 stack trace: #0 sandbox/scriptname.php(36): book->__construct() #1 {main}   thrown in sandbox/scriptname.php on line 12