Summary and usage examples of magic methods in PHP_PHP tutorial

Summary and usage examples of magic methods in PHP

This article mainly introduces the summary and usage examples of magic methods in PHP. Magic methods are a unique feature of PHP object-oriented , they are triggered under specific circumstances and all start with a double underscore. You can understand them as hooks. Friends in need can refer to it

Magic method is a unique feature of object-oriented PHP. They are triggered under specific circumstances and all start with a double underscore. You can understand them as hooks. Using pattern methods, you can easily implement overloading in PHP object-oriented (Overloading means dynamically creating class attributes and methods). Many magic methods appear in pairs. The following lists all the current pattern methods in PHP.

1.__construct, __destruct

__constuct is called when constructing an object;

__destruct is called when the object is explicitly destroyed or the script ends;

2.__get, __set

__set is called when assigning a value to an inaccessible or non-existent property

__get is called when reading an inaccessible or non-existent attribute

3.__isset, __unset

__isset is called when isset() or empty() is called on an inaccessible or non-existent property

__unset is called when unsetting an inaccessible or non-existent property

4.__call, __callStatic

__call is called when calling an inaccessible or non-existent method

__callStatic is called when calling a static method that is inaccessible or does not exist

5.__sleep, __wakeup

__sleep is called when using serialize, useful when you don’t need to save all the data of a large object

__wakeup is called when unserialize is used and can be used to initialize objects

　6.__clone

Called when an object is cloned, used to adjust the cloning behavior of the object

7.__toString

Called when a class is converted to a string

8.__invoke

Called when an object is called as a function

9.__set_state

This static method is called when var_export() is called to export a class. Use the return value of __set_state as the return value of var_export.

　10.__debuginfo

Called when var_dump() is called to print an object (when you don’t want to print all attributes) Applicable to PHP5.6 version

Examples of using PHP magic methods are as follows:

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class Magic { public $var = 'test';   //构造函数,在创建对象的时候调用 public function __construct() { echo '__construct called'.PHP_EOL; }   //某个对象的引用都被删除、对象被销毁、调用exit()后、脚本关闭时被调用 public function __destruct() { echo '__destruct called'.PHP_EOL; }   //当给不可访问或不存在属性赋值时被调用 public function __set($name, $value) { echo $name.'-'.$value; echo '__set called'.PHP_EOL; }   //读取不可访问或不存在属性时被调用 public function __get($name) { echo $name; echo '__get called'.PHP_EOL; }   //调用不可访问或不存在的方法时被调用 public function __call($name, $arguments) { echo $name . '-' . implode(',', $arguments); echo '__call called'.PHP_EOL; }   //调用不可访问或不存在的静态方法时被调用 public static function __callStatic($name, $arguments) { echo $name . '-' . implode(',', $arguments); echo '__callStatic called'.PHP_EOL; }   //对不可访问或不存在的属性调用isset()或empty()时被调用 public function __isset($name) { echo $name; echo '__isset called'.PHP_EOL; return true; }   //对不可访问或不存在的属性进行unset时被调用 public function __unset($name) { echo $name; echo '__unset called'.PHP_EOL; }   //serialize时被调用，当你不需要保存大对象的所有数据时很有用 public function __sleep() { echo '__sleep called'.PHP_EOL; return array('var1111111111'); }   //unserialize时被调用，可用于做些对象的初始化操作 public function __wakeup() { echo '__wakeup called'.PHP_EOL; $this->var = 'test after wakeup'; }   //当一个类被转换成字符串时被调用 public function __toString() { return '__toString called'.PHP_EOL; }   //进行对象clone时被调用，用来调整对象的克隆行为 public function __clone() { echo '__clone called'.PHP_EOL; }   //当以函数方式调用对象时被调用 public function __invoke() { echo '__invoke called'.PHP_EOL; }   //当调用var_export()导出类时，此静态方法被调用。用__set_state的返回值做为var_export的返回值。 public static function __set_state($arr) { return '__set_state called'.PHP_EOL; }   // Called when var_dump() is called to print an object (when you don’t want to print all attributes) Applicable to PHP5.6 version public function __debuginfo($arr) { echo '__debuginfo called'.PHP_EOL; return array( 'var' => 'test fro __debuginfo' ); } } $m = new Magic(); //__construct() is called $m->not_exist_property = test; //__set() is called echo $m->not_exist_property;//__get() is called $m->abc(1,2,3); //__call() is called echo isset($m->not_exist_property); //__isset() is called and returns a bool value unset($m->not_exist_property); //__unset() is called echo $tmp = serialize($m); //__sleep() is called unserialize($tmp); //__wakeup() is called $m1 = clone $m; //__clone() is called, the object is passed by reference by default, and the object can be copied using the clone keyword $m(); //__invoke() eval( '$m2 = ' . var_export ( $m , true ) . ';' );var_dump($m2); var_dump($m); //Finally __destruct() is called /* Result: __construct called not_exist_property-test__set called not_exist_property__get called abc-1,2,3__call called not_exist_property__isset called 1not_exist_property__unset called __sleep called O:5:"Magic":1:{s:13:"var1111111111";N;}__wakeup called __destruct called __clone called __invoke called string(20) "__set_state called " class Magic#1 (1) { public $var => string(4) "test" } __destruct called __destruct called */

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