Summary and usage examples of magic methods in PHP, PHP magic summary examples_PHP tutorial

Summary and usage examples of magic methods in PHP, PHP magic summary examples

Magic methods are unique features in PHP object-oriented. 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 property

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 a method that is inaccessible or does not exist
__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 cloning an object 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 functionally

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:

<&#63;php
 
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;
  }
 
  //当调用var_dump()打印对象时被调用（当你不想打印所有属性）适用于PHP5.6版本
  public function __debuginfo($arr)
  {
    echo '__debuginfo called'.PHP_EOL;
    return array(
      'var' => 'test fro __debuginfo'
    );
  }
}
 
$m = new Magic(); //__construct()被调用
$m->not_exist_property = test; //__set()被调用
echo $m->not_exist_property;//__get()被调用
$m->abc(1,2,3); //__call()被调用
echo isset($m->not_exist_property); //__isset()被调用，返回bool值
unset($m->not_exist_property); //__unset()被调用
echo $tmp = serialize($m); //__sleep()被调用
unserialize($tmp); //__wakeup()被调用
$m1 = clone $m; //__clone()被调用，对象默认是引用传递，使用clone关键词则可实现对象复制
$m(); //__invoke()
eval( '$m2 = ' . var_export ( $m , true ) . ';' );var_dump($m2);
var_dump($m);
//最后__destruct()被调用
 
/*
结果：
__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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