The definition and use of magic methods in PHP

This article mainly introduces the definition and use of magic methods in PHP. Magic methods are unique features of object-oriented PHP. They are triggered under specific circumstances and all start with a double underscore. You can understand them. For hooks, friends in need can refer to

Magic method is 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. 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 the 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 attribute
__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 on an inaccessible or non-existent property It is called when the attribute is unset

4.__call, __callStatic

#__call is called when it calls an inaccessible or non-existent method
__callStatic is called when it is inaccessible or does not exist The existing static methods are called

5.__sleep, __wakeup

__sleep is called when using serialize, which is very convenient when you don’t need to save all the data of a large object. Useful
__wakeup is called when using unserialize and can be used to initialize objects

6.__clone

It is called when cloning an object and is used to Adjust object cloning behavior

7.__toString

Invoked when a class is converted to a string

8.__invoke

Called when the object is called functionally

9.__set_state

This static method is called when var_export() is called to export the class is called. 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

PHP magic method usage examples are as follows:

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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