PHP Object-oriented Magic method explained

This article mainly introduces the method of magic in object-oriented oop in PHP, which has certain reference value, and the interested partners can refer to

One, what is the Magic method:

PHP provides us with a series of functions that begin with __, which do not need to be called manually, and are called automatically at the right time, such functions as magic functions.
For example:

function __construct(){}This function is called automatically when new object is newly

In PHP, there are magic methods and their effects:

1.__construct (): constructor, automatically called when new object

eg

Class person{public    $name;    public $age;        function __construct ($name, $age) {      $this->name= $name;      $this->age= $age;    }}

The __construct () function is automatically called when the new Person object is newly, assigning the passed arguments to $name, $age.

2.__destruct (): destructor, called automatically before an object is destroyed

Class person{public    $name;    public $age;        function __destruct () {    echo "This object has been destroyed";  }}

As mentioned above, this magic method is executed when the object is destroyed

3.__get (): automatically called when accessing private properties in a class, passing read property names, returning $this-> property names

Class person{    private $name;    public $age;        function __get ($name) {     return $this, $name;    }}

As in the code, the $name is set as a private property and cannot be read directly by $this->name;, so the __get () Magic method needs to be set to read.

4.__set (): Automatically called when assigning a value to a private property of a class, passing property names to be set, property values

Class person{    private $name;    public $age;        function __set ($key, $value) {      $this, $key = $value;    }}

With the __get () method, the private property cannot be set directly by $this->name= "AAA", the __set () method needs to be set, and the parameters passed in are the property name and the attribute value, respectively.

5.__isset (): Called when detecting private properties of an object using Isset, passing the detected property name, returning Isset ($this property name)

Class person{    private $name;    public $age;        function __isset ($name) {    return isset ($this, $name);}  }

Called when using Isset to detect the private properties of an object, as in the other.

6.__unset (): Called when the object private property is deleted using the unset () function, passing the deleted property name, executing the unset ($this-property name) in the method

Class person{    private $name;    public $age;        function __unset ($name) {      unset ($this, $name);}    }

Ditto, called when a private property is removed with the unset () function.

7.__tostring (): Called When using echo to print an object, returns the content to be displayed when the object is printed, and returns a string

Class person{public    $name;    public $age;        function __tostring () {      $str = <<<str      The content you want to print is:<br>      \ $name =>{$this->name};<br >      \ $age =>{$this->age};<br>str;      return $str;    }}

Called when you print an object with Echo, and returns what you want to display when you print the object.

8.__call (): called automatically when calling a method that is not defined or exposed in a class, passing the called function name and argument list

Class person{public    $name;    public $age;        function __call ($funcName, $funcParams) {      echo) {$funcName}, parameter list "you have called";      Print_r ($funcParams);      echo "does not exist/is not public";    }} $zhangsan =new person (); $zhangsan->say (a);

As shown in the code, the call does not exist for say (.

You call the function of the method, the parameter list array ([0] = 123) does not exist

9.__clone (): When cloning an object using the Clone keyword, it is called automatically to initialize the value of the newly cloned object

Class person{public    $name;    public $age;        function __clone () {    $this->name= "Lisi";    }}  $zhangsan =new person ("Zhangsan"), $lisi =clone $zhangsan, Echo $lisi->name;

The printed result is "Lisi", not "Zhangsan".

10.__sleep (): Automatically called when the object is serialized, returns an array where the values in the array are the properties that can be serialized

Class person{public    $name;    public $age;       function __sleep () {    return Array ("name", "Age");}  }

As in the above code, only "name" is used when serializing an object with serialize (), and the "age" property is serialized.

11.__wakeup (): Automatic invocation of object deserialization, initialization assignment for deserialization of newly generated objects

Class person{public    $name;    public $age;       function __wakeup () {    $this, name = "Lisi";  }}

Serializes the object and then deserializes it, assigning an initial value of "Lisi" to the object's Name property.

12.__autolode (): You need to declare a function outside the class, automatically call when an undeclared class is instantiated, pass the instantiated class name, and automatically load the corresponding class file using the class name.

function __autoload ($className) {  include "class/". Strtolower ($className). ". Class.php ";}  $zhangsan =new person (); $zhangsan->say ();

As the above code, the person class does not exist when calling the __autolode () method, loading a class written outside the file, "class/". Strtolower ($className). Class.php "; Is the relative path to the class file, $className is

The class name of the class that is not in this file, so the naming method must be a lowercase class name when creating an external class file. class.php. The __autolode () method is also the only one by one magic methods that are not written in the class.