/** PHP Put all in __ Class methods that begin with (two underscores) are used as magic methods. So when you define your own class methods, don't start with __ For the prefix. * */
// __toString , __set , __get__isset() , __unset()
/*
The __toString method allows a class to decide how it will react when it is converted to a string.
__set() is run when writing data to inaccessible members.
__get() is utilized for reading data from inaccessible members.
__isset() is triggered by calling isset() or empty() on inaccessible members.
__unset() is invoked when unset() is used on inaccessible members.
*/
class TestClass {
private $data = array();
public $foo;
public function __construct($foo) {
$this->foo = $foo;
}
public function __toString() {
return $this->foo;
}
public function __set($name, $value) {
echo "__set, Setting '$name' to '$value'\n";
$this->data[$name] = $value;
}
public function __get($name) {
echo "__get, Getting '$name'\n";
if (array_key_exists($name, $this->data)) {
return $this->data[$name];
}
}
/** As of PHP 5.1.0 */
public function __isset($name) {
echo "__isset, Is '$name' set?\n";
return isset($this->data[$name]);
}
/** As of PHP 5.1.0 */
public function __unset($name) {
echo "__unset, Unsetting '$name'\n";
unset($this->data[$name]);
}
}
$obj = new TestClass('Hello');
echo "__toString, $obj\n";
$obj->a = 1;
echo $obj->a . "\n\n";
var_dump(isset($obj->a));
unset($obj->a);
var_dump(isset($obj->a));
echo "\n\n";
/**
The output results are as follows:
__toString, Hello
__set, Setting 'a' to '1'
__get, Getting 'a'
__isset, Is 'a' set?
bool(true)
__unset, Unsetting 'a'
__isset, Is 'a' set?
bool(false)
**/
// __call __callStatic
/*
mixed __call ( string $name , array $arguments )
mixed __callStatic ( string $name , array $arguments )
__call() is triggered when invoking inaccessible methods in an object context.
__callStatic() is triggered when invoking inaccessible methods in a static context.
The $name argument is the name of the method being called.
The $arguments argument is an enumerated array containing the parameters passed to the $name'ed method.
*/
class MethodTest {
public function __call($name, $arguments) {
// Note: value of $name is case sensitive.
echo "__call, Calling object method '$name' " . implode(', ', $arguments) . "\n";
}
/** As of PHP 5.3.0 */
public static function __callStatic($name, $arguments) {
// Note: value of $name is case sensitive.
echo "__callStatic, Calling static method '$name' " . implode(', ', $arguments) . "\n";
}
}
$obj = new MethodTest;
$obj->runTest('in object context', 'param2', 'param3');
//MethodTest::runTest('in static context'); // As of PHP 5.3.0
echo "\n\n";
/**
The output results are as follows:
__call, Calling object method 'runTest' in object context, param2, param3
string(10) "__invoke: "
*/
// __invoke
/*
The __invoke method is called when a script tries to call an object as a function.
Note: This feature is available since PHP 5.3.0.
*/
class CallableClass {
function __invoke($x) {
var_dump($x);
}
}
$obj = new CallableClass;
//$obj(5);
var_dump('__invoke: ' . is_callable($obj));
echo "\n\n";
// __sleep __wakeup
/*
serialization serialize You can include variables in objects , Into a continuum bytes data . You can put the serialized variables in there 1 In a file or over the network transfer .
Then it is de-serialized back to the original data . The class you defined before de-serializing the object of the class ,PHP Properties and methods of its object can be successfully stored .
Sometimes you might 1 Five objects are executed immediately after de-serialization . For this purpose ,PHP Will automatically look for __sleep and __wakeup methods .
when 1 Two objects are serialized ,PHP Will be called __sleep methods ( If it exists ). In anti-serialization 1 After an object ,PHP Will be called __wakeup methods .
Neither method accepts arguments . __sleep Method must return 1 An array , Contains properties that need to be serialized . PHP The values of other attributes are discarded .
If there is no __sleep methods ,PHP All attributes will be saved . The following example shows how to use it __sleep and __wakeup Method to serialize 1 An object .
Id Attributes are 1 A temporary property that is not intended to be retained in an object . __sleep Methods are guaranteed not to be included in the serialized object id attribute .
When you de-serialize 1 a User object ,__wakeup Method to establish id The new value of the . This example is designed to be self-sustaining .
In actual development , You may find included resources ( Such as images or data streams ) Objects need these methods
*/
class User {
public $name;
public $id;
function __construct() {
//give user a unique ID give 1 A difference between the ID
$this->id = uniqid();
}
//__sleep The type of the return value is an array, and the values in the array are fields that do not need to be serialized id
function __sleep() {
//do not serialize this->id Don't serialization id
return(array("name"));
}
function __wakeup() {
//give user a unique ID
$this->id = uniqid();
}
}
//create object Set up 1 A equipment
$u = new User;
$u->name = "Leon"; //serialize it serialization Note the non-serialization id attribute ,id Is abandoned
$s = serialize($u);
echo "__sleep, __wakeup, s: $s"; //unserialize it The serialization id Is reassigned
$u2 = unserialize($s); //$u and $u2 have different IDs $u and $u2 Is there a difference the ID
print_r($u);
print_r($u2);
echo "\n\n";
/**
The output results are as follows:
__sleep, __wakeup, s: O:4:"User":1:{s:4:"name";s:4:"Leon";}
User Object
(
[name] => Leon
[id] => 4db1b17640da1
)
User Object
(
[name] => Leon
[id] => 4db1b17640dbc
)
*/
// __set_state
/*
This static method is called for classes exported by var_export() since PHP 5.1.0.
The only parameter of this method is an array containing exported properties in the form array('property' => value, ...).
*/
class A {
public $var1;
public $var2;
public static function __set_state($an_array) { // As of PHP 5.1.0
//$an_array The printout is an array, not the object passed on the call
print_r($an_array);
$obj = new A;
$obj->var1 = $an_array['var1'];
$obj->var2 = $an_array['var2'];
return $obj;
}
}
$a = new A;
$a->var1 = 5;
$a->var2 = 'foo';
echo "__set_state:\n";
eval('$b = ' . var_export($a, true) . ';');
// $b = A::__set_state(array(
// 'var1' => 5,
// 'var2' => 'foo',
// ));
var_dump($b);
echo "\n\n";
/**
The output results are as follows:
__set_state:
Array
(
[var1] => 5
[var2] => foo
)
object(A)#5 (2) {
["var1"]=>
int(5)
["var2"]=>
string(3) "foo"
}
*/
// __clone
class SubObject {
static $instances = 0;
public $instance;
public function __construct() {
$this->instance = ++self::$instances;
}
public function __clone() {
$this->instance = ++self::$instances;
}
}
class MyCloneable {
public $object1;
public $object2;
function __clone() {
// Force a copy of this->object, otherwise
// it will point to same object.
$this->object1 = clone $this->object1;
}
}
$obj = new MyCloneable();
$obj->object1 = new SubObject();
$obj->object2 = new SubObject();
$obj2 = clone $obj;
print("__clone, Original Object:\n");
print_r($obj);
print("__clone, Cloned Object:\n");
print_r($obj2);
echo "\n\n";
/**
The output results are as follows:
__clone, Original Object:
MyCloneable Object
(
[object1] => SubObject Object
(
[instance] => 1
) [object2] => SubObject Object
(
[instance] => 2
))
__clone, Cloned Object:
MyCloneable Object
(
[object1] => SubObject Object
(
[instance] => 3
) [object2] => SubObject Object
(
[instance] => 2
))
*/