php教程之魔术方法的使用示例(php魔术函数)

复制代码 代码如下:

// __toString、__set、__get__isset()、__unset()

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];
        }
    }

   
    public function __isset($name) {
        echo "__isset, Is '$name' set?n";
        return isset($this->data[$name]);
    }

   
    public function __unset($name) {
        echo "__unset, Unsetting '$name'n";
        unset($this->data[$name]);
    }

}

$obj = new TestClass('Hello');
echo "__toString, $objn";
$obj->a = 1;
echo $obj->a . "nn";
var_dump(isset($obj->a));
unset($obj->a);
var_dump(isset($obj->a));
echo "nn";

// __call  __callStatic

class MethodTest {
    public function __call($name, $arguments) {
        // Note: value of $name is case sensitive.
        echo "__call, Calling object method '$name' " . implode(', ', $arguments) . "n";
    }

   
    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 "nn";

// __invoke

class CallableClass {
    function __invoke($x) {
        var_dump($x);
    }
}

$obj = new CallableClass;
//$obj(5);
var_dump('__invoke: ' . is_callable($obj));
echo "nn";

// __sleep  __wakeup

class User {

    public $name;
    public $id;

    function __construct() {
        //give user a unique ID 赋予一个差别 的ID
        $this->id = uniqid();
    }

    //__sleep返回值的类型是数组，数组中的值是不需要串型化的字段id

    function __sleep() {
        //do not serialize this->id 不串行化id
        return(array("name"));
    }

    function __wakeup() {
        //give user a unique ID
        $this->id = uniqid();
    }

}

//create object 成立一个器材
$u = new User;
$u->name = "Leon"; //serialize it 串行化 留意不串行化id属性,id的值被遗弃
$s = serialize($u);
echo "__sleep, __wakeup, s: $s"; //unserialize it 反串行化 id被重新赋值
$u2 = unserialize($s); //$u and $u2 have different IDs $u和$u2有差别 的ID
print_r($u);
print_r($u2);
echo "nn";

// __set_state

class A {

    public $var1;
    public $var2;

    public static function __set_state($an_array) { // As of PHP 5.1.0
        //$an_array打印出来是数组，而不是调用时传递的对象
        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 "nn";

// __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 "nn";