对象方法PHP中魔术方法的用法对象方法

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    每日一道理
美丽是平凡的，平凡得让你感觉不到她的存在；美丽是平淡的，平淡得只剩下温馨的回忆；美丽又是平静的，平静得只有你费尽心思才能激起她的涟漪。

/** PHP把全部以__（两个下划线）头开的类方法成当术魔方法。所以你义定自己的类方法时，不要以 __为前缀。 * */

// __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"; 
/**
  输出结果如下：
  __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"; 
/**
 输出结果如下：
 __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
/*
  串行化serialize可以把量变括包对象,转化成连续bytes数据. 你可以将串行化后的量变存在一个文件里或在网络上传输. 
  然后再反串行化还原为来原的数据. 你在反串行化类的对象之前义定的类,PHP可以成功地存储其对象的性属和方法. 
  时有你可能须要一个对象在反串行化后当即执行. 为了这样的目标,PHP会动自寻觅__sleep和__wakeup方法.
  当一个对象被串行化,PHP会调用__sleep方法(如果存在的话). 在反串行化一个对象后,PHP 会调用__wakeup方法. 
  这两个方法都不受接参数. __sleep方法必须返回一个数组,含包须要串行化的性属. PHP会摈弃其它性属的值. 
  如果没有__sleep方法,PHP将存保全部性属.上面的例子示显了如何用__sleep和__wakeup方法来串行化一个对象. 
  Id性属是一个不算打保留在对象中的临时性属. __sleep方法保障在串行化的对象中不含包id性属. 
  当反串行化一个User对象,__wakeup方法建立id性属的新值. 这个例子被计设成自我坚持. 
  在现实开辟中,你可能发明含包源资(如像图或数据流)的对象须要这些方法
 */

class User {

    public $name;
    public $id;

    function __construct() {
        //give user a unique ID 予赋一个别差 的ID
        $this->id = uniqid();
    }

    //__sleep返回值的类型是数组，数组中的值是不须要串型化的段字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 立成一个东西
$u = new User;
$u->name = "Leon"; //serialize it 串行化 留心不串行化id性属,id的值被遗弃
$s = serialize($u);
echo "__sleep, __wakeup, s: $s"; //unserialize it 反串行化 id被从新赋值
$u2 = unserialize($s); //$u and $u2 have different IDs $u和$u2有别差 的ID
print_r($u);
print_r($u2);
echo "\n\n"; 
/**
 输出结果如下：
  __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打印出来是数组，而不是调用时递传的对象
        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 "\n\n"; 
/**
  输出结果如下：
  __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";
/**
 输出结果如下：
 __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
  )) 
 */

文章结束给大家分享下程序员的一些笑话语录： 火车
一个年轻的程序员和一个项目经理登上了一列在山里行驶的火车，他们发现 列车上几乎都坐满了，只有两个在一起的空位，这个空位的对面是一个老奶 奶和一个年轻漂亮的姑娘。两个上前坐了下来。程序员和那个姑娘他们比较 暧昧地相互看对方。这时，火车进入山洞，车厢里一片漆黑。此时，只听见 一个亲嘴的声音，随后就听到一个响亮的巴掌声。很快火车出了山洞，他们 四个人都不说话。
那个老奶奶在喃喃道， “这个年轻小伙怎么这么无礼， 不过我很高兴我的孙女 扇了一个巴掌”。
项目经理在想，“没想到这个程序员居然这么大胆，敢去亲那姑娘，只可惜那 姑娘打错了人，居然给打了我。”
漂亮的姑娘想，“他亲了我真好，希望我的祖母没有打疼他”。
程序员坐在那里露出了笑容， “生活真好啊。 这一辈子能有几次机会可以在亲 一个美女的同时打项目经理一巴掌啊”