<?php class MemberTest { /** 被重载的数据保存在此 */ private $data = array(); /** 重载不能被用在已经定义的属性 */ public $declared = 1; /** 只有从类外部访问这个属性时,重载才会发生 */ private $hidden = 2; public function __set($name, $value) { echo "Setting '$name' to '$value'\n"; $this->data[$name] = $value; } public function __get($name) { echo "Getting '$name'\n"; if (array_key_exists($name, $this->data)) { return $this->data[$name]; } $trace = debug_backtrace(); trigger_error( 'Undefined property via __get(): ' . $name . ' in ' . $trace[0]['file'] . ' on line ' . $trace[0]['line'], E_USER_NOTICE); return null; } /** PHP 5.1.0之后版本 */ public function __isset($name) { echo "Is '$name' set?\n"; return isset($this->data[$name]); } /** PHP 5.1.0之后版本 */ public function __unset($name) { echo "Unsetting '$name'\n"; unset($this->data[$name]); } /** 非魔术方法 */ public function getHidden() { return $this->hidden; } } echo "<pre>\n";$obj = new MemberTest;$obj->a = 1; echo $obj->a . "\n\n";var_dump(isset($obj->a)); unset($obj->a); var_dump(isset($obj->a)); echo "\n";echo $obj->declared . "\n\n";echo "Let's experiment with the private property named 'hidden':\n"; echo "Privates are visible inside the class, so __get() not used...\n"; echo $obj->getHidden() . "\n"; echo "Privates not visible outside of class, so __get() is used...\n"; echo $obj->hidden . "\n"; ?>Setting 'a' to '1' Getting 'a' 1Is 'a' set? bool(true) Unsetting 'a' Is 'a' set? bool(false)1Let's experiment with the private property named 'hidden': Privates are visible inside the class, so __get() not used... 2 Privates not visible outside of class, so __get() is used... Getting 'hidden' Notice: Undefined property via __get(): hidden in <file> on line 70 in <file> on line 29
5.1.0 新增 __isset() 和 __unset()两个魔术方法.
5.3.0 新增 __callStatic()魔术方法. 可见性未设置为public或未声明为static的时候会产生一个警告
属性重载void __set ( string $name , mixed $value )
mixed __get ( string $name )
bool __isset ( string $name )
void __unset ( string $name )
在给未定义的变量赋值时,__set() 会被调用。读取未定义的变量的值时,__get() 会被调用。当对未定义的变量调用isset() 或 empty()时,__isset() 会被调用。当对未定义的变量调用unset()时,__unset() 会被调用。参数$name是指要操作的变量名称。__set() 方法的$value 参数指定了$name变量的值。属性重载只能在对象中进行。在静态方法中,这些魔术方法将不会被调用。所以这些方法都不能被 声明为static。
<?php
class MemberTest {
/** 被重载的数据保存在此 */
private $data = array();
/** 重载不能被用在已经定义的属性 */
public $declared = 1; /** 只有从类外部访问这个属性时,重载才会发生 */
private $hidden = 2; public function __set($name, $value) {
echo "Setting '$name' to '$value'\n";
$this->data[$name] = $value;
} public function __get($name) {
echo "Getting '$name'\n";
if (array_key_exists($name, $this->data)) {
return $this->data[$name];
} $trace = debug_backtrace();
trigger_error(
'Undefined property via __get(): ' . $name .
' in ' . $trace[0]['file'] .
' on line ' . $trace[0]['line'],
E_USER_NOTICE);
return null;
} /** PHP 5.1.0之后版本 */
public function __isset($name) {
echo "Is '$name' set?\n";
return isset($this->data[$name]);
} /** PHP 5.1.0之后版本 */
public function __unset($name) {
echo "Unsetting '$name'\n";
unset($this->data[$name]);
} /** 非魔术方法 */
public function getHidden() {
return $this->hidden;
}
}
echo "<pre>\n";$obj = new MemberTest;$obj->a = 1;
echo $obj->a . "\n\n";var_dump(isset($obj->a));
unset($obj->a);
var_dump(isset($obj->a));
echo "\n";echo $obj->declared . "\n\n";echo "Let's experiment with the private property named 'hidden':\n";
echo "Privates are visible inside the class, so __get() not used...\n";
echo $obj->getHidden() . "\n";
echo "Privates not visible outside of class, so __get() is used...\n";
echo $obj->hidden . "\n";
?>Setting 'a' to '1'
Getting 'a'
1Is 'a' set?
bool(true)
Unsetting 'a'
Is 'a' set?
bool(false)1Let's experiment with the private property named 'hidden':
Privates are visible inside the class, so __get() not used...
2
Privates not visible outside of class, so __get() is used...
Getting 'hidden'
Notice: Undefined property via __get(): hidden in <file> on line 70 in <file> on line 29