class intercept_demo{
private $xingming = "";
private $age = 10;

// 若访问一个未定义的属性，则将调用get{$property}对应的方法
function __get($property){
$method = "get{$property}";
if (method_exists($this, $method)){
return $this->$method();
}
}

// 若给一个未定义的属性设置值，则将调用set{$property}对应的方法
function __set($property, $value){
$method = "set{$property}";
if (method_exists($this, $method)){
return $this->$method($value);
}
}

// 若用户对未定义的属性调用isset方法，
function __isset($property){
$method = "isset{$property}";
if (method_exists($this, $method)){
return $this->$method();
}
}

// 若用户对未定义的属性调用unset方法，
// 则认为调用对应的unset{$property}方法
function __unset($property){
$method = "unset{$property}";
if (method_exists($this, $method)){
return $this->$method();
}
}

function __call($method, $arg_array){
if (substr($method,0,3)=="get"){
$property = substr($method,3);
$property = strtolower(substr($property,0,1)).substr($property,1);
return $this->$property;
}
}

function testIsset(){
return isset($this->Name);
}

function getName(){
return $this->xingming;
}

function setName($value){
$this->xingming = $value;
}

function issetName(){
return !is_null($this->xingming);
}

function unsetName(){
$this->xingming = NULL;
}
}

$intercept = new intercept_demo();
echo "设置属性Name为Li";
$intercept->Name = "Li";
echo "\$intercept->Name={$intercept->Name}";
echo "isset(Name)={$intercept->testIsset()}";
echo "";
echo "清空属性Name值";
unset($intercept->Name);
echo "\$intercept->Name={$intercept->Name}";
echo "";
echo "调用未定义的getAge函数";
echo "age={$intercept->getAge()}";