php魔术方法： __get() 和 __set()的妙用

woyoudn

<?php
class Post {
private $title;
private $content;
private $author;
private $comments;
private $_getters = array('title', 'content', 'author', 'comments');
private $_setters = array('title', 'content', 'author');
public function __get($property) {
if (in_array($property, $this->_setters)) {
return $this->$property;
}
else if (method_exists($this, '_get_' . $property))
return call_user_func(array($this, '_get_' . $property));
else if (in_array($property, $this->_getters) OR method_exists($this, '_set_' . $property))
throw new Exception('Property "' . $property . '" is write-only.');
else
throw new Exception('Property "' . $property . '" is not accessible.');
}
public function __set($property, $value) {
if (in_array($property, $this->_getters)) {
$this->$property = $value;
}
else if (method_exists($this, '_set_' . $property))
call_user_func(array($this, '_set_' . $property), $value);
else if (in_array($property, $this->_setters) OR method_exists($this, '_get_' . $property))
throw new Exception('Property "' . $property . '" is read-only.');
else
throw new Exception('Property "' . $property . '" is not accessible.');
}
}
?>
This way the variables in the $_getters array can be read from the outside and the variables in the $_setters array can be modified from the outside, like this:
<?php
$post = new Post();
$post->title = 'Hello, World';
echo $post->title;
// The following will throw an exception since $comments is read-only:
$post->comments = 23;
?>
And in case you need a less generic getter or setter at some point, you can remove the variable from the $_getters or $_setters array and implement a method like:
<?php
private function _set_title($value) {
$this->title = str_replace('World', 'Universe', $value);
}
?>
And from the outside the property could still be used with:
<?php
$post->title = 'Hello, World!';
?>
　　上面是手册里的例子，但是我觉得应该是先判断类里面是否有处理属性的方法，有的话就调用该方法，没有就直接设置该属性。