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电梯直达

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发表于 2012-03-11 18:24 |只看该作者 |倒序浏览

php魔术方法： __get() 和 __set()的妙用

Php代码

1.<?php
2.class Post {
3. private $title;
4. private $content;
5. private $author;
6. private $comments;
7.
8. private $_getters = array('title', 'content', 'author', 'comments');
9. private $_setters = array('title', 'content', 'author');
10.
11. public function __get($property) {
12. if (in_array($property, $this->_setters)) {
13. return $this->$property;
14. }
15. else if (method_exists($this, '_get_' . $property))
16. return call_user_func(array($this, '_get_' . $property));
17. else if (in_array($property, $this->_getters) OR method_exists($this, '_set_' . $property))
18. throw new Exception('Property "' . $property . '" is write-only.');
19. else
20. throw new Exception('Property "' . $property . '" is not accessible.');
21. }
22.
23. public function __set($property, $value) {
24. if (in_array($property, $this->_getters)) {
25. $this->$property = $value;
26. }
27. else if (method_exists($this, '_set_' . $property))
28. call_user_func(array($this, '_set_' . $property), $value);
29. else if (in_array($property, $this->_setters) OR method_exists($this, '_get_' . $property))
30. throw new Exception('Property "' . $property . '" is read-only.');
31. else
32. throw new Exception('Property "' . $property . '" is not accessible.');
33. }
34.}
35.?>
36.
37.This way the variables in the $_getters array can be read from the outside and the variables in the $_setters array can be modified from the outside, like this:
38.
39.<?php
40.$post = new Post();
41.$post->title = 'Hello, World';
42.echo $post->title;
43.
44.// The following will throw an exception since $comments is read-only:
45.$post->comments = 23;
46.?>
47.
48.And in case you need a less generic getter or setter at some point, you can remove the variable from the $_getters or $_setters array and implement a method like:
49.
50.<?php
51.private function _set_title($value) {
52. $this->title = str_replace('World', 'Universe', $value);
53.}
54.?>
55.
56.And from the outside the property could still be used with:
57.
58.<?php
59.$post->title = 'Hello, World!';
60.?>
<?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!';
?>