php __call方法使用说明
本文章来给大家介绍php __call方法使用说明，有需要学习php __call方法的朋友不防进入参考。 相信刚开始接触PHP的童鞋都，在参考书上看到过__call这个魔法方法，而且也看到了它的应用实例！但是，等你真的开始写代码的时候，你用过它吗！？说实话，我用PHP也有一段时间了，但真的从没将它应用到实际开发中。
先说一下__call 的作用吧："PHP5 对象新增的一个专用方法 ，这个方法用来监视一个对象中的其它方法。如果你试着调用一个对象中不存在的方法，__call 方法将会被自动调用。"
典型用例：
| 代码如下 | 复制代码 |
|
runTest('in object context'); |
|
运行结果：
Calling object method 'runTest' in object context
不过，最近终于看到了一个__call在实际开发中的应用。thinkphp作为国内应用比较普遍的框架，在它里面对这个方法应用个人觉得算的上是完美啊！
比如在thinkphp的：lib->think->core->model.class.php文件里面（Model类）有这么一段代码：
| 代码如下 | 复制代码 |
| /** +---------------------------------------------------------- * 利用__call方法实现一些特殊的Model方法 +---------------------------------------------------------- * @access public +---------------------------------------------------------- * @param string $method 方法名称 * @param array $args 调用参数 +---------------------------------------------------------- * @return mixed +---------------------------------------------------------- */ public function __call($method,$args) { if(in_array(strtolower($method),array('field','table','where','order','limit','page','alias','having','group','lock','distinct'),true)) { // 连贯操作的实现 $this->options[strtolower($method)] = $args[0]; return $this; }elseif(in_array(strtolower($method),array('count','sum','min','max','avg'),true)){ // 统计查询的实现 $field = isset($args[0])?$args[0]:'*'; return $this->getField(strtoupper($method).'('.$field.') AS tp_'.$method); }elseif(strtolower(substr($method,0,5))=='getby') { // 根据某个字段获取记录 $field = parse_name(substr($method,5)); $where[$field] = $args[0]; return $this->where($where)->find(); }else{ throw_exception(__CLASS__.':'.$method.L('_METHOD_NOT_EXIST_')); return; } } |
|
代码的具体功能，我就不解释了，第一可能我也解释不清楚；第二自己去看一下里面的编程思想还是有很多值的学习的。
说一下他的调用方法，就能看出他的"强大"了。
调用：
$this->dao= M('table'); //快速高性能实例化一个 table 表的模型
$this->dao->field($field)->where($where)->limit($offset . ',' . $limit)->select(); //设置查询字段，查询条件，设置查询数量，最后执行查询操作。当然返回的就是数据库记录了
看到"不对劲"了吧，field方法成对象了，where、limit、select方法也成对象了，其实field、where这些方法在 Model类 里面都不存在。正是因为这些方法不存在，所以这个时候__call方法被执行了，然后又会返回$this对象。所以可以实现这种"衔接"写法，一行代码搞了所有的SQL语句。
不再说下去了，就是向大家介绍一个__call方法的实际应用。要想完全理解它还是建议你自己去看thinkphp的源码吧！（申明：本人跟thinkphp没有任何关系，并不是在鼓吹它的好）
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