Usage of __call, __set and __get

1. Usage of __call

PHP5 objects have a new special method __call(), which is used to monitor other methods in an object. If you try to call a method that does not exist on the object, the __call method will be called automatically.

Example: __call

<?php  
class foo {  
    function __call($name,$arguments) {  
        print("Did you call me? I&#39;m $name!<br>");  
        print_r($arguments);  
        print("<br><br>");  
    }  
  
    function doSecond($arguments)  
    {  
        print("Right, $arguments!<br>");  
    }  
}   
   
$test = new foo();  
$test->doFirst(&#39;no this function&#39;);  
$test->doSecond(&#39;this function exist&#39;);  
?>

2. __call implements the "overloading" action

This special method can be used to implement the "overloading" action so that you can check your parameters and call a Private method to pass parameters.

Example: Use __call to implement "overload" action

<?php  
class Magic {  
    function __call($name,$arguments) {  
        if($name==&#39;foo&#39;) {  
            if(is_int($arguments[0])) $this->foo_for_int($arguments[0]);  
            if(is_string($arguments[0])) $this->foo_for_string($arguments[0]);  
        }  
    }     
      
    private function foo_for_int($x) {  
        print("oh an int!");  
    }     
          
    private function foo_for_string($x) {  
        print("oh a string!");  
    }  
}   
  
$test = new Magic();  
$test->foo(3);  
$test->foo("3");  
?>

3. Object-oriented overloading

<?php  
/*__call(string $name,array $arg)的用法 
*当调用一个不可访问的方法的时候调用$name是方法名称 $arg是个数组包含要传递给方法的参数 
*/  
class Account{  
    private $user=1;  
    private $pwd=2;  
    public function __call($name,$arg){  
        switch(count($arg)){  
            case 2:  
                echo $arg[0]*$arg[1],PHP_EOL;  
                break;  
            case 3:  
                echo array_sum($arg),PHP_EOL;  
                break;  
            default:  
                echo "参数不对",PHP_EOL;  
                break;  
        }  
    }  
  
}  
    $a= new Account();  
    //这里模拟了重载  
    //重载:一个类中可以定义参数列表不同但名字相同的多个方法  
    $a->make(5);  
    $a->make(5,6);

4. Use the __call() method to achieve coherent database operations

<?php  
  // 使用__call()方法来实现数据库连贯操作  
 // 申明一个Db类（数据库操作类）的简单操作模型  
  
class Db{  
    private $sql = array(  
        "field" => "",  
        "where" => "",  
        "order" => "",  
        "limit" => "",  
        "group" => "",  
        "having" => "",  
    );  
     
    // 连贯操作调用field() where() order() limit() group() having()方法，组合sql语句  
    function __call($methodName,$args){  
        // 将第一个参数(代表不存在方法的方法名称),全部转成小写方式，获取方法名称  
        $methodName = strtolower($methodName);  
         
        // 如果调用的方法名和成员属性数组$sql下标对应上，则将第二个参数给数组中下标对应的元素  
        if(array_key_exists($methodName,$this->sql)){  
            $this->sql[$methodName] = $args[0];  
        }else{  
            echo &#39;调用类&#39;.get_class($this).&#39;中的方法&#39;.$methodName.&#39;()不存在&#39;;  
        }  
        // 返回自己对象，则可以继续调用本对象中的方法，形成连贯操作  
        return $this;  
    }  
    // 输出连贯操作后组合的一个sql语句，是连贯操作最后的一个方法  
    function select(){  
        echo "SELECT {$this->sql[&#39;field&#39;]} FROM  user {$this->sql[&#39;where&#39;]} {$this->sql[&#39;order&#39;]} {$this->sql[&#39;limit&#39;]} {$this->sql[&#39;group&#39;]}  
                {$this->sql[&#39;having&#39;]}";  
    }  
}  
  
$db = new Db();  
  
// 连贯操作  
$db->field(&#39;sex, count(sex)&#39;)  
   ->where(&#39;where sex in ("男","女")&#39;)  
   ->group(&#39;group by sex&#39;)  
   ->having(&#39;having avg(age) > 25&#39;)  
   ->select();  
?>

5. Usage of __set and __get

This is a great method. The __set and __get methods can be used to capture variables and methods that do not exist in an object.

Example: __set and __get

<?php  
class foo {  
    function __set($name,$val) {  
        print("Hello, you tried to put $val in $name<br>");  
    }  
   
    function __get($name) {  
        print("Hey you asked for $name<br>");  
    }  
}  
  
$test = new foo();  
$test->__set(&#39;name&#39;,&#39;justcoding&#39;);  
$test->__get(&#39;name&#39;);  
?>