php 語言特性學習（三）

1.__get __set

class  Test {
    private $arr = array(
        'x'=>null,
        'y'=>null
    );

    function __get($property) {
        if(array_key_exists($property,$this->arr)) {
            return $this->arr[$property];
        } else {
            print "error:can not read this property is not exist other than x or y\n";
        }
    }

    function __set($property,$value) {
        if(array_key_exists($property,$this->arr)) {
            $this->arr[$property] = $value;
        } else {
            print "error:can not write this property is not exist other than x or y\n";
        }
    }
}

$cl = new Test();
$cl->x = 1;
echo $cl->x;

$cl->t = 2;
echo $cl->t;

//結果是
1
error:can not write this property is not exist other than x or 
y 
error:can not read this property is not exist other than x or y

2.__call 函數使用

class HelloWorld {
    function display($time) {
        for($i=0;$i<$time;$i++) {
            print "hello world\n";
        }
    }
}

class callHelloWorld {
    private $obj;
    function __construct() {
        $this->obj = new HelloWorld();
    }

    function __call($method,$arg) {
        return call_user_func_array(array($this->obj,$method),$arg);
    }
}

$me = new callHelloWorld();
$me->display(3);

結果是

hello world hello world hello world

3.迭代器

class numberSquare implements Iterator {
    private $start;
    private $end;
    private $cur;
    public function __construct($start, $end) {
        $this->start = $start;
        $this->end = $end;
    }

    public function rewind() {
        $this->cur = $this->start;
    }

    public function key() {
        return $this->cur;
    }

    public function current() {
        return pow($this->cur,3);
    }

    public function next() {
        $this->cur++;
    }

    public function valid() {
        return $this->cur <= $this->end;
    }
}

$obj = new numberSquare(2,5);
foreach($obj as $key => $value) {
    print "the square of $key is $value <br>\n";
}

結果是

the square of 2 is 8 
the square of 3 is 27 
the square of 4 is 64 
the square of 5 is 125

4.工廠模式

//定義抽象類 user類   讀權限給，修改，刪除權限不給
abstract class User {
    private $name = null;
    function __construct($name) {
        $this->name = $name ;
    }
    function getName() {
        return $this->name;
    }
    //權限方法
    function hasReadPermission() {
        return true;
    }
    function hasModifyPermission() {
        return false;
    }
    function hasDeletePermission() {
        return false;
    }
    //定製方法
    function wantsFlsahInterFace() {
        return true;
    }
}

class GuestUser extends User {
}

class CustomerUser extends User {
    //customer 有修改權限
    function hasModifyPermission() {
        return true ;
    }
}

class AdminUser extends User {
    function hasModifyPermission() {
        return true ;
    }
    function hasDeletePermission() {
        return true ;
    }
    function wantsFlsahInterFace() {
        return false;
    }
}

class UserFactory {
    private static $users = array(
        "andy"=>'Admin',
        "tom"=>'customer',
        "jack"=>'guest'
    );
    static function create($name) {
          switch(self::$users[$name]) {
            case 'Admin' :
                return new AdminUser($name);
                  break;
            case 'customer' :
                return new CustomerUser($name);
                break;
            case 'guest' :
                return new GuestUser($name);
                break;
            default:
                break;
          }

    }
}

function boolToString($b) {
    if($b == true) {
        return "yes";
    } else {
        return "no";
    }
}

function displayPermission( $obj) {
        print $obj->getName() . "'s permission:\n";
        print "Read: " . boolToString($obj->hasReadPermission());
        print "Modify: " . boolToString($obj->hasModifyPermission());
        print "Delete: " . boolToString($obj->hasDeletePermission());
}

function displayRequirement( $obj) {
    if($obj->wantsFlsahInterFace()) {
        print $obj->getName() . "require flash\n";
    }
}

$login = array("andy",'str','jack');
foreach($login as $key =>$val) {
    displayPermission(UserFactory::create($val));
}

結果是

received updated received updated
//實例化時不會有任何輸出，直到有一個事件或者一個參數被設置纔有所行動，一開始有一個觀察類。實現類繼承觀察類，實現類裏面有改變值的類在初始化的時候實例一下。當有值改變時調用實現類繼承觀察類的方法（即完成通知）方法裏面能夠寫被通知以後的操做，如打印字符串等等

5.觀察者模式

**

給程序員一個鼓勵唄！

**

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