如何將返回的函數局部變量綁定到方法參數？

Question

我想獲得下面的PHP代碼來工作。不工作的部分是內部變量$greetingCount（返回的函數的局部變量）不綁定到外部變量$greetingCount（方法參數變量）。

class Greetings { 

    public static function getRepeatGreeterFunc($greetingCount) { 

    $repeatGreeter = function($greeting) { 

     // I want $greetingCount to bind to the outer $greetingCount here. 
     // If 4 is passed to getRepeatGreeterFunc, then it should be 4 here, 
     // so that what I get is a function that prints the greeting 4 times. 

     for ($i = 0; $i < $greetingCount; $i++) { 

     echo $greeting . "\n"; 

     } 

    }; 

    return $repeatGreeter; 

    } 

    public function greet() { 

    $repeatGreeter = self::getRepeatGreeterFunc(4); 
    call_user_func($repeatGreeter, "HELLO"); 

    } 

} 

$greetings = new Greetings(); 
$greetings->greet(); 

//輸出：

none 

//預期輸出：

HELLO 
HELLO 
HELLO 
HELLO 

注：我想一個解決方案時，靜態方法是由非靜態的也工作，否則兩張這兩種情況下的不同解決方案都可以。

Answer 1

答案就是利用PHP use關鍵字：

class Greetings { 

    public static function getRepeatGreeterFunc($greetingCount) { 

    $repeatGreeter = function($greeting) use ($greetingCount) { 

     // I want $greetingCount to bind to the outer $greetingCount here. 
     // If 4 is passed to getRepeatGreeterFunc, then it should be 4 here, 
     // so that what I get is a function that prints the greeting 4 times. 

     for ($i = 0; $i < $greetingCount; $i++) { 

     echo $greeting . "\n"; 

     } 

    }; 

    return $repeatGreeter; 

    } 

    public function greet() { 

    $repeatGreeter = self::getRepeatGreeterFunc(4); 
    call_user_func($repeatGreeter, "HELLO"); 

    } 

} 

$greetings = new Greetings(); 
$greetings->greet(); 

OUTPUT：

HELLO 
HELLO 
HELLO 
HELLO