How to bind returned function local variable to method parameter?

Question

I would like to get the following PHP code to work. The part that is not working is that the inner variable $greetingCount (the returned function's local variable) is not binding to the outer variable $greetingCount (the method parameter variable).

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();

// OUTPUT:

none

// EXPECTED OUTPUT:

HELLO
HELLO
HELLO
HELLO

NOTE: I would like a solution that also works when the static method is made nonstatic, otherwise two different solutions for these two cases will do.

score 0 · Accepted Answer · answered Feb 10 '15 at 17:00

The answer is to make use of the PHP use keyword:

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

How to bind returned function local variable to method parameter?

1 Answers1