$a = function() use($b) {}

function callback($fun) {$fun();}$msg = "Hello, everyone";$fun = function () use($msg) {print "This is a closure use string value, msg is: $msg. <br />/n";};$msg = "Hello, everybody";callback($fun);

/**  * 一个利用闭包的计数器产生器  * 这里其实借鉴的是python中介绍闭包时的例子...  * 我们可以这样考虑:  *      1. counter函数每次调用, 创建一个局部变量$counter, 初始化为1.  *      2. 然后创建一个闭包, 闭包产生了对局部变量$counter的引用.  *      3. 函数counter返回创建的闭包, 并销毁局部变量, 但此时有闭包对$counter的引用,   *          它并不会被回收, 因此, 我们可以这样理解, 被函数counter返回的闭包, 携带了一个游离态的  *          变量.  *      4. 由于每次调用counter都会创建独立的$counter和闭包, 因此返回的闭包相互之间是独立的.  *      5. 执行被返回的闭包, 对其携带的游离态变量自增并返回, 得到的就是一个计数器.  * 结论: 此函数可以用来生成相互独立的计数器.  */  function counter() {      $counter = 1;      return function() use(&$counter) {return $counter ++;};  }  $counter1 = counter();  $counter2 = counter();  echo "counter1: " . $counter1() . "<br />/n";  echo "counter1: " . $counter1() . "<br />/n";  echo "counter1: " . $counter1() . "<br />/n";  echo "counter1: " . $counter1() . "<br />/n";  echo "counter2: " . $counter2() . "<br />/n";  echo "counter2: " . $counter2() . "<br />/n";  echo "counter2: " . $counter2() . "<br />/n";  echo "counter2: " . $counter2() . "<br />/n";  ?>

<?php// 一个基本的购物车，包括一些已经添加的商品和每种商品的数量。// 其中有一个方法用来计算购物车中所有商品的总价格。该方法使用了一个closure作为回调函数。class Cart{    const PRICE_BUTTER  = 1.00;    const PRICE_MILK    = 3.00;    const PRICE_EGGS    = 6.95;     protected   $products = array();         public function add($product, $quantity)    {        $this->products[$product] = $quantity;    }         public function getQuantity($product)    {        return isset($this->products[$product]) ? $this->products[$product] :               FALSE;    }         public function getTotal($tax)    {        $total = 0.00;                 $callback =            function ($quantity, $product) use ($tax, &$total)            {                $pricePerItem = constant(__CLASS__ . "::PRICE_" .                    strtoupper($product));                $total += ($pricePerItem * $quantity) * ($tax + 1.0);            };        //使用用户自定义函数对数组中的每个元素做回调处理        array_walk($this->products, $callback);        return round($total, 2);;    }} $my_cart = new Cart; // 往购物车里添加条目$my_cart->add(‘butter‘, 1);$my_cart->add(‘milk‘, 3);$my_cart->add(‘eggs‘, 6); // 打出出总价格，其中有 5% 的销售税.print $my_cart->getTotal(0.05) . "\n";// The result is 54.29?>

function html($code , $id="", $class=""){if ($id !== "") $id = " id = \"$id\"" ;$class = ($class !== "")? " class =\"$class\">":">";$open = "<$code$id$class";$close = "</$code>";return function ($inner = "") use ($open, $close){return "$open$inner$close";    };}

<?php$fib = function($n) use(&$fib) {    if($n == 0 || $n == 1) return 1;    return $fib($n - 1) + $fib($n - 2);}; echo $fib(2) . "\n"; // 2$lie = $fib;$fib = function(){die(‘error‘);};//rewrite $fib variable echo $lie(5); // error   because $fib is referenced by closure

<?php$recursive = function () use (&$recursive){// The function is now available as $recursive}

<?php$result = 0; $one = function(){    var_dump($result);}; $two = function() use ($result){    var_dump($result);}; $three = function() use (&$result){    var_dump($result);}; $result++; $one();    // outputs NULL: $result is not in scope$two();    // outputs int(0): $result was copied$three();    // outputs int(1)