php闭包有什么用？

products[$product] =$quantity; } publicfunction getQuantity($product) { returnisset($this->products[$product]) ?$this->products[$product] : FALSE; } publicfunction getTotal($tax) { $total= 0.00; $callback= function($quantity,$product) use ($tax, &$total) { $pricePerItem= constant(__CLASS__. "::PRICE_" . strtoupper($product)); $total+= ($pricePerItem* $quantity) * ($tax+ 1.0); }; array_walk($this->products,$callback); returnround($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"; $close = ""; return function ($inner= "")use ($open,$close){ return "$open$inner$close";}; }

        

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