匿名函数
// Example1$func = function( $param ) { echo $param;};$func( 'some string' );//输出：some string// Example2function callFunc( $func ) { $func( 'some string' );}$printStrFunc = function( $str ) { echo $str;};callFunc( $printStrFunc );//可以直接将匿名函数进行传递。如果你了解js，这种写法可能会很熟悉callFunc( function( $str ) { echo $str;} );闭包
PHP在默认情况下，匿名函数内不能调用所在代码块的上下文变量，而需要通过使用use关键字。
//1. 通过闭包获取当前函数环境外的变量值副本。function getMoney() { $rmb = 1; $dollar = 6; $func = function() use ( $rmb ) { echo $rmb; //1 echo $dollar; //报错，找不到dorllar变量 }; $func();}getMoney();//2. 之所以称为副本，是因为通过闭包传值到匿名函数内的变量,值也是不能改变。function getMoney() { $rmb = 1; $func = function() use ( $rmb ) { $rmb += 2; echo $rmb; // 3 }; $func(); echo $rmb; // 还是1没有改变;}getMoney();//3. 如果要改变外部变量的值，还是得通过传址的方法function getMoney() { $rmb = 1; $func = function() use ( &$rmb ) { $rmb += 2; echo $rmb; // 3 }; $func(); echo $rmb; // 3;}getMoney();//4. function getMoneyFunc() { $rmb = 1; $func = function() use(&$rmb){ echo $rmb; //把$rmb的值加1 $rmb++; }; return $func; // 如果将匿名函数返回给外界，匿名函数会保存use所引用的变量，而外界则不能得到这些变量，这样形成‘闭包’}$getMoney = getMoneyFunc();$getMoney(); // 1$getMoney(); // 2$getMoney(); // 3闭包的好处
1. 减少循环
// 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; // 使用闭包减少循环; $callback = function($quantity , $product) use ($tax , &$total){ $pricePerItem = constant(__CLASS__ . "::PRICE_" . strtoupper($product)); $total += ($pricePerItem * $quantity) * ($tax + 1.0); }; 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 $my_cart->getTotal(0.05) . "\n";// The result is 54.292. 减少函数的参数
function html($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"; };}$tag = html('div','','class');// 可读性和可维护性大大提高;echo $tag('div1,div1,div1');echo PHP_EOL;echo $tag('div2,div2,div2');3. 解除递归函数
// ↓↓ 注意,这里的fib一定要用引用哦,因为第一次的时候就会Notice: Undefined variable,然后后面的fib()就会错误;$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 variableecho $lie(5); // error 达到递归解除;4. 关于延迟绑定
$result = 0;$one = function(){ var_dump($result);};$two = function() use ($result){ var_dump($result);};// 在回调生成的时候进行赋值;$four = function() use ($result){ //0 回调生成的时候赋值，也就是$result = 0; var_dump($result);};// 如果使用引用,就能使use里面的变量完成延迟绑定,也就是在调用的时候再赋值;$three = function() use (&$result){ //1 在调用的时候再赋值进去，也就是1，注意对象类型也属于引用； var_dump($result);};$result += 1;$one(); // outputs NULL: $result is not in scope$two(); // outputs int(0): $result was copied$three(); // outputs int(1)$four(); // outputs int(0)几个配合回调或闭包的函数
bool array_walk ( array &$array , callable $funcname [, mixed $userdata = NULL ] )
/** * @param array $array * @param callable $funcname () * @param mixed|NULL $userdata * @return bool * bool array_walk ( array &$array , callable $funcname [, mixed $userdata = NULL ] ) */$fruits = array( "d" => "lemon" , "a" => "orange" , "b" => "banana" , "c" => "apple");$test_print = function(&$item2 , $key, $prefix){ $item2 .= ' 10'; echo "{$prefix} : $key => $item2\n";};/* this result : d => lemon this result : a => orange this result : b => banana this result : c => apple */array_walk($fruits , $test_print, 'this result');print_r($fruits);/* Array ( [d] => lemon 10 [a] => orange 10 [b] => banana 10 [c] => apple 10 ) */bool array_walk_recursive ( array &$input , callable $funcname [, mixed $userdata = NULL ]
$sweet = array( 'a' => 'apple' , 'b' => 'banana');$fruits = array( 'sweet' => $sweet , 'sour' => 'lemon');$test_print = function($item , $key){ echo "$key holds $item\n";};array_walk_recursive($fruits , $test_print);/* * 自动跳过sweet,因为sweet是数组;任何其值为 array 的键都不会被传递到回调函数中去 a holds apple b holds banana sour holds lemon */array array_filter ( array $array [, callable $callback [, int $flag = 0 ]] )
$odd = function($var){ return ($var & 1);};$even = function($var){ return (!($var & 1));};$array1 = array( "a" => 1 , "b" => 2 , "c" => 3 , "d" => 4 , "e" => 5 );$array2 = array( 6 , 7 , 8 , 9 , 10 , 11 , 12 );echo "Odd :\n";print_r(array_filter($array1 , "odd"));/*Odd :Array( [a] => 1 [c] => 3 [e] => 5) */echo "Even:\n";print_r(array_filter($array2 , "even"));/*Even:Array( [0] => 6 [2] => 8 [4] => 10 [6] => 12) */ # 如果不传第二参数的的话 $entry = array( 0 => 'foo', 1 => false, 2 => -1, 3 => null, 4 => '');print_r(array_filter($entry));/* * 当前值为false的话就filter;Array( [0] => foo [2] => -1) */array array_map ( callable $callback , array $arr1 [, array $array ] )
/** * @param callable $callback * @param array $arr1 * @param array $array */$func = function($value) { return $value * 2;};print_r(array_map($func, range(1, 5)));/*Array( [0] => 2 [1] => 4 [2] => 6 [3] => 8 [4] => 10) */ $show_Spanish = function($n , $m){ return ("The number $n is called $m in Spanish");};$a = array( 1 , 2 , 3 , 4 , 5 );$b = array( "uno" , "dos" , "tres" , "cuatro" , "cinco" );$c = array_map($show_Spanish , $a , $b);/**print_r($c);Array([0] => The number 1 is called uno in Spanish[1] => The number 2 is called dos in Spanish[2] => The number 3 is called tres in Spanish[3] => The number 4 is called cuatro in Spanish[4] => The number 5 is called cinco in Spanish) */$map_Spanish = function($n , $m){ return (array($n => $m));};$d = array_map($map_Spanish , $a , $b);print_r($d);/** Array ( [0] => Array ( [1] => uno ) [1] => Array ( [2] => dos ) [2] => Array ( [3] => tres ) [3] => Array ( [4] => cuatro ) [4] => Array ( [5] => cinco ) ) */mixed array_reduce ( array $input , callable $function [, mixed $initial = NULL ] )
/** * 用回调函数迭代地将数组简化为单一的结果值,解释不清楚的一看代码就明白了; * @param array $input * @param callable $function * @param mixed|NULL $initial 如果指定了可选参数 initial，该参数将被当成是数组中的第一个值来处理，或者如果数组为空的话就作为最终返回值。 */$rsum = function($result , $value){ // $result 初始值为NULL, 如果有第三参数的话,第三参数为初始值; $result += $value; return $result;};$rmul = function($result , $value){ $result *= $value; return $result;};$a = array(1, 2, 3, 4, 5);$x = array();$b = array_reduce($a, $rsum); // (NULL)0+1+2+3+4+5 = 15;$c = array_reduce($a, $rmul, 10); // 10*1*2*3*4*5 = 1200;$d = array_reduce($x, $rsum, "No data to reduce"); // No data to reducemixed preg_replace_callback ( mixed $pattern , callable $callback , mixed $subject [, int $limit = -1 [, int &$count ]] )
/** * @param mixed $pattern 正则模式; * @param callable $callback * @param mixed $subject * @param int $limit 对于每个模式用于每个 subject 字符串的最大可替换次数。 默认是-1（无限制）。 * @param int $count 如果指定，这个变量将被填充为替换执行的次数。 * mixed preg_replace_callback ( mixed $pattern , callable $callback , mixed $subject [, int $limit = -1 [, int &$count ]] ) */// 将文本中的年份增加一年.$text = "April fools day is 04/01/2002\n";$text .= "Last christmas was 12/24/2001\n";// 回调函数$next_year = function($matches){ // 通常: $matches[0]是完成的匹配 // $matches[1]是第一个捕获子组的匹配 // 以此类推 return $matches[1] . ($matches[2] + 1);};echo preg_replace_callback("|(\d{2}/\d{2}/)(\d{4})|" , $next_year , $text);mixed call_user_func ( callable $callback [, mixed $parameter [, mixed $... ]] )
mixed call_user_func_array ( callable $callback , array $param_arr )
/** * @param callable $callback 第一个参数为需要调用的函数; 如果是数组array($classname, $methodname) * @param mixed $parameter 第二个参数开始就是队列进该函数的参数; * @param mixed $parameter2 * @param mixed $parameter3 * .. * @return 返回值：返回调用函数的结果，或FALSE */$eat = function($fruit , $num){ //参数可以为多个 echo "You want to eat $fruit $num pcs, no problem\n";};call_user_func($eat , "apple" , 10); //print: You want to eat apple 10 pcs, no problem;call_user_func($eat , "orange" , 5); //print: You want to eat orange 5 pcs,no problem;// 调用类方法class myclass { public static function say_hello($name,$message) { echo "Hello! $name $message"; }}//array(类名，静态方法名),参数call_user_func(array('myclass', 'say_hello'), 'dain_sun', 'good person');call_user_func_array(array('myclass', 'say_hello'), array('dain_sun', 'good person'));// Hello! dain_sun good person