php7匿名類，導入類別和閉包使用等新特性介紹

匿名類別 (PHP 7)

#現在支援透過new class 來實例化一個匿名類，這可以用來取代一些「用後即焚」的完整類別定義。

<?php
interface Logger {
 public function log(string $msg);
}

class Application {
 private $logger;

 public function getLogger(): Logger {
   return $this->logger;
 }

 public function setLogger(Logger $logger) {
   $this->logger = $logger;
 }
}

$app = new Application;
$app->setLogger(new class implements Logger {
 public function log(string $msg) {
  echo $msg;
 }
});

var_dump($app->getLogger());
?>

以上程式會輸出：

object(class@anonymous)#2 (0) {
}

Closure::call() (PHP 7)

Closure::call() 現在有著更好的效能，簡短幹練的暫時綁定一個方法到物件上閉包並呼叫它。

<?php
class A {private $x = 1;}

// Pre PHP 7 code
$getXCB = function() {return $this->x;};
$getX = $getXCB->bindTo(new A, &#39;A&#39;); // intermediate closure
echo $getX();

// PHP 7+ code
$getX = function() {return $this->x;};
echo $getX->call(new A);

以上例程會輸出：

1
1

#為unserialize()提供篩選(PHP 7)

這個特性旨在提供更安全的方式解包不可靠的資料。它透過白名單的方式來防止潛在的程式碼注入。

<?php
// converts all objects into PHP_Incomplete_Class object
$data = unserialize($foo, ["allowed_classes" => false]);

// converts all objects into PHP_Incomplete_Class object except those of MyClass and MyClass2
$data = unserialize($foo, ["allowed_classes" => ["MyClass", "MyClass2"]);

// default behaviour (same as omitting the second argument) that accepts all classes
$data = unserialize($foo, ["allowed_classes" => true]);

Group use declarations (PHP 7)

從相同namespace 匯入的類別、函數和常數現在可以透過單一use語句一次性導入了。

<?php

// Pre PHP 7 code
use some\namespace\ClassA;
use some\namespace\ClassB;
use some\namespace\ClassC as C;

use function some\namespace\fn_a;
use function some\namespace\fn_b;
use function some\namespace\fn_c;

use const some\namespace\ConstA;
use const some\namespace\ConstB;
use const some\namespace\ConstC;

// PHP 7+ code
use some\namespace\{ClassA, ClassB, ClassC as C};
use function some\namespace\{fn_a, fn_b, fn_c};
use const some\namespace\{ConstA, ConstB, ConstC};
?>

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