MS-特性-PHP7

标量类型声明，返回值类型声明

 declare(strict_types=1);    //开启强制类型模式
 class obj {
     public function sum(int ...$nums):int {
         return array_sum($nums);
     }
 }

 $o = new obj;
 var_dump($o->sum(1, 2, 3, 4, 5, 6));  //21
 var_dump($o->sum(1.11, 2));  //Fatal error: Uncaught TypeError: Argument 1 passed to obj::sum() must be of the type integer, float given

NULL 合并运算符 ??

 $username = $_GET['user'] ?? 'nobody';  
 // #$username = is_null($_GET['user']) ? 'nobody': $_GET['user'];

太空船操作符 <=>
比较两个表达式，前者小于后者时，返回-1，相等时返回0， 大于时返回1，区别于strcmp

 echo "abc" <=> "aec"; //-1

定义常量数组

 define("ANIMAL", [
     "cat",
     "dog",
     "elephant"
 ]);
 echo ANIMAL[0]."<br>";  //cat

匿名类

 interface Logger {
     public function log();
 }

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

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

 $app = new Application;
 $app->setLogger(new class implements Logger{
     public function log()
     {
         echo "This is log"."<br>";
     }
 });

 $app->getLogger()->log();