MS-特性-PHP7

1. 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
   

2. NULL 合并运算符 ??

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

3. 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
   

4. 定义常量数组

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

5. 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"."
   ";
        }
    });
   
    $app->getLogger()->log();