Vergleich und Verständnis der neuen Funktionen von PHP7

//php7以前  if判断
if(empty($_GET['param'])) {
      $param = 1;
}else{
    $param = $_GET['param'];
}
//php7以前  三元运算符
$param = empty($_GET['param']) ? 1 : $_GET['param'];
//PHP7  null合并运算符
$param = $_GET['param'] ?? 1;//1

//php7以前
define("CONTENT", "hello world");
echo CONTENT;//hello world
//PHP7
define('ANIMALS', [
    'dog',
    'cat',
    'bird'
]);
echo ANIMALS[2];//bird
//PHP7 类外也可使用const来定义常量
const CONSTANT = 'Hello World'; 
echo CONSTANT;//Hello World

//整数
echo 1 <=> 1; // 0
echo 1 <=> 2; // -1
echo 2 <=> 1; // 1
//浮点数
echo 1.5 <=> 1.5; // 0
echo 1.5 <=> 2.5; // -1
echo 2.5 <=> 1.5; // 1
 
//字符串
echo "a" <=> "a"; // 0
echo "a" <=> "b"; // -1
echo "b" <=> "a"; // 1

//... 操作符: 表示这是一个可变参数. php5.6及以上的版本可使用: 函数定义的时候变量前使用.
function intSum(int ...$ints){
    return array_sum($ints);
}
var_dump(intSum(2,'3.5'));//5
//严格模式
//模式声明：declare(strict_types=1);  默认情况值为0，值为1代表为严格校验的模式 
declare(strict_types=1);
function add(int $a,int $b){
    return $a+$b;
}
var_dump(add(2,'3.5')); //Fatal error: Uncaught TypeError: Argument 2 passed to add() must be of the type integer

//有效的返回类型
declare(strict_types = 1);
function getInt(int $value): int {
  return $value;
}
print(getInt(6));//6

//无效返回类型
declare(strict_types = 1);
function getNoInt(int $value): int {
  return $value+'2.5';
}
print(getNoInt(6));//Fatal error: Uncaught TypeError: Return value of getNoInt() must be of the type integer

<?php
//php7以前 接口实现
interface User{
    public function getDiscount();
}
class VipUser implements User{
    //折扣系数
    private $discount = 0.6;
    public function getDiscount() {
        return $this->discount;
    }
}
class Goods{
    private $price = 200;
    private $objectVipUser;
    //User接口VipUser类实现
    public function getUserData(User $User){
        $this->objectVipUser = $User;
        $discount = $this->objectVipUser->getDiscount();
        echo "商品价格:".$this->price*$discount;
    }
}
$display = new Goods();
//常规实例化接口实现对象
$display->getUserData(new VipUser);//商品价格:120

<?php
//php7 创建一个匿名的对象
interface User{
    public function getDiscount();
}
class Goods{
    private $price = 200;
    private $objectVipUser;
    public function getUserData($User){
        $this->objectVipUser = $User;
        $discount = $this->objectVipUser->getDiscount();
        echo "商品价格:".$this->price*$discount;
    }
}
$display = new Goods();
//new匿名对象实现user接口
$display->getUserData(new class implements User{
    private $discount = 0.6;
    public function getDiscount() {
        return $this->discount;
    }
});//商品价格:120

<?php
//php7以前
class A {
    private  $attribute = &#39;hello world&#39;;
}
$getClosure = function(){
    return $this->attribute;
};
$getAttribute = $getClosure->bindTo(new A, &#39;A&#39;);//中间层闭包
echo $getAttribute();//hello world

<?php 
class A{  
   public $name = &#39;admin_a&#39;;    
} 
class B{ 
   public $name = &#39;admin_b&#39;; 
} 
$objA = new A(); 
$objB = new B(); 
$serializedObjA = serialize($objA); 
$serializedObjB = serialize($objB); 
//默认行为是接收所有类; 第二个参数可以忽略
$dataA = unserialize($serializedObjA , ["allowed_classes" => true]); 
var_dump($dataA);//object(A)#3 (1) { ["name"]=> string(7) "admin_a" }
//如果allowed_classes设置为false,unserialize会将所有对象转换为__PHP_Incomplete_Class对象 
$dataA = unserialize($serializedObjA , ["allowed_classes" => false]); 
var_dump($dataA);//object(__PHP_Incomplete_Class)#4 (2) { ["__PHP_Incomplete_Class_Name"]=> string(1) "A" ["name"]=> string(7) "admin_a" }
//转换所有对象到 __PHP_Incomplete_Class对象，除了对象"B"
$dataB = unserialize($serializedObjB , ["allowed_classes" => ["B"]]); 
var_dump($dataB);//object(B)#3 (1) { ["name"]=> string(7) "admin_b" }