🎉PHP 8.3发布与新特性

_posts/编程/PHP/PHP8.3-Released.md

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+---
+title: 🎉PHP 8.3发布与新特性
+date: 2023-11-23
+tags: PHP
+---
+PHP 8.3已经如期发不了，看一下新版特带来哪些特性！
+
+## 常量类型化(Typed class constants)
+
+定义常量目前可以标识类型了！
+
+8.3 之前
+
+```php
+interface I {
+    // 过往历史长河中总是认为PHP常量总是一个字符串
+    const PHP = 'PHP 8.2';
+}
+
+class Foo implements I {
+    // 但是实现类可能会将其定义为数组。
+    const PHP = [];
+}
+```
+
+8.3 之后
+
+```php
+interface I {
+    const string PHP = 'PHP 8.3';
+}
+
+class Foo implements I {
+    const string PHP = [];
+}
+
+//代码会发生致命错误：无法将数组用作类常量的值
+```
+<!--more-->
+## 动态类常量获取(Dynamic class constant fetch)
+
+8.3 之前
+
+```php
+class Foo {
+    const PHP = 'PHP 8.2';
+}
+
+$searchableConstant = 'PHP';
+
+var_dump(constant(Foo::class . "::{$searchableConstant}"));
+```
+
+8.3 之后
+
+```php
+class Foo {
+    const PHP = 'PHP 8.3';
+}
+
+$searchableConstant = 'PHP';
+
+var_dump(Foo::{$searchableConstant});
+```
+
+## #[\Override] 新注解
+
+通过将#[\Override]属性添加到方法中，PHP将确保在父类或实现的接口中存在具有相同名称的方法。如下面`MyTest`的父类`TestCase`中没有`taerDown`方法将抛出异常
+
+```php
+
+use PHPUnit\Framework\TestCase;
+
+final class MyTest extends TestCase {
+    protected $logFile;
+
+    protected function setUp(): void {
+        $this->logFile = fopen('/tmp/logfile', 'w');
+    }
+
+    #[\Override]
+    protected function taerDown(): void {
+        fclose($this->logFile);
+        unlink('/tmp/logfile');
+    }
+}
+
+// Fatal error: MyTest::taerDown() has #[\Override] attribute,
+// but no matching parent method exists
+
+```
+
+## 深度克隆只读属性(Deep-cloning of readonly properties)
+
+只读属性现在可以在__clone方法中修改一次，以启用只读属性的深度克隆。
+
+8.3 之前
+
+```php
+class PHP {
+    public string $version = '8.2';
+}
+
+readonly class Foo {
+    public function __construct(
+        public PHP $php
+    ) {}
+
+    public function __clone(): void {
+        $this->php = clone $this->php;
+    }
+}
+
+$instance = new Foo(new PHP());
+$cloned = clone $instance;
+
+// Fatal error: Cannot modify readonly property Foo::$php
+
+```
+
+8.3 之后
+
+```php
+class PHP {
+    public string $version = '8.2';
+}
+
+readonly class Foo {
+    public function __construct(
+        public PHP $php
+    ) {}
+
+    public function __clone(): void {
+        $this->php = clone $this->php;
+    }
+}
+
+$instance = new Foo(new PHP());
+$cloned = clone $instance;
+
+$cloned->php->version = '8.3';
+```
+
+## json_validate 函数
+
+8.3 之前验证json 需要json_decode之后根据json_last_error()错误去判断，如今8.3新增json_validate函数支持
+
+## Randomizer 新特性
+
+1. getBytesFromString()
+2. getFloat()
+3. nextFloat()
+
+## 其他
+
+其余bug和特性请移步到，[php官方8.3发布页面介绍](https://www.php.net/releases/8.3/en.php)。