PHP 8.2 新特性之 DNF Types

hi，我是温新，一名 PHPer

PHP 8.2 引入一个新的类型叫 DNF（Disjunctive Normal Form）。这个类型是 | 和 & 运算符的组合。它允许指定一种类型是两个或多个类型的联合，而每个类型是一个或多个其他类型的交集。

这样说挺不容易理解的，先通过 demo 演示，后续再来解释吧。

<span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(86, 182, 194) !important"><?</span><span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">php</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">interface</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">User</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">{</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">public</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">function</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">getName</span>(): <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">string</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">}</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">interface</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">Admin</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">{</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">public</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">function</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">getName</span>(): <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">string</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">}</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">interface</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">SuperAdmin</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">{</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">public</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">function</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">getName</span>(): <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">string</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">}</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(98, 151, 85) !important">// PHP 7 特性,匿名类</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$user</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">=</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">new</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">class</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">implements</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Admin</span>, <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">SuperAdmin</span> {</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">public</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">function</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">getName</span>(): <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">string</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    {</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">     <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">return</span> <span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">'PHP 8.2 DNF'</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    }</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">};</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(98, 151, 85) !important">// 这是重点，看参数，接收的参数含义是：</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(98, 151, 85) !important">// 该函数接收一个 同时实现了 Admin 和 SpuerAdmin 接口的 User 对象实例</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">function</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">get_user_name</span>((<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Admin</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">&</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">SuperAdmin</span>) <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">|</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">User</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$user</span>): <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">string</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">{</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">return</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$user</span><span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">-></span><span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">getName</span>();</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">}</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">echo</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">get_user_name</span>(<span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$user</span>); <span style="box-sizing: border-box;color: rgb(98, 151, 85) !important">// 输出：PHP 8.2 DNF</span></span>

代码解释：

• 1、定义了三个接口，User、Admin、SuperAdmin；
• 2、定义一个匿名类，并实现 Admin、SuperAdmin 接口；
• 3、定义一个函数，该参数使用 dnf 类对参数进行限制，只允许接收同时实现了 Admin 和 SuperAdmin 接口的实例对象调用，否则报错；
• 4、调用函数。

下面将针对几种情况进行演示。

DNF 正确的使用方法

• A|B|C
• A|B|(C&D)
• (A&B&C)|null

使用 & 时，必须使用 () 进行包裹。

A|B|C 用法

A B C 三个接口只要实现其中一个即可

<span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(98, 151, 85) !important">// 该匿名名实现了 User 接口</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$user</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">=</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">new</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">class</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">implements</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">User</span> {</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">public</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">function</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">getName</span>(): <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">string</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    {</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">     <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">return</span> <span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">'PHP 8.2 DNF'</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    }</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">};</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(98, 151, 85) !important">// A|B|C 只要有一个实现了即可，否则会报错</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">function</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">get_user_name</span>(<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Admin</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">|</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">SuperAdmin</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">|</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">User</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$user</span>): <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">string</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">{</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">return</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$user</span><span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">-></span><span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">getName</span>();</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">}</span>

(A&B)|C

实例对象 C 必须实现 A、B两个接口。本案例中 $user 实例对象必须实现 Admin 、SuperAdmin 接口。

<span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$user</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">=</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">new</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">class</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">implements</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Admin</span>, <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">SuperAdmin</span>{</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">public</span> <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">function</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">getName</span>(): <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">string</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    {</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">     <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">return</span> <span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">'PHP 8.2 DNF'</span>;</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    }</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">};</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box"></span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px"><span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">function</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">get_user_name</span>((<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Admin</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">&</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">SuperAdmin</span>) <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">|</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">User</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$user</span>): <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">string</span></span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">{</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">    <span style="box-sizing: border-box;color: rgb(198, 120, 221) !important">return</span> <span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$user</span><span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">-></span><span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">getName</span>();</span><br></br><span style="box-sizing: border-box;color: rgb(171, 178, 191);padding-right: 0.1px">}</span>