PHP 8.2 新特性之 const 表达式中获取枚举的属性

作者: 温新

分类: 【PHP基础】

阅读: 957

时间: 2023-02-20 17:11:59

hi,我是温新,一名 PHPer

此 RFC 建议允许使用->/?->来获取常量表达式中枚举的属性。此更改的主要动机是允许在不允许枚举对象的地方获取名称和值属性,例如数组键。

<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><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(209, 154, 102) !important">enum</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Status</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">case</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Draft</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">=</span> <span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">'draft'</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">case</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Pending</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">=</span> <span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">'pending'</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">case</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Published</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">=</span> <span style="box-sizing: border-box;color: rgb(152, 195, 121) !important">'published'</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 8.2 用法</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">const</span> <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">IntStatusValue</span> <span style="box-sizing: border-box;color: rgb(86, 182, 194) !important">=</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">self</span>::<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Draft</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">value</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">0</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">self</span>::<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Pending</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">value</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">1</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">self</span>::<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Published</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">value</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">2</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(98, 151, 85) !important">// PHP 8.1</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">text</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(209, 154, 102) !important">match</span> (<span style="box-sizing: border-box;color: rgb(224, 108, 117) !important">$this</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">self</span>::<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Draft</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">0</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">self</span>::<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Pending</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">1</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">self</span>::<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Published</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">2</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><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">Status</span>::<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Draft</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">value</span> . <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">PHP_EOL</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">Status</span>::<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Draft</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">text</span>() . <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">PHP_EOL</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 8.2 用法</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">Status</span>::<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">IntStatusValue</span>[<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Status</span>::<span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">Draft</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">value</span>] . <span style="box-sizing: border-box;color: rgb(209, 154, 102) !important">PHP_EOL</span>;</span>

在这个枚举案例中,使用一个 IntStatusValue 数组,其元素对应着一个不同的值,这种用法在 PHP 8.1中是不允许的。

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