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| author | muqiuhan <[email protected]> | 2024-06-06 12:26:58 +0000 |
|---|---|---|
| committer | muqiuhan <[email protected]> | 2024-06-06 12:26:58 +0000 |
| commit | fb7c085bb02f386c2f1227a170f724fdf4c28501 (patch) | |
| tree | 5981129198a964052dd32419e2963da079329d0e /2024/05/24 | |
| parent | d47994217a2df8d80a244e8fcbad980bbcfd00c7 (diff) | |
| download | blog-fb7c085bb02f386c2f1227a170f724fdf4c28501.tar.gz | |
deploy: 1f3b4b7176d57d55dcf85329c213ae5d354fb044
Diffstat (limited to '2024/05/24')
| -rw-r--r-- | 2024/05/24/Rust-闭包-lifetime-may-not-live-long-enough-问题/index.html | 274 |
1 files changed, 0 insertions, 274 deletions
diff --git a/2024/05/24/Rust-闭包-lifetime-may-not-live-long-enough-问题/index.html b/2024/05/24/Rust-闭包-lifetime-may-not-live-long-enough-问题/index.html deleted file mode 100644 index 310798ea..00000000 --- a/2024/05/24/Rust-闭包-lifetime-may-not-live-long-enough-问题/index.html +++ /dev/null @@ -1,274 +0,0 @@ -<!DOCTYPE html> -<html lang="en"> - <head> - <meta charset="UTF-8"> -<meta name="viewport" - content="width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"> -<meta http-equiv="X-UA-Compatible" content="ie=edge"> - - <meta name="author" content="韩暮秋"> - - - <meta name="subtitle" content="暮秋小屋"> - - - <meta name="description" content="这里是暮秋小屋，思念和灵感的寄存处"> - - - <meta name="keywords" content="韩暮秋,MuqiuHan,'Muqiu Han', 'muqiu han', muqiuhan"> - - - - -<title>Rust 闭包 lifetime may not live long enough 问题 | 暮秋小屋</title> - - - - <link rel="icon" href="/favicon.ico"> - - - -<style> - @import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Noto+Sans+SC:wght@300;400;500;700&family=Roboto+Mono&display=swap'); -</style> - - - - <!-- stylesheets list from _config.yml --> - - <link rel="stylesheet" href="/css/style.css"> - - - - - - <!-- scripts list from _config.yml --> - - <script src="/js/frame.js"></script> - - - - - - <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script> - <script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script> - - - - - - - - <meta name="generator" content="Hexo 6.3.0"></head> - <body> - <div class="mask-border"> - </div> - - <div class="wrapper"> - - <div class="header"> - <div class="flex-container"> - <div class="header-inner"> - <div class="site-brand-container"> - <a href="/"> - - 暮秋小屋 - - </a> - </div> - <div id="menu-btn" class="menu-btn" onclick="toggleMenu()"> - Menu - </div> - <nav class="site-nav"> - <ul class="menu-list"> - - - <li class="menu-item"> - <a href="/">主页</a> - </li> - - - - <li class="menu-item"> - <a href="/categories/gallery/">日记本</a> - </li> - - - - <li class="menu-item"> - <a href="/tags/Medicine/">医学</a> - 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-<p>编译错误：</p> -<figure class="highlight text"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br></pre></td><td class="code"><pre><span class="line">error: lifetime may not live long enough</span><br><span class="line"> --> src/storage/filesystem/mod.rs:45:34</span><br><span class="line"> |</span><br><span class="line">45 | routing::get(move || async {</span><br><span class="line"> | __________________________-------_^</span><br><span class="line"> | | | |</span><br><span class="line"> | | | return type of closure `{async block@src/storage/filesystem/mod.rs:45:34: 50:14}` contains a lifetime `'2`</span><br><span class="line"> | | lifetime `'1` represents this closure's body</span><br><span class="line">46 | | (</span><br><span class="line">47 | | StatusCode::OK,</span><br><span class="line">48 | | Json(json!(self.clone().tree(self.clone().root))),</span><br><span class="line">49 | | )</span><br><span class="line">50 | | }),</span><br><span class="line"> | |_____________^ returning this value requires that `'1` must outlive `'2`</span><br><span class="line"> |</span><br><span class="line"> = note: closure implements `Fn`, so references to captured variables can't escape the closure</span><br></pre></td></tr></table></figure> - -<p>这是因为 <code>handlers</code> 里面的闭包捕获了一个引用，并且尝试返回一个包含该引用的值导致的。</p> -<p>细说就是：闭包内部使用了 <code>self.clone()</code> 来获取一个新的实例，然后在异步块中返回一个 JSON 对象，这个 JSON 对象依赖于 <code>self.tree()</code> 的结果。因为闭包捕获了 <code>self</code> 的引用，所以它必须保证 <code>self</code> 在闭包执行完毕后仍然有效。</p> -<p>解决这个问题的思路是：确保闭包中的所有引用都在闭包执行完毕之前就不再被使用。<br>就是说，要将闭包的作用域限制在一个更短的生命周期内，或者使用其他方式来避免闭包捕获长期存在的引用:</p> -<figure class="highlight rust"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"></span><br><span class="line">...</span><br><span class="line"> <span class="keyword">fn</span> <span class="title function_">handlers</span>(<span class="keyword">self</span>) <span class="punctuation">-></span> crate::server::request::Handlers {</span><br><span class="line"> <span class="keyword">let</span> <span class="variable">tree</span> = json!(<span class="keyword">self</span>.<span class="title function_ invoke__">clone</span>().<span class="title function_ invoke__">tree</span>(<span class="keyword">self</span>.<span class="title function_ invoke__">clone</span>().root));</span><br><span class="line"> <span class="built_in">vec!</span>[(</span><br><span class="line"> <span class="string">"/tree"</span>,</span><br><span class="line"> routing::<span class="title function_ invoke__">get</span>(<span class="keyword">move</span> || <span class="keyword">async</span> { (StatusCode::OK, <span class="title function_ invoke__">Json</span>(tree)) }),</span><br><span class="line"> )]</span><br><span class="line"> }</span><br><span class="line">...</span><br></pre></td></tr></table></figure> -</div> - 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