deploy: 1f3b4b7176d57d55dcf85329c213ae5d354fb044

1 files changed, 283 insertions, 0 deletions

diff --git a/2023/05/03/Rust-NewType-模式/index.html b/2023/05/03/Rust-NewType-模式/index.html
new file mode 100644
index 00000000..7ad16dd5
--- /dev/null
+++ b/2023/05/03/Rust-NewType-模式/index.html
@@ -0,0 +1,283 @@
+<!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 NewType 模式 | 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>
+              </li> 
+                   
+          
+            
+              <li class="menu-item">
+                <a href="/tags/Technique/">计算机科学</a>
+              </li> 
+                   
+          
+            
+              <li class="menu-item">
+                <a href="/tags/Life/">生活</a>
+              </li> 
+                   
+          
+            
+              <li class="menu-item">
+                <a href="/about">关于</a>
+              </li> 
+                   
+          
+          
+            <li class="menu-item search-btn">
+              <a href="#">Search</a>
+            </li>
+          
+        </ul>
+      </nav>
+    </div>
+  </div>
+</div>
+
+
+      <div class="main">
+        <div class="flex-container">
+          <article id="post">
+
+  
+    <div class="post-head">
+    <div class="post-info">
+        <div class="tag-list">
+            
+                
+                    <span class="post-tag">
+                        <a href="/tags/Technique/">
+                            Technique
+                        </a>
+                    </span>    
+                
+                    <span class="post-tag">
+                        <a href="/tags/Rust/">
+                            Rust
+                        </a>
+                    </span>    
+                           
+            
+        </div>
+        <div class="post-title">
+            
+            
+                Rust NewType 模式
+            
+            
+        </div>
+        <span class="post-date">
+            May 3, 2023
+        </span>
+    </div>
+    <div class="post-img">
+        
+            <div class="h-line-primary"></div>
+              
+    </div>
+</div>
+    <div class="post-content">
+    <p>New Type模式是一种软件设计模式，用于在已有类型的基础上创建一个新的类型。在Rust中，这通常是通过<strong>定义一个结构体，其中只包含一个单一成员。这个结构体（New Type）对外提供了一个新的、独立的类型，用于对原始类型增加额外的语义或限制。</strong></p>
+<h2 id="加强类型安全"><a href="#加强类型安全" class="headerlink" title="加强类型安全"></a>加强类型安全</h2><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><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">struct</span> <span class="title class_">Meters</span>(<span class="type">f64</span>);</span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">Feet</span>(<span class="type">f64</span>);</span><br><span class="line"></span><br><span class="line"><span class="keyword">let</span> <span class="variable">length_in_meters</span> = <span class="title function_ invoke__">Meters</span>(<span class="number">100.0</span>);</span><br><span class="line"><span class="keyword">let</span> <span class="variable">length_in_feet</span> = <span class="title function_ invoke__">Feet</span>(<span class="number">328.084</span>);</span><br><span class="line"></span><br><span class="line"><span class="comment">// 编译器会防止以下代码执行，因为类型不匹配</span></span><br><span class="line"><span class="comment">// let wrong_length = Meters(length_in_feet); // 编译错误</span></span><br><span class="line"></span><br><span class="line"><span class="comment">// 正确的构造</span></span><br><span class="line"><span class="keyword">fn</span> <span class="title function_">add_lengths</span>(length1: Meters, length2: Meters) <span class="punctuation">-&gt;</span> Meters &#123;</span><br><span class="line">    <span class="title function_ invoke__">Meters</span>(length1.<span class="number">0</span> + length2.<span class="number">0</span>)</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
+
+<p>这个例子使用 newtype 模式避免将原始类型f64用于不同的量度，从而增强了类型的安全性。</p>
+<h2 id="实现特定-trait"><a href="#实现特定-trait" class="headerlink" title="实现特定 trait"></a>实现特定 trait</h2><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 class="keyword">struct</span> <span class="title class_">Kilometers</span>(<span class="type">f64</span>);</span><br><span class="line"></span><br><span class="line"><span class="keyword">impl</span> <span class="title class_">Kilometers</span> &#123;</span><br><span class="line">    <span class="keyword">fn</span> <span class="title function_">to_miles</span>(&amp;<span class="keyword">self</span>) <span class="punctuation">-&gt;</span> <span class="type">f64</span> &#123;</span><br><span class="line">        <span class="keyword">self</span>.<span class="number">0</span> * <span class="number">0.621371</span></span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">let</span> <span class="variable">distance</span> = <span class="title function_ invoke__">Kilometers</span>(<span class="number">10.0</span>);</span><br><span class="line"><span class="built_in">println!</span>(<span class="string">&quot;The distance in miles is &#123;&#125;&quot;</span>, distance.<span class="title function_ invoke__">to_miles</span>());</span><br></pre></td></tr></table></figure>
+
+<p>这里，Kilometers有一个方法to_miles，该方法是不会影响其他f64数据的。如果我们有另一个表示温度的f64类型，就不会意外调用到与距离相关的方法。</p>
+<p>New Type模式同样适用于对<code>Box&lt;dyn SomeTrait&gt;</code>类型的包装，这可以在需要动态分派（动态调用实现了某个接口的不同类型的对象的方法）的时候提供便利。通过创建一个New Type来包装这样的<code>Box&lt;dyn SomeTrait&gt;</code>类型，可以提供自定义的方法或实现更多的trait，同时也可以让API更加清晰和易于使用。</p>
+<h2 id="零成本抽象"><a href="#零成本抽象" class="headerlink" title="零成本抽象"></a>零成本抽象</h2><p>在Rust中，New Type模式不仅是类型安全的，还是一种零成本抽象。这是因为Rust编译器在编译时期会进行足够的优化，以确保New Type的使用没有运行时开销。 Rust的零成本抽象原则确保了抽象不会引入额外的运行时成本。例如，当你使用Meters这样的New Type时，Rust确保：</p>
+<ol>
+<li>无额外内存开销：Meters只包含一个f64，在内存中的表现和单独的f64是一样的。</li>
+<li>无额外运行时开销：使用Meters时，性能和直接使用f64完全相同。编译器会移除任何关于New Type的包装和解包的代码。</li>
+</ol>
+
+</div> 
+
+<script>
+    window.onload = detectors();
+</script>
+    <div class="post-footer">
+    <div class="h-line-primary"></div>
+    <nav class="post-nav">
+        <div class="prev-item">
+           
+                <div class="icon arrow-left"></div>
+                <div class="post-link">
+                    <a href="/2023/05/04/C-%E7%9A%84-Trait/">Prev</a>
+                </div>
+            
+        </div>
+        <div class="next-item">
+            
+                <div class="icon arrow-right"></div>
+                <div class="post-link">
+                  <a href="/2023/05/02/Rust-Partial-%E8%AF%AD%E4%B9%89/">Next</a>  
+                </div>  
+            
+        </div>
+    </nav>
+</div>
+
+    
+      <div class="post-comment">
+
+     
+
+     
+    
+    
+
+</div>
+     
+  
+</article>
+        </div>
+      </div>
+      
+      <div class="footer">
+    <div class="flex-container">
+        <div class="footer-text">
+            
+            
+                 | 
+            
+            
+                希望路过的人可以添点柴火让这里暖和点
+                
+        </div>
+    </div>
+</div>
+
+    </div>
+
+    
+      <div class="search-popup">
+    <div class="search-popup-overlay">  
+    </div>
+    <div class="search-popup-window" >
+        <div class="search-header">
+            <div class="search-input-container">
+              <input autocomplete="off" autocapitalize="off" maxlength="80"
+                     placeholder="Search Anything" spellcheck="false"
+                     type="search" class="search-input">
+            </div>
+            <div class="search-close-btn">
+                <div class="icon close-btn"></div>
+            </div>
+        </div>
+        <div class="search-result-container">
+        </div>
+    </div>
+</div>
+
+<script>
+    const searchConfig = {
+        path             : "/search.xml",
+        top_n_per_article: "1",
+        unescape         : "false",
+        trigger: "auto",
+        preload: "false"
+    }
+</script>
+<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/search.js"></script>
+<script src="/js/search.js"></script>
+    
+    
+
+  </body>
+</html>