https://elated-raman-42e0c2.netlify.app/tags/rules/Recent content in Rules on Sawyer Zheng's BlogHugozh-cnMon, 07 Mar 2022 16:55:27 +0800https://elated-raman-42e0c2.netlify.app/post/notes/python/syntax/Wed, 02 Sep 2020 00:00:00 +0000https://elated-raman-42e0c2.netlify.app/post/notes/python/syntax/<div id="outline-container-headline-1" class="outline-2"> <h2 id="headline-1"> Lambda functions λ 函数 更规范的使用 </h2> <div id="outline-text-headline-1" class="outline-text-2"> <p><a href="https://treyhunner.com/2018/09/stop-writing-lambda-expressions/">https://treyhunner.com/2018/09/stop-writing-lambda-expressions/</a></p> <div id="outline-container-headline-2" class="outline-3"> <h3 id="headline-2"> 错误用法 </h3> <div id="outline-text-headline-2" class="outline-text-3"> <div id="outline-container-headline-3" class="outline-4"> <h4 id="headline-3"> lambda 赋给变量 </h4> <div id="outline-text-headline-3" class="outline-text-4"> <ul> <li>错误</li> </ul> <div class="src src-python"> <div class="highlight"><div class="chroma"> <table class="lntable"><tr><td class="lntd"> <pre tabindex="0" class="chroma"><code><span class="lnt">1 </span></code></pre></td> <td class="lntd"> <pre tabindex="0" class="chroma"><code class="language-python" data-lang="python"><span class="line"><span class="cl"><span class="n">normalize_case</span> <span class="o">=</span> <span class="k">lambda</span> <span class="n">s</span><span class="p">:</span> <span class="n">s</span><span class="o">.</span><span class="n">casefold</span><span class="p">()</span></span></span></code></pre></td></tr></table> </div> </div> </div> <ul> <li> <p>正确</p> <ul> <li>定义单行，正常函数</li> </ul> </li> </ul> <div class="src src-python"> <div class="highlight"><div class="chroma"> <table class="lntable"><tr><td class="lntd"> <pre tabindex="0" class="chroma"><code><span class="lnt">1 </span></code></pre></td> <td class="lntd"> <pre tabindex="0" class="chroma"><code class="language-python" data-lang="python"><span class="line"><span class="cl"><span class="k">def</span> <span class="nf">normalize_case</span><span class="p">(</span><span class="n">s</span><span class="p">):</span> <span class="k">return</span> <span class="n">s</span><span class="o">.</span><span class="n">casefold</span><span class="p">()</span></span></span></code></pre></td></tr></table> </div> </div> </div> </div> </div> <div id="outline-container-headline-4" class="outline-4"> <h4 id="headline-4"> 多余的转换 </h4> <div id="outline-text-headline-4" class="outline-text-4"> <ul> <li> <p>错误</p> <ul> <li> <p>在 lambda 中又调用同样接口的函数</p> <div class="src src-python"> <div class="highlight"><div class="chroma"> <table class="lntable"><tr><td class="lntd"> <pre tabindex="0" class="chroma"><code><span class="lnt">1 </span></code></pre></td> <td class="lntd"> <pre tabindex="0" class="chroma"><code class="language-python" data-lang="python"><span class="line"><span class="cl"><span class="n">sorted_numbers</span> <span class="o">=</span> <span class="nb">sorted</span><span class="p">(</span><span class="n">numbers</span><span class="p">,</span> <span class="n">key</span><span class="o">=</span><span class="k">lambda</span> <span class="n">n</span><span class="p">:</span> <span class="nb">abs</span><span class="p">(</span><span class="n">n</span><span class="p">))</span></span></span></code></pre></td></tr></table> </div> </div> </div> </li> </ul> </li> <li> <p>正确</p> <ul> <li> <p>直接使用已有函数，不要多此一举</p>