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<h2 id="模块">模块<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#模块" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h2>
<p>在 Python 中，模块可以分为自定义模块、内置模块（标准模块）和第三方模块。使用模块主要有以下几个好处：</p>
<ul>
<li>提高了代码的可维护性。通过将代码拆分为多个模块，可以降低每个模块的复杂性，更容易进行理解和维护。</li>
<li>重用代码。当一个模块编写完毕，就可以被其他的模块引用。这避免了“重复造轮子”，允许开发者更加专注于新的任务。</li>
<li>避免命名冲突。同名的类、函数和变量可以分别存在于不同的模块中，防止名称冲突。但也要注意尽量避免与内置函数名（类名）冲突。</li>
</ul>
<h3 id="自定义模块">自定义模块<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#自定义模块" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>自定义模块是开发者根据实际需求编写的代码，封装为模块方便在多个地方使用。当创建一个新的 Python 文件时，比如 <code>mymodule.py</code>，我们就创建了一个名为 <code>mymodule</code> 的模块，可以通过 <code>import mymodule</code> 来导入和使用。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># mymodule.py</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> hello</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&quot;Hello, World!&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span></code></pre></figure>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># main.py</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> mymodule</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">mymodule.hello() </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 输出 &quot;Hello, World!&quot;</span></span></code></pre></figure>
<h3 id="标准模块">标准模块<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#标准模块" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>Python 拥有一个强大的标准库。Python 语言的核心只包含数值、字符串、列表、字典、文件等常见类型和函数，而由 Python 标准库提供了系统管理、网络通信、文本处理、数据库接口、图形系统、XML 处理等额外的功能。如文本处理、文件系统操作、操作系统功能、网络通信、W3C 格式支持等。</p>
<p>Python 标准库中的模块可以直接通过 <code>import</code> 语句来导入。比如，我们可以导入 <code>math</code> 模块，使用其中的 <code>sqrt</code> 函数来求平方根：</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> math</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(math.sqrt(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">16</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 输出 4.0</span></span></code></pre></figure>
<h3 id="第三方模块">第三方模块<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#第三方模块" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>Python 拥有大量的第三方模块，这也是其核心优点之一。这些模块通常在 Python 包管理系统 <a href="https://pypi.python.org/" class="external">PyPI<svg aria-hidden="true" class="external-icon" viewBox="0 0 512 512"><path d="M320 0H288V64h32 82.7L201.4 265.4 178.7 288 224 333.3l22.6-22.6L448 109.3V192v32h64V192 32 0H480 320zM32 32H0V64 480v32H32 456h32V480 352 320H424v32 96H64V96h96 32V32H160 32z"></path></svg></a> 中注册，你可以通过 <code>pip</code> 工具来安装。</p>
<p>比如，我们可以通过 <code>pip install requests</code> 来安装 <code>requests</code> 模块，然后在代码中使用它发送 HTTP 请求：</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> requests</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">response </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> requests.get(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'https://www.python.org'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(response.status_code) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 输出 200</span></span></code></pre></figure>
<h2 id="包">包<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#包" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h2>
<p>Python 为了避免模块名冲突，又引入了按目录来组织模块的方法，称为包（Package）。包是模块的集合，比模块又高一级的封装。包是一个分层次的文件目录结构，它定义了一个由模块及子包，和子包下的子包等组成的 Python 的应用环境。一般来说，包名通常为全部小写，避免使用下划线。</p>
<h3 id="标准包">标准包<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#标准包" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>标准包就是文件夹下必须存在 <code>__init__.py</code> 文件，该文件的内容可以为空。如果没有该文件，Python 无法识别出标准包。Python 中导入包后会初始化并执行 <code>__init__.py</code> 进行初始化；在 <code>__init__.py</code> 中，如果将 <code>__all__</code> 定义为列表，其中包含对象名称的字符串，程序就可以通过 * 的方式导入。</p>
<p>例如，我们有以下的目录结构：</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="markdown" data-theme="github-light github-dark"><code data-language="markdown" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">test.py</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">package_runoob</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">|-- </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;--shiki-light-font-weight:bold;--shiki-dark-font-weight:bold;">__init__</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">.py</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">|-- runoob1.py</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">|-- runoob2.py</span></span></code></pre></figure>
<p>它们的代码如下：</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># package_runoob/runoob1.py</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> runoob1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&quot;I'm in runoob1&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># package_runoob/runoob2.py</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> runoob2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&quot;I'm in runoob2&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># package_runoob/__init__.py</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">if</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> __name__</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ==</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> '__main__'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'作为主程序运行'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">else</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'package_runoob 初始化'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># test.py</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> package_runoob.runoob1 </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> runoob1</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> package_runoob.runoob2 </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> runoob2</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">runoob1()</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">runoob2()</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 输出</span></span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># package_runoob 初始化</span></span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># I'm in runoob1</span></span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># I'm in runoob2</span></span></code></pre></figure>
<h2 id="模块和包的导入">模块和包的导入<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#模块和包的导入" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h2>
<p>Python 模块是一个包含 Python 定义和语句的文件，模块可以定义函数，类和变量。模块也可以包含可执行的代码。包是一种管理 Python 模块命名空间的形式，采用 ” 点模块名称 “。</p>
<h3 id="导入方式">导入方式<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#导入方式" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>在 Python 中，可以通过以下四种方式导入模块或包：</p>
<h4 id="import-xxxx"><code>import xx.xx</code><a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#import-xxxx" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>这种方式将整个模块导入。如果模块中有函数、类或变量，我们需要以 <code>module.xxx</code> 的方式调用。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Module_a.py</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> func</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&quot;This is module A!&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Main.py</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> module_a</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">module_a.func() </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 调用函数</span></span></code></pre></figure>
<h4 id="from-xxxx-import-xx"><code>from xx.xx import xx</code><a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#from-xxxx-import-xx" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>这种方式从某个模块中导入某个指定的部分到当前命名空间，不会将整个模块导入。这种方式可以节省代码量，但需要注意避免名字冲突。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Main.py</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> module_a </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> func</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">func() </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 直接调用 func</span></span></code></pre></figure>
<h4 id="from-xxxx-import-xx-as-rename"><code>from xx.xx import xx as rename</code><a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#from-xxxx-import-xx-as-rename" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>为了避免命名冲突，我们可以在导入时重命名模块。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Main.py</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> module_a </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> func </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">as</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> f</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">f() </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 使用新名称 f 来调用函数</span></span></code></pre></figure>
<h4 id="from-xxxx-import-"><code>from xx.xx import \*</code><a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#from-xxxx-import-" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>这种方式将模块中的所有内容全部导入，非常容易发生命名冲突，因此需要谨慎使用。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Main.py</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> module_a </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> *</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> func</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&quot;This is the main module!&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">func() </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># func 从 module_a 导入被 main 中的 func 覆盖</span></span></code></pre></figure>
<h3 id="绝对导入">绝对导入<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#绝对导入" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>绝对导入使用模块的完整路径来导入。这个路径是从项目的根目录开始的，也就是说，从 Python 解释器开始搜索模块的路径。让我们通过一个示例来理解绝对导入。</p>
<p>假设我们有以下项目结构：</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="markdown" data-theme="github-light github-dark"><code data-language="markdown" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">myproject/</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">│</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">├── main.py</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">│</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">└── mypackage/</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> ├── </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;--shiki-light-font-weight:bold;--shiki-dark-font-weight:bold;">__init__</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">.py</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> ├── module_a.py</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> └── subpackage/</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> ├── </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;--shiki-light-font-weight:bold;--shiki-dark-font-weight:bold;">__init__</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">.py</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> └── module_b.py</span></span></code></pre></figure>
<p>在这个项目中，我们有一个主程序 <code>main.py</code> 和一个包 <code>mypackage</code>，包含了模块 <code>module_a.py</code> 和一个子包 <code>subpackage</code>，包含了模块 <code>module_b.py</code>。</p>
<p>在 <code>main.py</code> 中，我们可以使用绝对导入来导入 <code>module_a.py</code>：</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># main.py</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> mypackage.module_a</span></span></code></pre></figure>
<p>在这里，<code>mypackage</code> 是项目的根目录，所以我们使用完整的路径来导入 <code>module_a</code>。</p>
<p>同样，在 <code>module_b.py</code> 中，我们可以使用绝对导入来导入 <code>module_a.py</code>：</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># mypackage/subpackage/module_b.py</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> mypackage.module_a</span></span></code></pre></figure>
<h4 id="适用场景">适用场景<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#适用场景" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>绝对导入的适用场景包括：</p>
<ul>
<li>明确：绝对导入提供了清晰的模块路径，使得其他开发人员更容易理解模块之间的关系。</li>
<li>项目结构不变：当项目结构发生变化时，绝对导入不需要更新导入路径。</li>
<li>可移植性：如果一个包被设计成可以独立安装并作为第三方库使用，绝对导入是更好的选择。</li>
</ul>
<h3 id="相对导入">相对导入<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#相对导入" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>相对导入是基于当前模块文件的目录结构的。使用 <code>.</code> 表示当前目录，<code>..</code> 表示父目录，以此类推。相对导入通常用在包内部，当模块之间互相导入时。让我们通过示例来理解相对导入。</p>
<p>在 <code>module_b.py</code> 中，我们可以使用相对导入来导入同一包下的 <code>module_a.py</code>：</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># mypackage/subpackage/module_b.py</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> .. </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> module_a</span></span></code></pre></figure>
<p>在这里，<code>..</code> 表示上一级目录，即 <code>mypackage</code>，然后我们导入了 <code>module_a</code>。</p>
<h4 id="注意事项">注意事项<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#注意事项" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>相对导入需要一些额外的注意事项：</p>
<ul>
<li>相对导入只能用于包内部模块之间的导入，不能用于顶级模块或脚本。</li>
<li>如果直接运行一个包含相对导入的模块，可能会导致 <code>ImportError</code>。</li>
</ul>
<h4 id="适用场景-1">适用场景<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#适用场景-1" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>相对导入通常更适合以下情况：</p>
<ul>
<li>包内部导入：当你在包内部工作时，相对导入可以更好地保持模块的封装性和可移植性。</li>
<li>封装和模块重构：相对导入在包内部重构时特别有用，因为它减少了需要更改的导入语句的数量。</li>
</ul>
<h3 id="模块路径搜索顺序">模块路径搜索顺序<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#模块路径搜索顺序" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>当我们尝试导入一个模块时，Python 解释器对模块位置的搜索顺序是：</p>
<ol>
<li>Python 项目的当前目录</li>
<li>在环境变量 PYTHONPATH 中列出的所有目录</li>
<li>Python 的安装目录和其他默认目录</li>
</ol>
<p>模块搜索路径存储在 <code>sys</code> 模块的 <code>sys.path</code> 变量中。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sys</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(sys.path)</span></span></code></pre></figure>
<h2 id="命名空间和作用域">命名空间和作用域<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#命名空间和作用域" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h2>
<p>在 Python 中，命名空间（Namespace）是从名称到对象的映射，主要用于避免命名冲突。命名空间的生命周期取决于对象的作用域，如果对象执行完成，则该命名空间的生命周期就结束。</p>
<h3 id="命名空间类型">命名空间类型<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#命名空间类型" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>Python 有三种命名空间：</p>
<ul>
<li><strong>内置名称（built-in names）</strong>：Python 语言内置的名称，如函数名 <code>abs</code>、<code>char</code> 和异常名称 <code>BaseException</code>、<code>Exception</code> 等。</li>
<li><strong>全局名称（global names）</strong>：模块中定义的名称，包括模块的函数、类、导入的模块、模块级别的变量和常量。</li>
<li><strong>局部名称（local names）</strong>：函数中定义的名称，包括函数的参数和局部定义的变量。</li>
</ul>
<p><img src="https://static.7wate.com/img/2022/11/20/7ee3813629181.png" alt="img"/></p>
<h3 id="作用域">作用域<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#作用域" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>作用域定义了命名空间可以直接访问的代码段，决定了在哪一部分程序可以访问特定的变量名。Python 的作用域一共有 4 种，分别是：</p>
<p><img src="https://static.7wate.com/img/2022/11/20/1e3af056f1ac0.png" alt="img"/></p>
<ul>
<li>L（Local）：最内层，包含局部变量，比如一个函数/方法内部。</li>
<li>E（Enclosing）：包含了非局部（non-local）也非全局（non-global）的变量。比如两个嵌套函数，一个函数（或类）A 里面又包含了一个函数 B，那么对于 B 中的名称来说 A 中的作用域就为 nonlocal。</li>
<li>G（Global）：当前脚本的最外层，比如当前模块的全局变量。</li>
<li>B（Built-in）： 包含了内建的变量/关键字等，最后被搜索。</li>
</ul>
<p>变量的查找顺序是：L <span>⇒</span> E <span>⇒</span> G <span>⇒</span> B。</p>
<h3 id="代码示例">代码示例<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#代码示例" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="python" data-theme="github-light github-dark"><code data-language="python" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 全局变量</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">x </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 10</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">z </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 40</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 定义函数 foo</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> foo</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 局部变量</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> x </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 20</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> z </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 50</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> bar</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> nonlocal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> z</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&quot;局部变量 z =&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, z) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 输出 &quot;局部变量 z = 50&quot;</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> baz</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> global</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> z</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&quot;全局变量 z =&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, z) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 输出 &quot;全局变量 z = 40&quot;</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&quot;局部变量 x =&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, x) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 输出 &quot;局部变量 x = 20&quot;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> bar()</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> baz()</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 定义函数 outer</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> outer</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> y </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 30</span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # 封闭作用域变量</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> inner</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> nonlocal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> y</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&quot;封闭作用域 y =&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, y) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 输出 &quot;封闭作用域 y = 30&quot;</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> inner()</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 执行函数</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">foo()</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&quot;全局变量 x =&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, x) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 输出 &quot;全局变量 x = 10&quot;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">outer()</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 调用内置函数</span></span>
<span data-line><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">abs</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 输出 5</span></span></code></pre></figure>
<p>这个例子展示了 Python 中的作用域和命名空间的概念。在函数 <code>foo</code> 中，变量 <code>x</code> 和 <code>z</code> 是局部变量，只在 <code>foo</code> 函数内部可见。函数 <code>bar</code> 和 <code>baz</code> 改变了 <code>z</code> 的作用域，<code>bar</code> 定义 <code>z</code> 为封闭作用域（<code>foo</code> 函数的作用域），而 <code>baz</code> 定义 <code>z</code> 为全局作用域。函数 <code>outer</code> 和 <code>inner</code> 展示了封闭作用域变量的使用，<code>outer</code> 函数内的 <code>y</code> 变量在 <code>inner</code> 函数中也可见。</p>
<p>最后，我们调用了内置函数 <code>abs</code>，这是一个内置命名空间的例子。所有的内置函数和关键字都在 Python 的内置命名空间中，无需导入就可以直接使用。</p></article><hr/><div class="page-footer"></div></div><div class="right sidebar"><div class="graph"><h3>关系图谱</h3><div class="graph-outer"><div id="graph-container" data-cfg="{&quot;drag&quot;:true,&quot;zoom&quot;:true,&quot;depth&quot;:1,&quot;scale&quot;:1.1,&quot;repelForce&quot;:0.5,&quot;centerForce&quot;:0.3,&quot;linkDistance&quot;:30,&quot;fontSize&quot;:0.6,&quot;opacityScale&quot;:1,&quot;showTags&quot;:true,&quot;removeTags&quot;:[],&quot;focusOnHover&quot;:false}"></div><button id="global-graph-icon" aria-label="Global Graph"><svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 55 55" fill="currentColor" xml:space="preserve"><path d="M49,0c-3.309,0-6,2.691-6,6c0,1.035,0.263,2.009,0.726,2.86l-9.829,9.829C32.542,17.634,30.846,17,29,17
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