-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathpython-oop.html
282 lines (282 loc) · 79.9 KB
/
python-oop.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
<!DOCTYPE html><html lang="zh-CN"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=2"><meta name="theme-color" content="#222"><meta http-equiv="X-UA-COMPATIBLE" content="IE=edge,chrome=1"><meta name="renderer" content="webkit"><link rel="icon" type="image/ico" sizes="32x32" href="/assets/favicon.ico"><link rel="apple-touch-icon" sizes="180x180" href="/assets/apple-touch-icon.png"><link rel="alternate" href="/rss.xml" title="Jiankychen's Blog" type="application/rss+xml"><link rel="alternate" href="/atom.xml" title="Jiankychen's Blog" type="application/atom+xml"><link rel="alternate" type="application/json" title="Jiankychen's Blog" href="https://jiankychen.github.io/feed.json"><link rel="preconnect" href="https://lf9-cdn-tos.bytecdntp.com"><link rel="preconnect" href="https://at.alicdn.com"><link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Mulish:400,400italic,700,700italic%7CFredericka%20the%20Great:400,400italic,700,700italic%7CNoto%20Serif%20JP:400,400italic,700,700italic%7CNoto%20Serif%20SC:400,400italic,700,700italic%7CInconsolata:400,400italic,700,700italic&display=swap&subset=latin,latin-ext" media="none" onload="this.media='all'"><link rel="stylesheet" href="/css/app.css?v=0.4.2"><link rel="modulepreload" href="/js/chunk-7IVLRIQ3.js"><link rel="modulepreload" href="/js/chunk-IXT6LZJL.js"><link rel="modulepreload" href="/js/chunk-PHSEV26P.js"><link rel="modulepreload" href="/js/chunk-XHQGHZCW.js"><link rel="modulepreload" href="/js/comments-TUWNDU5I.js"><link rel="modulepreload" href="/js/post-P6IN2S3Y.js"><link rel="modulepreload" href="/js/quicklink-HAJEHOPK.js"><link rel="modulepreload" href="/js/search-WFXK2K66.js"><link rel="modulepreload" href="/js/siteInit.js"><link rel="stylesheet" href="https://npm.webcache.cn/@waline/[email protected]/dist/waline.css" media="none" onload="this.media='all'"><link rel="preload" href="https://i.imgtg.com/2023/03/09/Y0iNK.jpg" as="image" fetchpriority="high"><link rel="preload" href="https://i.imgtg.com/2023/03/09/Y0zdB.jpg" as="image" fetchpriority="high"><link rel="preload" href="https://img.timelessq.com/images/2022/07/26/99fb5ff897a82984470abf5e2a235d94.jpg" as="image" fetchpriority="high"><link rel="preload" href="https://i.imgtg.com/2023/03/09/YS6XY.jpg" as="image" fetchpriority="high"><link rel="preload" href="https://img.timelessq.com/images/2022/07/26/e5221f7d85b0900837a45fb933fa34ec.jpg" as="image" fetchpriority="high"><link rel="preload" href="https://i.imgtg.com/2023/03/09/Y0kTl.jpg" as="image" fetchpriority="high"><link rel="canonical" href="https://jiankychen.github.io/python-oop"><title>Python 面向对象</title><meta name="generator" content="Hexo 7.0.0"></head><body itemscope="" itemtype="http://schema.org/WebPage"><div id="loading"><div class="cat"><div class="body"></div><div class="head"><div class="face"></div></div><div class="foot"><div class="tummy-end"></div><div class="bottom"></div><div class="legs left"></div><div class="legs right"></div></div><div class="paw"><div class="hands left"></div><div class="hands right"></div></div></div></div><div id="container"><header id="header" itemscope="" itemtype="http://schema.org/WPHeader"><div class="inner"><div id="brand"><div class="pjax"><h1 itemprop="name headline">Python 面向对象</h1><div class="meta"><span class="item" title="创建时间：2023-02-02 17:48:52"><span class="icon"><i class="ic i-calendar"></i></span><span class="text">发表于</span><time itemprop="dateCreated datePublished" datetime="2023-02-02T17:48:52+08:00">2023-02-02</time></span><span class="item" title="本文字数"><span class="icon"><i class="ic i-pen"></i></span><span class="text">本文字数</span><span>9.8k</span><span class="text">字</span></span><span class="item" title="阅读时长"><span class="icon"><i class="ic i-clock"></i></span><span class="text">阅读时长</span><span>9 分钟</span></span></div></div></div><nav id="nav"><div class="inner"><div class="toggle"><div class="lines" aria-label="切换导航栏"><span class="line"></span><span class="line"></span><span class="line"></span></div></div><ul class="menu"><li class="item title"><a href="/" rel="start">Jiankychen</a></li></ul><ul class="right" id="rightNav"><li class="item theme"><i class="ic i-sun"></i></li><li class="item search"><i class="ic i-search"></i></li></ul></div></nav></div><div class="pjax" id="imgs"><ul><li class="item" style="background-image: url("https://i.imgtg.com/2023/03/09/Y0iNK.jpg");"></li><li class="item" style="background-image: url("https://i.imgtg.com/2023/03/09/Y0zdB.jpg");"></li><li class="item" style="background-image: url("https://img.timelessq.com/images/2022/07/26/99fb5ff897a82984470abf5e2a235d94.jpg");"></li><li class="item" style="background-image: url("https://i.imgtg.com/2023/03/09/YS6XY.jpg");"></li><li class="item" style="background-image: url("https://img.timelessq.com/images/2022/07/26/e5221f7d85b0900837a45fb933fa34ec.jpg");"></li><li class="item" style="background-image: url("https://i.imgtg.com/2023/03/09/Y0kTl.jpg");"></li></ul></div></header><div id="waves"><svg class="waves" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 24 150 28" preserveAspectRatio="none" shape-rendering="auto"><defs><path id="gentle-wave" d="M-160 44c30 0 58-18 88-18s 58 18 88 18 58-18 88-18 58 18 88 18 v44h-352z"></path></defs><g class="parallax"><use xlink:href="#gentle-wave" x="48" y="0"></use><use xlink:href="#gentle-wave" x="48" y="3"></use><use xlink:href="#gentle-wave" x="48" y="5"></use><use xlink:href="#gentle-wave" x="48" y="7"></use></g></svg></div><main><div class="inner"><div class="pjax" id="main"><div class="article wrap"><div class="breadcrumb" itemlistelement="" itemscope="" itemtype="https://schema.org/BreadcrumbList"><i class="ic i-home"></i><span><a href="/">首页</a></span><i class="ic i-angle-right"></i><span class="current" itemprop="itemListElement" itemscope="itemscope" itemtype="https://schema.org/ListItem"><a href="/categories/Python/" itemprop="item" rel="index" title="分类于Python"><span itemprop="name">Python<meta itemprop="position" content="0"></span></a></span></div><article class="post block" itemscope="itemscope" itemtype="http://schema.org/Article" lang="zh-CN"><link itemprop="mainEntityOfPage" href="https://jiankychen.github.io/python-oop.html"><span hidden="hidden" itemprop="author" itemscope="itemscope" itemtype="http://schema.org/Person"><meta itemprop="image" content="/assets/avatar.jpg"><meta itemprop="name" content="Jiankychen"><meta itemprop="description" content="Never put off till tomorrow what you can do today, "></span><span hidden="hidden" itemprop="publisher" itemscope="itemscope" itemtype="http://schema.org/Organization"><meta itemprop="name" content="Jiankychen's Blog"></span><div class="body md" itemprop="articleBody"><p>Python 是一种面向对象的编程语言</p>
<p>简单理解 面向对象 ：基于模板（类）去创建实体（对象），使用对象完成功能开发</p>
<p>面向对象的三大特征：</p>
<ul>
<li>封装</li>
<li>继承</li>
<li>多态</li>
</ul>
<p>面向对象技术简介</p>
<ul>
<li>类（Class）: 用来描述具有相同的属性和方法的对象的集合。它定义了该集合中每个对象所共有的属性和方法。对象是类的实例</li>
<li>对象：通过类定义的数据结构实例。对象包括两个数据成员（类变量和实例变量）和方法</li>
<li>实例化：创建一个类的实例（类的具体对象）</li>
<li>方法：类中定义的函数</li>
<li>类变量：类变量在整个实例化的对象中是公用的。类变量定义在类中且在函数体之外。类变量通常不作为实例变量使用</li>
<li>数据成员：类变量或者实例变量用于处理类及其实例对象的相关的数据</li>
<li>方法重写：如果从父类继承的方法不能满足子类的需求，可以对其进行改写，这个过程叫方法的覆盖（override），也称为方法的重写</li>
<li>局部变量：定义在方法中的变量，只作用于当前实例的类</li>
<li>实例变量：在类的声明中，属性是用变量来表示的，这种变量就称为实例变量，实例变量就是一个用 self 修饰的变量</li>
<li>继承：即一个派生类（derived class）继承基类（base class）的字段和方法。继承也允许把一个派生类的对象作为一个基类对象对待。例如，有这样一个设计：一个 Dog 类型的对象派生自 Animal 类，这是模拟 "是一个（is-a）" 关系（即，Dog 是一个 Animal）</li>
</ul>
<h1 id="类和对象"><a class="anchor" href="#类和对象">#</a> 类和对象</h1>
<p>类的组成：</p>
<ul>
<li>成员变量：定义在类中的属性（变量）</li>
<li>成员方法：定义在类中的行为（函数）</li>
</ul>
<h2 id="类定义"><a class="anchor" href="#类定义">#</a> 类定义</h2>
<p>使用关键字 <code>class</code> 定义类：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Class_Name</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token operator"><</span>statement<span class="token operator">-</span><span class="token number">1</span><span class="token operator">></span></pre></td></tr><tr><td data-num="3"></td><td><pre> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></pre></td></tr><tr><td data-num="4"></td><td><pre> <span class="token operator"><</span>statement<span class="token operator">-</span>N<span class="token operator">></span></pre></td></tr></tbody></table></figure><p>其中， <code>Class_Name</code> 表示类的名称，通常需要首字母大写</p>
<h2 id="类对象"><a class="anchor" href="#类对象">#</a> 类对象</h2>
<p>创建对象（实例化）：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre>obj <span class="token operator">=</span> Class_Name<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr></tbody></table></figure><p>修改对象属性：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre>obj<span class="token punctuation">.</span>var_name <span class="token operator">=</span> xx</pre></td></tr></tbody></table></figure><p>删除对象属性：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token comment"># 使用 del 关键字删除对象的属性</span></pre></td></tr><tr><td data-num="2"></td><td><pre><span class="token keyword">del</span> obj<span class="token punctuation">.</span>var_name</pre></td></tr></tbody></table></figure><p>删除对象：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token comment"># 使用 del 关键字删除对象</span></pre></td></tr><tr><td data-num="2"></td><td><pre><span class="token keyword">del</span> obj</pre></td></tr></tbody></table></figure><h2 id="类的成员方法"><a class="anchor" href="#类的成员方法">#</a> 类的成员方法</h2>
<ul>
<li>函数：定义在类的外部</li>
<li>方法：定义在类的内部</li>
</ul>
<p>在类的内部，使用 <code>def</code> 关键字来定义一个方法，与一般函数定义不同，类的成员方法必须必须有一个额外的第一个参数名称，按照惯例它的名称是 <code>self</code> ，即：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">def</span> <span class="token function">func_name</span><span class="token punctuation">(</span>self<span class="token punctuation">,</span> parameter_1<span class="token punctuation">,</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">,</span> parameter_N<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></pre></td></tr></tbody></table></figure><p>其中：</p>
<ul>
<li>
<p><code>self</code> 参数是对类的当前实例的引用，用于访问属于该类的变量。它不必被命名为 <code>self</code> ，但它必须是类中任意函数的首个参数</p>
</li>
<li>
<p>在方法内部，想要访问类的成员变量，必须使用 <code>self</code> 。即，使用 <code>self.var_name</code> 访问成员变量 <code>var_nam</code></p>
</li>
<li>
<p>调用类的成员方法时， <code>self</code> 会被自动传入，即，不需要在实参列表中写出 <code>self</code></p>
</li>
</ul>
<h2 id="构造方法"><a class="anchor" href="#构造方法">#</a> 构造方法</h2>
<p>Python 类中的 <code>__init__</code> 方法，称之为 构造方法</p>
<p>每次使用类创建新对象时，都会自动调用 <code>__init__</code> 方法，并且会将创建类对象时的传入参数自动传递给 <code>__init__</code> 方法</p>
<p>因此，使用 <code>__init__</code> 方法可以将值赋给对象属性，或者在创建对象时需要执行的其他操作</p>
<p>注意，构造方法 也是 成员方法，因此：</p>
<ul>
<li>定义构造方法时需要在形参列表中写上 <code>self</code> 参数</li>
<li>在构造方法内部访问成员变量需要使用 <code>self.var_name</code></li>
</ul>
<p>例如：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token comment"># 定义类</span></pre></td></tr><tr><td data-num="2"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Person</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="3"></td><td><pre> name <span class="token operator">=</span> <span class="token boolean">None</span> <span class="token comment"># 由于定义了 __init__ 方法，可以省略这里的初始化</span></pre></td></tr><tr><td data-num="4"></td><td><pre> age <span class="token operator">=</span> <span class="token boolean">None</span> <span class="token comment"># 由于定义了 __init__ 方法，可以省略这里的初始化</span></pre></td></tr><tr><td data-num="5"></td><td><pre></pre></td></tr><tr><td data-num="6"></td><td><pre> <span class="token keyword">def</span> <span class="token function">__init__</span><span class="token punctuation">(</span>self<span class="token punctuation">,</span> name<span class="token punctuation">,</span> age<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="7"></td><td><pre> self<span class="token punctuation">.</span>name <span class="token operator">=</span> name</pre></td></tr><tr><td data-num="8"></td><td><pre> self<span class="token punctuation">.</span>age <span class="token operator">=</span> age</pre></td></tr><tr><td data-num="9"></td><td><pre></pre></td></tr><tr><td data-num="10"></td><td><pre></pre></td></tr><tr><td data-num="11"></td><td><pre><span class="token comment"># 创建类对象</span></pre></td></tr><tr><td data-num="12"></td><td><pre>p <span class="token operator">=</span> Person<span class="token punctuation">(</span><span class="token string">"John"</span><span class="token punctuation">,</span> <span class="token number">24</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="13"></td><td><pre></pre></td></tr><tr><td data-num="14"></td><td><pre><span class="token comment"># 打印类对象的属性</span></pre></td></tr><tr><td data-num="15"></td><td><pre><span class="token keyword">print</span><span class="token punctuation">(</span>p<span class="token punctuation">.</span>name<span class="token punctuation">)</span></pre></td></tr><tr><td data-num="16"></td><td><pre><span class="token keyword">print</span><span class="token punctuation">(</span>p<span class="token punctuation">.</span>age<span class="token punctuation">)</span></pre></td></tr></tbody></table></figure><h2 id="魔术方法"><a class="anchor" href="#魔术方法">#</a> 魔术方法</h2>
<p>魔术方法（Magic Methods）是 Python 中的内置方法，一般以 <code>__</code> （双下划线）为开头和结尾</p>
<p>例如：</p>
<ul>
<li><code>__init__</code> ：构造方法，当一个实例被创建的时候调用的初始化方法</li>
<li><code>__del__</code> ：析构方法，当一个实例被销毁的时候调用的方法</li>
<li><code>__str__</code> ：字符串方法，定义当被 <code>str()</code> 调用或者打印对象时的行为</li>
<li><code>__lt__</code> ：定义小于号的行为： <code>x < y</code> 调用 <code>x.__lt__(y)</code></li>
<li><code>__le__</code> ：定义小于等于号的行为： <code>x <= y</code> 调用 <code>x.__le__(y)</code></li>
<li><code>__eq__</code> ：定义等于号的行为： <code>x == y</code> 调用 <code>x.__eq__(y)</code></li>
</ul>
<p>之所以称之为魔法方法，是因为这些方法会在进行特定的操作时会被自动调用</p>
<p>如果希望根据自己的程序定制自己特殊功能的类，那么就需要对这些方法进行重写</p>
<p>参考：<a target="_blank" rel="noopener" href="https://www.cnblogs.com/dachenzi/p/8185792.html">Python 中类的魔术方法</a></p>
<h2 id="pass-语句"><a class="anchor" href="#pass-语句">#</a> pass 语句</h2>
<p><code>pass</code> 是占位语句，用来保证函数（方法）或类定义的完整性，表示无内容</p>
<p>如果因为某种原因写了无内容的函数定义或类定义，需使用 <code>pass</code> 语句来避免错误</p>
<p>例如：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token comment"># 继承</span></pre></td></tr><tr><td data-num="2"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">DerivedClassName</span><span class="token punctuation">(</span>BaseClassName<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="3"></td><td><pre> <span class="token keyword">pass</span></pre></td></tr></tbody></table></figure><p>参考资料：</p>
<ul>
<li><a target="_blank" rel="noopener" href="https://www.w3school.com.cn/python/python_classes.asp">W3school：Python 类和对象</a></li>
<li><a target="_blank" rel="noopener" href="https://www.runoob.com/python3/python3-class.html">菜鸟教程：Python3 面向对象</a></li>
</ul>
<h1 id="封装"><a class="anchor" href="#封装">#</a> 封装</h1>
<p>在程序设计中，封装（Encapsulation）是对具体对象的一种抽象，即将某些部分隐藏起来（即，定义成私有成员），在程序外部看不到（即，其他程序无法调用）</p>
<ul>
<li>封装数据：保护隐私</li>
<li>封装方法：隔离复杂度（只保留部分接口对外使用）</li>
</ul>
<h2 id="私有成员"><a class="anchor" href="#私有成员">#</a> 私有成员</h2>
<p>类对象无法直接访问私有成员，但类内其它成员可以直接使用私有成员</p>
<p>私有成员变量：</p>
<ul>
<li>定义：变量名以 <code>__</code> （2 个下划线）开头，例如： <code>__private_attrs</code></li>
<li>声明该属性为私有属性，只能在类的内部使用，不能在类的外部使用或直接访问</li>
<li>在类内部的访问方式为： <code>self.__private_attrs</code></li>
</ul>
<p>私有成员方法（封装的方法）：</p>
<ul>
<li>方法名以 <code>__</code> （2 个下划线）开头，例如： <code>__private_method</code></li>
<li>声明该方法为私有方法，只能在类的内部调用，不能在类的外部调用</li>
<li>在类内部的调用方式为： <code>self.__private_method()</code></li>
</ul>
<blockquote>
<p>与 java 等语言不同，Python 的封装并不是真正意义上的外部无法调用。在 Python 中，如果需要在类外调用封装的属性或方法，须采用 <code>对象名._类名__方法名</code> 和 <code>对象名._类名__变量名</code> 的方式（不建议调用）</p>
</blockquote>
<p>例如：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Foo</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token keyword">def</span> <span class="token function">__init__</span><span class="token punctuation">(</span>self<span class="token punctuation">,</span> height<span class="token punctuation">,</span> weight<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment"># 构造方法</span></pre></td></tr><tr><td data-num="3"></td><td><pre> self<span class="token punctuation">.</span>height <span class="token operator">=</span> height</pre></td></tr><tr><td data-num="4"></td><td><pre> self<span class="token punctuation">.</span>weight <span class="token operator">=</span> weight</pre></td></tr><tr><td data-num="5"></td><td><pre> </pre></td></tr><tr><td data-num="6"></td><td><pre> <span class="token keyword">def</span> <span class="token function">__heightpow</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment"># 私有方法</span></pre></td></tr><tr><td data-num="7"></td><td><pre> <span class="token keyword">return</span> self<span class="token punctuation">.</span>height <span class="token operator">*</span> self<span class="token punctuation">.</span>height</pre></td></tr><tr><td data-num="8"></td><td><pre> </pre></td></tr><tr><td data-num="9"></td><td><pre> <span class="token keyword">def</span> <span class="token function">tell_bmi</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="10"></td><td><pre> <span class="token keyword">return</span> self<span class="token punctuation">.</span>weight <span class="token operator">/</span> self<span class="token punctuation">.</span>__heightpow<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment"># 私有成员可以被类内其它成员直接使用</span></pre></td></tr><tr><td data-num="11"></td><td><pre></pre></td></tr><tr><td data-num="12"></td><td><pre>egon <span class="token operator">=</span> Foo<span class="token punctuation">(</span><span class="token number">1.7</span><span class="token punctuation">,</span> <span class="token number">120</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="13"></td><td><pre><span class="token keyword">print</span><span class="token punctuation">(</span>egon<span class="token punctuation">.</span>tell_bmi<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="14"></td><td><pre><span class="token keyword">print</span><span class="token punctuation">(</span>egon<span class="token punctuation">.</span>_Foo__heightpow<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token comment"># 尽管是私有成员方法，但也可以在类外调用以供查看</span></pre></td></tr></tbody></table></figure><h2 id="property"><a class="anchor" href="#property">#</a> property</h2>
<p>property 是一种特殊的属性，访问它时会执行一段功能（函数）然后返回值（就是一个装饰器）</p>
<p>将一个类的方法 <code>func_name</code> 用 propery 装饰以后，类对象 <code>obj</code> 可直接通过 <code>obj.func_name</code> 去使用，以遵循统一访问的原则</p>
<blockquote>
<p>被 property 装饰的属性会优先于对象的属性被使用</p>
</blockquote>
<p>被 propery 装饰的属性分成三种：</p>
<ul>
<li>property</li>
<li>被装饰的函数名.setter</li>
<li>被装饰的函数名.deleter</li>
</ul>
<p>例如， <code>@property</code> 把类中的方法伪装成属性：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">from</span> math <span class="token keyword">import</span> pi</pre></td></tr><tr><td data-num="2"></td><td><pre></pre></td></tr><tr><td data-num="3"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Circle</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="4"></td><td><pre> <span class="token keyword">def</span> <span class="token function">__init__</span><span class="token punctuation">(</span>self<span class="token punctuation">,</span> radius<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="5"></td><td><pre> self<span class="token punctuation">.</span>radius <span class="token operator">=</span> radius</pre></td></tr><tr><td data-num="6"></td><td><pre></pre></td></tr><tr><td data-num="7"></td><td><pre> <span class="token decorator annotation punctuation">@property</span> <span class="token comment"># 装饰器：将一个方法当成一个属性用</span></pre></td></tr><tr><td data-num="8"></td><td><pre> <span class="token keyword">def</span> <span class="token function">area</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="9"></td><td><pre> <span class="token keyword">return</span> self<span class="token punctuation">.</span>radius <span class="token operator">*</span> self<span class="token punctuation">.</span>radius <span class="token operator">*</span> pi</pre></td></tr><tr><td data-num="10"></td><td><pre></pre></td></tr><tr><td data-num="11"></td><td><pre> <span class="token decorator annotation punctuation">@property</span></pre></td></tr><tr><td data-num="12"></td><td><pre> <span class="token keyword">def</span> <span class="token function">peimeter</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="13"></td><td><pre> <span class="token keyword">return</span> <span class="token number">2</span> <span class="token operator">*</span> pi <span class="token operator">*</span> self<span class="token punctuation">.</span>radius</pre></td></tr><tr><td data-num="14"></td><td><pre></pre></td></tr><tr><td data-num="15"></td><td><pre>c <span class="token operator">=</span> Circle<span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="16"></td><td><pre><span class="token keyword">print</span><span class="token punctuation">(</span>c<span class="token punctuation">.</span>area<span class="token punctuation">)</span> <span class="token comment"># 当成一个属性来调用（即，不需要加括号）</span></pre></td></tr><tr><td data-num="17"></td><td><pre><span class="token keyword">print</span><span class="token punctuation">(</span>c<span class="token punctuation">.</span>peimeter<span class="token punctuation">)</span> <span class="token comment"># 当成一个属性来调用（即，不需要加括号）</span></pre></td></tr></tbody></table></figure><p>注意：此时的特性 area 和 perimeter 不能被赋值</p>
<p>参考资料：</p>
<ul>
<li><a target="_blank" rel="noopener" href="https://www.cnblogs.com/Michael--chen/p/6740455.html">Python 基础之封装</a></li>
<li><a target="_blank" rel="noopener" href="https://www.cnblogs.com/haiyan123/p/7367343.html">Python 封装</a></li>
</ul>
<h1 id="继承"><a class="anchor" href="#继承">#</a> 继承</h1>
<p>继承允许我们定义继承（复制）另一个类的所有方法和属性的类</p>
<p>继承可以分为：</p>
<ul>
<li>单继承：一个类继承另一个类</li>
<li>多继承：一个类继承多个类，按照顺序从左向右依次继承</li>
</ul>
<p>父类是被继承的类，也称为基类</p>
<p>子类是从另一个类继承所得的类，也称为派生类</p>
<h2 id="单继承"><a class="anchor" href="#单继承">#</a> 单继承</h2>
<blockquote>
<p>任何类都可以是父类，因此，创建父类的语法与创建任何其他类相同</p>
</blockquote>
<p>要创建从其他类继承功能的类，只需在创建子类时将父类作为参数传递即可：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">DerivedClassName</span><span class="token punctuation">(</span>BaseClassName<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token operator"><</span>statement<span class="token operator">-</span><span class="token number">1</span><span class="token operator">></span></pre></td></tr><tr><td data-num="3"></td><td><pre> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></pre></td></tr><tr><td data-num="4"></td><td><pre> <span class="token operator"><</span>statement<span class="token operator">-</span>N<span class="token operator">></span></pre></td></tr></tbody></table></figure><p>其中， <code>DerivedClassName</code> 为子类名， <code>BaseClassName</code> 为父类名</p>
<blockquote>
<p>如果不希望向子类中添加任何其他属性或方法，可使用 <code>pass</code> 关键字</p>
</blockquote>
<p>例如：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token comment"># 创建 Person 类</span></pre></td></tr><tr><td data-num="2"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Person</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="3"></td><td><pre> <span class="token keyword">def</span> <span class="token function">__init__</span><span class="token punctuation">(</span>self<span class="token punctuation">,</span> fname<span class="token punctuation">,</span> lname<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="4"></td><td><pre> self<span class="token punctuation">.</span>firstname <span class="token operator">=</span> fname</pre></td></tr><tr><td data-num="5"></td><td><pre> self<span class="token punctuation">.</span>lastname <span class="token operator">=</span> lname</pre></td></tr><tr><td data-num="6"></td><td><pre></pre></td></tr><tr><td data-num="7"></td><td><pre> <span class="token keyword">def</span> <span class="token function">print_name</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="8"></td><td><pre> <span class="token keyword">print</span><span class="token punctuation">(</span>self<span class="token punctuation">.</span>firstname<span class="token punctuation">,</span> self<span class="token punctuation">.</span>lastname<span class="token punctuation">)</span></pre></td></tr><tr><td data-num="9"></td><td><pre></pre></td></tr><tr><td data-num="10"></td><td><pre><span class="token comment"># 创建 Person 类对象，并执行 print_name 方法</span></pre></td></tr><tr><td data-num="11"></td><td><pre>x <span class="token operator">=</span> Person<span class="token punctuation">(</span><span class="token string">"Bill"</span><span class="token punctuation">,</span> <span class="token string">"Gates"</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="12"></td><td><pre>x<span class="token punctuation">.</span>print_name<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="13"></td><td><pre></pre></td></tr><tr><td data-num="14"></td><td><pre></pre></td></tr><tr><td data-num="15"></td><td><pre><span class="token comment"># 创建继承自 Person 类的子类 Student</span></pre></td></tr><tr><td data-num="16"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Student</span><span class="token punctuation">(</span>Person<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="17"></td><td><pre> <span class="token keyword">def</span> <span class="token function">__init__</span><span class="token punctuation">(</span>self<span class="token punctuation">,</span> fname<span class="token punctuation">,</span> lname<span class="token punctuation">,</span> gra<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="18"></td><td><pre> self<span class="token punctuation">.</span>firstname <span class="token operator">=</span> fname</pre></td></tr><tr><td data-num="19"></td><td><pre> self<span class="token punctuation">.</span>lastname <span class="token operator">=</span> lname</pre></td></tr><tr><td data-num="20"></td><td><pre> self<span class="token punctuation">.</span>grade <span class="token operator">=</span> gra</pre></td></tr><tr><td data-num="21"></td><td><pre> </pre></td></tr><tr><td data-num="22"></td><td><pre> <span class="token keyword">def</span> <span class="token function">print_info</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="23"></td><td><pre> <span class="token keyword">print</span><span class="token punctuation">(</span>self<span class="token punctuation">.</span>firstname<span class="token punctuation">,</span> self<span class="token punctuation">.</span>lastname<span class="token punctuation">,</span> self<span class="token punctuation">.</span>grade<span class="token punctuation">)</span></pre></td></tr><tr><td data-num="24"></td><td><pre></pre></td></tr><tr><td data-num="25"></td><td><pre><span class="token comment"># 使用 Student 类创建一个对象，然后执行 print_name 和 print_info 方法</span></pre></td></tr><tr><td data-num="26"></td><td><pre>y <span class="token operator">=</span> Student<span class="token punctuation">(</span><span class="token string">"Elon"</span><span class="token punctuation">,</span> <span class="token string">"Musk"</span><span class="token punctuation">,</span> <span class="token number">6</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="27"></td><td><pre>y<span class="token punctuation">.</span>print_name<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="28"></td><td><pre>y<span class="token punctuation">.</span>print_info<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr></tbody></table></figure><h2 id="多继承"><a class="anchor" href="#多继承">#</a> 多继承</h2>
<p>创建子类的语法：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">DerivedClassName</span><span class="token punctuation">(</span>Base1<span class="token punctuation">,</span> Base2<span class="token punctuation">,</span> Base3<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token operator"><</span>statement<span class="token operator">-</span><span class="token number">1</span><span class="token operator">></span></pre></td></tr><tr><td data-num="3"></td><td><pre> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></pre></td></tr><tr><td data-num="4"></td><td><pre> <span class="token operator"><</span>statement<span class="token operator">-</span>N<span class="token operator">></span></pre></td></tr></tbody></table></figure><p>如果多个父类中含有同名的成员，那么默认按照从左向右顺序依次继承，先继承的保留，后继承的被覆盖</p>
<h2 id="方法重写"><a class="anchor" href="#方法重写">#</a> 方法重写</h2>
<p>子类继承父类的成员属性和成员方法后，如果对其 “不满意”，可以在子类重写父类的方法</p>
<p>即：在子类中重新定义同名的属性或方法</p>
<p>例如：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Parent</span><span class="token punctuation">:</span> <span class="token comment"># 定义父类</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token keyword">def</span> <span class="token function">myMethod</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="3"></td><td><pre> <span class="token keyword">print</span> <span class="token punctuation">(</span><span class="token string">'调用父类方法'</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="4"></td><td><pre></pre></td></tr><tr><td data-num="5"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Child</span><span class="token punctuation">(</span>Parent<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment"># 定义子类</span></pre></td></tr><tr><td data-num="6"></td><td><pre> <span class="token keyword">def</span> <span class="token function">myMethod</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment"># 重写父类方法</span></pre></td></tr><tr><td data-num="7"></td><td><pre> <span class="token keyword">print</span> <span class="token punctuation">(</span><span class="token string">'调用子类方法'</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="8"></td><td><pre></pre></td></tr><tr><td data-num="9"></td><td><pre>c <span class="token operator">=</span> Child<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment"># 子类实例</span></pre></td></tr><tr><td data-num="10"></td><td><pre>c<span class="token punctuation">.</span>myMethod<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment"># 子类调用重写方法</span></pre></td></tr></tbody></table></figure><h2 id="调用父类同名成员"><a class="anchor" href="#调用父类同名成员">#</a> 调用父类同名成员</h2>
<p>一旦在子类中重写父类成员以后，子类的类对象调用成员时将是调用复写后的新成员</p>
<p>如果需要使用被复写的父类的成员，需要特殊的调用方式:</p>
<ul>
<li>
<p>方式一：通过父类调用（单继承</p>
<ul>
<li>调用父类成员变量： <code>父类名.成员变量</code></li>
<li>调用父类成员方法： <code>父类名.成员方法(self)</code></li>
</ul>
</li>
<li>
<p>方式二：使用 <code>super()</code> 调用</p>
<ul>
<li>调用父类成员变量： <code>super().成员变量</code></li>
<li>调用父类成员方法： <code>super().成员方法()</code></li>
</ul>
</li>
</ul>
<p>如果是单继承的情况，可以直接用父类名调用父类方法</p>
<p>但是，如果是多继承的情况，可能会涉及到查找顺序（MRO）、重复调用（钻石继承）等种种问题，此时，推荐采用 <code>super()</code> 函数调用，以解决多重继承问题。具体可参考：<a target="_blank" rel="noopener" href="https://www.runoob.com/python/python-func-super.html">Python super () 函数</a></p>
<p>参考资料：</p>
<ul>
<li><a target="_blank" rel="noopener" href="https://www.w3school.com.cn/python/python_inheritance.asp">Python 继承</a></li>
</ul>
<h1 id="类型注解"><a class="anchor" href="#类型注解">#</a> 类型注解</h1>
<p>类型注解：在代码中涉及数据交互的地方，提供数据类型的注解（显式的说明）</p>
<ul>
<li>帮助第三方 IDE 工具（如 PyCharm）对代码进行类型推断，协助做代码提示</li>
<li>帮助开发者自身对变量进行类型注释</li>
</ul>
<p>有两种注解：</p>
<ul>
<li>变量的类型注解</li>
<li>函数（方法）的类型注解</li>
</ul>
<p>需注意：类型注解仅仅是提示性的，不是决定性的，并不会真正地对类型做验证和判断（也就是说：即使注解的数据类型与实际数据类型不一致，程序也不会报错）</p>
<h2 id="变量的类型注解"><a class="anchor" href="#变量的类型注解">#</a> 变量的类型注解</h2>
<p>事实上，对于显式的变量定义，一般无需注解。即便不写类型注解，也可以明确知晓变量的类型</p>
<p>一般而言，在无法直接看出变量类型时（例如，将函数返回值赋给一个变量时），才会添加变量的类型注解</p>
<h3 id="方式一常用"><a class="anchor" href="#方式一常用">#</a> 方式一（常用）</h3>
<p>基础语法：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre>变量<span class="token punctuation">:</span> 类型</pre></td></tr></tbody></table></figure><p>例如：</p>
<p>基础数据类型注解：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre>var1<span class="token punctuation">:</span> <span class="token builtin">int</span> <span class="token operator">=</span> <span class="token number">3</span></pre></td></tr><tr><td data-num="2"></td><td><pre>var2<span class="token punctuation">:</span> <span class="token builtin">float</span> <span class="token operator">=</span> <span class="token number">3.14</span></pre></td></tr><tr><td data-num="3"></td><td><pre>var3<span class="token punctuation">:</span> <span class="token builtin">bool</span> <span class="token operator">=</span> <span class="token boolean">True</span></pre></td></tr></tbody></table></figure><p>类对象类型注解:</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Person</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token keyword">pass</span></pre></td></tr><tr><td data-num="3"></td><td><pre>p<span class="token punctuation">:</span> Person <span class="token operator">=</span> Person<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr></tbody></table></figure><p>容器类型简易注解：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre>mylist<span class="token punctuation">:</span> <span class="token builtin">list</span> <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span></pre></td></tr><tr><td data-num="2"></td><td><pre>mytuple<span class="token punctuation">:</span> <span class="token builtin">tuple</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="3"></td><td><pre>myset<span class="token punctuation">:</span> <span class="token builtin">set</span> <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">}</span></pre></td></tr><tr><td data-num="4"></td><td><pre>mydict<span class="token punctuation">:</span> <span class="token builtin">dict</span> <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token number">0</span><span class="token punctuation">:</span> <span class="token string">"a"</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">:</span> <span class="token string">"b"</span><span class="token punctuation">}</span></pre></td></tr><tr><td data-num="5"></td><td><pre>mystr<span class="token punctuation">:</span> <span class="token builtin">str</span> <span class="token operator">=</span> <span class="token string">"Jiankychen"</span></pre></td></tr></tbody></table></figure><p>容器类型详细注解：</p>
<ul>
<li>元组类型设置类型详细注解：需要将每一个元素都标记出来</li>
<li>字典类型设置类型详细注解：需要 2 个类型，第一个是 key ，第二个是 value</li>
</ul>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre>mylist<span class="token punctuation">:</span> <span class="token builtin">list</span><span class="token punctuation">[</span><span class="token builtin">int</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span></pre></td></tr><tr><td data-num="2"></td><td><pre>mytuple<span class="token punctuation">:</span> <span class="token builtin">tuple</span><span class="token punctuation">[</span><span class="token builtin">str</span><span class="token punctuation">,</span> <span class="token builtin">int</span><span class="token punctuation">,</span> <span class="token builtin">bool</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token string">"a"</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token boolean">True</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="3"></td><td><pre>myset<span class="token punctuation">:</span> <span class="token builtin">set</span><span class="token punctuation">[</span><span class="token builtin">int</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">}</span></pre></td></tr><tr><td data-num="4"></td><td><pre>mydict<span class="token punctuation">:</span> <span class="token builtin">dict</span><span class="token punctuation">[</span><span class="token builtin">int</span><span class="token punctuation">,</span> <span class="token builtin">str</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token number">0</span><span class="token punctuation">:</span> <span class="token string">"a"</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">:</span> <span class="token string">"b"</span><span class="token punctuation">}</span></pre></td></tr></tbody></table></figure><h3 id="方式二"><a class="anchor" href="#方式二">#</a> 方式二</h3>
<p>除了使用 <code>变量: 类型</code> 这种语法做注解外，也可以 <strong>在注释中进行类型注解</strong></p>
<p>基础语法：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token comment"># type: 类型</span></pre></td></tr></tbody></table></figure><p>例如：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Person</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token keyword">pass</span></pre></td></tr><tr><td data-num="3"></td><td><pre></pre></td></tr><tr><td data-num="4"></td><td><pre><span class="token keyword">def</span> <span class="token function">func</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="5"></td><td><pre> <span class="token keyword">return</span> <span class="token number">3.14159</span></pre></td></tr><tr><td data-num="6"></td><td><pre></pre></td></tr><tr><td data-num="7"></td><td><pre>var1 <span class="token operator">=</span> random<span class="token punctuation">.</span>randint<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">)</span> <span class="token comment"># type: int</span></pre></td></tr><tr><td data-num="8"></td><td><pre>var2 <span class="token operator">=</span> Person<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment"># type: Person</span></pre></td></tr><tr><td data-num="9"></td><td><pre>var3 <span class="token operator">=</span> func<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment"># type: float</span></pre></td></tr></tbody></table></figure><h2 id="函数方法的类型注解"><a class="anchor" href="#函数方法的类型注解">#</a> 函数（方法）的类型注解</h2>
<h3 id="形参注解"><a class="anchor" href="#形参注解">#</a> 形参注解</h3>
<p>函数（方法）的形参类型注解语法：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">def</span> <span class="token function">func_name</span><span class="token punctuation">(</span>形参名<span class="token punctuation">:</span> 类型<span class="token punctuation">,</span> 形参名<span class="token punctuation">:</span> 类型<span class="token punctuation">,</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="2"></td><td><pre> statement</pre></td></tr></tbody></table></figure><p>例如：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">def</span> <span class="token function">add</span><span class="token punctuation">(</span>x<span class="token punctuation">:</span> <span class="token builtin">int</span><span class="token punctuation">,</span> y<span class="token punctuation">:</span> <span class="token builtin">int</span><span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token keyword">return</span> x <span class="token operator">+</span> y</pre></td></tr></tbody></table></figure><h3 id="返回值注解"><a class="anchor" href="#返回值注解">#</a> 返回值注解</h3>
<p>函数（方法）的返回值也是可以添加类型注解的，语法如下：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">def</span> <span class="token function">func_name</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">></span> 返回值类型<span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> statement</pre></td></tr></tbody></table></figure><p>例如：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">def</span> <span class="token function">func</span><span class="token punctuation">(</span>data<span class="token punctuation">:</span> <span class="token builtin">list</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">></span> <span class="token builtin">list</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token keyword">return</span> data</pre></td></tr></tbody></table></figure><h2 id="union-类型"><a class="anchor" href="#union-类型">#</a> Union 类型</h2>
<p>通过 <code>Union</code> 可以定义联合类型</p>
<ul>
<li>导包： <code>from typing import Union</code></li>
<li>使用： <code>Union[类型, ..., 类型]</code></li>
</ul>
<p>在变量注解、函数（方法）形参和返回值注解中，均可使用 <code>Union</code> 联合类型</p>
<p>例如：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">from</span> typing <span class="token keyword">import</span> Union</pre></td></tr><tr><td data-num="2"></td><td><pre></pre></td></tr><tr><td data-num="3"></td><td><pre>mylist<span class="token punctuation">:</span> <span class="token builtin">list</span><span class="token punctuation">[</span>Union<span class="token punctuation">[</span><span class="token builtin">str</span><span class="token punctuation">,</span> <span class="token builtin">int</span><span class="token punctuation">]</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token string">"3"</span><span class="token punctuation">,</span> <span class="token string">"4"</span><span class="token punctuation">]</span> <span class="token comment"># list 元素的数据类型可能是 str ，也可能是 int</span></pre></td></tr><tr><td data-num="4"></td><td><pre></pre></td></tr><tr><td data-num="5"></td><td><pre>mydict<span class="token punctuation">:</span> <span class="token builtin">dict</span><span class="token punctuation">[</span><span class="token builtin">str</span><span class="token punctuation">,</span> Union<span class="token punctuation">[</span><span class="token builtin">str</span><span class="token punctuation">,</span> <span class="token builtin">int</span><span class="token punctuation">]</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token string">"name"</span><span class="token punctuation">:</span> <span class="token string">"Jiankychen"</span><span class="token punctuation">,</span> <span class="token string">"age"</span><span class="token punctuation">:</span> <span class="token number">24</span><span class="token punctuation">}</span> <span class="token comment"># value 的数据类型可能是 str ，也可能是 int</span></pre></td></tr><tr><td data-num="6"></td><td><pre></pre></td></tr><tr><td data-num="7"></td><td><pre><span class="token keyword">def</span> <span class="token function">func</span><span class="token punctuation">(</span>data<span class="token punctuation">:</span> Union<span class="token punctuation">[</span><span class="token builtin">int</span><span class="token punctuation">,</span> <span class="token builtin">str</span><span class="token punctuation">]</span><span class="token punctuation">)</span> <span class="token operator">-</span><span class="token operator">></span> Union<span class="token punctuation">[</span><span class="token builtin">int</span><span class="token punctuation">,</span> <span class="token builtin">str</span><span class="token punctuation">]</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="8"></td><td><pre> <span class="token keyword">return</span> data</pre></td></tr></tbody></table></figure><p>参考资料：</p>
<ul>
<li><a target="_blank" rel="noopener" href="https://www.bilibili.com/video/BV1qW4y1a7fU?p=122">黑马程序员 Python 教程：类型注解</a></li>
</ul>
<h1 id="多态"><a class="anchor" href="#多态">#</a> 多态</h1>
<p>多态：多种状态，即：对于某个行为（函数），使用不同的对象将会得到不同的状态</p>
<p>例如： <code>Cat</code> 类和 <code>Dog</code> 类都有 <code>speak</code> 成员方法， <code>Cat</code> 类对象和 <code>Dog</code> 类对象都能被传入 <code>command</code> 函数；但是由于两个类定义的 <code>speak</code> 方法的功能不一致，传入不同类的对象就会得到不同的状态</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Cat</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token keyword">def</span> <span class="token function">speak</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="3"></td><td><pre> <span class="token keyword">print</span> <span class="token string">"meow!"</span></pre></td></tr><tr><td data-num="4"></td><td><pre></pre></td></tr><tr><td data-num="5"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Dog</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="6"></td><td><pre> <span class="token keyword">def</span> <span class="token function">speak</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="7"></td><td><pre> <span class="token keyword">print</span> <span class="token string">"woof!"</span></pre></td></tr><tr><td data-num="8"></td><td><pre></pre></td></tr><tr><td data-num="9"></td><td><pre><span class="token keyword">def</span> <span class="token function">command</span><span class="token punctuation">(</span>pet<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="10"></td><td><pre> pet<span class="token punctuation">.</span>speak<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="11"></td><td><pre></pre></td></tr><tr><td data-num="12"></td><td><pre>cat <span class="token operator">=</span> Cat<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="13"></td><td><pre>command<span class="token punctuation">(</span>cat<span class="token punctuation">)</span> <span class="token comment"># 输出：meow!</span></pre></td></tr><tr><td data-num="14"></td><td><pre></pre></td></tr><tr><td data-num="15"></td><td><pre>dog <span class="token operator">=</span> Dog<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="16"></td><td><pre>command<span class="token punctuation">(</span>dog<span class="token punctuation">)</span> <span class="token comment"># 输出：woof!</span></pre></td></tr></tbody></table></figure><p>多态常作用在继承关系上，比如：定义函数（方法），通过类型注解声明需要父类对象，实际传入子类对象进行工作，从而获得不同的工作状态</p>
<p>例如，可以将上例中的代码修改为：</p>
<figure class="highlight python"><figcaption data-lang="python"></figcaption><table><tbody><tr><td data-num="1"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Pet</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="2"></td><td><pre> <span class="token keyword">def</span> <span class="token function">speak</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span></pre></td></tr><tr><td data-num="3"></td><td><pre> <span class="token keyword">pass</span></pre></td></tr><tr><td data-num="4"></td><td><pre></pre></td></tr><tr><td data-num="5"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Cat</span><span class="token punctuation">(</span>Pet<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="6"></td><td><pre> <span class="token keyword">def</span> <span class="token function">speak</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="7"></td><td><pre> <span class="token keyword">print</span> <span class="token string">"meow!"</span></pre></td></tr><tr><td data-num="8"></td><td><pre></pre></td></tr><tr><td data-num="9"></td><td><pre><span class="token keyword">class</span> <span class="token class-name">Dog</span><span class="token punctuation">(</span>Pet<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="10"></td><td><pre> <span class="token keyword">def</span> <span class="token function">speak</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span></pre></td></tr><tr><td data-num="11"></td><td><pre> <span class="token keyword">print</span> <span class="token string">"woof!"</span></pre></td></tr><tr><td data-num="12"></td><td><pre></pre></td></tr><tr><td data-num="13"></td><td><pre><span class="token keyword">def</span> <span class="token function">command</span><span class="token punctuation">(</span>pet<span class="token punctuation">:</span> Pet<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment"># 函数形参的类型注解</span></pre></td></tr><tr><td data-num="14"></td><td><pre> pet<span class="token punctuation">.</span>speak<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="15"></td><td><pre></pre></td></tr><tr><td data-num="16"></td><td><pre>cat <span class="token operator">=</span> Cat<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="17"></td><td><pre>command<span class="token punctuation">(</span>cat<span class="token punctuation">)</span> <span class="token comment"># 输出：meow!</span></pre></td></tr><tr><td data-num="18"></td><td><pre></pre></td></tr><tr><td data-num="19"></td><td><pre>dog <span class="token operator">=</span> Dog<span class="token punctuation">(</span><span class="token punctuation">)</span></pre></td></tr><tr><td data-num="20"></td><td><pre>command<span class="token punctuation">(</span>dog<span class="token punctuation">)</span> <span class="token comment"># 输出：woof!</span></pre></td></tr></tbody></table></figure><h2 id="抽象类接口"><a class="anchor" href="#抽象类接口">#</a> 抽象类（接口）</h2>
<p>抽象方法：没有具体实现的方法（即：方法体是 <code>pass</code> 语句）</p>
<p>抽象类：包含抽象方法的类，也可以称之为 接口，比如上例中的 <code>Pet</code> 类</p>
<p>抽象类相当于定义一个标准，包含了一些抽象的方法，要求子类必须实现</p>
<p>这种设计的意义在于：</p>
<ul>
<li>父类用来确定有哪些方法</li>
<li>具体的方法实现，由子类自行决定</li>
</ul>
<p>参考资料：</p>
<ul>
<li><a target="_blank" rel="noopener" href="https://www.bilibili.com/video/BV1qW4y1a7fU?p=123">黑马程序员 Python 教程：多态</a></li>
</ul>
</div><footer><div class="meta"><span class="item"><span class="icon"><i class="ic i-calendar-check"></i></span><span class="text">更新于</span><time title="修改时间：2024-06-08 23:09:21" itemprop="dateModified" datetime="2024-06-08T23:09:21+08:00">2024-06-08</time></span></div><div id="copyright"><ul><li class="author"><strong>本文作者：</strong>Jiankychen<i class="ic i-at"><em>@</em></i>Jiankychen's Blog</li><li class="link"><strong>本文链接：</strong><a href="https://jiankychen.github.io/python-oop.html" title="Python 面向对象">https://jiankychen.github.io/python-oop.html</a></li><li class="license"><strong>版权声明：</strong>本站所有文章除特别声明外，均采用 <a target="_blank" rel="noopener" href="https://creativecommons.org/licenses/by-nc-sa/4.0/deed.zh"><i class="ic i-creative-commons"><em>(CC)</em></i>BY-NC-SA</a> 许可协议。转载请注明出处！</li></ul></div></footer></article></div><div class="post-nav"><div class="item left"><a href="/python-pandas.html" rel="prev" itemprop="url" data-background-image="https://img.timelessq.com/images/2022/07/26/e5221f7d85b0900837a45fb933fa34ec.jpg" title="pandas 基础"><span class="type">上一篇</span><span class="category"><i class="ic i-flag"></i>Python</span><h3>pandas 基础</h3></a></div><div class="item right"><a href="/sql-basics.html" rel="next" itemprop="url" data-background-image="https://i.imgtg.com/2023/03/09/YS2LU.jpg" title="SQL 基础"><span class="type">下一篇</span><span class="category"><i class="ic i-flag"></i>SQL</span><h3>SQL 基础</h3></a></div></div><div class="wrap" id="comments"></div></div><div id="sidebar"><div class="inner"><div class="panels"><div class="inner"><div class="contents panel pjax" data-title="文章目录"><ol class="toc"><li class="toc-item toc-level-1"><a class="toc-link" href="#%E7%B1%BB%E5%92%8C%E5%AF%B9%E8%B1%A1"><span class="toc-number">1.</span> <span class="toc-text"> 类和对象</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#%E7%B1%BB%E5%AE%9A%E4%B9%89"><span class="toc-number">1.1.</span> <span class="toc-text"> 类定义</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E7%B1%BB%E5%AF%B9%E8%B1%A1"><span class="toc-number">1.2.</span> <span class="toc-text"> 类对象</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E7%B1%BB%E7%9A%84%E6%88%90%E5%91%98%E6%96%B9%E6%B3%95"><span class="toc-number">1.3.</span> <span class="toc-text"> 类的成员方法</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E6%9E%84%E9%80%A0%E6%96%B9%E6%B3%95"><span class="toc-number">1.4.</span> <span class="toc-text"> 构造方法</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E9%AD%94%E6%9C%AF%E6%96%B9%E6%B3%95"><span class="toc-number">1.5.</span> <span class="toc-text"> 魔术方法</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#pass-%E8%AF%AD%E5%8F%A5"><span class="toc-number">1.6.</span> <span class="toc-text"> pass 语句</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#%E5%B0%81%E8%A3%85"><span class="toc-number">2.</span> <span class="toc-text"> 封装</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#%E7%A7%81%E6%9C%89%E6%88%90%E5%91%98"><span class="toc-number">2.1.</span> <span class="toc-text"> 私有成员</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#property"><span class="toc-number">2.2.</span> <span class="toc-text"> property</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#%E7%BB%A7%E6%89%BF"><span class="toc-number">3.</span> <span class="toc-text"> 继承</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%8D%95%E7%BB%A7%E6%89%BF"><span class="toc-number">3.1.</span> <span class="toc-text"> 单继承</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%A4%9A%E7%BB%A7%E6%89%BF"><span class="toc-number">3.2.</span> <span class="toc-text"> 多继承</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E6%96%B9%E6%B3%95%E9%87%8D%E5%86%99"><span class="toc-number">3.3.</span> <span class="toc-text"> 方法重写</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E8%B0%83%E7%94%A8%E7%88%B6%E7%B1%BB%E5%90%8C%E5%90%8D%E6%88%90%E5%91%98"><span class="toc-number">3.4.</span> <span class="toc-text"> 调用父类同名成员</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#%E7%B1%BB%E5%9E%8B%E6%B3%A8%E8%A7%A3"><span class="toc-number">4.</span> <span class="toc-text"> 类型注解</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%8F%98%E9%87%8F%E7%9A%84%E7%B1%BB%E5%9E%8B%E6%B3%A8%E8%A7%A3"><span class="toc-number">4.1.</span> <span class="toc-text"> 变量的类型注解</span></a><ol class="toc-child"><li class="toc-item toc-level-3"><a class="toc-link" href="#%E6%96%B9%E5%BC%8F%E4%B8%80%E5%B8%B8%E7%94%A8"><span class="toc-number">4.1.1.</span> <span class="toc-text"> 方式一（常用）</span></a></li><li class="toc-item toc-level-3"><a class="toc-link" href="#%E6%96%B9%E5%BC%8F%E4%BA%8C"><span class="toc-number">4.1.2.</span> <span class="toc-text"> 方式二</span></a></li></ol></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%87%BD%E6%95%B0%E6%96%B9%E6%B3%95%E7%9A%84%E7%B1%BB%E5%9E%8B%E6%B3%A8%E8%A7%A3"><span class="toc-number">4.2.</span> <span class="toc-text"> 函数（方法）的类型注解</span></a><ol class="toc-child"><li class="toc-item toc-level-3"><a class="toc-link" href="#%E5%BD%A2%E5%8F%82%E6%B3%A8%E8%A7%A3"><span class="toc-number">4.2.1.</span> <span class="toc-text"> 形参注解</span></a></li><li class="toc-item toc-level-3"><a class="toc-link" href="#%E8%BF%94%E5%9B%9E%E5%80%BC%E6%B3%A8%E8%A7%A3"><span class="toc-number">4.2.2.</span> <span class="toc-text"> 返回值注解</span></a></li></ol></li><li class="toc-item toc-level-2"><a class="toc-link" href="#union-%E7%B1%BB%E5%9E%8B"><span class="toc-number">4.3.</span> <span class="toc-text"> Union 类型</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#%E5%A4%9A%E6%80%81"><span class="toc-number">5.</span> <span class="toc-text"> 多态</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#%E6%8A%BD%E8%B1%A1%E7%B1%BB%E6%8E%A5%E5%8F%A3"><span class="toc-number">5.1.</span> <span class="toc-text"> 抽象类（接口）</span></a></li></ol></li></ol></div><div class="related panel pjax" data-title="系列文章"><ul><li><a href="/python-basics.html" rel="bookmark" title="Python 基本语法">Python 基本语法</a></li><li><a href="/python-container.html" rel="bookmark" title="Python 数据容器">Python 数据容器</a></li><li><a href="/python-files.html" rel="bookmark" title="Python 文件操作">Python 文件操作</a></li><li><a href="/python-modules.html" rel="bookmark" title="Python 异常、模块、包">Python 异常、模块、包</a></li><li><a href="/python-conda.html" rel="bookmark" title="conda 常用命令">conda 常用命令</a></li><li><a href="/python-pandas.html" rel="bookmark" title="pandas 基础">pandas 基础</a></li><li class="active"><a href="/python-oop.html" rel="bookmark" title="Python 面向对象">Python 面向对象</a></li></ul></div><div class="overview panel" data-title="站点概览"><div class="author" itemprop="author" itemscope="itemscope" itemtype="http://schema.org/Person"><img class="image" loading="lazy" decoding="async" itemprop="image" alt="Jiankychen" src="/assets/avatar.webp"><p class="name" itemprop="name">Jiankychen</p><div class="description" itemprop="description"></div></div><nav class="state"><div class="item posts"><a href="/archives/"><span class="count">51</span><span class="name">文章</span></a></div><div class="item categories"><a href="/categories/"><span class="count">8</span><span class="name">分类</span></a></div><div class="item tags"><a href="/tags/"><span class="count">20</span><span class="name">标签</span></a></div></nav><div class="social"><a target="_blank" rel="noopener" href="https://github.com/jiankychen" class="item github" title="https://github.com/jiankychen"><i class="ic i-github"></i></a><a href="mailto:[email protected]" class="item email" title="mailto:[email protected]"><i class="ic i-envelope"></i></a><a target="_blank" rel="noopener" href="https://music.163.com/#/user/home?id=447771275" class="item music" title="https://music.163.com/#/user/home?id=447771275"><i class="ic i-cloud-music"></i></a><a target="_blank" rel="noopener" href="https://www.zhihu.com/people/jiankychen" class="item zhihu" title="https://www.zhihu.com/people/jiankychen"><i class="ic i-zhihu"></i></a></div><div class="menu"><li class="item"><a href="/" rel="section"><i class="ic i-home"></i>首页</a></li><li class="item dropdown"><a href="#" onclick="return false;"><i class="ic i-feather"></i>文章</a><ul class="submenu"><li class="item"><a href="/archives/" rel="section"><i class="ic i-list-alt"></i>归档</a></li><li class="item"><a href="/categories/" rel="section"><i class="ic i-th"></i>分类</a></li><li class="item"><a href="/tags/" rel="section"><i class="ic i-tags"></i>标签</a></li></ul></li><li class="item dropdown"><a href="#" onclick="return false;"><i class="ic i-feather"></i>链接</a><ul class="submenu"><li class="item"><a href="/peers/" rel="section"><i class="ic i-magic"></i>链环</a></li><li class="item"><a href="/friends/" rel="section"><i class="ic i-heart"></i>友链</a></li></ul></li><li class="item dropdown"><a href="#" onclick="return false;"><i class="ic i-stars"></i>关于</a><ul class="submenu"><li class="item"><a href="/owner/" rel="section"><i class="ic i-user"></i>关于博主</a></li><li class="item"><a href="/site/" rel="section"><i class="ic i-paw"></i>关于本站</a></li><li class="item"><a href="/update/" rel="section"><i class="ic i-cloud"></i>更新日志</a></li></ul></li></div></div></div></div><ul id="quick"><li class="prev pjax"><a href="/sql-basics.html" rel="prev" title="上一篇"><i class="ic i-chevron-left"></i></a></li><li class="up"><i class="ic i-arrow-up"></i></li><li class="down"><i class="ic i-arrow-down"></i></li><li class="next pjax"><a href="/python-pandas.html" rel="next" title="下一篇"><i class="ic i-chevron-right"></i></a></li><li class="percent"></li></ul></div></div><div class="dimmer"></div></div></main><footer id="footer"><div class="inner"><div class="widgets"><div class="rpost pjax"><h2>随机文章</h2><ul><li class="item"><div class="breadcrumb"><a href="/categories/Data-Structure/" title="分类于Data Structure">Data Structure</a></div><span><a href="/Dijkstra.html">Dijkstra</a></span></li><li class="item"><div class="breadcrumb"><a href="/categories/Data-Structure/" title="分类于Data Structure">Data Structure</a></div><span><a href="/algorithm-complexity.html">算法复杂度</a></span></li><li class="item"><div class="breadcrumb"><a href="/categories/C/" title="分类于C++">C++</a></div><span><a href="/cpp-variables.html">C++ 变量和基本类型</a></span></li><li class="item"><div class="breadcrumb"><a href="/categories/Data-Structure/" title="分类于Data Structure">Data Structure</a></div><span><a href="/date-structure.html">数据结构简介</a></span></li><li class="item"><div class="breadcrumb"><a href="/categories/Data-Structure/" title="分类于Data Structure">Data Structure</a></div><span><a href="/KMP.html">KMP 算法</a></span></li><li class="item"><div class="breadcrumb"><a href="/categories/Python/" title="分类于Python">Python</a></div><span><a href="/python-modules.html">Python 异常、模块、包</a></span></li><li class="item"><div class="breadcrumb"><a href="/categories/Python/" title="分类于Python">Python</a></div><span><a href="/python-container.html">Python 数据容器</a></span></li><li class="item"><div class="breadcrumb"><a href="/categories/C/" title="分类于C++">C++</a></div><span><a href="/cpp-vectors.html">C++ 字符串、向量和数组</a></span></li><li class="item"><div class="breadcrumb"><a href="/categories/Coding/" title="分类于Coding">Coding</a></div><span><a href="/leetcode-greedy.html">LeetCode - 贪心专题</a></span></li><li class="item"><div class="breadcrumb"><a href="/categories/Coding/" title="分类于Coding">Coding</a></div><span><a href="/leetcode-dynamicprogramming.html">LeetCode - 动态规划专题</a></span></li></ul></div><div class="rpost pjax"><h2>最新评论</h2><ul class="leancloud-recent-comment" id="new-comment"></ul></div></div><div class="status"><div class="copyright">© 2021 -<span itemprop="copyrightYear">2024</span><span class="with-love"><i class="ic i-sakura rotate"></i></span><span class="author" itemprop="copyrightHolder">Jiankychen @ Jiankychen</span></div><div class="count"><span class="post-meta-item-icon"><i class="ic i-chart-area"></i></span><span title="站点总字数">955k 字</span><span class="post-meta-divider"> | </span><span class="post-meta-item-icon"><i class="ic i-coffee"></i></span><span title="站点阅读时长">14:28</span></div><div class="powered-by">基于 <a target="_blank" rel="noopener" href="https://hexo.io/">Hexo</a> & Theme.<a target="_blank" rel="noopener" href="https://github.com/theme-shoka-x/hexo-theme-shokaX/">ShokaX</a></div></div><script src="https://unpkg.com/[email protected]/bsz.pure.mini.js"></script><div id="busuanzi-wrap"><span class="ic i-eye"></span><span id="busuanzi_container_site_pv">本站总访问量 <span id="busuanzi_value_site_pv"></span> 次</span> | <span class="ic i-user"></span><span id="busuanzi_container_site_uv">本站总访客量 <span id="busuanzi_value_site_uv"></span> 次</span></div></div></footer></div><script data-config="" type="text/javascript">var LOCAL = {
ispost: true,
path: `/python-oop`,
favicon: {
show: `Jiankychen`,
hide: `Jiankychen`
},
search: {
placeholder: "文章搜索",
empty: "关于 「 ${query} 」，什么也没搜到",
stats: "${time} ms 内找到 ${hits} 条结果"
},
copy_tex: false,
katex: false,
mermaid: false,
audio: undefined,
fancybox: true,
nocopy: false,
outime: true,
template: `<div class="note warning"><p><span class="label warning">文章时效性提示</span><br>这是一篇发布于 {{publish}} 天前，最后一次更新在 {{updated}} 天前的文章，部分信息可能已经发生改变，请注意甄别。</p></div>`,
quiz: {
choice: `单选题`,
multiple: `多选题`,
true_false: `判断题`,
essay: `问答题`,
gap_fill: `填空题`,
mistake: `错题备注`
},
ignores: [
(uri) => uri.includes('#'),
(uri) => new RegExp(LOCAL.path + '$').test(uri),
[]
]
};
</script><script src="https://lf9-cdn-tos.bytecdntp.com/cdn/expire-6-M/pace/1.2.4/pace.min.js" async=""></script><script src="https://polyfill.io/v3/polyfill.min.js?features=default,fetch" defer=""></script><script src="/js/siteInit.js?v=0.4.2" type="module" fetchpriority="high" defer=""></script></body></html>