April 2023
Intermediate to advanced
769 pages
25h 16m
Chinese
Content preview from 流畅的Python（第2版）
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279
第 11章
符合
Python
风格的对象
一个库或框架是否符合
Python
风格，要看它能不能让
Python
程序员以一种简单
而自然的方式执行任务。
——
Martijn Faassen
Python
和
JavaScript
框架开发者
1
得益于
Python
数据模型，自定义类型的行为可以像内置类型那样自然。实现如此自然的行
为，靠的不是继承，而是
鸭子类型
：只需按照预定行为实现对象所需的方法即可。
前几章分析了很多内置对象的行为。本章会自己定义类，让类的行为跟真正的
Python
对象
一样。你在开发应用程序时，不一定要像本章的示例那样实现那么多特殊方法。然而，对
库或框架来说，程序员可能希望你定义的类能像
Python
内置的类一样
。满足这个预期也算
得上是符合“
Python
风格”
。
本章接续第
1
章，说明如何实现很多
Python
类型中常见的特殊方法。
本章包含以下话题：
•
把对象转换成其他类型的内置函数（例如
repr()
、
bytes()
、
complex()
等 ）；
•
通过一个类方法实现备选构造函数；
•
扩展
f
字符串、内置函数
format()
和
str.format()
方法使用的格式化微语言；
•
实现只读属性；
•
把对象变为可哈希的，以便在集合中及作为
dict
的键使用；
•
利用
__slots__
节省内存。
本章将开发一个简单的二维欧几里得向量类型
Vector2d
，在这个过程中涵盖上述全部话
注
1
：
摘自
Faassen
的题为“
What is Pythonic?
”的博客文章。
280
｜
第
11
章
题。
Vector2d
将为第
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.