April 2023
Intermediate to advanced
769 pages
25h 16m
Chinese
Content preview from 流畅的Python（第2版）
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123
第 5 章
数据类构建器
数据类就像小孩子。作为一个起点很好，但若要让它们像成熟的对象那样参与整
个系统的工作，它们就必须承担一定责任。
——
Martin Fowler
和
Kent Beck
1
Python
提供了几种构建简单类的方式，这些类只是字段的容器，几乎没有额外功能。这种
模式称为“数据类”（
data
class
），
dataclasses
包就支持该模式。本章介绍以下
3
个可简
化数据类构建过程的类构建器。
collections.namedtuple
最简单的构建方式，从
Python 2.6
开始提供。
typing.NamedTuple
另一种构建方式，需要为字段添加类型提示，从
Python 3.5
开始提供。
class
句法在
Python 3.6
中增加。
@dataclasses.dataclass
一个类装饰器，与前两种方式相比，可定制的内容更多，增加了大量选项，可实现更复
杂的功能，从
Python 3.7
开始提供。
介绍这些类构建器之后，接下来将讨论为什么
数据类
模式也是一种代码异味，它的出现可
能意味着面向对象设计欠佳。
注
1
：
《重构：改善既有代码的设计》（后面简称《重构》），第
3
章，
3.20
节。
124
｜
第
5
章
typing.TypedDict
与
typing.NamedTuple
句法相似，而且在
Python ...
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