什么是数据类？它们与普通类有何不同？

Question

WithPEP 557数据类被引入到python标准库中。

它们使用@dataclassdecorator，它们应该是“带默认值的可变namedtuples”，但我不确定这到底意味着什么，以及它们与普通类的区别。

python数据类到底是什么？什么时候最好使用它们？

Answer 1

从PEP specification：

A class decorator is provided which inspects a class definition for variables with type annotations as defined in PEP 526, "Syntax for Variable Annotations". In this document, such variables are called fields. Using these fields, the decorator adds generated method definitions to the class to support instance initialization, a repr, comparison methods, and optionally other methods as described in the Specification section. Such a class is called a Data Class, but there's really nothing special about the class: the decorator adds generated methods to the class and returns the same class it was given.

@dataclass生成器将方法添加到类中，否则您会将这些方法定义为__repr__、__init__、__lt__和__gt__。