Python 3.10可选参数：键入联合vs none默认值

发布于 2025-01-24 15:33:38 字数 965 浏览 0 评论 0原文

这不是一个大问题，但是作为样式，我想知道指示可选函数参数的最佳方法

... /code>：

def my_func(a, b = None)

在Python 3.10之前，使用类型提示：

def my_func(a, b: Optional[str])

使用Python 3.10的可爱管道型符号（请参阅“ noreferrer”> PEP 604 ）：

def my_func(a, b: str | None)

后者似乎是三个选项的明显选择，但是我想知道这是否完全消除了指定 default none value，这将是：

def my_func(a, b: str | None = None)

编辑：感谢@deceze和@jonrsharpe指出def my_func（a，b：b：b：str | none）仍然需要您将值传递给b ：如果您愿意，您将明确必须通过无。

因此，最简洁的方法是确保b是可选的（即，呼叫者确实必须完全传递一个值）是：

def my_func(a, b: str = None)

造型上，合并显式键入，是def my_func（a，b：str | none = none），即显式可选键入 plus plus default none none 值

原文

It's not a huge issue, but as a matter of style, I was wondering about the best way to indicate optional function parameters...

Before type hints, it was like this for parameter b:

def my_func(a, b = None)

Before Python 3.10, using type hints:

def my_func(a, b: Optional[str])

With Python 3.10's lovely pipe-type notation (see PEP 604):

def my_func(a, b: str | None)

The latter seems the obvious choice of the three options, but I was wondering if this completely eliminates the need to specify the default None value, which would be:

def my_func(a, b: str | None = None)

EDIT: Thanks to @deceze and @jonrsharpe for pointing out that def my_func(a, b: str | None) would still require you to pass a value to b: you would explicitly have to pass None if you wanted that.

So, the most concise one that will work to ensure that b is optional (i.e. the caller does not have to pass a value at all) is:

def my_func(a, b: str = None)

Stylistically, incorporating explicit typing, is def my_func(a, b: str | None = None), i.e. explicit optional typing plus default None value, ever an option?

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