Python中switch语句的替换?

2022-01-19 00:00:00 python switch-statement

问题描述

我想用 Python 编写一个函数，它根据输入索引的值返回不同的固定值.

I want to write a function in Python that returns different fixed values based on the value of an input index.

在其他语言中，我会使用 switch 或 case 语句，但 Python 似乎没有 switch 语句.在这种情况下推荐的 Python 解决方案是什么?

In other languages I would use a switch or case statement, but Python does not appear to have a switch statement. What are the recommended Python solutions in this scenario?

解决方案

下面的原答案是2008年写的.从那时起，Python 3.10(2021)引入了match-case 语句提供了switch"的一流实现;对于 Python.例如:

The original answer below was written in 2008. Since then, Python 3.10 (2021) introduced the match-case statement which provides a first-class implementation of a "switch" for Python. For example:

def f(x):
    match x:
        case 'a':
            return 1
        case 'b':
            return 2
        case _:        
            return 0   # 0 is the default case if x is not found

match-case 语句比这个简单的例子要强大得多.

The match-case statement is considerably more powerful than this simple example.

你可以使用字典:

def f(x):
    return {
        'a': 1,
        'b': 2,
    }[x]

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