How to use switch in Python?

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Let's use switch in Python.

To implement a switch structure in Python

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

switch = {
    'add': lambda x, y: x + y,
    'sub': lambda x, y: x - y,
    'mul': lambda x, y: x * y,
    'div': lambda x, y: x / y,
}

if __name__ == '__main__':
    print(switch['add'](1, 8))
    print(switch['sub'](1, 8))
    print(switch['mul'](1, 8))
    print(switch['div'](1, 8))

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0.125

Modern alternative: Python 3.10+ match/case

This article was written before Python 3.10 (released Oct 2021). If you are on
Python 3.10 or newer, use the native match statement instead of a dict of lambdas.

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#!/usr/bin/env python

def calculate(operator: str, x: float, y: float) -> float:
    match operator:
        case 'add':
            return x + y
        case 'sub':
            return x - y
        case 'mul':
            return x * y
        case 'div':
            return x / y
        case _:  # default
            raise ValueError(f"unknown operator: {operator}")

if __name__ == '__main__':
    print(calculate('add', 1, 8))
    print(calculate('sub', 1, 8))
    print(calculate('mul', 1, 8))
    print(calculate('div', 1, 8))

Same output as above. The dict-of-lambdas trick still works, but match is the idiomatic
Python 3.10+ way, and it can also match on data structures and guards, not just strings.