reimplemented-operator (FURB118)

Derived from the refurb linter.

Fix is sometimes available.

This rule is unstable and in preview. The --preview flag is required for use.

What it does

Checks for lambda expressions and function definitions that can be replaced with a function from the operator module.

Why is this bad?

The operator module provides functions that implement the same functionality as the corresponding operators. For example, operator.add is equivalent to lambda x, y: x + y. Using the functions from the operator module is more concise and communicates the intent of the code more clearly.

Example

import functools

nums = [1, 2, 3]
total = functools.reduce(lambda x, y: x + y, nums)

Use instead:

import functools
import operator

nums = [1, 2, 3]
total = functools.reduce(operator.add, nums)

Fix safety

This fix is usually safe, but if the lambda is called with keyword arguments, e.g., add = lambda x, y: x + y; add(x=1, y=2), replacing the lambda with an operator function, e.g., operator.add, will cause the call to raise a TypeError, as functions in operator do not allow keyword arguments.