use-set-for-membership / R6201

Message emitted:

Consider using set for membership test

Description:

Membership tests are more efficient when performed on a lookup optimized datatype like ``sets``.

Problematic code:

def fruit_is_dangerous_for_cat(fruit: str) -> bool:
    """This list is only a silly example, don't make decision regarding your cat diet based on it."""
    return fruit in ["cherry", "grapes"]  # [use-set-for-membership]

Correct code:

def fruit_is_dangerous_for_cat(fruit: str) -> bool:
    """This list is only a silly example, don't make decision regarding your cat diet based on it."""
    return fruit in {"cherry", "grapes"}

Configuration file:

[MAIN]
load-plugins=pylint.extensions.set_membership

Note

This message is emitted by the optional 'set_membership'

checker which requires the pylint.extensions.set_membership plugin to be loaded.

Created by the set_membership checker.