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sys-version-slice3 (YTT101)

Added in v0.0.113 · Related issues · View source

Derived from the flake8-2020 linter.

What it does

Checks for uses of sys.version[:3].

Why is this bad?

If the current major or minor version consists of multiple digits, sys.version[:3] will truncate the version number (e.g., "3.10" would become "3.1"). This is likely unintended, and can lead to subtle bugs if the version string is used to test against a specific Python version.

Instead, use sys.version_info to access the current major and minor version numbers as a tuple, which can be compared to other tuples without issue.

Example

import sys

sys.version[:3]  # Evaluates to "3.1" on Python 3.10.

Use instead:

import sys

sys.version_info[:2]  # Evaluates to (3, 10) on Python 3.10.

References