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redefined-while-unused (F811)

Added in v0.0.171 · Related issues · View source

Derived from the Pyflakes linter.

Fix is sometimes available.

What it does

Checks for variable definitions that redefine (or "shadow") unused variables.

Why is this bad?

Redefinitions of unused names are unnecessary and often indicative of a mistake.

Example

import foo
import bar
import foo  # Redefinition of unused `foo` from line 1

Use instead:

import foo
import bar

Preview

When preview is enabled, this rule also flags annotated variable redeclarations. For example, bar: int = 1 followed by bar: int = 2 will be flagged as a redefinition of an unused variable, whereas plain reassignments like bar = 1 followed by bar = 2 remain unflagged.

In preview, this rule will also flag redefinitions in typing.TYPE_CHECKING blocks:

import typing
from collections.abc import Sequence

if typing.TYPE_CHECKING:
    # Redefinition of unused `Sequence` from line 2
    from collections.abc import Sequence

Use instead:

from collections.abc import Sequence

Options

This rule ignores dummy variables, as determined by: