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undefined-name (F821)

Derived from the Pyflakes linter.

What it does

Checks for uses of undefined names.

Why is this bad?

An undefined name is likely to raise NameError at runtime.

Example

def double():
    return n * 2  # raises `NameError` if `n` is undefined when `double` is called

Use instead:

def double(n):
    return n * 2

Options

  • target-version: Can be used to configure which symbols Ruff will understand as being available in the builtins namespace.

References