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undefined-export (F822)

Added in v0.0.25 · Related issues · View source

Derived from the Pyflakes linter.

What it does

Checks for undefined names in __all__.

Why is this bad?

In Python, the __all__ variable is used to define the names that are exported when a module is imported as a wildcard (e.g., from foo import *). The names in __all__ must be defined in the module, but are included as strings.

Including an undefined name in __all__ is likely to raise NameError at runtime, when the module is imported.

In preview, this rule will flag undefined names in __init__.py file, even if those names implicitly refer to other modules in the package. Users that rely on implicit exports should disable this rule in __init__.py files via lint.per-file-ignores.

Example

from foo import bar


__all__ = ["bar", "baz"]  # undefined name `baz` in `__all__`

Use instead:

from foo import bar, baz


__all__ = ["bar", "baz"]

References