lazy-import-immediately-resolved (TID255)

Preview (since 0.15.13) · Related issues · View source

Derived from the flake8-tidy-imports linter.

Fix is sometimes available.

This rule is unstable and in preview. The --preview flag is required for use.

What it does

Checks for lazy imports that are resolved immediately at module load time.

Why is this bad?

Python 3.15 adds support for lazy import and lazy from ... import ..., which defer the actual import work until the imported name is first used.

When a lazily imported name is used immediately at module load time, the import is resolved eagerly, defeating the purpose of marking the import as lazy. This is commonly caused by using a lazily imported module in a module global or in a top-level class definition.

Example

lazy import foo


class Bar(foo.Foo): ...

Use instead:

import foo


class Bar(foo.Foo): ...

Fix safety

This rule's fix is marked as unsafe because converting a lazy import to an eager import changes when the imported module is executed, which can change runtime behavior if the module has import-time side effects.

The fix is only available when the lazy import statement imports a single member, since removing lazy from a multi-member import would make every imported member eager, including names that may not be resolved immediately.