Should Imports Be at the Top of a Python Module or Within Functions?

Where Should Import Statements Be Placed in a Module?

PEP 8 dictates that import statements should reside at the module's commencement, following module comments and docstrings. However, some argue that importing rarely used functions within the function itself improves efficiency.

Why Place Imports at the Top?

Despite being a trivial cost, importing a module is not instantaneous. Placing imports at the top of the module ensures it's paid only once. Conversely, importing within functions prolongs function call execution time.

Arguments for Lazy Imports

While prioritizing efficiency warrants placing imports at the top, there are specific scenarios where lazy imports may be beneficial:

• Optional Library Support: Avoid breaking code dependencies on optional libraries by performing imports only when required.
• Plug-in Initialization: Limit importing dependencies in plugin __init__.py files, preventing unnecessary loading in unused plugins.

Conclusion

Efficiency concerns dictate placing imports at the module's start. Lazy imports should be considered only when profiling identifies specific performance benefits or when the aforementioned scenarios apply.

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