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4.2 Modules and Packages

Python modules and packages help structure larger codebases for reuse and maintainability.

Modules​

A module is a .py file containing definitions and statements.

import mymodule
from mymodule import helper

Script entry point pattern​

if __name__ == "__main__":
    main()

When run directly, __name__ is "__main__"; when imported, module-level entry logic does not execute.

Import search path​

sys.path determines where imports are resolved from, including script directory and environment locations.

Packages​

A regular package is a directory containing __init__.py that organizes related modules. Python also supports namespace packages (an advanced case) that may not include __init__.py.

Example import patterns:

from package import submodule
from package.submodule import function

Use explicit imports in production code; avoid wildcard imports (from x import *) except for limited interactive exploration.

Official references​