BerriAI / litellm
github.com·3d ago
Developer Tools
Real Python·Sep 9·5 min read
Python 3.15 Preview: Lazy Imports
TL;DR
Python 3.15 introduces lazy imports, allowing modules to load only when first accessed, significantly improving startup times for command-line tools. This change keeps import statements at the top of files while deferring execution until necessary.
✦ Why It Matters
Implement lazy imports in your Python projects today to enhance startup performance without altering your code structure.
Key Takeaways
- Use lazy imports to improve application startup speed.
- Keep import statements at the top of your files.
- Only load modules when they are first accessed.
- Ensure error handling for ImportError remains intact.
Full Summary
Lazy imports in Python 3.15 enable developers to delay the loading of modules until they are actually needed, which can lead to faster startup times for applications. Traditionally, all imports are executed at the beginning of a script, which can slow down the initial loading process, especially for large applications.
With lazy imports, the module's name is bound immediately, but the actual loading occurs the first time the name is referenced in the code. This means that if certain code paths do not utilize specific modules, those imports can be deferred, resulting in a more efficient startup.
For instance, a command-line tool can start more than twice as fast without changing the location of import statements. However, it's important to note that lazy imports cannot bypass error handling for ImportError, ensuring that any issues with module loading are still caught.