Talks - Pat Viafore: Extensible Python: Robustness Through Addition

Make code open to extension but closed for modification - add new functionality without changing existing code

Separate policies (business logic) from mechanisms (implementation details) to make systems more flexible and maintainable

Use event-driven architectures and message brokers to decouple producers from consumers

Leverage data-driven designs by putting policies in declarative formats (YAML, TOML) rather than code

Build pluggable architectures using entry points and plugin systems like stevedore

Design libraries to be extensible from the start with clear documentation, tests, and composable interfaces

Keep dependencies manageable by being mindful of high fan-in/fan-out modules and visualizing dependency graphs

Make common operations easy - if simple tasks require many file changes, rethink the design

Use dependency injection to make code more flexible and testable

Consider the humans - both current and future developers need to understand and maintain the code

Break large changes into smaller, focused commits that are easier to review

Build composable building blocks that can be combined in different ways rather than monolithic implementations

Leverage Python’s ecosystem of plugin systems (pytest, poetry, hypothesis) to extend functionality

Store configuration and policies in data formats rather than hardcoding them in source