Method hooking is a powerful tool you can use to extend, enhance, or alter any library or framework that doesn't have the necessary features you require.
HookPHP is licensed under the LGPL version 3. This allows HookPHP to be used in both open source and proprietary software. No matter what you're building, you can use HookPHP without worry.
HookPHP's API is so simple, you can learn it in the time it takes to guzzle one cup of coffee. Check out the readme to learn how to start.