When your Symfony application grows or when you maintain multiple applications that reuse code, you probably maintain some shared library and/or bundle. Even if you don’t, you are likely using bundles and libraries from the Symfony- and PHP-ecosystem. Chances are that you run into issues with dependencies, especially now with PHP 8.1 and Symfony 6. How can you avoid dependencies blocking your upgrade and what can you do as a maintainer to make sure you don’t block others? That is not an easy question, but package design principles are a good way to start.

In this talk we will discuss package design principles and how Symfony and other popular PHP packages implement or deviate from them and how it affects users and maintainers. We will look at how PHP open source projects have dealt with dependencies blocking them and have a look at some of the famous problems from JS and NPM and what lessons we can learn from them. Hopefully, at the end you will be well prepared for upgrading your own libraries, bundles and applications and know how to confidently handle dependency issues in the future.