In his latest post Matthias Noback talks about a problem common to Symfony bundles (and, well, software in general) - dealing with backwards compatibility and breaks that could be introduced with new changes.

With a new bundle release you may want to rename services or parameters, make a service private, change some constructor arguments, change the structure of the bundle configuration, etc. Some of these changes may acually be backwards incompatible changes for the users of that bundle. Luckily, the Symfony DependenyInjection component and Config component both provide you with some options to prevent such backwards compatibility (BC) breaks.

He breaks the post up into a few different kinds of backwards compatibility breaks that could happen and code examples of each:

• Renaming things
• Changing visibility
• Changing values

Each topic also includes methods for preventing issues with older users who maybe aren't using the new features. This includes things like sane default values for new settings, renaming services and creating new extensions for working with new properties.