Modification of third party code

During the Entwicklerkonferenz (5.-6.11.2015), we agreed to not modify third-party code. This includes the WordPress Core, third-party themes as well as plugins.

Instead, we write our own plugins and themes to adapt third-party functionality to our needs. Using Hooks and the filters in WordPress, this should work in all cases.

Rationale: When updating WordPress/Themes/Plugins, any files that are updated will be overwritten with the new content which would undo all of our changes.

However currently some changes to the core and plugins are necessary. See Updating Wordpress and Plugins.