Trace is a project that started, like these things tend to, as an innocent, experimental Drupal module I hacked together to implement all of the core hooks exported by Drupal.

I was at the time working on Boost and wanted to gain a deeper understanding of the conditions and exact sequence in which the Drupal module hooks were invoked, so I took the API listing and wrote out the skeleton for each hook, sprinkling logging statements to capture and output the arguments passed to the hooks by Drupal.