Tubefeeder Extractor

This is a part of Tubefeeder Extractor.

This contains the definitions of the classic observer and observable pattern.

lib.rs:

The traits Observable and Observer construct the typical observer-pattern.

The messages parsed in between Observable and Observer is the generic variable T. Because keeping track of all Observers when implementing Observable can be hard, this module also contains a ObserverList where Observers can be attached, detached and notified.