A customer reported an issue with Orpheus, made by the now defunct “TurboPower”, and while investigating his issue, I've updated the references in Orpheus 4.06 so that it can now compile, and install into the component palette in Delphi 2005.
The updated Orpheus for Delphi 2005 can be downloaded from here.
In 2017, with the release of Delphi 10.2 Tokyo, Embarcadero introduced a specialized implementation of the Observer pattern into the System.Classes unit. While it has been in the wild for 9 years, it remains a "hidden" architecture for many, primarily because it serves as the invisible engine behind LiveBindings. Other than live bindings, you can also use the Observer pattern as a way to update component settings to the Windows registry, an .ini file, or persist it elsewhere.
System.Classes