Download the file : pbs-delphi-interface-delegation-demo

A single-file Delphi console program showing how the implements keyword lets a host class delegate an interface to a property. The host claims IWorker without writing its methods; the work is done by whichever implementation the Worker property holds.

The demo obtains IWorker from the host, runs it, then swaps in a second implementation at runtime to show the caller does not change. It also shows how the delegate is reference counted while the host, held in a class-typed variable, is freed explicitly.