> What is wrong with implementing the states with polymorphic classes providing the API or an interface to it? Yeah that's pretty much the basic approach to th

> What is wrong with implementing the states with polymorphic classes providing the API or an interface to it? Yeah that's pretty much the basic approach to this problem: use a strategy pattern in all states of the state machine, and just provide definitions for each method in the state that the method makes sense. That's pretty much how HTTP-based protocols are implemented when status codes drive a state machine. I wonder why the author decided to ignore the most basic and simple solutions to a frequent problem in favour of a convoluted solution that doesn't add anything and is harder to debug.