Mastering Python Design Patterns - Second Edition

Summary

In this chapter, we covered the State design pattern. The State pattern is an implementation of one or more finite-state machines (in short, state machines) used to solve a particular software-engineering problem.

A state machine is an abstract machine with two main components: states and transitions. A state is the current status of a system. A state machine can have only one active state at any point in time. A transition is a switch from the current state to a new state. It is normal to execute one or more actions before or after a transition occurs. State machines can be represented visually using state diagrams.

State machines are used to solve many computational and non-computational problems. Some of them are traffic lights, ...