Implementing State Machines With the State Pattern
Explore how to implement state machines in C by applying the State pattern. Understand how function pointers enable dynamic state behavior, how to structure states and context, and techniques to avoid dependency cycles while maintaining clear, debuggable code.
State Pattern
According to Design Patterns "the State pattern models state-specific behavior, whereas the table-driven approach focuses on defining state transitions". When applying the State pattern to our example, the structure in Illustration 1 emerges.
This diagram looks like an object-oriented solution. However, we will not emulate inheritance in C. Before developing a concrete implementation, let’s explain the involved participants.
- DigitalStopWatch:
Design Patterns defines DigitalStopWatch as the context. The context has a reference to one of our concrete states, without knowing exactly which one. It is the context that specifies