[agopaul]

What a coincidence, I've been working on a PHP state machine implementation myself in the last few days.

Anyway, I find the concept of "events" a bit weird in this case and I prefer to work with "states" only (state transitions rather than events that change the state). It seems like an unnecessary abstraction to think in terms of an event rather than a state.

[pwm]

Ultimately state is a function of time. Events are thus temporal effects from the outside world that can, depending on their values, cause a transition from a state to another state within the machine. If you model the machine as a graph where vertices are states and edges are events then a transition can be seen as a function from a (state, event) pair to a state, ie. (CurrState, Event) -> NewState. I've posted a simple explanation below, check it out if you like.