I am trying to release one technique that I use a lot in my projects as an open source library. A way to quicly generate state machines in Arduino projects.
You create a class for your state machine, and this class inherits from a StateMachine superclass. Then you wrap your state functions around State objects that are called inside the main loop, and each state informs the next state at the end. It is hard to explain but easy to show up.
#include "StateMachine.h"
class Blink : public StateMachine{
private:
int port;
int waitTime;
CREATE_STATE(Blink, low);
CREATE_STATE(Blink, high);
void low() {
digitalWrite(port, LOW);
*this << &STATE(high) + waitTime;
}
void high() {
digitalWrite(port, HIGH);
*this << &STATE(low) + waitTime;
}
public:
Blink(int port, int waitTime) :
StateMachine(&STATE(low)),
port(port),
waitTime(waitTime),
INIT_STATE(Blink, low),
INIT_STATE(Blink, high)
{
pinMode(port, OUTPUT);
}
};
Blink led1(13, 1000);
Blink led2(14, 2000);
Blink led3(15, 3000);
void setup() {}
void loop() {
led1();
led2();
led3();
}
The most complex parts are abstracted inside the macros CREATE_STATE(), STATE and INIT_STATE.
CREATE_STATE creates an wrapper for the state function. INIT_STATE runs the wrapper constructor. STATE references to the wrapper inside the code.
They looks like this:
#define CREATE_STATE(statemachine, state) State<statemachine> state_##state
#define INIT_STATE(statemachine, state) state_##state(this, &statemachine::state)
#define STATE(state) state_##state
The problem is that this solution is too verbose for my liking. I wish I could cut up some verbosity removing the class name from the wrapper declaration and initiation, getting the name from context. In order to do so, I would require a way to retrieve the current scope class name on compile time. Is there any way to do so?
