This is to get a general idea of what handrolling could look like:
- Statechart Pattern
- states
- triggers
- transitions
# database.py
from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
Base = declarative_base()
class TrafficLight(Base):
__tablename__ = 'traffic_lights'
id = Column(Integer, primary_key=True)
state = Column(String)
# Setup the database connection and session
engine = create_engine('sqlite:///traffic_lights.db')
Base.metadata.create_all(engine)
Session = sessionmaker(bind=engine)# state_machine.py
from database import TrafficLight, Session
from enum import Enum
class TrafficLightStates(Enum):
GREEN = 'Green'
YELLOW = 'Yellow'
RED = 'Red'
class TrafficLightMachine:
def __init__(self, traffic_light_id):
self.session = Session()
self.traffic_light = self.session.query(TrafficLight).get(traffic_light_id)
if not self.traffic_light:
raise ValueError("Traffic Light not found")
def change_state(self, new_state):
print(f"Changing from {self.traffic_light.state} to {new_state}")
self.traffic_light.state = new_state
self.session.commit()
def to_yellow(self):
self.change_state(TrafficLightStates.YELLOW.value)
def to_red(self):
self.change_state(TrafficLightStates.RED.value)
def to_green(self):
self.change_state(TrafficLightStates.GREEN.value)
# Example usage
# traffic_light_machine = TrafficLightMachine(traffic_light_id=1)
# traffic_light_machine.to_yellow()
# traffic_light_machine.to_red()
# traffic_light_machine.to_green()