| paul@792 | 1 | class SignalState: |
| paul@792 | 2 | Red = 1 |
| paul@792 | 3 | Amber = 2 |
| paul@792 | 4 | Green = 3 |
| paul@792 | 5 | AmberAgain = 4 |
| paul@792 | 6 | Off = None |
| paul@792 | 7 | |
| paul@792 | 8 | class Signal: |
| paul@792 | 9 | def __init__(self): |
| paul@792 | 10 | self.disable() |
| paul@792 | 11 | |
| paul@792 | 12 | def enable(self): |
| paul@792 | 13 | self.state = SignalState.Red |
| paul@792 | 14 | |
| paul@792 | 15 | def disable(self): |
| paul@792 | 16 | self.state = SignalState.Off |
| paul@792 | 17 | |
| paul@792 | 18 | def next(self): |
| paul@792 | 19 | if self.state == SignalState.Red: |
| paul@792 | 20 | self.state = SignalState.Amber |
| paul@792 | 21 | elif self.state == SignalState.Amber: |
| paul@792 | 22 | self.state = SignalState.Green |
| paul@792 | 23 | elif self.state == SignalState.Green: |
| paul@792 | 24 | self.state = SignalState.AmberAgain |
| paul@792 | 25 | elif self.state == SignalState.AmberAgain: |
| paul@792 | 26 | self.state = SignalState.Red |
| paul@792 | 27 | else: |
| paul@792 | 28 | self.state = SignalState.Off |
| paul@792 | 29 | |
| paul@792 | 30 | s = Signal() |
| paul@792 | 31 | print s.state # None |
| paul@792 | 32 | s.next() |
| paul@792 | 33 | print s.state # None |
| paul@792 | 34 | s.enable() |
| paul@792 | 35 | print s.state # 1 |
| paul@792 | 36 | s.next() |
| paul@792 | 37 | print s.state # 2 |
| paul@792 | 38 | s.next() |
| paul@792 | 39 | print s.state # 3 |
| paul@792 | 40 | s.next() |
| paul@792 | 41 | print s.state # 4 |
| paul@792 | 42 | s.next() |
| paul@792 | 43 | print s.state # 1 |
