Kasampalis -- Mastering Python Design Patterns -- 2015

from pyparsing import Word, OneOrMore, Optional, Group, Suppress, alphanums class Gate: def __init__(self): self.is_open = False def __str__(self): return 'open' if self.is_open else 'closed' def open(self): print('opening the gate') self.is_open = True def close(self): print('closing the gate') self.is_open = False class Garage: def __init__(self): self.is_open = False def __str__(self): return 'open' if self.is_open else 'closed' def open(self): print('opening the garage') self.is_open = True def close(self): print('closing the garage') self.is_open = False class Aircondition: def __init__(self): self.is_on = False def __str__(self): return 'on' if self.is_on else 'off' def turn_on(self): print('turning on the aircondition') self.is_on = True def turn_off(self): print('turning off the aircondition') self.is_on = False class Heating: def __init__(self): self.is_on = False def __str__(self): return 'on' if self.is_on else 'off' def turn_on(self): print('turning on the heating') self.is_on = True def turn_off(self): print('turning off the heating') self.is_on = False class Boiler: def __init__(self): self.temperature = 180 # in fahrenheit def __str__(self): return 'boiler temperature: {}'.format(self.temperature) def increase_temperature(self, amount): print("increasing the boiler's temperature by {} degrees".format(amount)) self.temperature += amount def decrease_temperature(self, amount): print("decreasing the boiler's temperature by {} degrees".format(amount)) self.temperature -= amount class Fridge: def __init__(self): self.temperature = 35 # in fahrenheit def __str__(self): return 'fridge temperature: {}'.format(self.temperature) def increase_temperature(self, amount): print("increasing the fridge's temperature by {} degrees".format(amount)) self.temperature += amount def decrease_temperature(self, amount): print("decreasing the fridge's temperature by {} degrees".format(amount)) self.temperature -= amount def main(): word = Word(alphanums) command = Group(OneOrMore(word)) token = Suppress("->") device = Group(OneOrMore(word)) argument = Group(OneOrMore(word)) event = command + token + device + Optional(token + argument) gate = Gate() garage = Garage() airco = Aircondition() heating = Heating() boiler = Boiler() fridge = Fridge() tests = ('open -> gate', 'close -> garage', 'turn on -> aircondition', 'turn off -> heating', 'increase -> boiler temperature -> 20 degrees', 'decrease -> fridge temperature -> 6 degree') open_actions = {'gate':gate.open, 'garage':garage.open, 'aircondition':airco.turn_on, 'heating':heating.turn_on, 'boiler temperature':boiler.increase_temperature, 'fridge temperature':fridge.increase_temperature} close_actions = {'gate':gate.close, 'garage':garage.close, 'aircondition':airco.turn_off, 'heating':heating.turn_off, 'boiler temperature':boiler.decrease_temperature, 'fridge temperature':fridge.decrease_temperature} for t in tests: if len(event.parseString(t)) == 2: # no argument cmd, dev = event.parseString(t) cmd_str, dev_str = ' '.join(cmd), ' '.join(dev) if 'open' in cmd_str or 'turn on' in cmd_str: open_actions[dev_str]() elif 'close' in cmd_str or 'turn off' in cmd_str: close_actions[dev_str]() elif len(event.parseString(t)) == 3: # argument cmd, dev, arg = event.parseString(t) cmd_str, dev_str, arg_str = ' '.join(cmd), ' '.join(dev), ' '.join(arg) num_arg = 0 try: num_arg = int(arg_str.split()[0]) # extract the numeric part except ValueError as err: print("expected number but got: '{}'".format(arg_str[0])) if 'increase' in cmd_str and num_arg > 0: open_actions[dev_str](num_arg) elif 'decrease' in cmd_str and num_arg > 0: close_actions[dev_str](num_arg) if __name__ == '__main__': main()