Python
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1# Define the Subject class
2class Subject:
3    def __init__(self):
4        self.__observers = []
5
6    def register_observer(self, observer):
7        self.__observers.append(observer)
8
9    def unregister_observer(self, observer):
10        self.__observers.remove(observer)
11
12    def notify_observers(self):
13        for observer in self.__observers:
14            observer.update(self)
15
16# Define the SecuritySystem class
17class SecuritySystem(Subject):
18    def __init__(self):
19        super().__init__()
20        self.__state = None
21
22    def set_state(self, state):
23        self.__state = state
24        self.notify_observers()
25        
26    def get_state(self):
27        return self.__state
28
29# Define the Observer interface
30class Observer:
31    def update(self, subject):
32        pass
33
34# Implement the SecurityApp observer
35class SecurityApp(Observer):
36    def update(self, subject):
37        if isinstance(subject, SecuritySystem):
38            print(f"SecurityApp notified. New state: {subject.get_state()}")
39
40# Implement the SecurityLight observer
41class SecurityLight(Observer):
42    def update(self, subject):
43        if isinstance(subject, SecuritySystem):
44            print(f"SecurityLight activated! State: {subject.get_state()}")
45
46# Example usage
47security_system = SecuritySystem()
48app = SecurityApp()
49light = SecurityLight()
50security_system.register_observer(app)
51security_system.register_observer(light)
52security_system.set_state("Intrusion Detected")
53
54# Expected Output:
55# SecurityApp notified. New state: Intrusion Detected
56# SecurityLight activated! State: Intrusion Detected

Python
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1# Define the TemperatureControlStrategy interface
2class TemperatureControlStrategy:
3    def control_temperature(self, temperature):
4        pass
5
6# Implement the HeatingStrategy
7class HeatingStrategy(TemperatureControlStrategy):
8    def control_temperature(self, temperature):
9        print(f"Heating to {temperature} degrees.")
10
11# Implement the CoolingStrategy
12class CoolingStrategy(TemperatureControlStrategy):
13    def control_temperature(self, temperature):
14        print(f"Cooling to {temperature} degrees.")
15
16# Define the ClimateControl context
17class ClimateControl:
18    def __init__(self, strategy: TemperatureControlStrategy):
19        self.__strategy = strategy
20
21    def set_strategy(self, strategy: TemperatureControlStrategy):
22        self.__strategy = strategy
23    
24    def control_temperature(self, temperature):
25        self.__strategy.control_temperature(temperature)
26
27# Example usage
28climate_control = ClimateControl(HeatingStrategy())
29climate_control.control_temperature(22) # Expected Output: Heating to 22 degrees.
30
31climate_control.set_strategy(CoolingStrategy())
32climate_control.control_temperature(18) # Expected Output: Cooling to 18 degrees.