组合与设计灵活性

1class Engine:
2    def __init__(self, horsepower):
3        self.horsepower = horsepower
4
5    def describe(self):
6        return f"{self.horsepower} HP Engine"
7
8class Vehicle:
9    def __init__(self):
10        # The Vehicle "has" an Engine.
11        # It takes responsibility for creating it.
12        self.engine = Engine(200)
13
14    def get_specs(self):
15        # Accessing the component to get data
16        engine_info = self.engine.describe()
17        print(f"Vehicle Specs: {engine_info}")
18
19# Usage
20my_car = Vehicle()
21my_car.get_specs()

1class Engine:
2    def start_up(self):
3        print("Engine: Fuel injection active. Pistons firing.")
4
5class Dashboard:
6    def boot_system(self):
7        print("Dashboard: GPS loaded. Radio ready.")
8
9class Vehicle:
10    def __init__(self):
11        self.engine = Engine()
12        self.dashboard = Dashboard()
13
14    def start(self):
15        print("Vehicle: Driver pressed start button.")
16        # Delegation: The vehicle coordinates, but components do the work
17        self.engine.start_up()
18        self.dashboard.boot_system()
19        print("Vehicle: Ready to drive.")
20
21# Usage
22suv = Vehicle()
23suv.start()

1class V8Engine:
2    def run(self):
3        print("V8 Engine: Roaring with gas power!")
4
5class ElectricMotor:
6    def run(self):
7        print("Electric Motor: Humming silently with battery power.")
8
9class Vehicle:
10    def __init__(self, engine):
11        # Dependency Injection: We assign the engine passed in from outside.
12        # The Vehicle doesn't care what type it is, as long as it fits.
13        self.engine = engine
14
15    def drive(self):
16        print("Vehicle: Engaging movement...")
17        self.engine.run() # Polymorphic delegation
18
19# Usage
20# 1. We build the components (dependencies) first
21gas_engine = V8Engine()
22battery_motor = ElectricMotor()
23
24# 2. We inject them into the Vehicle
25sports_car = Vehicle(gas_engine)
26ev_truck = Vehicle(battery_motor)
27
28print("--- Sports Car ---")
29sports_car.drive()
30
31print("\n--- EV Truck ---")
32ev_truck.drive()