flyweight.py

import random 
from enum import Enum 
 
CarType = Enum('CarType', 'subcompact compact suv') 
 
class Car: 
    pool = dict() 
 
    def __new__(cls, car_type): 
        obj = cls.pool.get(car_type, None) 
        if not obj: 
            obj = object.__new__(cls) 
            cls.pool[car_type] = obj 
            obj.car_type = car_type 
        return obj 
 
    def render(self, color, x, y):
        type = self.car_type
        msg = f'render a car of type {type} and color {color} at ({x}, {y})'
        print(msg)
 
def main(): 
    rnd = random.Random() 
    #age_min, age_max = 1, 30    # in years 
    colors = 'white black silver gray red blue brown beige yellow green'.split()
    min_point, max_point = 0, 100 
    car_counter = 0 
 
    for _ in range(10): 
        c1 = Car(CarType.subcompact) 
        c1.render(random.choice(colors), 
                  rnd.randint(min_point, max_point), 
                  rnd.randint(min_point, max_point)) 
        car_counter += 1 
 
    for _ in range(3): 
        c2 = Car(CarType.compact) 
        c2.render(random.choice(colors), 
                  rnd.randint(min_point, max_point), 
                  rnd.randint(min_point, max_point)) 
        car_counter += 1 
 
    for _ in range(5): 
        c3 = Car(CarType.suv) 
        c3.render(random.choice(colors), 
                  rnd.randint(min_point, max_point), 
                  rnd.randint(min_point, max_point)) 
        car_counter += 1 
 
    print(f'cars rendered: {car_counter}') 
    print(f'cars actually created: {len(Car.pool)}') 
 
    c4 = Car(CarType.subcompact) 
    c5 = Car(CarType.subcompact) 
    c6 = Car(CarType.suv) 
    print(f'{id(c4)} == {id(c5)}? {id(c4) == id(c5)}') 
    print(f'{id(c5)} == {id(c6)}? {id(c5) == id(c6)}') 

    
if __name__ == '__main__': 
    main()