from dataclasses import FrozenInstanceError, dataclass

@dataclass(init=False)

class CarWithoutInit:

manufacturer: str = None

@dataclass(repr=False)

class CarWithoutRepr:

manufacturer: str = None

@dataclass(eq=False)

class CarWithoutEq:

manufacturer: str = None

@dataclass(order=True)

class CarOrderable:

seats: int = None

doors: int = None

@dataclass(frozen=True)

class ImmutableCar:

seats: int = None

@dataclass()

class Car:

manufacturer: str = None

model: str = None

color: str = None

length: float = None

seats: int = None

is_suv: bool = None

def main():

new_car = Car(

manufacturer="Tesla",

model="Model X",

color="blue",

length=5.0,

seats=5,

is_suv=True,

)

print(new_car)

if new_car.is_suv:

print(f"{new_car.manufacturer} {new_car.model} is a SUV")

# should show a warning for a wrong type. is_suv should be a boolean

# and we use a string instead

another_car = Car(manufacturer="VW", is_suv="No")

print(another_car)

def with_init():

# a class without default init method

try:

CarWithoutInit(manufacturer="Tesla")

except TypeError:

print("CarWithoutInit could not be created")

new_car_without_init = CarWithoutInit()

new_car_without_init.manufacturer = "BMW"

print(new_car_without_init)

def with_repr():

# a class without default repr method

new_car_without_repr = CarWithoutRepr(manufacturer="Audi")

print(new_car_without_repr)

def equals():

# equality comparison

tesla_a = Car(manufacturer="Tesla")

tesla_b = Car(manufacturer="Tesla")

bmw = Car(manufacturer="BMW")

print("tesla_a == tesla_b :", tesla_a == tesla_b)

print("tesla_a is tesla_b :", tesla_a is tesla_b)

print("tesla_a is tesla_a :", tesla_a is tesla_a)

print("bmw == tesla :", bmw == tesla_a)

# equality comparison disabled

tesla_a = CarWithoutEq(manufacturer="Tesla")

tesla_b = CarWithoutEq(manufacturer="Tesla")

print("tesla_a == tesla_b :", tesla_a == tesla_b)

print("tesla_a is tesla_b :", tesla_a is tesla_b)

print("tesla_a is tesla_a :", tesla_a is tesla_a)

def order():

# order by seats

car_with_2_seats = CarOrderable(seats=2)

car_with_3_seats = CarOrderable(seats=3)

car_with_4_seats = CarOrderable(seats=4)

print("2 > 3 :", car_with_2_seats > car_with_3_seats)

print("4 > 3 :", car_with_4_seats > car_with_3_seats)

print("2 <= 4 :", car_with_2_seats <= car_with_4_seats)

# order by seats and doors

car_with_2_seats_and_3_doors = CarOrderable(seats=2, doors=3)

car_with_3_seats_and_2_doors = CarOrderable(seats=3, doors=2)

print(

"2,3 > 3,2 :",

car_with_2_seats_and_3_doors >= car_with_3_seats_and_2_doors,

)

print(

"2,3 < 3,2 :",

car_with_2_seats_and_3_doors <= car_with_3_seats_and_2_doors,

)

car_with_3_seats_and_3_doors = CarOrderable(seats=3, doors=3)

car_with_3_seats_and_2_doors = CarOrderable(seats=3, doors=2)

print(

"3,3 > 3,2 :",

car_with_3_seats_and_3_doors >= car_with_3_seats_and_2_doors,

)

print(

"3,3 < 3,2 :",

car_with_3_seats_and_3_doors <= car_with_3_seats_and_2_doors,

)

def frozen():

immutable_car = ImmutableCar(seats=5)

print(immutable_car)

immutable_car.seats = 6

if __name__ == "__main__":

main()

with_init()

with_repr()

equals()

order()

frozen()