Accessor & Mutator methods (Python)

问题

I am trying to figure out encapsulation in Python. I was doing a simple little test in shell to see how something worked and it doesn't work like I was expecting. And I can't get it to work. Here's my code:

class Car:
    def __init__(self, carMake, yrMod):
        self.__make = carMake
        self.__yearModel = yrMod
        self.__speed = 0

    #Mutator Methods
    def set_make(self, make):
        self.__make = carMake

    def set_model(self, yrMod):
        self.__yearModel = yrMod

    #def set_speed(self, speed):
        #self.__speed = speed

    #Accessor Methods
    def get_make(self):
        return self.__make

    def get_yearModel(self):
        return self.__yearModel

    def get_speed(self):
        return self.__speed

myCar=Car('Ford', 1968)
myCar2=Car('Nissan', 2012)
myCar.get_make()
'Ford'
myCar.set_make=('Porche')
myCar.get_make()
'Ford'

Why doesn't myCar.set_make change Ford into Porche? Thank you.

回答1:

With myCar.set_make=('Porche'), you are setting this member the Car class as the 'Porche' string, but you are not calling the method.

Just remove the = to solve it:

myCar.set_make('Porche')
myCar.get_make() # Porche

Besides, as @DSM points out, there is an error in the argument of set_make:

def set_make(self, make):
    self.__make = make # carMake is not defined!

However, this use of getters and setters in Python is strongly discouraged. If you need something similar for any reason, consider using properties.

回答2:

new_car = Car(...)
new_car2 = Car(...)

new_car._make = 'Ford'
new_car2.make = 'Jetta'

print new_car._make
print new_car2.make

来源：https://stackoverflow.com/questions/15867664/accessor-mutator-methods-python

标签

python

mutators