在类中使用私有变量创建列表

Question

I am creating a class called Pet . I am making my variables private so no one can modify them (ensuring encapsulation). I want to create a list using private variables. Then I want to be able to call my pet_list list outside the class where I will be using it for a later purpose (would I need to create a getter for my list inside the Pet class to do this?).

I am new to python but I'm trying to code using the object orientated principles.

This is my code so far. I'm thinking because my pet variable is private I need to use a setter to set the Pet s in the list? But I get this error when I want to print set_pet() missing 1 required positional argument: 'pet' .

class Pet:
      def __init__(self, pet ):
          self.pet = pet

      def set_pet(self, pet):
         self.__pet = pet

      def get_pet(self):
         return self.__pet


#creating list

pet_list = []

p = Pet

pet_list.append(p.set_pet("cat"))
pet_list.append( Pet("dogs"))
pet_list.append( Pet("fish"))
pet_list.append( Pet("horses"))
pet_list.append( Pet("birds"))

for obj in pet_list:
    print(obj.pet)

Answer 1

The problem is at p = Pet . Here you are not initializing an instance of the class Pet but you are instead setting p equal to the class. Instead use

p = Pet("The pet you want")

The reason you are getting the errror set_pet() missing 1 required positional argument: 'pet' is because "cat" is being passed as a positional argument in the place of self and thus it is as if you passed only 1 argument.

Also, pet_list.append(p.set_pet("cat")) would append None into the list since you are only setting the property and not returning anything, all the other's should work fine as expected.