How Do I Make Private Variables Inaccessable in Py

问题:

This question already has an answer here:

• Does Python have “private” variables in classes? 11 answers

class Car(object):
    def __init__(self, color, engine, oil):
        self.color = color
        self.__engine = engine
        self.__oil = oil

a = Car('black', 'a cool engine', 'some cool oil')

We assume that __engine and __oil variables are private which means I cannot access them through a call like a.__engine. However, I can use __dict__ variable to access and even change those variables.

# Accessing
a.__dict__
{'_Car__engine': 'a cool engine', 'color': 'black', '_Car__oil': 'some cool oil'}

# Changing
a.__dict__['_Car__engine'] = "yet another cool engine"
a.__dict__
{'_Car__engine': 'yet another cool engine', 'color': 'black', '_Car__oil': 'some cool oil'}

The problem is simple. I want private variables to be accessed and changed only inside the class.

回答1:

What you are trying to do is not possible in Python.

“Private” instance variables that cannot be accessed except from inside an object don’t exist in Python.

https://docs.python.org/2/tutorial/classes.html#private-variables-and-class-local-references

回答2:

The problem is simple. I want private variables to be accessed and changed only inside the class.

So, don't write code outside the class that accesses variables starting with __. Use pylint or the like to catch style mistakes like that.