Question

Python question about creating classes, methods and objects.

1. Class instance variables can be referenced using two different ways: either using the accessor methods or direct referencing by using the instance variable reference (for example to get the day of the date you can use self.d or self.getDay()). Which one abides more towards the principle of information hiding?

Answer 1

self.d abides more towards information hiding.

Consider the following example code:

class Test:

def __init__(self, a, b):

self.__a = a
self.b = b
  

def getaval(self):

return self.__a
  

def getbval(self):

return self.b

t = Test(1234, 5678)
print(t.getbval())
print(t.getaval())

print(t.b)
print(t.a)

Output

5678                                                               

1234                                                               

5678                                                               

Traceback (most recent call last):                                 

  File "main.py", line 17, in <module>                             

    print(t.a)                                                     

AttributeError: 'Test' object has no attribute 'a'

The class instances can be accessed using accessor methods as well as instance variable reference as by default they are public.

But when hidden value a is used using double underscores as prefix, it can be accessed using method but not direct reference.

Hence, infomation hiding is more when using direct references.