Can static variables be declared as private in python?

Question

class Applicant:
    applicant_id_count=1000
    application_dict={
                        "A":0,
                        "B":0,
                        "C":0
                     }
    def __init__(self,applicant_name):
        self.__applicant_name=applicant_name
        self.__applicant_id=None
        self.__job_band=None

I need to make the static variables in the above class i.e. application_dict and applicant_id_count as private static variables. Or is there any such thing in python?

Answer 1

Python does not have access modifiers. If you want to access an instance (or class) variable from outside the instance or class, you are always allowed to do so.

That said there's a convention using underscores(_) that most developers follow to indicate that a variable/method is private. A single underscore is a convention of saying that it's a private variable but it actually doesn't change the access privilege. Example:

class Applicant:
    _applicant_id_count = 1000

Applicant._applicant_id_count # equals to 1000

If you want to emulate private variables for some reason, you can always use the __ prefix. Python mangles the names of variables so that they're not easily visible. Example:

class Applicant:
    __applicant_id_count=1000

You will get the following error when someone tries to directly access it:

Applicant.__applicant_id_count
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: class Applicant has no attribute '__applicant_id_count'

Someone can hack their way and use the variable like this:

Applicant._Applicant__applicant_id_count # prints out 1000

You can read more about it here: https://www.geeksforgeeks.org/private-variables-python/

Answer 2

In Python, you can always access all variables. But, there is a convention for naming of this classes and attributes. You can use the __ prefix (two underscores) from PEP 8. Python mangles the names of variables like __foo so that they're not easily visible to code outside the class that contains them. Also, if you want a protected variable scope, you can use _ prefix (one underscore).