Access Modifiers
Through object-oriented programming, Python gives us the ability to control Access Modifiers which allow us to restrict the access of selected variables and functions within a class or an object. There are 3 Access Modifiers that we can use and they are common for most programming languages, they are:
- Public
- Protected
- Private
Access Modifiers play a key role in security by allowing us to secure data from unauthorized access. In Python, we use an underscore ‘_’ to modify access specifiers.
Public
Any or all variables and functions that are Public can be accessed from any part of the program. By default, all variables and functions of a class are Public, all the classes we wrote in the previous blogs have Public Access Modifiers.
class Subject:
# constructor
def __init__(self, subject_name, subject_teacher):
# public variables
self.subject_name = subject_name
self.subject_teacher = subject_teacher
# public function
def display_details(self):
print(self.subject_name, "teaches", self.subject_teacher)
object_1 = Subject("Physics", "Rose")
print(object_1.subject_name) # Prints Physics
print(object_1.subject_teacher) # Prints Rose
object_1.display_details() # Prints 'Rose teaches Physics'
Protected
When we declare a variable or a function to be protected, it can only be accessed by an object of its class or an object of its sub-class. To make a variable or a function Protected all we have to do is add an underscore before it.
class Subject:
# constructor
def __init__(self, subject_name, subject_teacher):
# protected variables
self._subject_name = subject_name
self._subject_teacher = subject_teacher
# protected function
def _display_details(self):
print(self._subject_name, "teaches", self._subject_teacher)
object_1 = Subject("Physics", "Rose")
print(object_1._subject_name) # Prints Physics
print(object_1._subject_teacher) # Prints Rose
object_1._display_details() # Prints 'Rose teaches Physics'
Private
When we declare a variable or a function as Private it can only be accessed within the class. If an object tries to access a Private variable or function it will raise an error. To declare a variable or function as Private we need to add two underscores.
class Subject:
# constructor
def __init__(self, subject_name, subject_teacher):
# private variables
self.__subject_name = subject_name
self.__subject_teacher = subject_teacher
# private function
def __display_details(self):
print(self.__subject_name, "teaches", self.__subject_teacher)
# public function
def call_private_function(self):
self.__display_details()
object_1 = Subject("Physics", "Rose")
print(object_1.__subject_name) # Prints an error
print(object_1.__subject_teacher) # Prints an error
object_1.__display_details() # Prints an error
object_1.call_private_function() # Prints 'Rose teaches Physics'
Only the last line of code will run without an error, as we are calling a Public function within a class that class a Private function. In other words, we can access the function “call_private_function” as it is Public and in the same class as the Private function called “display_details”.
What have we learned?
- What are Access Modifiers?
- What are the three Access Modifiers in Python?
- Which is the default Access Modifier in Python?
- What do we use to modify access specifiers?
- What advantage do we have using Access Modifiers?
