Encapsulation In an object oriented python program, you can restrict access to methods and variables. This can prevent the data from being modified by accident and is known as encapsulation. Let's start with an example.
class Mobile:
def __init__(self):
self.__update_software()
def switch_on(self):
print 'driving'
def __update_software(self):
print 'updating software'
smobile = Mobile()
smobile.switch_on()
#smobile.__updateSoftware() not accesible from object.
print('-'*100)Explanation The private method __update_software() can only be called within the class itself. It can never be called from outside the class.
Private variables Variables can be private which can be useful on many occasions. Objects can hold crucial data for your application and you do not want that data to be changeable from anywhere in the code. An example:
class Mobile:
__os = 'andriod'
__name = ""
def __init__(self):
self.__os = 'andriod'
self.__name = "Supercar"
def switch_on(self):
print 'Mobile Os is ' + str(self.__os)
smobile = Mobile()
smobile.switch_on()
smobile.__os = 'ios' > will not change variable because its private
smobile.switch_on()
print('-'*100)If you want to change the value of a private variable, a setter method is used. This is simply a method that sets the value of a private variable.
class Mobile:
__os = 'andriod'
__name = ""
def __init__(self):
self.__os = 'andriod'
self.__name = "Supercar"
def switch_on(self):
print 'Mobile Os is ' + str(self.__os)
def set_os(self, os):
self.__os = os
smobile = Mobile()
smobile.switch_on()
smobile.set_os('ios')
smobile.switch_on()
print('-'*100)Summary To summarize, in Python there are:
| Type | Description |
|---|---|
| public methods | accessible from anywhere |
| private methods | accessible only in their own class. starts with two underscores |
| public variables | accessible from anywhere |
| private variables | accesible only in their own class or by a method if defined. starts with two underscores |