3.7 public vs private attributes

Based on accessibility, attributes can be categorized into 3 categories: * Public * Protected * Private

** Naming ** | ** Type ** | ** Description ** |

— | — | — |

name | public | The attribute is available both inside and outside class |

|_name | protected | should not be should outside class definition | |__name | private | inaccessible and invisible outside class definition |

class Insan():

    def __init__(self):
        self.__ghar = "I am private"
        self._gari = "I am protected"
        self.name = "I am public"


x = Insan()

print(x.name)

I am public

print(x._gari)

I am protected

# uncomment following line
# x.__ghar  # AttributeError

Although the Insan class do have an attribute anmed __priv, however the error is saying Insan object has no attribute __priv. What better privacy can there be? We can also set the values of public attributes.

x.name = 'hasan'

print(x.name)

hasan

As said earlier private attribute is not accessible outside the class but we can use them inside class definition as follows:

class Insan():

    def __init__(self):
        self.__ghar = "I am private"
        self._gari = "I am protected"
        self.name = "I am public"

    def get_ghar(self):
        return self.__ghar


ali = Insan()
ali.get_ghar()

'I am private'

name mangling

Every attribute with double underscore will be changed to object._class__attribte

print(ali._Insan__ghar)

I am private

Ways of accessing and setting attribute values

class Insan:

    def __init__(self, name=None, dob=2000):
        self.__name = name
        self.__dob = dob

    def say_salam(self):
        if self.__name:
            print("Salam, I am " + self.__name)
        else:
            print("Salam, I am a person without a name")

    def set_name(self, name):
        self.__name = name

    def get_name(self):
        return self.__name

    def set_dob(self, by):
        self.__dob = by

    def get_dob(self):
        return self.__dob

    def __repr__(self):
        return "Insan('" + self.__name + "', " + str(self.__dob) + ")"

    def __str__(self):
        return "Name: " + self.__name + ", born in Year: " + str(self.__dob)


x = Insan("Mutahri", 1920)
y = Insan("Sadr", 1935)

for fard in [x, y]:
    fard.say_salam()
    if fard.get_name() == "Sadr":
        fard.set_dob(1353)
    print("I was born in the year " + str(fard.get_dob()) + "!")

Salam, I am Mutahri
I was born in the year 1920!
Salam, I am Sadr
I was born in the year 1353!