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from datetime import date # Importing date in order to get the current date

# Classes and objects

# The "self" in Python classes: self represents the instance of the class. By using the “self” keyword we can access

# the attributes and methods of the class in python. It binds the attributes with the given arguments. The reason you

# need to use self is because Python does not use the @ syntax to refer to instance attributes. Python decided to do

# methods in a way that makes the instance to which the method belongs be passed automatically, but not received

# automatically: the first parameter of methods is the instance the method is called on

class Person:

# init method / constructor

def __init__(self, name, age):

# The "_" on _name shows that this is a private variable and doesn't change from the outside without going

# through one the methods

self._name = name

self._age = age

def get_name(self):

return self._name

# Self is a convention and not a real python keyword.

# self is parameter in function and you can actually use another parameter name

# in place of it. But it is advisable to use self because it increases the readability of the code.

def get_age(in_place_of_self):

return in_place_of_self._age

def set_name(self, name):

self._name = name

def set_age(self, age):

self._age = age

def __str__(self):

return "Person:\n Name: " + self._name + ", Age: " + str(self._age)

# a method-function to create a CV object by the Person's object details.

def create_cv(self):

return CV(self)

# a static method-function (notice there is no self as a parameter-argument)

@staticmethod

def calculate_age_difference(person1, person2):

if isinstance(person1, Person) and isinstance(person1, Person):

return abs(person1.get_age() - person2.get_age())

else:

return "The parameters given were not instances of Person"

# Different constructor - a class method to create a Person object by birth year.

@classmethod

def from_birth_year(cls, name, year):

return cls(name, date.today().year - year)

class CV:

# init method / constructor

def __init__(self, person):

if isinstance(person, Person):

self._details = str(person)

def __str__(self):

return "CV: " + self._details

# Creates an object of the class Person with my name and age

me = Person("Nick", 22)

print(me)

# Creates an object of the class Person with my name and age by calculating the difference of years since my birth year

me2 = Person.from_birth_year("Nick", 1998)

print(me2)

my_brother = Person("Leo", 16)

# In order to find the age difference of me and my brother

print(Person.calculate_age_difference(16, me)) # This should not work since 16 is not an instance of Person

print(Person.calculate_age_difference(my_brother, me)) # This should work and print 6'

# Creates an object of CV from the instance me

my_cv = me.create_cv()

print(my_cv)