Usage of built-in class `property`

property_example.py

"""
    class_property.py
    =================

    Shows how to use python's built-in class 'property' for implementation of
    encapsulation by pythonic way.

    Use 'python3 -i class_property' for testing Man class interfaces.
    Instance of this class will be already initialized as 'man' variable.

    ***Pay special attention to birth_date and birth_year properties***
"""

import datetime


class Man:
    """Sample class in which @property uses for encapsulation.
    """

    def __init__(self, first_name, last_name, age):
        self.first_name = first_name
        self.last_name = last_name
        self.age = age
        self._birthdate = None
        self.anonymous = False

    def __repr__(self):
        return f'Man: {self.full_name}'

    @property
    def _current_datetime(self):
        return datetime.datetime.now()

    @property
    def full_name(self):
        if not self.anonymous:
            return ' '.join((self.first_name, self.last_name))
        return 'Anonymous'

    @full_name.setter
    def full_name(self, val):
        try:
            self.first_name, self.last_name = val.split(' ')
        except: 
            print('You must set the first name and the last name.')

    @full_name.deleter
    def full_name(self):
        self.first_name = 'Anonymous'
        self.last_name = 'Anonymous'
        self.anonymous = True

    @property
    def birth_year(self):
        now = self._current_datetime
        return now.replace(year=now.year-self.age).year

    @property
    def birthdate(self):
        if self._birthdate:
            return self._birthdate
        raise AttributeError('birthdate not setted yet.')
    
    @birthdate.setter
    def birthdate(self, val):
        if isinstance(val, datetime.datetime):
            self.age = (self._current_datetime - val).days // 365
            self._birthdate = val


man = Man(first_name='Ben', last_name='Dowson', age=18)