lazy_loading_property.py

class lazy_loading_property:
    attr_name: str
    method_name: str

    def __init__(self, method_name):
        self.method_name = method_name

    def __set_name__(self, owner, name):
        if not hasattr(owner, self.method_name):
            raise TypeError(f'method {self.method_name} does not exists')
        elif not callable(getattr(owner, self.method_name)):
            raise TypeError(f'{self.method_name} is not callable')
        self.attr_name = name
    
    def load_data(self, instance):
        if not getattr(instance, f'_{self.method_name}_called', False):
            getattr(instance, self.method_name)()
            setattr(instance, f'_{self.method_name}_called', True)

    def __get__(self, instance=None, owner=None):
        if instance is None:
            return self
        self.load_data(instance)
        return instance.__dict__[self.attr_name]

    def __set__(self, instance=None, value=None):
        if instance is None:
            raise AttributeError('Cannot modify class only instances')
        instance.__dict__[self.attr_name] = value


class Person:
    name = lazy_loading_property('load_db_a')
    address = lazy_loading_property('load_db_b')

    def __init__(self, cpf):
        self.cpf = cpf

    def load_db_a(self):
        print('load_db_a was called')
        self.name = 'Meu nome'

    def load_db_b(self):
        print('load_db_b was called')
        self.address = 'This is my addres'