abstract_class.py

from abc import ABC, abstractmethod


class Employee(ABC):
    """Abstract definition of an employee.

    The `Employee` class is abstract because it inherits the `ABC` class
    and has at least one `abstractmethod`. That means we cannot create
    an instance directly from its constructor. Also, all subclasses
    need to implement every `abstractmethod` in this class.

    For more about abstract classes, click the link below:

    https://www.python.org/dev/peps/pep-3119/
    """

    def __init__(self, name, title):
        self.name = name
        self.title = title

    def __str__(self):
        return self.name

    @abstractmethod
    def do_work(self):
        """Do something for work."""
        raise NotImplementedError

    @abstractmethod
    def do_relax(self):
        """Do something to relax."""
        raise NotImplementedError


class Engineer(Employee):
    """Concrete definition of an engineer.

    The Engineer class is concrete because it implements every
    `abstractmethod` that was not implemented above.

    Notice that we leverage the parent's constructor when creating
    this object. We also define `do_refactor` for an engineer, which
    is something that a manager prefers not to do.
    """

    def __init__(self, name, title, skill):
        super().__init__(name, title)
        self.skill = skill

    def do_work(self):
        return f"{self} is coding in {self.skill}"

    def do_relax(self):
        return f"{self} is watching YouTube"

    def do_refactor(self):
        """Do the hard work of refactoring code, unlike managers."""
        return f"{self} is refactoring code"


class Manager(Employee):
    """Concrete definition of a manager.

    The Manager class is concrete for the same reasons as the Engineer
    class is concrete. Notice that a manager has direct reports and
    has the responsibility of hiring people on the team, unlike an
    engineer.
    """

    def __init__(self, name, title, direct_reports):
        super().__init__(name, title)
        self.direct_reports = direct_reports

    def do_work(self):
        return f"{self} is meeting up with {len(self.direct_reports)} reports"

    def do_relax(self):
        return f"{self} is taking a trip to the Bahamas"

    def do_hire(self):
        """Do the hard work of hiring employees, unlike engineers."""
        return f"{self} is hiring employees"


def main():
    # Declare two engineers
    engineer_john = Engineer("John Doe", "Software Engineer", "Android")
    engineer_jane = Engineer("Jane Doe", "Software Engineer", "iOS")
    engineers = [engineer_john, engineer_jane]

    # These engineers are employees but not managers
    assert all(isinstance(engineer, Employee) for engineer in engineers)
    assert all(not isinstance(engineer, Manager) for engineer in engineers)

    # Engineers can work, relax and refactor
    assert engineer_john.do_work() == "John Doe is coding in Android"
    assert engineer_john.do_relax() == "John Doe is watching YouTube"
    assert engineer_john.do_refactor() == "John Doe is refactoring code"

    # Declare manager with engineers as direct reports
    manager_max = Manager("Max Doe", "Engineering Manager", engineers)

    # Managers are employees but not engineers
    assert isinstance(manager_max, Employee)
    assert not isinstance(manager_max, Engineer)

    # Managers can work, relax and hire
    assert manager_max.do_work() == "Max Doe is meeting up with 2 reports"
    assert manager_max.do_relax() == "Max Doe is taking a trip to the Bahamas"
    assert manager_max.do_hire() == "Max Doe is hiring employees"


if __name__ == "__main__":
    main()