property examples

property.py

class Ramone(object):
    def __init__(self, name, instrument):
        self.name = name
        self.instrument = instrument
    
    @property
    def countdown(self):
        if not hasattr(self, '_countdown'):
            self._countdown = 1
        return self._countdown

    @countdown.setter
    def countdown(self, new_countdown):
        if new_countdown not in (1, 2, 3, 4):
            raise ValueError("ONE TWO THREE FOUR!")
        self._countdown = new_countdown


# alternate definition, without using decorator syntax
class Ramone(object):
    def __init__(self, name, instrument):
        self.name = name
        self.instrument = instrument

    def countdown_getter(self):
        if not hasattr(self, '_countdown'):
            self._countdown = 1
        return self._countdown

    def countdown_setter(self, new_countdown):
        if new_countdown not in (1, 2, 3, 4):
            raise ValueError("ONE TWO THREE FOUR!")
        self._countdown = new_countdown

    countdown = property(countdown_getter, countdown_setter)