KaprekarConstant.py

class KaperkarConstant(object):

    _run = 0

    def __init__(self, starting_number):
        self._starting_n = None
        self._first_n = None
        self._second_n = None
        self._resulting_n = None

        self.starting_n = starting_number
        self.rearrange_n()
        self.get_difference()
        KaperkarConstant._run += 1
        print('#{}:{} -> {}'.format(KaperkarConstant._run, self.starting_n, self._resulting_n))
        if not self.starting_n == self._resulting_n:
            self.child = KaperkarConstant(self._resulting_n)

    @property
    def starting_n(self):
        """Starting 4 digit number."""
        return self._starting_n

    @starting_n.setter
    def starting_n(self, value):
        # Make it int or crash
        if isinstance(value, float) or isinstance(value, str) or isinstance(value, int):
            value = int(value)
        else:
            raise TypeError('Got to be int or float or str')

        if abs(value) > 9999:
            raise ValueError('Only 4 character long numbers are allowed')
        self._starting_n = str(abs(value)).zfill(4)

    def rearrange_n(self):
        self._first_n = self.starting_n[3] + self.starting_n[0] + self.starting_n[1] + self.starting_n[2]
        self._second_n = self.starting_n[1] + self.starting_n[2] + self.starting_n[0] + self.starting_n[3]

    def get_difference(self):
        self._first_n = int(self._first_n)
        self._second_n = int(self._second_n)
        self._resulting_n = max(self._first_n, self._second_n) - min(self._first_n, self._second_n)


kc = KaperkarConstant(7339)