incrementable_date.py

import datetime
import copy

class IncrementableDate:
    def __init__(self, date_time=None, datestring=None, dateformat='%Y%m%d'):
        if date_time is not None:
            self.value = date_time

        elif datestring is not None:
            self.value = datetime.datetime.strptime(datestring,  dateformat)

    def to_string(self, dateformat='%Y%m%d'):
        return datetime.datetime.strftime(self.value, dateformat)

    def increment(self, offset=1):
        self.value += datetime.timedelta(days=offset)
        
    def copy(self):
        return copy.copy(self)

    def __eq__(self, other):
        if isinstance(other, IncrementableDate):
            return self.value == other.value
        return NotImplemented

    def __ne__(self, other):
        x = self.__eq__(other)
        if x is not NotImplemented:
            return not x
        return NotImplemented

    def __gt__(self, other):
        if isinstance(other, IncrementableDate):
            return self.value > other.value
        return NotImplemented
    
    def __lt__(self, other):
        if isinstance(other, IncrementableDate):
            return self.value < other.value
        return NotImplemented

    def __ge__(self, other):
        return self.__gt__(other) or self.__eq__(other)

    def __le__(self, other):
        return self.__lt__(other) or self.__eq__(other)