Codes for the post https://binary-coffee.dev/post/refactorizando-codigo-duplicado-y-poder-ejecutar-pruebas-facilmente

DateRange_Iterator.py

import datetime
from datetime import date
from datetime import timedelta

def IsDate(value):
    return type(value) is date

class DateRange:
    """
    Iterator over every date in a range [date_a, date_b). If a predicate is defined
    then iterate only over those dates thats evaluate filter(date) as True. Examples:

    >>> list(DateRange(datetime.date(2019, 12, 30), datetime.date(2020, 1, 3)))
    [datetime.date(2019, 12, 30), datetime.date(2019, 12, 31), datetime.date(2020, 1, 1), datetime.date(2020, 1, 2)]

    >>> list(DateRange(datetime.date(2019, 12, 30), datetime.date(2020, 1, 3), lambda x: x.day % 2 == 0))
    [datetime.date(2019, 12, 30), datetime.date(2020, 1, 2)]

    >>> IsPal = lambda date: str(date).replace('-', '') == str(date).replace('-', '')[: : -1]
    >>> list(DateRange(datetime.date(2020, 1, 1), datetime.date(2020, 12, 31), IsPal))
    [datetime.date(2020, 2, 2)]
    """

    __oneDay = timedelta(days=1)

    def __init__(self, date_a, date_b, filter=None):
        pass
        if not IsDate(date_a) or not IsDate(date_b):
            raise ValueError("Arguments must be of type datetime.date")
        if date_a > date_b:
            raise ValueError("The first date must be the same or before the second date")
        self.__A = date_a
        self.__B = date_b
        self.__filter = filter

    def __iter__(self):
        return self

    def __next__(self):
        while not self._filter(self.__A):
            self.__checkif_must_stop()
            self.__A += DateRange.__oneDay
        result = self.__A
        self.__checkif_must_stop()
        self.__A += DateRange.__oneDay
        return result

    def __checkif_must_stop(self):
        if self.__A >= self.__B:
            raise StopIteration()

    def _filter(self, date):
        if self.__filter is None:
            return True
        return self.__filter(date)

DateRange_yield.py

import datetime
from datetime import date
from datetime import timedelta

__oneDay = timedelta(days=1)

def DateRange(date_a, date_b, filter=None):
    """    
    Iterator over every date in a range [date_a, date_b). If a predicate is defined
    then iterate only over those dates thats evaluate filter(date) as True. Examples:

    >>> list(DateRange(datetime.date(2019, 12, 30), datetime.date(2020, 1, 3)))
    [datetime.date(2019, 12, 30), datetime.date(2019, 12, 31), datetime.date(2020, 1, 1), datetime.date(2020, 1, 2)]

    >>> list(DateRange(datetime.date(2019, 12, 30), datetime.date(2020, 1, 3), lambda x: x.day % 2 == 0))
    [datetime.date(2019, 12, 30), datetime.date(2020, 1, 2)]

    >>> IsPal = lambda date: str(date).replace('-', '') == str(date).replace('-', '')[: : -1]
    >>> list(DateRange(datetime.date(2020, 1, 1), datetime.date(2020, 12, 31), IsPal))
    [datetime.date(2020, 2, 2)]
    """
    _filter = lambda date: True
    if filter is not None:
        _filter = filter
    while date_a < date_b:
        if _filter(date_a):
            yield date_a
        date_a += __oneDay

OriginalSol.py

# https://binary-coffee.dev/post/fechas-palindromos

from datetime import date
from datetime import timedelta

oneDay = timedelta(days=1)

def IsPalindromoDate(date):
    strDate = str(date).replace('-', '')
    return strDate == strDate[: : -1]

print('Past palindromes:')
while str(currentDate) != '1000-01-01':
    if IsPalindromoDate(currentDate):
        print(currentDate)
    currentDate -= oneDay

currentDate = date.today() + oneDay
print('Future palindromes:')
while str(currentDate) != '2999-12-31':
    if IsPalindromoDate(currentDate):
        print(currentDate)
    currentDate += oneDay

SolUsingDateRangeModule.py

from datetime import date
# Rename or make a copy of DateRange_iterator.py or DateRange_yield.py to the file DateRange.py
from DateRange import DateRange

def IsPalindromoDate(date):
    strDate = str(date).replace('-', '')
    return strDate == strDate[: : -1]

print('Past palindromes:')
for pd in DateRange(date(1000, 1, 1), date.today(), IsPalindromoDate):
    print(pd)

print('Future palindromes:')
for pd in DateRange(date.today(), date(2999, 12, 31), IsPalindromoDate):
    print(pd)