Clean Code in Python

Creating iterable objects

When we try to iterate an object, Python will call the iter() function over it. One of the first things this function checks for is the presence of the __iter__ method on that object, which, if present, will be executed.

The following code creates an object that allows iterating over a range of dates, producing one day at a time on every round of the loop:

from datetime import timedeltaclass DateRangeIterable:    """An iterable that contains its own iterator object."""    def __init__(self, start_date, end_date):        self.start_date = start_date        self.end_date = end_date        self._present_day = start_date    def __iter__(self):        return self    def __next__(self):        if self._present_day >= self.end_date:            raise StopIteration today = self._present_day ...