iterator_alt.py

"""
Implementation of the iterator pattern using the iterator protocol from Python

*TL;DR
Traverses a container and accesses the container's elements.
"""
from __future__ import annotations


class NumberWords:
    """Counts by word numbers, up to a maximum of five"""

    _WORD_MAP = (
        "one",
        "two",
        "three",
        "four",
        "five",
    )

    def __init__(self, start: int, stop: int) -> None:
        self.start = start
        self.stop = stop

    def __iter__(self) -> NumberWords:  # this makes the class an Iterable
        return self

    def __next__(self) -> str:  # this makes the class an Iterator
        if self.start > self.stop or self.start > len(self._WORD_MAP):
            raise StopIteration
        current = self.start
        self.start += 1
        return self._WORD_MAP[current - 1]


# Test the iterator


def main():
    """
    # Counting to two...
    >>> for number in NumberWords(start=1, stop=2):
    ...     print(number)
    one
    two

    # Counting to five...
    >>> for number in NumberWords(start=1, stop=5):
    ...     print(number)
    one
    two
    three
    four
    five
    """


if __name__ == "__main__":
    import doctest

    doctest.testmod()