blackknight.py

"""
This class is inspired by the Black Knight scene in the movie
"Monty Python and the Holy Grail", where King Arthur fights the
Black Knight, slicing off his arms and legs, but the knight
refuses to concede defeat.

# tag::BLACK_KNIGHT_DEMO[]
    >>> knight = BlackKnight()
    >>> knight.member
    next member is:
    'an arm'
    >>> del knight.member
    BLACK KNIGHT (loses an arm) -- 'Tis but a scratch.
    >>> del knight.member
    BLACK KNIGHT (loses another arm) -- It's just a flesh wound.
    >>> del knight.member
    BLACK KNIGHT (loses a leg) -- I'm invincible!
    >>> del knight.member
    BLACK KNIGHT (loses another leg) -- All right, we'll call it a draw.

# end::BLACK_KNIGHT_DEMO[]
"""

# tag::BLACK_KNIGHT[]
class BlackKnight:

    def __init__(self):
        self.phrases = [
            ('an arm', "'Tis but a scratch."),
            ('another arm', "It's just a flesh wound."),
            ('a leg', "I'm invincible!"),
            ('another leg', "All right, we'll call it a draw.")
        ]

    @property
    def member(self):
        print('next member is:')
        return self.phrases[0][0]

    @member.deleter
    def member(self):
        member, text = self.phrases.pop(0)
        print(f'BLACK KNIGHT (loses {member}) -- {text}')
# end::BLACK_KNIGHT[]