我正在学习python中的面向对象编程。我在thinkpython之前看到了Allen B. Downey这本书。我正在尝试运行以下示例card.py，但我收到了一些错误。
"""This module contains code from
Think Python by Allen B. Downey
http://thinkpython.com
Copyright 2012 Allen B. Downey
License: GNU GPLv3 http://www.gnu.org/licenses/gpl.html
"""
import random
class Card(object):
"""Represents a standard playing card.
Attributes:
suit: integer 0-3
rank: integer 1-13
"""
suit_names = ["Clubs", "Diamonds", "Hearts", "Spades"]
rank_names = [None, "Ace", "2", "3", "4", "5", "6", "7",
"8", "9", "10", "Jack", "Queen", "King"]
def __init__(self, suit=0, rank=2):
self.suit = suit
self.rank = rank
def __str__(self):
"""Returns a human-readable string representation."""
return '%s of %s' % (Card.rank_names[self.rank],
Card.suit_names[self.suit])
def __cmp__(self, other):
"""Compares this card to other, first by suit, then rank.
Returns a positive number if this > other; negative if other > this;
and 0 if they are equivalent.
"""
t1 = self.suit, self.rank
t2 = other.suit, other.rank
return cmp(t1, t2)
class Deck(object):
"""Represents a deck of cards.
Attributes:
cards: list of Card objects.
"""
def __init__(self):
self.cards = []
for suit in range(4):
for rank in range(1, 14):
card = Card(suit, rank)
self.cards.append(card)
def __str__(self):
res = []
for card in self.cards:
res.append(str(card))
return '\n'.join(res)
def add_card(self, card):
"""Adds a card to the deck."""
self.cards.append(card)
def remove_card(self, card):
"""Removes a card from the deck."""
self.cards.remove(card)
def pop_card(self, i=-1):
"""Removes and returns a card from the deck.
i: index of the card to pop; by default, pops the last card.
"""
return self.cards.pop(i)
def shuffle(self):
"""Shuffles the cards in this deck."""
random.shuffle(self.cards)
def sort(self):
"""Sorts the cards in ascending order."""
self.cards.sort()
def move_cards(self, hand, num):
"""Moves the given number of cards from the deck into the Hand.
hand: destination Hand object
num: integer number of cards to move
"""
for i in range(num):
hand.add_card(self.pop_card())
class Hand(Deck):
"""Represents a hand of playing cards."""
def __init__(self, label=''):
self.cards = []
self.label = label
def find_defining_class(obj, method_name):
"""Finds and returns the class object that will provide
the definition of method_name (as a string) if it is
invoked on obj.
obj: any python object
method_name: string method name
"""
for ty in type(obj).mro():
if method_name in ty.__dict__:
return ty
return None
if __name__ == '__main__':
deck = Deck()
deck.shuffle()
hand = Hand()
print(find_defining_class(hand, 'shuffle'))
deck.move_cards(hand, 5)
hand.sort()
print(hand)
当我尝试运行此代码时，我收到以下错误。
Traceback (most recent call last):
File "C:/Cubic/playpen/python/concepts/OO_concepts/card.py", line 120, in <module>
hand.sort()
File "C:/Cubic/playpen/python/concepts/OO_concepts/card.py", line 80, in sort
self.cards.sort()
TypeError: unorderable types: Card() < Card()
<class '__main__.Deck'>
我正在使用python版本3.5.1