一丶序幕

1.特殊方法名的作用

         特殊方法名能让你自己的对象实现和支持以下的语言构架，并与之交互：

1. 迭代
2. 集合类
3. 属性访问
4. 运算符重载
5. 函数和方法的调用
6. 对象的创建和销毁
7. 字符串表示形式和格式化
8. 管理上下文（即 with 块）

 

import collections#创建一个类表示纸牌#nametuple方法用于构建只有少数属性但没有方法的对象:#>>> beer_card = Card("7","diamonds")#>>> beer_card#Card(rank='7', suit='diamonds')#Card = collections.namedtuple("Card",["rank","suit"])#花色英文展示#hearts红心#diamonds红方#spades黑桃#clubs草花#查看一叠牌有多少张#主要还是关注FrenchDeck类,len()函数可以查看一叠牌有多少张#>>> deck = FrenchDeck()#>>> len(deck)#52#抽取固定顺序的牌#从一叠牌中抽取第一张和最后一张牌非常容易,这都是由__getitem__方法提供的#>>> deck[0]#Card(rank='2', suit='spades')#>>> deck[-1]#Card(rank='A', suit='hearts')#抽取随机的牌#from random import choice#choice(deck)#Card(rank='6', suit='spades')#>>> choice(deck)#Card(rank='6', suit='hearts')#>>> choice(deck)#Card(rank='8', suit='diamonds')#代码演示Card = collections.namedtuple("Card",["rank","suit"])class FrenchDeck:    ranks = [str(n) for n in range(2,11)] + list("JQKA")    suits = "spades diamonds clubs hearts".split()    def __init__(self):        self._cards = [Card(rank,suit) for suit in self.suits                       for rank in self.ranks]    def __len__(self):        return len(self._cards)    def __getitem__(self,position):        return self._cards[position]        suit_values = dict(spades=3, hearts=2, diamonds=1, clubs=0)        def spades_high(card):        rank_value = FrenchDeck.ranks.index(card.rank)        return rank_value * len(suit_values) + suit_values[card.suit]