如何使用类方法创建新实例

Question

我正在尝试为一个类编写一个方法，该方法将创建一个类的现有实例的新实例。问题是当我尝试new_handname时，我无法访问控制台中的新实例。

这是为了在python中创建二十一点游戏。代码的想法是，当手牌被拆分时，将创建一个新实例来创建新手牌

import random

class Card(object):
    def __init__(self, value, suit,nvalue):
        self.value = value
        self.suit = suit
        self.nvalue = nvalue
suit = ['Hearts','Spades','Clubs','Diamonds']
value = ['2','3','4','5','6','7','8','9','10','J','Q','K','A']
nvalue = [2,3,4,5,6,7,8,9,10,10,10,10,11]

class Hand(object):
    def __init__(self,current_hand):
        self.current_hand = current_hand
    def hand_total(self):
        current_sum = 0
        for i in range(0,len(self.current_hand)):
            current_sum += self.current_hand[i].nvalue
        return current_sum
    def hand_type(self):
        if self.current_hand[0].value == self.current_hand[1].value:
            return('pair')
        elif self.current_hand[0].value == 'A' or self.current_hand[1].value == 'A':
            return('soft')
        else:
            return('hard')
    def append(self,current_hand,some_card):
        self.current_hand = self.current_hand + some_card
    def hit(self):
        self.current_hand.append(deck[0])
        deck.pop(0)
    def double(self,new_handname):  
        new_handname = Hand(self)

def deal_start_hand():
    player_hand.append(deck[0])
    deck.pop(0)
    dealer_hand.append(deck[0])
    deck.pop(0)
    player_hand.append(deck[0]) #### player gets two cards ### assuming europe no hole card rules
    deck.pop(0)
def gen_deck():
    for v,n in zip(value,nvalue):
        for s in suit:
            deck.append(Card(v,s,n))

### variable initiation ###
deck = []
player_hand = []
dealer_hand = []

##program start ##
gen_deck()
random.shuffle(deck)
deal_start_hand()
p1 = Hand(player_hand)
p1.double('p2')
p2   ### I expect p2 to return an instance but does not 
>>> p1 
<__main__.Hand object at 0x00000006A80F0898>
>>> p2
Traceback (most recent call last):
  File "<pyshell#182>", line 1, in <module>
    p2
NameError: name 'p2' is not defined

注： current_hand是卡片对象的列表。

我希望 p2

返回类的实例，但未定义变量 p2

Answer 1

您的split例程可能如下所示，其中返回了类的新实例：

class Hand(object):
    def __init__(self, current_hand):
        self.current_hand = current_hand
    def split(self):
        return Hand(self.current_hand)

只需创建一个实例，然后稍后拆分：

# You need to define "some_default" somewhere
myhand = Hand(some_default)
second_hand = myhand.split()

但是，您的split例程需要考虑哪些牌已经打出，哪些牌仍在牌组中，而您的代码没有考虑这些。我可能会建议绘制出游戏的"状态"（将其视为状态机），将其绘制在纸上，然后考虑如何编写每个状态和转换。像这样的纸牌游戏比乍一看更复杂。