内置函数ltems、new、hash、eq

getitems  setitems  delitmes
dic = {'k':'v'}
# 对象 ： 存储属性 和调用方法
dic['k'] = 'v'
class Foo:
    def __init__(self,name,age,sex):
        self.name = name
        self.age = age
        self.sex = sex

    def __getitem__(self, item):
        if hasattr(self,item):
            return self.__dict__[item]

    def __setitem__(self, key, value):
        self.__dict__[key] = value

    def __delitem__(self, key):
        del self.__dict__[key]

f = Foo('egon',38,'男')
print(f['name'])
f['hobby'] = '男'
print(f.hobby,f['hobby'])
del f.hobby      # object 原生支持  __delattr__
del f['hobby']   # 通过自己实现的
print(f.__dict__)

new

# 设计模式
# 23种
# 单例模式
# 一个类 始终 只有 一个 实例
# 当你第一次实例化这个类的时候 # __init__ 初始化方法
# __new__  构造方法 : 创建一个对象
class A:
    def __init__(self):
        self.x = 1
        print('in init function')
     def __new__(cls, *args, **kwargs):
        print('in new function')
        return object.__new__(A, *args, **kwargs)

a1 = A()
a2 = A()
a3 = A()
 print(a1)就创建一个实例化的对象
# 当你之后再来实例化的时候 就用之前创建的对象

 class A:
     __instance = False
     def __init__(self,name,age):
         self.name = name
         self.age = age
     def __new__(cls, *args, **kwargs):
         if cls.__instance:
             return cls.__instance
         cls.__instance = object.__new__(cls)
        return cls.__instance

egon = A('egg',38)
egon.cloth = '小花袄'
nezha = A('nazha',25)
print(nezha)
print(egon)
print(nezha.name)
print(egon.name)
print(nezha.cloth)

hash

hash()   #__hash__
class A:
    def __init__(self,name,sex):
        self.name = name
        self.sex = sex
    def __hash__(self):
        return hash(self.name+self.sex)

a = A('egon','男')
b = A('egon','nv')
print(hash(a))
print(hash(b))

class A:
    def __init__(self,name):
        self.name = name

    def __eq__(self, other):
        if self.__dict__ == other.__dict__:
            return True
        else:
            return False

ob1 = A('egon')
ob2 = A('egg')
print(ob1 == ob2)














案例

import json
from collections import namedtuple
Card = namedtuple('Card',['rank','suit'])   # rank 牌面的大小 suit牌面的花色
class FranchDeck:
    ranks = [str(n) for n in range(2,11)] + list('JQKA')   # 2-A
    suits = ['红心','方板','梅花','黑桃']

    def __init__(self):
        self._cards = [Card(rank,suit) for rank in FranchDeck.ranks
                                        for suit in FranchDeck.suits]

    def __len__(self):
        return len(self._cards)

    def __getitem__(self, item):
        return self._cards[item]

    def __setitem__(self, key, value):
        self._cards[key] = value

    def __str__(self):
        return json.dumps(self._cards,ensure_ascii=False)

deck = FranchDeck()
print(deck[10])
from random import choice
print(choice(deck)) #随机抽取
# print(choice(deck))
from random import shuffle
shuffle(deck)#洗牌
print(deck[10])
print(deck)
print(deck[:5])

内置函数ltems、new、hash、eq

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