python学习之老男孩python全栈第九期_day028知识点总结——面向对象进阶、hashlib

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', 22, '男')
print(f['a'])
print(f['name'])
f['hobby'] = '男'
print(f.hobby,f['hobby'])

print(f.__dict__)
del f.hobby               # object 原生支持       __delattr__
print(f.__dict__)

print(f.__dict__)
del f['hobby']            # 通过自己实现
print(f.__dict__)

__init__ ：初始化方法
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)

a = A()
print(a.x)

设计模式：23 种
  1. 单例模式：一个类始终只有一个实例
当第一次实例化这个类的时候，就创建一个实例化的对象
当之后再来实例化的时候，就用之前创建的那个对象

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
        else:
            cls.__instance = object.__new__(A)
            return cls.__instance
egon = A('egon',22)
egon.cloth = '小花袄'
nezha = A('nezha',32)
print(nezha)
print(egon)                     # 内存地址一样
print(nezha.name)               # nezha
print(egon.name)                # nezha
print(nezha.cloth)              # 小花袄

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

    def __eq__(self,other):
        if self.name == other.name:
            return True
        else:
            return False
obj1 = A('egon')
obj2 = A('egn')
print(obj1 == obj2)         # 不实现__eq__时，默认比较内存地址     Flase

# __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','男')
print(hash(a))
print(hash(b))

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

---

实例

 1 import json
 2 from collections import namedtuple
 3 Card = namedtuple('Card',['rank','suit'])       # rank 牌的大小，suit 牌的花色
 4 # c1 = Card(2,'红桃')
 5 # print(c1)
 6 # print(c1.suit)
 7 class FranchDeck:
 8     ranks = [str(n) for n in range(2,11)] + list('JQKA')        # 2 - A
 9     suits = ['红桃', '方块', '梅花', '黑桃']
10 
11     def __init__(self):
12         self.__cards = [Card(rank, suit) for rank in FranchDeck.ranks
13                                         for suit in FranchDeck.suits]
14     def __len__(self):
15         return len(self.__cards)
16     def __getitem__(self, item):
17         return self.__cards[item]
18     def __setitem__(self, key, value):
19         self.__cards[key] = value
20     def __str__(self):
21         return json.dumps(self.__cards, ensure_ascii=False)
22 deck = FranchDeck()
23 print(deck[10])
24 from random import choice
25 print(choice(deck))
26 from random import shuffle
27 shuffle(deck)
28 print(deck[10])
29 print(deck)
30 print(deck[:4])

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