>>> a = [1, 2, 3]
>>> b = a
>>> a.append(4)
>>> b
[1, 2, 3, 4]

>>> lewis = charles
>>> lewis is charles
True
>>> id(lewis), id(charles)
(4303312648, 4303312648)
>>> lewis['balance'] = 950
>>> charles
{'name': 'Charles L. Dodgson', 'born': 1832, 'balance': 950}

>>> lewis
{'name': 'Charles L. Dodgson', 'born': 1832, 'balance': 950}
>>> alex = {'name': 'Charles L. Dodgson', 'born': 1832, 'balance': 950}
>>> lewis == alex
True
>>> alex is not lewis
True

>>> t1 = (1, 2, [30, 40])
>>> t2 = (1, 2, [30, 40])
>>> t1 == t2
True
>>> id(t1[-1])
>>> t1[-1].append(1000)
>>> t1
(1, 2, [30, 40, 1000])
>>> t1 == t2
False

>>> l1 = [3, [55, 44], (7, 8, 9)]
>>> l2 = list(l1)
>>> l3 = l1[:]
>>> l2
[3, [55, 44], (7, 8, 9)]
>>> l3
[3, [55, 44], (7, 8, 9)]
>>> l1 == l2 == l3
True
>>> l2 is l1
False
>>> l3 is l1
False

l1 = [3, [66, 55, 44], (7, 8, 9)]
l2 = list(l1)    #浅复制了l1
l1.append(100)    #l1列表在尾部添加数值100
l1[1].remove(55)   #移除列表中第1个索引的值
print('l1:', l1)
print('l2:', l2)
l2[1] += [33, 22]   #l2列表中第1个索引做列表拼接
l2[2] += (10, 11)   #l2列表中的第2个索引做元祖拼接
print('l1:', l1)
print('l2:', l2)

class Bus:

 def __init__(self, passengers=None):
  if passengers is None:
   self.passengers = []
  else:
   self.passengers = list(passengers)

 def pick(self, name):
  self.passengers.append(name)

 def drop(self, name):
  self.passengers.remove(name)

from copy import copy, deepcopy

bus1 = Bus(['Alice', 'Bill', 'Claire', 'David'])
bus2 = copy(bus1)      #bus2浅复制的bus1
bus3 = deepcopy(bus1)     #bus3深复制了bus1
print(id(bus1), id(bus2), id(bus3))  #查看三个对象的内存地址

bus1.drop('Bill')      #bus1的车上Bill下车了
print('bus2:', bus2.passengers)   #wtf....bus2中的Bill也没有了，见鬼了！
print(id(bus1.passengers), id(bus2.passengers), id(bus3.passengers)) #审查 passengers 属性后发现，bus1和bus2共享同一个列表对象，因为 bus2 是 bus1 的浅复制副本

print('bus3:', bus3.passengers)   #bus3是bus1 的深复制副本，因此它的 passengers 属性指代另一个列表

4324829840 4324830176 4324830736
bus2: ['Alice', 'Claire', 'David']
4324861256 4324861256 4324849608
bus3: ['Alice', 'Bill', 'Claire', 'David']

>>> a = [10, 20]
>>> b = [a, 30]
>>> a.append(b)
>>> a
[10, 20, [[...], 30]]
>>> from copy import deepcopy
>>> c = deepcopy(a)
>>> c
[10, 20, [[...], 30]]

>>> def f(a, b):
...  a += b
...  return a
... 
>>> x = 1
>>> y = 2
>>> f(x, y)
>>> x, y
(1, 2)
>>> a = [1, 2]
>>> b = [3, 4]
>>> f(a, b)
[1, 2, 3, 4]
>>> a, b
([1, 2, 3, 4], [3, 4])
>>> t = (10, 20)
>>> u = (30, 40)
>>> f(t, u)
(10, 20, 30, 40)
>>> t, u
((10, 20), (30, 40))

class HauntedBus:
 '''
 备受折磨的幽灵车
 '''

 def __init__(self, passengers=[]):
  self.passengers = passengers

 def pick(self, name):
  self.passengers.append(name)

 def drop(self, name):
  self.passengers.remove(name)


bus1 = HauntedBus(['Alice', 'Bill'])
print('bus1上的乘客：', bus1.passengers)
bus1.pick('Charlie')   #bus1上来一名乘客Charile
bus1.drop('Alice')    #bus1下去一名乘客Alice
print('bus1上的乘客：', bus1.passengers)   #打印bus1上的乘客

bus2 = HauntedBus()    #实例化bus2
bus2.pick('Carrie')    #bus2上来一名课程Carrie
print('bus2上的乘客：', bus2.passengers)

bus3 = HauntedBus()
print('bus3上的乘客：', bus3.passengers)
bus3.pick('Dave')
print('bus2上的乘客：', bus2.passengers)  #登录到bus3上的乘客Dava跑到了bus2上面

print('bus2是否为bus3的对象：', bus2.passengers is bus3.passengers)
print('bus1上的乘客：', bus1.passengers)

bus1上的乘客： ['Alice', 'Bill']
bus1上的乘客： ['Bill', 'Charlie']
bus2上的乘客： ['Carrie']
bus3上的乘客： ['Carrie']
bus2上的乘客： ['Carrie', 'Dave']
bus2是否为bus3的对象： True
bus1上的乘客： ['Bill', 'Charlie']

class TwilightBus:
 """让乘客销声匿迹的校车"""

 def __init__(self, passengers=None):
  if passengers is None:
   self.passengers = passengers
  else:
   self.passengers = passengers #这个地方就需要注意了,这里传递的是引用的别名

 def pick(self, name):
  self.passengers.append(name)  #会修改构造放的列表，也就是会修改外部的数据

 def drop(self, name):
  self.passengers.remove(name)  #会修改构造放的列表，也就是会修改外部的数据

basketball_team = ['Sue', 'Tina', 'Maya', 'Diana', 'Pat']
bus = TwilightBus(basketball_team)
bus.drop('Tina')  #bus中乘客Tina下去了
bus.drop('Pat')   #bus中课程Pat下去了

print(basketball_team) #wtf....为毛线的basketball的里面这两个人也木有了~~MMP

['Sue', 'Maya', 'Diana']

>>> a = [1, 2, 3]
>>> b = a
>>> c = list(a)
>>> b.append(10)
>>> a
[1, 2, 3, 10]
>>> b
[1, 2, 3, 10]
>>> c
[1, 2, 3]

>>> import weakref
>>> s1 = {1, 2, 3}
>>> s2 = s1　#s1和s2是别名，指向同一个集合
>>> def bye():　#这个函数一定不能是要销毁的对象的绑定方法，否则会有一个指向对象的引用
...  print('Gone with the wind...')
... 
>>> ender = weakref.finalize(s1, bye)　#在s1引用的对象上注册bye回调　
>>> ender.alive#调用finalize对象之前，.alive属性的值为True
True
>>> del s1　#del不删除对象，而是删除对象的引用
>>> ender.alive
True
>>> s2 = 'spam'　 #重新绑定最后一个引用s2，让{1, 2, 3}无法获取，对象呗销毁了，调用bye回调，ender.alive的值编程了False
Gone with the wind...
>>> ender.alive
False

>>> import weakref
>>> a_set = {0, 1}
>>> wref = weakref.ref(a_set)#创建弱引用对象wref，下一行审查它
>>> wref
<weakref at 0x101ce03b8; to 'set' at 0x101cd8d68>
>>> wref()　#调用wref()返回的是被引用的对象，{0, 1}。因为这是控制台会话，所以{0, 1}会绑定给_变量
{0, 1}
>>> a_set = {2, 3, 4} #a_set不在指代{0， 1}集合，因此集合的引用数量减少了，但是_变量仍然指代它
>>> wref() #调用wref()已经返回了{0， 1}
{0, 1}
>>> wref() is None#计算这个表达式时，{0， 1}存在，因此wref()不是None，但是，随后_绑定到结果值False，现在{0，1}没有强引用
False
>>> wref() is None#因为{0， 1}对象不存在了，所以wref()返回了None
True