python3 enum模块的应用实例详解

from enum import Enum #普通类
class dict():
  green = 1
  green = 2
  red = 3
dict.red = 4  
print(dict.red)
> 4
class VIP(Enum): 
  RED = 1
  GREEN =2
  YELLOW = 3
VIP.GREEN = 5 #枚举值不能动态更改
>File "D:\python\lib\enum.py", line 361, in __setattr__
　　raise AttributeError('Cannot reassign members.')
　　AttributeError: Cannot reassign members.
class VIP(Enum):
  RED = 1
  GREEN =2
  YELLOW = 3
  YELLOW = 3 #不能出现相同的标签
>File "D:\python\lib\enum.py", line 92, in __setitem__
    raise TypeError('Attempted to reuse key: %r' % key)
    TypeError: Attempted to reuse key: 'YELLOW'
class VIP(Enum):
  RED = 1
  GREEN =2
  YELLOW = 3
  BLUE = 3
print(VIP.BLUE)
>VIP.YELLOW  #即VIP.BLUE类似于VIP.YELLOW的别名
class VIP(Enum):
  RED = 1 #整型
  BLUE = 1.2 #浮点型
  GREEN = 'green' #str
  YELLOW = True #布尔值

from enum import Enum
class VIP(Enum):
  RED = 1
  GREEN = 'green'
  YELLOW = True
  BLUE = 1.2
print(VIP.RED) #枚举的类型
print(VIP.YELLOW.name)  #枚举的标签
print(VIP.YELLOW.value)  #枚举的数值
print('遍历成员。。。')
for i in VIP.__members__.items():  #枚举的遍历
  print(i)
>
VIP.RED
RED
1
遍历成员。。。
('RED', <VIP.RED: 1>)
('GREEN', <VIP.GREEN: 'green'>)
('YELLOW', <VIP.RED: 1>)
('BLUE', <VIP.BLUE: 1.2>)

class VIP(Enum):
  RED = 1
  GREEN = 'green'
  YELLOW = True
  BLUE = 2
#枚举的比较
a = VIP.RED == VIP.RED #枚举值可以做等值比较
b = VIP.RED == VIP.GREEN
c = VIP.RED is VIP.RED
d = VIP.RED == 1 #枚举标签与枚举值比较，并不相等
f = VIP.RED < VIP.BLUE #枚举值不支持大小比较，打印会报错TypeError: '<' not supported between instances of 'VIP' and 'VIP'
print(a)
print(b)
print(c)
print(d)
>
True
False
True
False

class VIP(Enum):
  RED = 1
  GREEN = 'green'
  YELLOW = True
  BLUE = 2
print(VIP(2))  #通过具体值获取枚举类型，返回VIP.BLUE
print(VIP('green'))  #返回VIP.GREEN

from enum import Enum,unique
@unique
class VIP(Enum):
  RED = 1
  GREEN = 1
  YELLOW = True
  BLUE = 2
>报错
ValueError: duplicate values found in <enum 'VIP'>: GREEN -> RED, YELLOW -> RED

from enum import Enum,auto
class VIP(Enum):
  RED = auto()
  GREEN = auto()
  YELLOW = auto()
  BLUE = auto()
for i in VIP.__members__.items():  #遍历枚举
  print(i)
>
('RED', <VIP.RED: 1>)
('GREEN', <VIP.GREEN: 2>)
('YELLOW', <VIP.YELLOW: 3>)
('BLUE', <VIP.BLUE: 4>)

from enum import Enum,auto
class auto_test(Enum):
  def _generate_next_value_(name, start, count, last_values):
    return name
class VIP(auto_test):
  RED = auto()
  GREEN = auto()
  YELLOW = auto()
  BLUE = auto()
# for i in VIP.__members__.items(): #遍历枚举
#   print(i)
print(list(VIP))  #转换列表
>
[<VIP.RED: 'RED'>, <VIP.GREEN: 'GREEN'>, <VIP.YELLOW: 'YELLOW'>, <VIP.BLUE: 'BLUE'>]