具有复杂类型的Python枚举

Question

我是Python的新手,我想知道我是否可以构建具有复杂结构的枚举,而不仅仅是原始类型.例如(在伪代码中):

Point::Enum
  x, y
  constructor ( x, y ) {
    ...
  }

  bottom_left = Point ( 0, 0 )
  top_left = Point ( 0, 100 )
  top_right = Point ( 100, 100 )
  bottom_right = Point ( 100, 0 )

到目前为止,我只能找到提到字符串或整数的枚举的Python文档.

Answer 1

如果你想要跟踪角落Point的单独实体Enum,那么你需要将它们分开:

from enum import Enum

class Point(object):
    def __init__(self, x, y):
        self.x = x
        self.y = y
    def __repr__(self):
        return 'Point(%r, %r)' % (self.x, self.y)

class Corner(Enum):
    BottomLeft = Point(0, 0)
    TopLeft = Point(0, 100)
    TopRight = Point(100, 100)
    BottmRight = Point(100, 0)

这样做意味着每个都enum包含一个Pointas作为其值,但不是一个Point本身:

>>> Corner.BottomLeft
<Corner.BottomLeft: Point(0, 0)>
>>> Corner.BottomLeft.value
Point(0, 0)

如果你想enum成员是 a Point,那么在Point课堂上混合:

from enum import Enum

class Point(object):
    def __init__(self, x, y):
        self.x = x
        self.y = y
    def __repr__(self):
        return 'Point(%r, %r)' % (self.x, self.y)

class Corner(Point, Enum):
    BottomLeft = 0, 0
    TopLeft = 0, 100
    TopRight = 100, 100
    BottmRight = 100, 0

>>> Corner.TopLeft
<Corner.TopLeft: (0, 0)>
>>> isinstance(Corner.TopLeft, Point)
True
>>> Corner.TopLeft.value
(0, 100)
>>> Corner.TopLeft.x
0
>>> Corner.TopLeft.y
100

最后,如果您需要的是enums具有x和y属性:

from aenum import Enum

class Corner(Enum):
    __init__ = 'x y'
    BottomLeft = 0, 0
    TopLeft = 0, 100
    TopRight = 100, 100
    BottmRight = 100, 0

>>> Corner.TopLeft
<Corner.TopLeft: (0, 100)>
>>> Corner.TopLeft.value
(0, 100)
>>> Corner.TopLeft.x
0
>>> Corner.TopLeft.y
100

请注意,最后一个示例使用的是aenum包¹.你可以通过为类编写一个enum34或者stdlib 来完成同样的事情.enum__init__Point

¹披露:我是Python stdlibEnum,enum34backport和Advanced Enumeration(aenum) 库的作者.