带属性的 python 枚举

考虑：

class Item:
   def __init__(self, a, b):
       self.a = a
       self.b = b

class Items:
    GREEN = Item('a', 'b')
    BLUE = Item('c', 'd')

有没有办法使简单枚举的思想适应这种情况？ （看这个问题）理想情况下，就像在 Java 中一样，我想将所有内容都塞进一个类中。

Java模型：

enum EnumWithAttrs {
    GREEN("a", "b"),
    BLUE("c", "d");

    EnumWithAttrs(String a, String b) {
      this.a = a;
      this.b = b;
    }

    private String a;
    private String b;

    /* accessors and other java noise */
}

Python 3.4 has a new Enum data type (which has been backported as enum34 and enhanced as aenum¹). Both enum34 and aenum² easily support your use case:

• aenum（Python 2/3）

    import aenum
    class EnumWithAttrs(aenum.AutoNumberEnum):
        _init_ = 'a b'
        GREEN = 'a', 'b'
        BLUE = 'c', 'd'
  

• enum34(Python 2/3) 或标准库enum（Python 3.4+）

    import enum
    class EnumWithAttrs(enum.Enum):
  
        def __new__(cls, *args, **kwds):
            value = len(cls.__members__) + 1
            obj = object.__new__(cls)
            obj._value_ = value
            return obj
        def __init__(self, a, b):
            self.a = a
            self.b = b
  
        GREEN = 'a', 'b'
        BLUE = 'c', 'd'
  

并在使用中：

>>> EnumWithAttrs.BLUE
<EnumWithAttrs.BLUE: 1>

>>> EnumWithAttrs.BLUE.a
'c'

¹ Disclosure: I am the author of the Python stdlib Enum, the enum34 backport, and the Advanced Enumeration (aenum) library.

² aenum also supports NamedConstants and metaclass-based NamedTuples.