Membarui enum lain sebagai nilai enum dengan Python? [duplikat]

Question

Misalkan saya memiliki Python Enum , setiap instance Enum harus mereferensikan instance lain dari enum yang sama. Bagaimana aku melakukan itu?

Ketika saya mencoba sesuatu seperti ini:

    class Direction(Enum):
        NORTH = (1,0, Direction.EAST, Direction.WEST)
        SOUTH = (-1,0, Direction.WEST, Direction.EAST)
        EAST = (0,1, Direction.SOUTH, Direction.NORTH)
        WEST = (0, -1, Direction.NORTH, Direction.SOUTH)
        
        def __init__(self, y, x, r, l):
            self.y = y
            self.x = x
            self.r = r
            self.l = l

Saya mendapatkan kesalahan yang terlihat seperti ini:

Traceback (most recent call last):
  File "lol.py", line 2, in <module>
    class Direction(Enum):
  File "lol.py", line 3, in Direction
    NORTH = (1,0, Direction.EAST, Direction.WEST)
NameError: name 'Direction' is not defined

Saya mendapatkan masalah yang sama saat mengganti "Direction" dengan "self" pada contoh di atas.

Apakah ada cara untuk melakukan ini?

Answer 1

Jika Anda tidak keberatan sedikit mengubah urutan Enum, ini cukup mudah:

class Directions(Enum):
    #
    NORTH = 1, 0
    EAST = 0, 1
    SOUTH = -1, 0
    WEST = 0, -1
    #
    def __init__(self, x, y):
        self.x = x
        self.y = y
        if len(self.__class__):
            # make links
            all = list(self.__class__)
            left, right = all[0], all[-1]
            self.left = left
            self.right = right
            left.right = self
            right.left = self

dan sedang digunakan:

>>> Directions.NORTH
<Directions.NORTH: (1, 0)>

>>> Directions.NORTH.left
<Directions.EAST: (0, 1)>

>>> Directions.NORTH.right
<Directions.WEST: (0, -1)>

>>> Directions.WEST.left
<Directions.NORTH: (1, 0)>

>>> Directions.WEST.right
<Directions.SOUTH: (-1, 0)>

---

Pengungkapan: Saya penulis Python stdlibEnum , enum34backport , dan pustaka Advanced Enumeration ( aenum) .

Answer 2

Anda dapat menggunakan saran @antont dan menggunakan kamus, itu benar-benar valid.

Solusi lain, mendekati aslinya:

from enum import Enum


class Direction(Enum):
    NORTH = 0
    SOUTH = 1
    EAST = 2
    WEST = 3

    @property
    def x(self):
        return 0 if self in [self.NORTH, self.SOUTH] else 1 if self == self.EAST else -1

    @property
    def y(self):
        return 0 if self in [self.EAST, self.WEST] else 1 if self == self.NORTH else -1

    def _turn(self, left=True):
        dirs = [self.NORTH, self.EAST, self.SOUTH, self.WEST]
        return dirs[(dirs.index(self) + (-1 if left else 1)) % 4]

    @property
    def left(self):
        return self._turn()

    @property
    def right(self):
        return self._turn(left=False)


direction = Direction.SOUTH
print(direction.y)
print(direction.left)

Keluaran:

-1
Direction.EAST