python - 搁置:无法pickle <class 'method' >:属性查找builtins.method失败

Question

我正在使用 shelve 来存储一些数据。

Traceback (most recent call last):
    File "rogue.py", line 312, in <module>
    curses.wrapper(game)
File "/usr/lib/python3.3/curses/__init__.py", line 94, in wrapper
    return func(stdscr, *args, **kwds)
File "rogue.py", line 289, in game
    save_game(y,x)
File "rogue.py", line 119, in save_game
    file['player'] = player
File "/usr/lib/python3.3/shelve.py", line 124, in __setitem__
    p.dump(value)

_pickle.PicklingError: Can't pickle <class 'method'>: attribute lookup builtins.method failed

我环顾四周，发现有关未绑定(bind)方法的内容可能会导致此问题，但我在代码中找不到问题。

问题出现在

file['player'] = player

玩家是类实体:

player = entity(y,x, '@', 200, False)

这是类实体的代码:

class entity:
def __init__(self, y, x, ch, speed, ai=True):
    self.y = y
    self.x = x
    self.ch = ch
    self.speed = speed
    self.ai = ai


    self.ap = 0
    self.current_action = {'action': self.wait, 'cost': self.speed}
    self.my_turn = False

def draw(self):
    world[self.y][self.x].walkable = False
    gamepad.addch(self.y, self.x, self.ch)

def take_turn(self):

    self.my_turn = True
    cost = self.current_action['cost']
    self.current_action['action']()

    return cost
def move(self, dy, dx):

    if self.my_turn == False:
        self.current_action = {'action': partial(self.move, dy,dx), 'cost':200}
        deck.append(self)

    if self.my_turn == True:

        #p = previous
        py = self.y
        px = self.x


        pt = world[py][px]
        #Paint previous ground tile
        pt.walkable = True
        gamepad.addch(pt.y,pt.x,pt.ch)

        if world[dy][dx].walkable == True:
            self.y = dy
            self.x = dx
            world[dy][dx].walkable = False

        if self.ai == False:
            draw_map(self.y,self.x)


        self.my_turn = False
    return self.y,self.x

def wait(self):
    self.current_action = {'action': self.wait, 'cost': self.speed}
def drunk_move(self):
    dy = self.y + random.randint(-1,1)
    dx = self.x + random.randint(-1,1)
    self.move(dy, dx)
def ai_simple(self):

    #Figure out if player is higher or not:
    wherey = self.y - player.y
    if wherey > 0:
        dy = self.y-1
    else:
        dy = self.y+1

    wherex = self.x - player.x
    if wherex > 0:
        dx = self.x-1
    else:
        dx = self.x+1

    self.move(dy, dx)

---

在发布此内容之前，我尝试使用 pudb 最后查看一下 - 而且我也遇到了错误

file['world'] = world

_

│  File "/usr/lib/python3.3/shelve.py", line 124, in                    │
│__setitem__                                                            │
│    p.dump(value)                                                      │         
│_pickle.PicklingError: Can't pickle <class                             │
│'__main__.tile'>: attribute lookup __main__.tile failed                │

(在没有 pudb 运行代码时不会显示)

这就是世界:

world = [[ tile(yy,xx,True,'.')
    for xx in range(WORLD_WIDTH) ]
        for yy in range(WORLD_HEIGHT) ]

这是类图 block :

class tile:
def __init__(self,y,x,walkable,ch):
    self.x = x
    self.y = y
    self.walkable = walkable
    self.ch = ch

最后，这是调用 shelve 的完整函数:

def save_game():
    file = shelve.open('savegame', 'n')
    file['world'] = world
    file['player']= player

    file.close()

我相信这就是所有相关代码。

导致这些错误的原因是什么？

Answer 1

第一个问题是由实体类中的这一行引起的:

self.current_action = {'action': self.wait, 'cost': self.speed}

current_action 包含对绑定(bind)方法的引用，无法对其进行 pickle。您可以使用 __getstate__和 __setstate__确实会改变你的 pickle 行为，所以你不会在 pickle 时 pickle 方法，而是 pickle 它的名称(或者在分配了 partial 对象的情况下的名称和参数)，并在取消 pickle 时恢复该值。

我不太确定你的第二个问题，但如果它仅在调试器内运行时发生，则可能是调试器如何加载 __main__ 模块的问题。您可以尝试将 __main__ block 移动到另一个模块中，然后从那里导入并启动您的代码。有时这可以解决此类问题。