如何组织此代码？

Question

我试图通过将函数转换为方法将函数分类为适当的类（如果合适的话，可以将函数留在类之外）。但我不确定如何处理这个特定函数（如下所示）。你知道吗

首先，这是我的课：

class OreBlobAction:
   def __init__(self, entity, image_store):
      self.entity = entity
      self.image_store = image_store

   def ore_blob_action(self, world, action, ticks):
      entity = self.entity
      entity_pt = entities.get_position(self.entity)
      vein = find_nearest(world, entity_pt, entities.Vein)
      (tiles, found) = blob_to_vein(world, self.entity, vein)

      next_time = ticks + entities.get_rate(entity)
      if found:
         quake = create_quake(world, tiles[0], ticks, self.image_store)
         worldmodel.add_entity(world, quake)
         next_time = ticks + entities.get_rate(entity) * 2

      schedule_action(world, self.entity,
         OreBlobAction(self.entity, self.image_store), next_time)

      return tiles

现在，函数如下：

def take_action(world, action, ticks):
   entities.remove_pending_action(action.entity, action)
   if isinstance(action, VeinAction):
      return vein_action(world, action, ticks)
   elif isinstance(action, MinerNotFullAction):
      return miner_not_full_action(world, action, ticks)
   elif isinstance(action, MinerFullAction):
      return miner_full_action(world, action, ticks)
   elif isinstance(action, OreBlobAction):
      return ore_blob_action(world, action, ticks)
   elif isinstance(action, OreTransformAction):
      return ore_transform_action(world, action, ticks)
   elif isinstance(action, EntityDeathAction):
      return entity_death_action(world, action, ticks)
   elif isinstance(action, WyvernSpawnAction):
      return wyvern_spawn_action(world, action, ticks)
   elif isinstance(action, WyvernAction):
      return wyvern_action(world, action, ticks)
   elif isinstance(action, VeinSpawnAction):
      return vein_spawn_action(world, action, ticks)
   elif isinstance(action, AnimationAction):
      return animation_action(world, action, ticks)

   return []

如您所见，此函数不仅考虑了OreBlobAction类的操作，还考虑了其他多个类的操作。把这个函数留在OreBlobAction类之外会更好吗？还是有更好的办法？你知道吗

注意：如果我将此函数从OreBlobAction类中保留，并尝试运行该程序，则会出现以下错误：

NameError: global name 'ore_blob_action' is not defined

Answer 1

关于动作类型的大开关语句是重构的危险信号。有什么方法可以阻止您将“take action”方法移到action类本身吗？例如

class Action(object):
    """ An action that can be performed on the game world. """

    def perform(self, world, ticks):
        """ Perform the action. """
        raise NotImplementedError()

这将是您的基本操作类，然后在每种类型的操作中，您将重写perform(...)方法，例如

class WyvernSpawnAction(Action):
    """ An action that spawns a Wyvern. """

    [... Some action specific initialisation code here ...]

    def perform(self, world, ticks):
        """ Spawn a Wyvern. """
        world.spawn(Wyvern(...))

从世界上删除操作的样板文件将保留下来，现在您可以自由添加新类型的操作，而无需在函数中添加更多的比较。此外，您现在可以处理这样的情况：操作可以继承其他操作的行为，而不必非常小心比较的顺序。你知道吗