如何組織此代碼？

Question

我試圖通過將函數轉換為方法來將函數分類到適當的類中（如果合適，可以將函數留在類之外）。 但我不確定如何處理這個特定的功能（如下所示）。

首先，這是我的課：

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

現在，這是函數：

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 []

如您所見，此函數不僅考慮了 OreBlobAction 類的操作，還考慮了多個其他類的操作。 將此函數留在 OreBlobAction 類之外會更好嗎？ 或者有沒有更好的方法來做到這一點？

注意：如果我將此函數排除在 OreBlobAction 類之外，並嘗試運行該程序，則會出現以下錯誤：

NameError: global name 'ore_blob_action' is not defined

Answer 1

你關於動作類型的大 switch 語句是重構的危險信號。 有什么可以阻止您將“采取行動”方法轉移到行動類本身中嗎？ 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()

這將是您的基本操作類，然后在每種類型的操作中，您將覆蓋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(...))

從世界中刪除動作的樣板將保留，您現在可以自由添加新類型的動作，而無需最終在您的函數中添加數百個比較。 此外，您現在可以處理操作可以繼承其他操作的行為的情況，而不必非常小心比較的順序。