如何重构Python“switch 语句”

发布于 2024-12-03 23:55:05 字数 1062 浏览 1 评论 0原文

我正在重构一位朋友编写的一些代码，最近偶然发现了这个函数：

def setup_parameters(self, data):
    '''Parse raw data to determine game settings.'''
    for line in data.split('\n'):
      line = line.strip().lower()
      if line:
        tokens = line.split()

        self.L.debug("tokens: " + str(tokens))

        key = tokens[0]
        if key == 'cols':
          self.width = int(tokens[1])
        elif key == 'rows':
          self.height = int(tokens[1])
        elif key == 'player_seed':
          random.seed(int(tokens[1]))
        elif key == 'turntime':
          self.turntime = int(tokens[1])
        elif key == 'loadtime':
          self.loadtime = int(tokens[1])
        elif key == 'viewradius2':
          self.viewradius2 = int(tokens[1])
        elif key == 'attackradius2':
          self.attackradius2 = int(tokens[1])
        elif key == 'spawnradius2':
          self.spawnradius2 = int(tokens[1])

如您所见，这里有一种令人讨厌的 switch 语句，它显然需要字典。我很想将其写为类字典，因为键是不变的，但由于键映射到实例的属性（即“cols”：self.width），因此无法编译。

那么我的问题是，重构此类代码的正确方法是什么？

原文

I'm refactoring some code that a friend wrote and recently stumbled across this function:

def setup_parameters(self, data):
    '''Parse raw data to determine game settings.'''
    for line in data.split('\n'):
      line = line.strip().lower()
      if line:
        tokens = line.split()

        self.L.debug("tokens: " + str(tokens))

        key = tokens[0]
        if key == 'cols':
          self.width = int(tokens[1])
        elif key == 'rows':
          self.height = int(tokens[1])
        elif key == 'player_seed':
          random.seed(int(tokens[1]))
        elif key == 'turntime':
          self.turntime = int(tokens[1])
        elif key == 'loadtime':
          self.loadtime = int(tokens[1])
        elif key == 'viewradius2':
          self.viewradius2 = int(tokens[1])
        elif key == 'attackradius2':
          self.attackradius2 = int(tokens[1])
        elif key == 'spawnradius2':
          self.spawnradius2 = int(tokens[1])

As you can see, there is a nasty kind of switch statement here, that clearly calls for a dictionary. I'm tempted to write this as a class dictionary since the keys are constant, but since the keys map to attributes of an instance (ie, 'cols': self.width) this doesn't compile.

My question is then, what is the right way to refactor such code?

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怀中猫帐中妖 2024-12-10 23:55:05

将键映射到属性的名称，并使用setattr(self, attribute_name, int(tokens[1]) 设置值。例如：

attribute_dict = dict(cols="width", rows="height", turntime="turntime", ...)
[...]
value = int(tokens[1])
if key == "player_seed":
    random.seed(value)
else:
    setattr(self, attribute_dict[key], value)

Map the keys to the names of the attributes, and use setattr(self, attribute_name, int(tokens[1]) to set the value. E.g.:

attribute_dict = dict(cols="width", rows="height", turntime="turntime", ...)
[...]
value = int(tokens[1])
if key == "player_seed":
    random.seed(value)
else:
    setattr(self, attribute_dict[key], value)

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囚我心虐我身 2024-12-10 23:55:05

您可以构建一个字典，其中键作为访问器，并使用 lambda 函数来执行每个键的代码。

回复收藏 0 原文

拥抱我好吗 2024-12-10 23:55:05

使用以下操作设置一个字典

actions = dict(cols = lambda tokens: setattr(self, "width", int(tokens[1]), ... 
               player_seed = lambda tokens: random.seed(int(tokens[1]))
              )

：

 actions[key](tokens)

setup a dict with actions like

actions = dict(cols = lambda tokens: setattr(self, "width", int(tokens[1]), ... 
               player_seed = lambda tokens: random.seed(int(tokens[1]))
              )

and then: