如何重构Python“switch语句" [英] How to refactor Python "switch statement"

问题描述

我正在重构朋友写的一些代码，最近偶然发现了这个函数:

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])

如您所见，这里有一种令人讨厌的 switch 语句，它显然需要字典.我很想把它写成一个类字典，因为键是常量，但由于键映射到实例的属性(即，'cols': self.width)这不会编译.

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.

那么我的问题是，重构此类代码的正确方法是什么?

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

推荐答案

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:

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)

这篇关于如何重构Python“switch语句"的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！