Question

我试图在python中编写一个简单的对象，它将使用ConfigParser加载设置，将所有项目作为字典，然后将它们设置为对象的属性。

如果我不包含__setattr__方法，这似乎有效。我可以调用“settings.top_travel”并获得答案。但是，一旦我尝试放置__setattr__，我似乎就会收到错误。

它看起来相当递归，所以我假设Get正在调用Set等。在set属性部分中，我希望将其写回配置文件。因此，只要其中一个设置属性发生更改，它就会存储回文件来源。

您将在下面找到代码和错误。

import ConfigParser

class settingsFile(object):

    def __init__(self):

        """
        Reloads the configuration file and returns a dictionary with the 
        settings :
        [config]
        top_travel = 250
        """
        # Create a configuration object and read in the file
        configuration = ConfigParser.ConfigParser()
        configuration.read('config/config.cfg')

        # Return all the "config" section as a list and convert to a dictionary
        self.configuration = dict(configuration.items("config"))

    def refresh(self):

        self.__init__()

    def __getattr__(self, attr):
        return self.configuration[attr]

    def __setattr__(self, attr, value):
        print attr, " is now ", value
        # Do some clever storing with ConfigParser

if __name__ == "__main__":

    settings = settingsFile()
    print settings.top_travel
    settings.top_travel = 600
    print settings.top_travel

错误：

Traceback (most recent call last):
  File "/home/stuff/Documents/Software/Python/dBControllers v2/dBControllers.py", line 52, in <module>
    settings = settingsFile()
  File "/home/stuff/Documents/Software/Python/dBControllers v2/dBControllers.py", line 37, in __init__
    self.configuration = dict(configuration.items("config"))
  File "/home/stuff/Documents/Software/Python/dBControllers v2/dBControllers.py", line 47, in __setattr__
    print self.configuration[attr], " is now ", value
  File "/home/stuff/Documents/Software/Python/dBControllers v2/dBControllers.py", line 44, in __getattr__
    return self.configuration[attr]
  File "/home/stuff/Documents/Software/Python/dBControllers v2/dBControllers.py", line 44, in __getattr__
    return self.configuration[attr]
......
RuntimeError: maximum recursion depth exceeded

Answer 1

问题是设置self.configuration会调用self.__setattr__

您可以通过将分配更改为对超类__setattr__的调用来规避这一点：

class settingsFile(object):

    def __init__(self):
        ...
        # Return all the "config" section as a list and convert to a dictionary
        object.__setattr__(self, 'configuration', dict(configuration.items("config")))

Answer 2

使__setattr__对不以'_'开头的属性独占，并将配置存储在self._configuration中，然后添加一个要求，即配置文件不接受名称以下划线开头的选项。< / p>

def __setattr__(self, attribute, value):
     if attribute.startswith('_'):
          super(settingsFile, self).__setattr__(attribute, value)
          return
     # Clever stuff happens here

Answer 3

无论你使用ConfigParser做什么聪明的东西，都会无限递归。我无法确定，因为我没有看到代码，但如果您正在使用递归，请确保涵盖所有基本情况。

在python中引入setattr时的递归错误

3 个答案: