如何处理内部类属性依赖关系? [英] How to handle innerclass attribute dependencies?

问题描述

如果要更改属性的类on change中的其他变量，只需为它编写一个property即可.如果您有简单的数据类型，那很好.但是，如果您的变量包含复杂的类型(如列表)(不是很不典型)，则可以更改内容本身，而无需再次调用variable.setter.

In case you want to change other variables in a class on change of an attribute you simply just write a property for it. That works fine, if you have a simple data type. But if your variable contains a complex type like a list (not so untypical), the content itself can be changed without calling the variable.setter again.

是否可以使用任何回调或事件来跟踪对类的列表属性的更改?还有什么其他方法可以使代码保持干净，又不破坏类的内部功能?

Are there any callbacks or events that can be used to track changes to a list attribute of a class? What else can be done to keep the code clean and not destroy the inner functionality of the class?

示例:

class Accumulator(object)
  def __init__(self,all_things):
     # :param all_things: a list of stuff of any kind
     self.__all_things = all_things
  @property
  def all_things(self):
     return self.__all_things
  @all_things.setter
  def all_things(self,input):
      self.__all_things = input

跳出框框思考可能是解决方案.首要任务不是使类结构保持活动状态，而是找到一种有效且允许使用干净API的模式！

Thinking outside the box is probably the solution. The priority is not to keep the class structure alive, but to find a pattern that works and allows a clean API!

推荐答案

您将不得不使用list的自定义子类来检测更改:

You would have to use a custom subclass of list to detect changes:

class MyList(list):
    on_change_callback = None

    def _notify(self):
        if self.on_change_callback is not None:
            self.on_change_callback(self)

    def __setitem__(self, index, value):
        super(MyList, self).__setitem__(self, index, value)
        self._notify()

    # Etc, each mutating method needs to be overridden.

您需要覆盖每个变异方法，调用原始方法(通过super())，然后调用self._notify().有关方法列表，请参见模拟容器类型部分.

You'd need to override each mutating method, call the original method (through super()), then call self._notify(). For a list of methods, see the Emulating container types section.

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