检测是否包含在字典中的值发生变化 [英] Detecting if a value contained in a Dictionary has changed

问题描述

如果我得到从IDictionary的一类，我怎么能肯定，之后它被添加到底层集合任何给定的V有没有变化？

If I derive a class from IDictionary, how can I be certain that any given V has not changed after it is added to the underlying collection?

推荐答案

有很多方法，但要看...

There's many ways, but it depends...

如果添加到字典中的值类型包含了一个改变事件类型，订阅它。

If the value type added to the dictionary contains a "Changed" type of event, subscribe to it.

如果值类型不包含这样的事件，但你控制的来源$ C ​​$ C，添加事件，并订阅了。

If the value type doesn't contain such an event, but you control the source code, add the event and subscribe to it.

如果值类型不包含这样一个事件，你不控制源头code，考虑维护的值的卷影副本与克隆的价值或什么的，并做比较。

If the value type doesn't contain such an event, and you don't control the source code, consider maintaining a shadow copy of the values with cloned values or something, and do comparisons.

我怕在最后一种情况出现，在那里你不用管的类型，它不包含事件，你别无选择，而是以某种方式使每个值的当前状态的记录，后来就比较的国家，看它是否已经改变了。

I'm afraid that in the last case there, where you don't control the type and it doesn't contain events, you're left with no choice but to somehow make a record of the current state of each value, and later on compare to that state to see if it has changed.

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