为什么你会使用在字典中一个不变的价值？ [英] Why would you use an immutable value in a dictionary?

问题描述

的多个答案质疑多值字典建议使用一个不变的类 TValue 在 字典＆LT; TKEY的，TValue＆GT; 类。

The multiple answers to question "Multi value Dictionary" propose to use an immutable class as TValue in Dictionary<TKey, TValue> Class.

在接受乔恩斯基特的回答提出了一种类对与只读属性和 @ teedyay的回答使用一成不变的 元组 。

The accepted Jon Skeet's answer proposes a class Pair with readonly properties and @teedyay's answer to use the immutable Tuple.

什么是基本原理（或可能带来的好处）这样的办法？

What is the rationale (or the possible benefits) of such approaches?

和抵押的问题：
为什么使TFirst和TSecond只读如果各自的属性第一和第二没有setter方法​​呢：

And collateral question:
Why to make TFirst and TSecond readonly if the respective properties First and Second do not have setters anyway:

private readonly TFirst first;
private readonly TSecond second;

public TFirst First
{
   get { return first; }
}

public TSecond Second
{
   get { return second; }
}

更新：
我使用的字典，可以自定义类在他们的价值观。
而VA梅毒正在更新。照片 可能是什么原因（利益），我让他们一成不变？

Update:
I am using dictionaries with custom classes for values in them.
And the va lues are being updated.
What are the possible reasons (benefits) for me to make them immutable?

我看到 查找＆LT; TKEY的，TElement＆GT;类 也是不可改变的，以为我会错过使用LINQ查询一些好处（？）
如果是这样，你能给我什么样的例子我错过？

I see that Lookup<TKey, TElement> Class is also immutable and thought that I miss some benefits of using LINQ queries (?)
If so, can you give me examples what do I miss?

推荐答案

第二个问题的答案是，成员变量依然可设置不用只读关键字 - 只在类本身，但它仍然是可能的。

Second question's answer is that the member variables are still settable without the readonly keyword - only within the class itself, but it is still possible.

顺便说一句，这个类似乎是一个坚实的候选人为结构。

BTW, this class seems like a solid candidate for a struct.

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