有没有一种更简单的方法来初始化一个List＆LT; KeyValuePair＆LT; T，U＆GT;＆gt;中像字典＆LT; T，U＆GT;？ [英] Is there a an easier way to initialize a List<KeyValuePair<T, U>>, like a Dictionary<T, U>?

问题描述

其实我需要的东西像名单，其中，KeyValuePair＆LT; T，U＆GT;＆GT; ，但我希望能够将其初始化像字典（即不写新KeyValuePair <​​/ code>每次）。像这样的：

 词典＆LT;字符串，字符串＆GT; DIC =新字典＆LT;字符串，字符串＆GT;
{
    {键1，值1}，
    {KEY2，值2}
};
 

解决方案

编辑：原来，.NET的确实的有一个组合列表/字典类型已：的 OrderedDictionary 。不幸的是，这是一个非泛型类型，使得它，而在我看来不那么有吸引力。但是，它保留了插入顺序，如果你只需要调用添加反复。

这是一个有点怪的叫添加并的没有的影响，其中一个键已经存在的条目，而使用的索引添加一个键/值对将覆盖previous关联。基本上，它似乎并不像一个非常不错的API，而我个人还是避免它，除非你的用例的完全的匹配它的行为。

---

没有，.NET没有任何插入命令 - preserving字典。你总是可以编写自己的基于列表的类型有关添加方法。这甚至可能是几个地方我会考虑扩展现有的类型之一：

 公共类KeyValueList＆LT; TKEY的，TValue＆GT; ：列表＆LT; KeyValuePair＆LT; TKEY的，TValue＆GT;＆GT;
{
    公共无效添加（TKEY的关键，TValue值）
    {
        加入（新KeyValuePair＆LT; TKEY的，TValue＆GT;（键，值））;
    }
}
 

然后：

  VAR列表=新KeyValueList＆LT;字符串，字符串＆GT;
{
    {键1，值1}，
    {KEY2，值2}
};
 

另一种方法是使用成分，但我的的感觉：的是，这是一个合理的使用继承。我不能把为什么我很高兴在这种情况下，而不是通常情况下，你要知道...

Actually I need something like List<KeyValuePair<T, U>> but I want to be able to initialize it like dictionary (i.e. without writing new KeyValuePair every time). Like this:

Dictionary<string, string> dic = new Dictionary<string, string>
{
    { "key1", "value1"}, 
    { "key2", "value2"}
};

解决方案

EDIT: It turns out .NET does have a combination list/dictionary type already: OrderedDictionary. Unfortunately this is a non-generic type, making it rather less attractive in my view. However, it retains the insertion order if you just call Add repeatedly.

It's a little strange as calling Add does not affect entries where a key already exists, whereas using the indexer to add a key/value pair will overwrite a previous association. Basically it doesn't seem like a terribly nice API, and I would personally still avoid it unless your use case exactly matches its behaviour.

---

No, .NET doesn't have any insertion-order-preserving dictionaries. You could always write your own list-based type with the relevant Add method. This might even be one of the few places I'd consider extending an existing type:

public class KeyValueList<TKey, TValue> : List<KeyValuePair<TKey, TValue>>
{
    public void Add(TKey key, TValue value)
    {
        Add(new KeyValuePair<TKey, TValue>(key, value));
    }
}

Then:

var list = new KeyValueList<string, string>
{
    { "key1", "value1"}, 
    { "key2", "value2"}
};

An alternative is to use composition, but my gut feeling is that this is a reasonable use of inheritance. I can't place why I'm happy in this case but not usually, mind you...

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