如何使字典扩展方法？ [英] How to make dictionary extension-methods?

问题描述

我正在尝试编写一个独立于Key / Value的数据类型的字典扩展。我尝试通过使用对象数据类型传递它，假设它将适用于任何类型。

I'm trying to write a Dictionary extension that works independently of the data types of Key/Value. I tried pass it by using the object data type, assuming that it will works with any type.

我的代码：

 public static class DictionaryExtensionsClass
    {
        public static void AddFormat(this Dictionary< ?? unknow type/*object*/, ??unknow type/*object*/> Dic, ??unknow type/*object*/ Key, string str, params object[] arglist)
        {
            Dic.Add(Key, String.Format(str, arglist));
        }
    }

推荐答案

你只需使方法通用：

public static void AddFormat<TKey>(this Dictionary<TKey, string> dictionary,
    TKey key,
    string formatString,
    params object[] argList)
{
    dictionary.Add(key, string.Format(formatString, argList));
}

请注意，这只是通用的键类型因为 将 code> string implements，我猜）给定你要添加一个字符串值。

Note that it's only generic in the key type as the value would have to be string (or potentially object or an interface that string implements, I guess) given that you're going to add a string value to it.

不幸的是你可以'真的表达了限制，只允许值类型，其中 string 是一个有效的值在通用类型约束。

Unfortunately you can't really express the constraint of "only allow value types where string is a valid value" in a generic type constraint.

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