C#创建一个不可为空的字符串.是否有可能?不知何故? [英] C# creating a non-nullable string. Is it possible? Somehow?

问题描述

所以您不能继承string.您不能创建不可为空的string.但是我想这样做.我想要一个类，我们将其称为nString，否则它将为null时将返回默认值.我有可能知道谁有多少个空字符串甚至什至空对象的JSON对象.我想创建具有永远不会返回null的字符串的结构.

So you can't inherit string. You can't make a non-nullable string. But I want to do this. I want a class, let's call it nString that returns a default value when it would otherwise be null. I have JSON objects that might have who knows how many null strings, or even null objects. I want to create structs that have strings that will never return null.

public struct Struct
{
    public nString value;
    public nString value2;
}

我想我可以做这样的事情:

I suppose I could do something like this:

public struct Struct
{
    public string val { get { return val ?? "N/A"; } set { val = value; } }
    public string val2 { get { return val2 ?? "N/A"; } set { val2 = value; } };
}

但是还有很多工作要做.有什么办法吗?

But that's so much more work. Is there any way to do this?

推荐答案

您当然可以具有以下nString结构:

You could of course have the following nString struct:

public struct nString
{
    public nString(string value)
        : this()
    {
        Value = value ?? "N/A";
    }

    public string Value
    {
        get;
        private set;
    }

    public static implicit operator nString(string value)
    {
        return new nString(value);
    }

    public static implicit operator string(nString value)
    {
        return value.Value;
    }
}

...

public nString val 
{ 
    get;
    set;
}

obj.val = null;
string x = obj.val; // <-- x will become "N/A";

这将允许从string进行投射.在幕后，它执行与示例相同的转换，您不必为每个属性都键入它.我确实想知道这对您的应用程序的可维护性有什么影响.

This would allow casting from and to string. Under the hood it performs the same cast as your example, you just don't have to type it out for every property. I do wonder what this does to maintainability for your application though.

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