Class Object返回覆盖的Dictionary< string，object> [英] Class Object return overrided Dictionary<string, object>

问题描述

我有这段代码：

I have this code:

public class DB
{
public Dictionary<string,object> DATA = new Dictionary<string,object>();
public DB()
{
this.DATA = new Dictionary<string,object>();
}
public override string ToString()
{
    return DATA.Count.ToString();
}
}

我想覆盖字典< string，object> as对象就像覆盖字符串ToString（），如下面的代码：

I wanting to override the Dictionary<string,object> as object just like the "override string ToString()" like the codes below:

void main()
{
DB value = new DB();
value.Add("Attr1", new ClassA());
value.Add("Attr2", new ClassB());
value["Attr1"] = new ClassC();
}

但是现在，我只能做到这一点而不是以上：

But for now, I only able to do this instead of above:

void main()
{
DB value = new DB();
value.DATA.Add("Attr1", new ClassA());
value.DATA.Add("Attr2", new ClassB());
value.DATA["Attr1"] = new ClassC();
}

是否有任何解决方案或类似的解决方案？

Is there any solution to that or similar to it?

推荐答案

好吧，你不能覆盖一个字段。但我认为你想要一个索引属性 - 但你仍然需要实现Add（）方法。看看这里： https://msdn.microsoft.com/en -us / library / aa288464％28v = vs.71％29.aspx [ ^ ]。



[Update1]

如果你只需要使用ToString，只需覆盖它：

Well, you can't override a field. But I think you want an indexed property - but you will still need to implement the Add() methods. Take a look here: https://msdn.microsoft.com/en-us/library/aa288464%28v=vs.71%29.aspx[^].

[Update1]
If yor only need is to oveddide ToString, override it simply:

public class DB : Dictionary<string,object>
{
public override string ToString()
{
    return this.Count.ToString();
}
}

[Update2]

了解在这种情况下如何使用真正的封装和索引属性。完全按照您的意愿：

[Update2]
See how real encapsulation and index property could be used in this case. Exactly as you wanted:

public class DB
{
    private Dictionary<string,object> DATA = new Dictionary<string,object>();
    public DB()
    {
        this.DATA = new Dictionary<string,object>();
    }

    public string ToString()
    {
        return DATA.Count.ToString();
    }

    public void Add(string index, object value)
    {
        DATA.Add(index, value);
    }

    public object this[string index]
    {
        get
        {
            if(DATA.ContainsKey(index))
            {
                return DATA[index];
            }
            else
            {
                return null;
            }
        }
        set
        {
            if(DATA.ContainsKey(index))
            {
                DATA[index] = value;
            }
            else
            {
                DATA.Add(index, value);
            }
        }
    }
}

void Main()
{
    DB value = new DB();
    value.Add("Attr1", 1);
    value.Add("Attr2", 2);
    value["Attr1"] = 3;
    value["Attr3"] = 4;

    Console.WriteLine(value.ToString()); // 3
    Console.WriteLine(value["Attr1"]);// 3
    Console.WriteLine(value["Attr2"]);// 2
    Console.WriteLine(value["Attr3"]);// 4
    Console.WriteLine(value["Attr4"]);// null
}

使用e xtend

use extend

public class DB 
{
public Dictionary<string,object> DATA = new Dictionary<string,object>();
public DB()
{
this.DATA = new Dictionary<string,object>();
}
public override string ToString()
{
    return DATA.Count.ToString();
}
}

to：

to:

public class DB : Dictionary<string,object>
{
public Dictionary<string,object> DATA = new Dictionary<string,object>();
public DB()
{
this.DATA = new Dictionary<string,object>();
}
public override string ToString()
{
    return DATA.Count.ToString();
}
}

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