使用成员作为关键的字典 [英] Dictionary using member as key

问题描述

你有多少次创建了一个如下所示的字典：

how many times have you created a dictionary that looks like this:

MyClass a;
var data = new Dictionary<string, MyClass>();
data.Add(a.Name,a);

或者更糟糕的是：

Or maybe worse:

var data = new Dictionary<string, string>();
data.Add(a,a);

如果我们可以创建一个将键绑定到成员的字典怎么办？ ？

类似于：

what if we could create a Dictionary that bound the key to a member?
something like:

MyClass a;
var data = new MemberBindingDictionary<MyClass>("Name");
data.Add(a);
if(data.ContainsKey(a.Name))
{
...
}

我找不到类似的东西。那是因为这是一个愚蠢的想法吗？还是太贵了？

I couldn''t find anything like it. Is that because it''s a stupid idea? or is it too expensive?

推荐答案

这里没有班级在C＃中。但你可以自己创建一个类：

Hi,

There''s not a class like that in C#. But you can create a class like that yourself:

public class MemberBindingDictionary<T>:Dictionary<object, T>
    {
        Func<T,object> _binding = null;
        public MemberBindingDictionary(Func<T,object> binding)
        {
            _binding = binding;
        }
        public void Add(T value)
        {
            this.Add(_binding(value), value);
        }
    }

我没有使用字符串作为参数构造函数，但 Func 。现在，您可以使用此类，并使用lambda表达式将值绑定到键：

I don''t use a string as a parameter in the constructor, but a Func. Now, you can use this class, and bind the value to a key using a lambda expression:

MyClass a;
var data = new MemberBindingDictionary<MyClass>(x => x.Name);
data.Add(a);
if(data.ContainsKey(a.Name))
{
...
}

所以，不要写姓名，但要写 x => x.Name 。这是一个 lambda表达式 [ ^ ]



希望这有帮助。



格式化问题已修复[/编辑]

So, don''t write "Name", but write x => x.Name. This is a lambda expression[^]

Hope this helps.

Formatting problems fixed[/Edit]

我可能会像这样使用MyClass数组的链接。

I would probably just use link with an array of MyClass like this.

IEnumerable<myclass> data = new MyClass[] { new MyClass("Greg"), new MyClass("Peter"), new MyClass("Bobby") };

if (data.Count(x => x.Name == "Peter") > 0)
{
   // Do something.
}

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