在运行时动态添加 C# 属性 [英] Dynamically Add C# Properties at Runtime

问题描述

我知道有一些问题可以解决这个问题，但答案通常遵循推荐字典或参数集合的方式，这在我的情况下不起作用.

I know there are some questions that address this, but the answers usually follow along the lines of recommending a Dictionary or Collection of parameters, which doesn't work in my situation.

我正在使用一个通过反射工作的库来对具有属性的对象做很多聪明的事情.这适用于定义的类以及动态类.我需要更进一步，并按照以下方式做一些事情:

I am using a library that works through reflection to do lots of clever things with objects with properties. This works with defined classes, as well as dynamic classes. I need to take this one step further and do something along these lines:

public static object GetDynamicObject(Dictionary<string,object> properties) {
    var myObject = new object();
    foreach (var property in properties) {
        //This next line obviously doesn't work... 
        myObject.AddProperty(property.Key,property.Value);
    }
    return myObject;
}

public void Main() {
    var properties = new Dictionary<string,object>();
    properties.Add("Property1",aCustomClassInstance);
    properties.Add("Property2","TestString2");

    var myObject = GetDynamicObject(properties);

    //Then use them like this (or rather the plug in uses them through reflection)
    var customClass = myObject.Property1;
    var myString = myObject.Property2;

}

该库与动态变量类型一起工作正常，手动分配属性.但是我不知道事先会添加多少或哪些属性.

The library works fine with a dynamic variable type, with properties assigned manually. However I don't know how many or what properties will be added beforehand.

推荐答案

你看过 ExpandoObject 了吗?

Have you taken a look at ExpandoObject?

见:http://blogs.msdn.com/b/csharpfaq/archive/2009/10/01/dynamic-in-c-4-0-introducing-the-expandoobject.aspx

来自 MSDN:

ExpandoObject 类使您能够在运行时添加和删除其实例的成员，还可以设置和获取这些成员的值.该类支持动态绑定，这使您可以使用像 sampleObject.sampleMember 这样的标准语法，而不是像 sampleObject.GetAttribute("sampleMember") 这样更复杂的语法.

The ExpandoObject class enables you to add and delete members of its instances at run time and also to set and get values of these members. This class supports dynamic binding, which enables you to use standard syntax like sampleObject.sampleMember instead of more complex syntax like sampleObject.GetAttribute("sampleMember").

允许你做很酷的事情，比如:

Allowing you to do cool things like:

dynamic dynObject = new ExpandoObject();
dynObject.SomeDynamicProperty = "Hello!";
dynObject.SomeDynamicAction = (msg) =>
    {
        Console.WriteLine(msg);
    };

dynObject.SomeDynamicAction(dynObject.SomeDynamicProperty);

<小时>

根据您的实际代码，您可能更感兴趣:

---

Based on your actual code you may be more interested in:

public static dynamic GetDynamicObject(Dictionary<string, object> properties)
{
    return new MyDynObject(properties);
}

public sealed class MyDynObject : DynamicObject
{
    private readonly Dictionary<string, object> _properties;

    public MyDynObject(Dictionary<string, object> properties)
    {
        _properties = properties;
    }

    public override IEnumerable<string> GetDynamicMemberNames()
    {
        return _properties.Keys;
    }

    public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        if (_properties.ContainsKey(binder.Name))
        {
            result = _properties[binder.Name];
            return true;
        }
        else
        {
            result = null;
            return false;
        }
    }

    public override bool TrySetMember(SetMemberBinder binder, object value)
    {
        if (_properties.ContainsKey(binder.Name))
        {
            _properties[binder.Name] = value;
            return true;
        }
        else
        {
            return false;
        }
    }
}

那样你只需要:

var dyn = GetDynamicObject(new Dictionary<string, object>()
    {
        {"prop1", 12},
    });

Console.WriteLine(dyn.prop1);
dyn.prop1 = 150;

从 DynamicObject 派生允许您想出自己的策略来处理这些动态成员请求，注意这里有怪物:编译器将无法验证很多动态调用，你不会得到智能感知，所以请记住这一点.

Deriving from DynamicObject allows you to come up with your own strategy for handling these dynamic member requests, beware there be monsters here: the compiler will not be able to verify a lot of your dynamic calls and you won't get intellisense, so just keep that in mind.

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