创建使用反射泛型列表 [英] Create a generic list using reflection

问题描述

我有一个使用反射来设置对象A从对象B.属性功能 在一个点上，我需要实例化一个泛型集合。但是，我无法得到它的工作。以下是我现在有：

I have a function that uses reflection to set properties of object A from object B. At one point, I need to instantiate a generic collection. However, I am unable to get it working. Here is what I have now:

IList list = destProperty.PropertyType.GetGenericTypeDefinition()
                .MakeGenericType(destProperty.PropertyType.GetGenericArguments())
                .GetConstructor(Type.EmptyTypes)
                .Invoke(null) as IList;

我想设置destProperty的价值。它必须是一个列表 在运行时，destProperty的类型的ICollection＆LT的;>。我想，这是怎么回事是，因为ICollection的是一个接口，它没有构造函数。什么是正确的方式来实例化它呢？

I am trying to set the value of the destProperty. It has to be a List At runtime, the destProperty is of type ICollection<>. I think what's happening is that since ICollection is an interface, it has no constructor. What is the proper way to instantiate it then?

谢谢！

推荐答案

我重新写你的code，进入一个例子的形式（希望符合你想做什么！=），尝试更清楚的问题是什么：

I've re-written your code, into the form of an example (hopefully that matches what you're trying to do! =), to try and make it clearer what the problem is:

public class Program
{
    public struct MyType
    {
        public ICollection<string> MyProperty { get; set; }
    }
    static void Main(string[] args)
    {
        var type = typeof(MyType);
        var properties = type.GetProperties();
        var destProperty = properties[0];

        var genericTypeDefinition = destProperty.PropertyType.GetGenericTypeDefinition();
        var madeGenericType = genericTypeDefinition.MakeGenericType(destProperty.PropertyType.GetGenericArguments());
        var ctor = madeGenericType.GetConstructor(Type.EmptyTypes);
    }
}

如果你把一个断点上的倒数第二个括号，你会看到男星回来为空，其中是因为，当你正确地推测，的ICollection＆LT; T＆GT; 没有任何构造函数，由于它是一个界面

If you put a breakpoint on the penultimate brace you'll see that ctor comes back as null, which is because, as you correctly surmised, ICollection<T> doesn't have any constructors due to it being an interface.

正因为如此，有这样做，因为没有固有的方式说不超通用的方式有什么的的ICollection＆LT最好的执行情况; T＆GT; 来使用在这种情况下。你需要做出决定和新一，根据你反映回来的信息。

Because of this, there's no "super-generic" way of doing this because there's no inherent way to say "what's the best implementation of ICollection<T> to use in this situation". You'll need to make that decision and new one, based on the information you get back from reflection.

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