关于DataGrid 取选中行的值时Mscorlib_CollectionDebugView问题

当Mscorlib_CollectionDebugView解析不出来时，可添加如下的namespace，原理不太清楚，是我在microsoft官网上查询相关的类，添加出来的，Generic里应该不需要那么多的类，节省时间，我基本上都粘贴复制了，能用就好

using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.Contracts;
using System.Collections.ObjectModel;
using System.Security.Permissions;

namespace System.Collections.Generic
{
using System;
using System.Collections.ObjectModel;
using System.Security.Permissions;
using System.Diagnostics;
using System.Diagnostics.Contracts;

//
// VS IDE can't differentiate between types with the same name from different
// assembly. So we need to use different names for collection debug view for 
// collections in mscorlib.dll and system.dll.
//
public sealed class Mscorlib_CollectionDebugView<T>
{

    private ICollection<T> collection;

    public Mscorlib_CollectionDebugView(ICollection<T> collection)
    {
        if (collection == null)
            ThrowHelper.ThrowArgumentNullException(ExceptionArgument.collection);

        this.collection = collection;
    }

    internal static class ThrowHelper
    {
        internal static void ThrowArgumentNullException(ExceptionArgument argument)
        {
            throw new System.ArgumentNullException(GetArgumentName(argument));
        }
    }


    internal enum ExceptionArgument
    {
        obj,
        dictionary,
        dictionaryCreationThreshold,
        array,
        info,
        key,
        collection,
        list,
        match,
        converter,
        queue,
        stack,
        capacity,
        index,
        startIndex,
        value,
        count,
        arrayIndex,
        name,
        mode,
        item,
        options,
        view,
        sourceBytesToCopy,
    }

    internal static string GetArgumentName(ExceptionArgument argument)
    {
        string argumentName = null;

        switch (argument)
        {
            case ExceptionArgument.array:
                argumentName = "array";
                break;

            case ExceptionArgument.arrayIndex:
                argumentName = "arrayIndex";
                break;

            case ExceptionArgument.capacity:
                argumentName = "capacity";
                break;

            case ExceptionArgument.collection:
                argumentName = "collection";
                break;

            case ExceptionArgument.list:
                argumentName = "list";
                break;

            case ExceptionArgument.converter:
                argumentName = "converter";
                break;

            case ExceptionArgument.count:
                argumentName = "count";
                break;

            case ExceptionArgument.dictionary:
                argumentName = "dictionary";
                break;

            case ExceptionArgument.dictionaryCreationThreshold:
                argumentName = "dictionaryCreationThreshold";
                break;

            case ExceptionArgument.index:
                argumentName = "index";
                break;

            case ExceptionArgument.info:
                argumentName = "info";
                break;

            case ExceptionArgument.key:
                argumentName = "key";
                break;

            case ExceptionArgument.match:
                argumentName = "match";
                break;

            case ExceptionArgument.obj:
                argumentName = "obj";
                break;

            case ExceptionArgument.queue:
                argumentName = "queue";
                break;

            case ExceptionArgument.stack:
                argumentName = "stack";
                break;

            case ExceptionArgument.startIndex:
                argumentName = "startIndex";
                break;

            case ExceptionArgument.value:
                argumentName = "value";
                break;

            case ExceptionArgument.name:
                argumentName = "name";
                break;

            case ExceptionArgument.mode:
                argumentName = "mode";
                break;

            case ExceptionArgument.item:
                argumentName = "item";
                break;

            case ExceptionArgument.options:
                argumentName = "options";
                break;

            case ExceptionArgument.view:
                argumentName = "view";
                break;

            case ExceptionArgument.sourceBytesToCopy:
                argumentName = "sourceBytesToCopy";
                break;

            default:
                Contract.Assert(false, "The enum value is not defined, please checked ExceptionArgumentName Enum.");
                return string.Empty;
        }

        return argumentName;
    }


    [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
    public T[] Items
    {
        get
        {
            T[] items = new T[collection.Count];
            collection.CopyTo(items, 0);
            return items;
        }
    }
}

}