尝试赶上IEnumerable无法正常工作

问题描述

以下代码段旨在在枚举时捕获所有异常，并忽略该特定项。

using System;
using System.Linq;
using System.Collections.Generic;

public class Program
{
     public static void Main()
        {
            DataProvider[] dataproviders = new DataProvider[]
            {
                new DataProvider(itemCount: 3,throwAfter: 1),new DataProvider(itemCount: 4),};
            var output = ListEnumerable(dataproviders).ToList();
            // We'll never get there. I excepted items from second dataprovider here
            Console.WriteLine("Success");
        }
        private static IEnumerable<Item> ListEnumerable(IEnumerable<DataProvider> providers)
        {
            ArgumentException providerException = null;
            foreach (DataProvider provider in providers)
            {
                providerException = null;
                try
                {
                    return provider.GetData();
                }
                catch (ArgumentException ex)
                {
                    // Expected to catch the argumentexception thrown in GetData here. This never happens
                    providerException = ex;
                    Console.WriteLine("Exception caught");
                }
            }
            if (providerException != null)
            {
                throw providerException;
            }
            return Enumerable.Empty<Item>();
        }
        private class DataProvider
        {
            public DataProvider(int itemCount = 3,int throwAfter = -1)
            {
                this.ItemCount = itemCount;
                this.ThrowAfter = throwAfter;
            }
            public int ItemCount { get; }
            public int ThrowAfter { get; }
            public IEnumerable<Item> GetData()
            {
                for (int i = 0; i < this.ItemCount; ++i)
                {
                    if (i == this.ThrowAfter)
                    {
                        throw new ArgumentException("Thrown after " + i);
                    }
                    yield return new Item();
                }
            }
        }
        private class Item
        {
            public string Name = Guid.NewGuid().ToString();
        }
}

我希望在ListEnumerable中引发异常，然后转到下一项。但是，运行摘要会导致在main中引发异常。

为什么会这样？用懒惰的评估仍然完整的数据来表达这一点的正确方法是什么？

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

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