相关疑难解决方法(0)

C#有一个名为yield的关键字.VB.NET缺少这个关键字.Visual Basic程序员如何解决缺少此关键字的问题？他们是否实现了自己的迭代器类？或者他们尝试编码以避免需要迭代器？

该产量关键字不强制编译器做幕后的一些编码.在C#中实现迭代器及其后果(第1部分)就是一个很好的例子.

可能重复:
VB.NET中的产量

在C#中,当编写返回a的函数时IEnumerble<>,您可以使用yield return返回枚举的单个项目并yield break;表示没有剩余项目.做同样事情的VB.NET语法是什么？

NerdDinner代码中的一个示例:

public IEnumerable<RuleViolation> GetRuleViolations() {

   if (String.IsNullOrEmpty(Title))
       yield return new RuleViolation("Title required","Title");

   if (String.IsNullOrEmpty(Description))
       yield return new RuleViolation("Description required","Description");

   if (String.IsNullOrEmpty(HostedBy))
       yield return new RuleViolation("HostedBy required", "HostedBy");

   if (String.IsNullOrEmpty(Address))
       yield return new RuleViolation("Address required", "Address");

   if (String.IsNullOrEmpty(Country))
       yield return new RuleViolation("Country required", "Country");

   if (String.IsNullOrEmpty(ContactPhone))
       yield return new RuleViolation("Phone# required", "ContactPhone");

   if (!PhoneValidator.IsValidNumber(ContactPhone, Country))
       yield return new RuleViolation("Phone# does not match country", "ContactPhone");

   yield break;
}

这将C#转换为VB.NET工具 …

请注意,我知道其他的产量 在 vb.net这里做题.

我最近和Caliburn一起玩.一堆伟大的东西,包括合作例程的实施.

我正在做的大部分工作都是基于C#的,但现在我也正在为基于Rob的小型MVVM框架的VB.NET专卖店创建架构指南.

除了使用VB的协同程序外,一切看起来都很顺利.自从使用VB 10以来,我们可以尝试像Bill McCarthy的建议:

Public Function Lines(ByVal rdr as TextReader) As IEnumerable(Of String)
     Return New GenericIterator(Of String) 
          (Function(ByRef nextItem As String) As Boolean
              nextItem = rdr.ReadLine
              Return nextItem IsNot Nothing
           End Function)
End Function

我只是无法理解如何在VB中编写一个更复杂的常规方法(如Rob的GameLibrary中的方法):

public IEnumerable<IResult> ExecuteSearch()
{
    var search = new SearchGames
    {
        SearchText = SearchText
    }.AsResult();

    yield return Show.Busy();
    yield return search;

    var resultCount = search.Response.Count();

    if (resultCount == 0)
        SearchResults = _noResults.WithTitle(SearchText); …

使用下面的C#代码,您将如何在Visual Basic中编写它？它试图说什么？

using System;
using System.Collections.Generic;
using System.IO;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;

namespace Microsoft.LiveLabs.Pivot
{
    /// <summary>
    ///     Tile Builder class
    /// </summary>
    public static class TileBuilder
    {
        /// <summary>
        ///     Specifies which images are required in the images array used in CreateTile
        ///     according to the Morton fractal pattern used by Seadragon.
        /// </summary>
        /// <remarks>
        ///     Usage of this and CreateTile are kind of tricky. Here's an example:
        ///     Say you have a results …