IOrderedEnumerable 到 vb.net IOrderedEnumerable 的转换答案

【问题标题】：IOrderedEnumerable to vb.net IOrderedEnumerable ConversionIOrderedEnumerable 到 vb.net IOrderedEnumerable 的转换
【发布时间】：2015-06-08 14:28:09
【问题描述】：

Private Sub UpdateListBox(message As String)
    Dim beeGroups As IOrderedEnumerable(Of IGrouping(Of BeeState, Bee)) = From beeGroup In From bee In Me.world.BeesGroup bee By bee.CurrentStateOrder By beeGroup.KeybeeGroup
    Me.listBox1.Items.Clear()

    For Each beeGroup As IGrouping(Of BeeState, Bee) In beeGroups
        Dim s As String
        s = If(beeGroup.Count() = 1, String.Empty, "s")

        Me.listBox1.Items.Add(Convert.ToString(beeGroup.Key) & ": " & beeGroup.Count() & " bee" & s)

        If beeGroup.Key <> BeeState.Idle OrElse beeGroup.Count() <> Me.world.Bees.Count() OrElse Me.framesRun <= 0 Then
            Continue For
        End If

        Me.listBox1.Items.Add("Simulation ended: all bees are idle")
        Me.toolStripButtonStartSimulation.Text = "Simulation ended."
        Me.statusStrip1.Items(0).Text = "Simulation ended"
        Me.timer1.Enabled = False
    Next
End Sub

在将c# 项目转换为vb.net 时，我完全陷入了这个错误。

我知道c#是这样的

IOrderedEnumerable<IGrouping<BeeState, Bee>> beeGroups = from bee in this.world.Bees
                                                                 group bee by bee.CurrentState
                                                                 into beeGroup orderby beeGroup.Key select beeGroup;

但一旦转换为vb.net，它会尝试用最少的声明在一行上声明所有内容。

在c# 中，您也可以逃脱 c#：

foreach (IGrouping<BeeState, Bee> beeGroup in beeGroups)

vb.net 尝试在自身内部声明 for 语句：

For Each group As var In beeGroups

【问题讨论】：

I'm absolutely stuck at this error in the conversion of a c# project to vb.net 究竟是什么错误？

标签： c# asp.net .net vb.net iorderedenumerable

【解决方案1】：

Private Sub UpdateListBox(message As String)
    Dim beeGroups = From bee In Me.world.Bees
                    Group By bee.CurrentState Into beeGroup = Group
                    Order By beeGroup.Key

    Me.listBox1.Items.Clear()

    For Each beeGroup In beeGroups
        Dim beeCount = beeGroup.Count ' to avoid reevaluation
        Dim s = If(beeCount >= 1, String.Empty, "s")

        Me.listBox1.Items.Add(Convert.ToString(beeGroup.Key) & ": " & beeCount & " bee" & s)

        If beeGroup.Key <> BeeState.Idle OrElse beeCount <> Me.world.Bees.Count OrElse Me.framesRun <= 0 Then
            Continue For
        End If

        Me.listBox1.Items.Add("Simulation ended: all bees are idle")
        Me.toolStripButtonStartSimulation.Text = "Simulation ended."
        Me.statusStrip1.Items(0).Text = "Simulation ended"
        Me.timer1.Enabled = False
    Next
End Sub

【讨论】：

【解决方案2】：

您的“For Each”语句是正确的（您的 C# 和 VB 版本都在循环头中声明了迭代器变量），但是 VB LINQ 查询应该是：

Dim beeGroups As IOrderedEnumerable(Of IGrouping(Of BeeState, Bee)) = From bee In Me.world.Bees
                                                                      Group bee By bee.CurrentState Into beeGroup = Group
                                                                      Order By CurrentState
                                                                      Select beeGroup

或用户选项推断开启：

Dim beeGroups = From bee In Me.world.Bees
                Group bee By bee.CurrentState Into beeGroup = Group
                Order By CurrentState
                Select beeGroup

【讨论】：

Select 默认情况下在 VB.Net 中不需要，查询返回当前在查询范围内的内容（在这种情况下只有 beeGroup）。此外，您忘记在Order By 子句中通过bee. 限定CurrentState ;)
select beeGroup from Dim beeGroups 之后。当我事后声明 For Each beeGroup In beeGroup 时，它的行为就像 select beeGroup 甚至不存在。我可以看到 beeGroup 在 beeGroup 中声明，错误是混淆。我会以错误的方式使用 IEnumerable 并声明吗？谢谢你之前的帮助:)
好的，错误是它没有被声明，我的困惑太大了，无法放入变量中：D。但是他们是在beeGroups之前声明beeGroup的一种方式，或者如果你能想到一个更好的方式。