WPF 命令类重写 CanExecuteChanged-Event？

Question

目前我有以下 Command 类：

Public Class SubscribeCommand
    Implements ICommand

    Private ReadOnly _vm As MainWindowViewModel

    Public Sub New(ByVal vm As MainWindowViewModel)
        _vm = vm
    End Sub

    Public Function CanExecute(ByVal parameter As Object) As Boolean Implements System.Windows.Input.ICommand.CanExecute
        Return Not String.IsNullOrEmpty(_vm.Symbol)
    End Function

    Public Event CanExecuteChanged(ByVal sender As Object, ByVal e As System.EventArgs) Implements System.Windows.Input.ICommand.CanExecuteChanged

    Public Sub Execute(ByVal parameter As Object) Implements System.Windows.Input.ICommand.Execute
        _vm.Subscribe()
    End Sub
End Class

在我读过的教程中，您必须为 canExecuteChanged-Event 实现 add {} 和 remove {} 。但是我怎样才能用vb.net做到这一点呢？

多谢..

Answer 1

我认为您不需要为 CanExecuteChanged 事件实现添加和删除部分。我很确定它会按照您现在的方式正常工作。但是，如果您出于某种原因确实想要（使其与您在 C# 中的这篇文章， 例如），您将更

Public Event CanExecuteChanged(ByVal sender As Object, ByVal e As System.EventArgs)

改为

Public Custom Event CanExecuteChanged As EventHandler

    AddHandler(ByVal value As EventHandler)

        CommandManager.RequestSuggested += value

    End AddHandler

    RemoveHandler(ByVal value As EventHandler)

           CommandManager.RequestSuggested -= value

    End RemoveHandler

End Event

Answer 2

如果你想在 wpf 中使用命令，请查看那里的 wpf 框架。你会发现至少有两个不错的命令实现：

• RelayCommand
• DelegateCommand