WPF命令類重寫CanExecuteChanged-Event？

Question

目前我有以下命令類：

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 

在教程中，我看，你必須實現加{}並去除{}爲canExecuteChanged的事件。但我怎麼能做到這一點，與VB.NET？

非常感謝..

Answer 1

你需要實現添加和移除件爲CanExecuteChanged事件，我不認爲。我很肯定它現在可以正常工作。但是，如果你確實想因爲某些原因（使它與您在this post in C#,例如見），你會改變

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

到

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

如果在WPF你想使用命令請看WPF的框架存在。你會發現至少有兩個漂亮的命令執行：

• RelayCommand
• DelegateCommand