Traduzione di C # ActionCommand: ICommand in VB.net

Ho trovato una class C # ActionCommand, che implementa ICommand e si basa su delegati per Execute e CanExecute. Sembra perfetto per me finora.

public class ActionCommand : ICommand { private readonly Action _executeHandler; private readonly Func _canExecuteHandler; public ActionCommand(Action execute, Func canExecute) { if (execute == null) throw new ArgumentNullException("Execute cannot be null"); _executeHandler = execute; _canExecuteHandler = canExecute; } public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } public void Execute(object parameter) { _executeHandler(parameter); } public bool CanExecute(object parameter) { if (_canExecuteHandler == null) return true; return _canExecuteHandler(parameter); } } 

Ora l’ho tradotto nella mia variante VB.net necessaria (usando i traduttori di codice e alcune mani)

 Public Class ActionCommand Implements ICommand Public Event CanExecuteChanged As EventHandler Implements ICommand.CanExecuteChanged Private ReadOnly _executeHandler As Action(Of Object) Private ReadOnly _canExecuteHandler As Func(Of Object, Boolean) Public Sub New(ByVal execute As Action(Of Object), ByVal canExecute As Func(Of Object, Boolean)) If execute Is Nothing Then Throw New ArgumentNullException("Execute cannot be null") End If _executeHandler = execute _canExecuteHandler = canExecute End Sub Public Sub Execute(ByVal parameter As Object) Implements ICommand.Execute _executeHandler(parameter) End Sub Public Function CanExecute(ByVal parameter As Object) As Boolean Implements ICommand.CanExecute If (_canExecuteHandler Is Nothing) Then Return True End If Return _canExecuteHandler(parameter) End Function End Class 

Il mio problema riguarda CanExecuteChanged e la registrazione / mapping degli eventi da CommandManager.RequerySuggested a CanExecuteChanged. Il traduttore del codice online suggerisce quanto segue:

 Public Custom Event CanExecuteChanged As EventHandler AddHandler(ByVal value As EventHandler) CommandManager.RequerySuggested += value End AddHandler RemoveHandler(ByVal value As EventHandler) CommandManager.RequerySuggested -= value End RemoveHandler End Event 

ma questo non può soddisfare ICommand.CanExecuteChanged Qualcuno può aiutare come tradurre o risolvere questo?

Questo articolo di MALIGUI .NET BLOG potrebbe aiutare:

 Public Custom Event CanExecuteChanged As EventHandler _ Implements ICommand.CanExecuteChanged AddHandler(ByVal value As EventHandler) Dim handler2 As EventHandler Dim canExecuteCommand = __CanExecuteCommand Do handler2 = canExecuteCommand Dim handler3 = DirectCast(System.Delegate.Combine(handler2, value), EventHandler) canExecuteCommand = Interlocked.CompareExchange((__CanExecuteCommand), handler3, handler2) Loop While (Not canExecuteCommand Is handler2) __CanExecuteCommand = canExecuteCommand End AddHandler RemoveHandler(ByVal value As EventHandler) Dim handler2 As EventHandler Dim canExecuteCommand = __CanExecuteCommand Do handler2 = canExecuteCommand Dim handler3 = DirectCast(System.Delegate.Remove(handler2, value), EventHandler) canExecuteCommand = Interlocked.CompareExchange((__CanExecuteCommand), handler3, handler2) Loop While (Not canExecuteCommand Is handler2) __CanExecuteCommand = canExecuteCommand End RemoveHandler RaiseEvent(ByVal sender As Object, ByVal e As EventArgs) If (__CanExecuteCommand IsNot Nothing) Then __CanExecuteCommand.Invoke(sender, e) End If End RaiseEvent End Event 
 Public Custom Event CanExecuteChanged As EventHandler AddHandler(ByVal value As EventHandler) AddHandler CommandManager.RequerySuggested, value End AddHandler RemoveHandler(ByVal value As EventHandler) RemoveHandler CommandManager.RequerySuggested, value End RemoveHandler End Event 

Penso che quello che stai cercando sia più simile a:

  Public Custom Event CanExecuteChanged As EventHandler _ Implements ICommand.CanExecuteChanged AddHandler(ByVal value As EventHandler) AddHandler CommandManager.RequerySuggested, value End AddHandler RemoveHandler(ByVal value As EventHandler) RemoveHandler CommandManager.RequerySuggested, value End RemoveHandler RaiseEvent(ByVal sender As Object, ByVal e As System.EventArgs) CanExecute(sender) End RaiseEvent End Event