C#的翻译ActionCommand:ICommand的成VB.net [英] Translation of C# ActionCommand:ICommand into VB.net
问题描述
我发现了一个C#类ActionCommand,实现了ICommand和依据代表的执行和CanExecute。 。看上去很适合我至今
I found a C# class ActionCommand, that implements ICommand and bases on delegates for Execute and CanExecute. Looks perfect for me so far.
public class ActionCommand : ICommand
{
private readonly Action<object> _executeHandler;
private readonly Func<object, bool> _canExecuteHandler;
public ActionCommand(Action<object> execute, Func<object, bool> 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);
}
}
现在我将它译成我需要VB.net变种(使用代码翻译和一些手)
Now I translated it into my needed VB.net variant (using code translators and some hands on)
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
我的问题是围绕CanExecuteChanged和注册/映射从CommandManager.RequerySuggested到CanExecuteChanged的事件。网上代码翻译建议如下:
My problem is around CanExecuteChanged and registering/mapping the events from CommandManager.RequerySuggested to CanExecuteChanged. The online code translator suggest the following:
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
但是这不能satify ICommand.CanExecuteChanged
是否有人可以帮助如何翻译或解决这个问题?
but this cannot satify ICommand.CanExecuteChanged Can someone please help how to translate or solve this?
推荐答案
本文从的 MALIGUI .NET博客可能有帮助:
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
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