Emmanuele Sassi
68 lines
2.0 KiB
VB.net
68 lines
2.0 KiB
VB.net
''' <summary>
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''' A command whose sole purpose is to
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''' relay its functionality to other
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''' objects by invoking delegates. The
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''' default return value for the CanExecute
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''' method is 'true'.
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''' </summary>
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Public Class RelayCommand
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Implements ICommand
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#Region "Fields"
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Private ReadOnly _execute As Action(Of Object)
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Private ReadOnly _canExecute As Predicate(Of Object)
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#End Region ' Fields
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#Region "Constructors"
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''' <summary>
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''' Creates a new command that can always execute.
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''' </summary>
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''' <param name="execute">The execution logic.</param>
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Public Sub New(ByVal execute As Action(Of Object))
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Me.New(execute, Nothing)
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End Sub
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''' <summary>
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''' Creates a new command.
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''' </summary>
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''' <param name="execute">The execution logic.</param>
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''' <param name="canExecute">The execution status logic.</param>
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Public Sub New(ByVal execute As Action(Of Object), ByVal canExecute As Predicate(Of Object))
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If execute Is Nothing Then
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Throw New ArgumentNullException("execute")
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End If
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_execute = execute
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_canExecute = canExecute
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End Sub
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#End Region ' Constructors
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#Region "ICommand Members"
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<DebuggerStepThrough> _
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Public Function CanExecute(ByVal parameter As Object) As Boolean Implements ICommand.CanExecute
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Return If(_canExecute Is Nothing, True, _canExecute(parameter))
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End Function
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Public Custom Event CanExecuteChanged As EventHandler Implements ICommand.CanExecuteChanged
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AddHandler(ByVal value As EventHandler)
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AddHandler CommandManager.RequerySuggested, value
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End AddHandler
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RemoveHandler(ByVal value As EventHandler)
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RemoveHandler CommandManager.RequerySuggested, value
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End RemoveHandler
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RaiseEvent(ByVal sender As System.Object, ByVal e As System.EventArgs)
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End RaiseEvent
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End Event
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Public Sub Execute(ByVal parameter As Object) Implements ICommand.Execute
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_execute(parameter)
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End Sub
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#End Region ' ICommand Members
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End Class |