Command パターン

なおこ(・∀・)さんのサイトではこちら。

処理をクラスとして表現するわけですね。共通の情報を元にいくつかの処理がある場合、一つの分岐によって処理クラス自体を入れ替えて使用すると。
これも面白そうなので書いてみました。

[Visual Basic]

Imports System

 

 

Public Class Demand

 

 

  Private _name As String = String.Empty

 

  Public ReadOnly Property Name() As String

    Get

      Return _name

    End Get

  End Property

 

 

  Public Sub New(ByVal name As String)

 

    Me._name = name

 

  End Sub

 

 

End Class

 

 

 

Public MustInherit Class AbstractCommand

 

 

  Protected _demand As Demand

 

 

  Public Sub SetDemand(ByVal d As Demand)

 

    Me._demand = d

 

  End Sub

 

 

  Public MustOverride Sub Execute()

 

 

End Class

 

 

 

Public Class RalCommand

  Inherits AbstractCommand

 

 

  Public Overrides Sub Execute()

 

    If MyBase._demand IsNot Nothing Then

 

      Console.WriteLine("{0}とは違うのだよ、{0}とは！！", MyBase._demand.Name)

 

    End If

 

  End Sub

 

 

End Class

 

 

 

Public Class JaianCommand

  Inherits AbstractCommand

 

 

  Public Overrides Sub Execute()

 

    If MyBase._demand IsNot Nothing Then

 

      Console.WriteLine("{0}のくせになまいきだぞ！", MyBase._demand.Name)

 

    End If

 

  End Sub

 

 

End Class

 

 

 

Public Class Program

 

 

  Public Shared Sub Main(ByVal args As String())

 

    If args.Length < 2 Then

 

      Exit Sub

 

    End If

 

    Dim command As AbstractCommand

 

    If args(0) = "R" Then

 

      command = New RalCommand

 

    ElseIf args(0) = "J" Then

 

      command = New JaianCommand

 

    Else

 

      command = Nothing

 

    End If

 

    If command IsNot Nothing Then

 

      Dim d As New Demand(args(1))
      command.SetDemand(d)

      command.Execute()

 

    End If

 

  End Sub

 

 

End Class