Abstract Factory in VB.NET

   1:  ' Abstract Factory Design Pattern.

   2:  ' See description in //www.vb-net.com/ProgramTheory/AbstractFactory.htm

   3:  Class MainApp

   4:      ' Entry point into console application.

   5:      Public Shared Sub Main()

   6:          ' Abstract factory #1

   7:          Dim factory1 As AbstractFactory = New ConcreteFactory1()

   8:          Dim client1 As New Client(factory1)

   9:          client1.Run()

  10:          ' Abstract factory #2

  11:          Dim factory2 As AbstractFactory = New ConcreteFactory2()

  12:          Dim client2 As New Client(factory2)

  13:          client2.Run()

  14:          ' Wait for user input

  15:          Console.ReadKey()

  16:      End Sub

  17:  End Class

  18:   

  19:  ' The 'AbstractFactory' abstract class

  20:  MustInherit Class AbstractFactory

  21:      Public MustOverride Function CreateProductA() As AbstractProductA

  22:      Public MustOverride Function CreateProductB() As AbstractProductB

  23:  End Class

  24:   

  25:  ' The 'ConcreteFactory1' class

  26:  Class ConcreteFactory1

  27:      Inherits AbstractFactory

  28:      Public Overrides Function CreateProductA() As AbstractProductA

  29:          Return New ProductA1()

  30:      End Function

  31:      Public Overrides Function CreateProductB() As AbstractProductB

  32:          Return New ProductB1()

  33:      End Function

  34:  End Class

  35:   

  36:  ' The 'ConcreteFactory2' class

  37:  Class ConcreteFactory2

  38:      Inherits AbstractFactory

  39:   

  40:      Public Overrides Function CreateProductA() As AbstractProductA

  41:          Return New ProductA2()

  42:      End Function

  43:   

  44:      Public Overrides Function CreateProductB() As AbstractProductB

  45:          Return New ProductB2()

  46:      End Function

  47:  End Class

  48:   

  49:  ' The 'AbstractProductA' abstract class

  50:  MustInherit Class AbstractProductA

  51:  End Class

  52:   

  53:  ' The 'AbstractProductB' abstract class

  54:  MustInherit Class AbstractProductB

  55:      Public MustOverride Sub Interact(a As AbstractProductA)

  56:  End Class

  57:   

  58:  ' The 'ProductA1' class

  59:  Class ProductA1

  60:      Inherits AbstractProductA

  61:  End Class

  62:   

  63:  ' The 'ProductB1' class

  64:  Class ProductB1

  65:      Inherits AbstractProductB

  66:      Public Overrides Sub Interact(a As AbstractProductA)

  67:          Console.WriteLine(Me.[GetType]().Name + " interacts with " + a.[GetType]().Name)

  68:      End Sub

  69:  End Class

  70:   

  71:  ' The 'ProductA2' class

  72:  Class ProductA2

  73:      Inherits AbstractProductA

  74:  End Class

  75:   

  76:  ' The 'ProductB2' class

  77:  Class ProductB2

  78:      Inherits AbstractProductB

  79:      Public Overrides Sub Interact(a As AbstractProductA)

  80:          Console.WriteLine(Me.[GetType]().Name + " interacts with " + a.[GetType]().Name)

  81:      End Sub

  82:  End Class

  83:   

  84:  ' The 'Client' class. Interaction environment for the products.

  85:  Class Client

  86:      Private _abstractProductA As AbstractProductA

  87:      Private _abstractProductB As AbstractProductB

  88:      ' Constructor

  89:      Public Sub New(factory As AbstractFactory)

  90:          _abstractProductB = factory.CreateProductB()

  91:          _abstractProductA = factory.CreateProductA()

  92:      End Sub

  93:      Public Sub Run()

  94:          _abstractProductB.Interact(_abstractProductA)

  95:      End Sub

  96:  End Class