Wrapping an object with another in VB 2013

[TripVoltage]

I am trying to wrap an instance of a created class with another that share the same super class in Visual Basic 2013. I'm new to VB and been struggling with this.

This is for a Java to VB conversion..

Code example of what I have written:

' Abstract product creator Class
Public MustInherit Class PizzaMaker

' Abstract Method to create a pizza
Public MustOverride Function createPizza(ByRef size As Integer, ByRef crust As String) As Pizza

Public Function orderPizza(ByRef size, ByRef crust) As Pizza
    Dim pizza As Pizza
    pizza = createPizza(size, crust)

    Return pizza
End Function
End Class

' Concrete factory Class
Public Class MargheritaMaker
Inherits PizzaMaker

' Override abstrat method in superclass
Public Overrides Function createPizza(ByRef size As Integer, ByRef crust As String) As Pizza
    Dim pizza As New MargheritaPizza(size, crust)

    Return pizza
End Function

End Class

' Abstract component product Class
Public MustInherit Class Pizza
' Consatant variables used for pizza size
Public Const SMALL As Integer = 1
Public Const MEDIUM As Int16 = 2
Public Const LARGE As Int16 = 3
Public Const EXTRA_LARGE As Int16 = 4

' Crust type of pizza
Private crustType As String

' Size of the pizza
Private size As Int16

' Description of the pizza
Public description As String = "Pizza"

' Abstract method to return the cost of the pizza
Public MustOverride Function getCost() As Double

' Returns size description
Public Function getSizeDescription() As String
    Dim desc As String

    ' Determin pizza size and return String description
    If (size = 1) Then
        desc = "Small"
    ElseIf (size = 2) Then
        desc = "Medium"
    ElseIf (size = 3) Then
        desc = "Large"
    Else
        desc = "Extra Large"
    End If

    Return desc
End Function

Public Function getCrust() As String
    Return crustType
End Function

' Sets the pizza crust type
Public Sub setCrust(ByRef crust)
    crustType = crust
End Sub

' Returns the pizza size
Public Function getSize() As Integer
    Return size
End Function

' Set the size of our Pizza
Public Sub setSize(ByVal i)
    size = i
End Sub

' Returns the String description of the pizza
Public Function getDescription() As String
    Return getSizeDescription() + " " + crustType + " " + description
End Function


End Class

' Concrete component product Class defining a Margherita Pizza
Public Class MargheritaPizza
Inherits Pizza
'Dim cost
' Constructor set's the Pizza size, crust type & description
Sub New(ByRef size As Integer, ByRef crust As String)
    setSize(size)
    setCrust(crust)
    description = "Margherita Pizza"
End Sub

' Returns the Pizza base cost based on it's size
Public Overrides Function getCost() As Double
    Dim cost As Double
    If (getSize() = Pizza.SMALL) Then
        'Console.Write("in if" & vbNewLine)
        cost = 9.5
    ElseIf (getSize() = Pizza.MEDIUM) Then
        cost = 10.5
    ElseIf (getSize() = Pizza.LARGE) Then
        cost = 11.5
    ElseIf (getSize() = Pizza.EXTRA_LARGE) Then
        cost = 12.5
    End If
    'Console.Write("in if" * vbNewLine)
    Return cost
End Function

End Class

' Abstract component product decorator Class
Public MustInherit Class PizzaDecorator
Inherits Pizza

' Abstract method that returns decorator description
Public MustOverride Overloads Function getDescription()

End Class

' Concrete component product decorator Class (used as Object wrapper)
Public Class Cheese
Inherits PizzaDecorator

Dim pizza ' As Pizza

' Check that the construtor paramaters are correct!!! Also check scope of variables!!!
Sub New(ByVal pizz)
    pizza = pizz
    'pizza.setSize(pizz.getSize())
    'pizza.setCrust(pizz.getCrust())
End Sub

' Returns cost of product by delegating call to wrapped objects
Public Overrides Function getCost() As Double
    Dim cost ' As Double = pizza.getCost()

    If (pizza.getSize() = pizza.SMALL) Then
        Console.Write(" In cheese pizza = SMALL" & vbNewLine)
        cost += 0.1
    ElseIf (pizza.getSize() = pizza.MEDIUM) Then
        cost += 0.2
    ElseIf (pizza.getSize() = pizza.LARGE) Then
        cost += 0.3
    ElseIf (pizza.getSize() = pizza.EXTRA_LARGE) Then
        cost += 0.4
    End If
    Console.Write(" Pizza size = " + pizza.getSize().ToString & vbNewLine)
    Console.Write(" in end if" & vbNewLine)
    Return cost + pizza.getCost()
End Function

Public Overrides Function getDescription() As Object
    Return pizza.getDescription() + ", Extra Cheese"
End Function

End Class

Then run a test with this:

Public Class TestForm

Public margheritaM ' As MargheritaMaker
Public pizza ' As Pizza

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    'Dim m As New MargheritaMaker()
    'Dim pizza
    'Dim margheritaM As New MargheritaMaker()
    margheritaM = New MargheritaMaker()
    pizza = margheritaM.createPizza(1, "Deep Pan")

    MargheritaBox.AppendText(pizza.getDescription() & vbNewLine)
End Sub

Private Sub CheeseButton_Click(sender As Object, e As EventArgs) Handles CheeseButton.Click
    'pizza As New Cheese(pizza)
    pizza = New Cheese(pizza)
    MargheritaBox.AppendText(pizza.getDescription() & vbNewLine)
End Sub

Private Sub CostButton_Click(sender As Object, e As EventArgs) Handles CostButton.Click
    MargheritaBox.AppendText(pizza.getCost() & vbNewLine)
End Sub

Private Sub PepperoniButton_Click(sender As Object, e As EventArgs) Handles PepperoniButton.Click
    pizza = New Pepperoni(pizza)
    MargheritaBox.AppendText(pizza.getDescription() & vbNewLine)
End Sub
End Class

I assumed I could create a MargheritaPizza objcet with Button1 click and assign a pizza object to pizza via it's factory method createPizza

then on cheeseButton click I could wrap the pizza object created with the call pizza = New Cheese(pizza)!! The cheese class encapsulates the extra topping for the pizza. I thought that I could then call cost on the original pizza object wiich would delegate the cost through the wrapped objects?? As in the Decorator Pattern.

Some screen shot of output below:



Here I clicked create pizza then calculate cost then extra cheese finally calculate cost, all seems well!



This time I also clicked extra cheese and calculate cost, but the cost is not delegating through the objects correctly!




Here I added several extra cheese and also show some output to the console window for the test, the console window shows the size of the pizza each time the object is wrapped and shows that pizza size is 0 except on the inner most wrapper...What am I doing wrong??

My first language is Java and have no problem with this technique in the past, but new to VB 2013 and appreciate some help here..

All constructive comments welcome.

Many thanks

Please ignore code that's been commented out during testing