Convert C# to VB (CartLine)

Question

User-2089506584 posted

Hi,

I have this code taken from the book of Sanders "Pro ASP.NET MVC 1.0"  and I don't get the conversion from C# to VB of the following code below. Error is "'Lines' is already declared as 'Private lines As System.Collections.Generic.List(Of CartLine)' in this class."

C#

namespace DomainModel.Entities
{
public class Cart
{
private List<CartLine> lines = new List<CartLine>();
public IList<CartLine> Lines { get { return lines; } }
public void AddItem(Product product, int quantity) { }
public decimal ComputeTotalValue() { throw new NotImplementedException(); }
public void Clear() { throw new NotImplementedException(); }
}
public class CartLine
{
public Product Product { get; set; }
public int Quantity { get; set; }
}
}

As the error implies, I know such variable already exist but isn't what the C# version did? Or I am wrong.

VB

Namespace DomainModel.Entities

    Public Class Cart

        Private lines As List(Of CartLine) = New List(Of CartLine)

        Public ReadOnly Property Lines() As IList(Of CartLine)
            Get
                Return Lines
            End Get
        End Property

        Public Sub AddItem(ByVal product As Product, ByVal quantity As Integer)

        End Sub

        Public Function ComputeTotalValue() As Decimal
            Throw New NotImplementedException
        End Function

        Public Sub Clear()
            Throw New NotImplementedException
        End Sub

    End Class

    Public Class CartLine

        Dim _Product As Product
        Public Property Product() As Product
            Get
                Return _Product
            End Get
            Set(ByVal value As Product)
                _Product = value
            End Set
        End Property

        Dim _Quantity As Integer
        Public Property Quantity() As Integer
            Get
                Return Quantity
            End Get
            Set(ByVal value As Integer)
                _Quantity = value
            End Set
        End Property
    End Class

End Namespace

Answer 1

User1506406490 posted

 Hi good day

 i had gone through u's code.As i check that,r u trying to covert the code of c# to VB.In this case the error is only for C#,as may be in declaring your private & public methods,class the error evolves.Check with the variable name 'lines' etc,hope u code will work.

good luck 

Answer 2

User-2089506584 posted

In this case the error is only for C#

Are you saying the code in the book has errors? Just like the above code?

Is there any workaround on this?

Namespace DomainModel.Entities

    Public Class Cart

        Private lines As List(Of CartLine) = New List(Of CartLine)
        Public ReadOnly Property Lines() As IList(Of CartLine)
            Get
                Return _Lines
            End Get
        End Property

        Public Sub AddItem(ByVal product As Product, ByVal quantity As Integer)
            Dim line = Lines.FirstOrDefault(Function(l) (l.Product.ProductID = product.ProductID))
            If line Is Nothing Then
                Lines.Add(New CartLine() With {.Product = product, .Quantity = quantity})
            Else
                line.Quantity = (line.Quantity + quantity)
            End If
        End Sub

        Public Function ComputeTotalValue() As Decimal
            Throw New NotImplementedException
        End Function

        Public Sub Clear()
            Throw New NotImplementedException
        End Sub

    End Class

    Public Class CartLine

        Dim _Product As Product
        Public Property Product() As Product
            Get
                Return _Product
            End Get
            Set(ByVal value As Product)
                _Product = value
            End Set
        End Property

        Dim _Quantity As Integer
        Public Property Quantity() As Integer
            Get
                Return Quantity
            End Get
            Set(ByVal value As Integer)
                _Quantity = value
            End Set
        End Property
    End Class

End Namespace

Answer 3

User397347636 posted

VB does not allow you to declare a field with the same name as a method in the class.  Since VB is not case-sensitive, "Lines" is regarded the same as "lines" (C# is case-sensitive, so it has no problem with this.)

The correct VB9 conversion of this code is:

Namespace DomainModel.Entities
	Public Class Cart
'INSTANT VB NOTE: The variable lines was renamed since Visual Basic does not allow class members with the same name:
		Private lines_Renamed As New List(Of CartLine)()
		Public ReadOnly Property Lines() As IList(Of CartLine)
			Get
				Return lines_Renamed
			End Get
		End Property
		Public Sub AddItem(ByVal product As Product, ByVal quantity As Integer)
		End Sub
		Public Function ComputeTotalValue() As Decimal
			Throw New NotImplementedException()
		End Function
		Public Sub Clear()
			Throw New NotImplementedException()
		End Sub
	End Class
	Public Class CartLine
		Private privateProduct As Product
		Public Property Product() As Product
			Get
				Return privateProduct
			End Get
			Set(ByVal value As Product)
				privateProduct = value
			End Set
		End Property
		Private privateQuantity As Integer
		Public Property Quantity() As Integer
			Get
				Return privateQuantity
			End Get
			Set(ByVal value As Integer)
				privateQuantity = value
			End Set
		End Property
	End Class
End Namespace

 

Answer 4

User-2089506584 posted

Since VB is not case-sensitive, "Lines" is regarded the same as "lines" (C# is case-sensitive, so it has no problem with this.)

Thank YOu so much DAvid! cheers!