Having Trouble With Class Inheritance

I am learning about class inheritance and need some help with the code below. I have two classes:

Product and Book.

In my Book class I have a line:

MyBase.new(code, description, price)

I am getting an error on that line stating:
Too many arguments to Public Sub New()

Can someone tell me why I am getting such an error?

Thanks

Code:

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Public Class Product


    Private m_Code As String
    Private m_Description As String
    Private m_Price As Decimal


    Public Property Code() As String
        Get
            Return m_Code
        End Get
        Set(ByVal value As String)
            m_Code = value
        End Set
    End Property

    Public Property Description() As String
        Get
            Return m_Description
        End Get
        Set(ByVal value As String)
            m_Description = value
        End Set
    End Property

    Public Property Price() As Decimal
        Get
            Return m_Price
        End Get
        Set(ByVal value As Decimal)
            m_Price = value
        End Set
    End Property


    Public Overridable Function GetDisplayText(ByVal sep As String) As String

        Return Code & sep & Description & sep & FormatCurrency(Price).ToString


    End Function



End Class



Public Class Book

    Inherits Product

    Public Author As String




    Public Sub New(ByVal code As String, ByVal description As String, ByVal author As String, ByVal price As Decimal)

        MyBase.new(code, description, price)
        Me.Author = author

    End Sub


End Class

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AAAHHHH!! I forgot the constructor in the base class.

Where is your New() for the class Product?

In the line MyBase.new() in Book.new(), you are passing three arguments to product.new(). If Product.new() is not defined with three parameters, you will get this error.

EDIT: haha, yes you got it while I was typing my reply :)

MyBase.New calls Sub New of the base class, the one from which you inherit. In this case, the base class is Product.

But Product doesn't have a Sub New yet, let alone one that takes those three arguments. So give it one!

regards, BB

edit: Oops, three at once. Well that happens with the easy questions, doesn't it.

Quote:

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But Product doesn't have a Sub New yet

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You dont need to create the default constructor though do you? Unless you have created another constructor that accepts parameters.

So I could do this:

vb Code:

Public Class MyClass
 
Public Sub SomeMethod
 'some stuff here
End Sub
 
End Class

then I could do this even though I havent written the parameterless constructor:

vb Code:

'In a form or wherever
 
Dim iMyClass As New MyClass
iMyClass.SomeMethod()

I know that doesnt affect the original question in this thread but just wanted to mention that :)

No, you don't need to specify a constructor if you don't use it for anything. If you want something to happen in the constructor, or if you want the constructor to take parameters, or if you want to hide it (make it Private for instance), only then you need to create the constructor code.

It seems the question is resolved already. Please mark the thread as resolved from the Thread Tools if it is. :)

You need to create the parameter-less constructor if you want both parametrized and parameter-less constructor overloads however.

I said that :)

Quote:

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Unless you have created another constructor that accepts parameters

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Quote:

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Originally Posted by chris128

I said that :)

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Didn't see that, my bad!