VB.net　継承の基本(Visual Basic)

オーバーライドは、基本クラスでOverridable（オーバーライドできるよ：意訳）して

派生クラスでOverrides（オーバーラードするよ：意訳）すればいい。

やっかいなのがコンストラクタNewで基本クラスにNewがあり、派生クラスにもNewがあるとオーバーライドされずに、それぞれが実行されるらしい（試していない）

https://docs.microsoft.com/ja-jp/dotnet/visual-basic/programming-guide/language-features/objects-and-classes/inheritance-basics

Const BonusRate As Decimal = 1.45D

Const PayRate As Decimal = 14.75D

Class Payroll

    Overridable Function PayEmployee( 

        ByVal HoursWorked As Decimal, 

        ByVal PayRate As Decimal) As Decimal

        PayEmployee = HoursWorked * PayRate

    End Function

End Class

Class BonusPayroll

    Inherits Payroll

    Overrides Function PayEmployee( 

        ByVal HoursWorked As Decimal, 

        ByVal PayRate As Decimal) As Decimal

        ‘ The following code calls the original method in the base 

        ‘ class, and then modifies the returned value.

        PayEmployee = MyBase.PayEmployee(HoursWorked, PayRate) * BonusRate

    End Function

End Class

Sub RunPayroll()

    Dim PayrollItem As Payroll = New Payroll

    Dim BonusPayrollItem As New BonusPayroll

    Dim HoursWorked As Decimal = 40

    MsgBox(“Normal pay is: ” & 

        PayrollItem.PayEmployee(HoursWorked, PayRate))

    MsgBox(“Pay with bonus is: ” & 

        BonusPayrollItem.PayEmployee(HoursWorked, PayRate))

End Sub