Visual Basic.NET How to Program (PDF)

418 Object-Oriented Programming: Polymorphism Chapter 10
29
30 ' employee reference to a CCommissionWorker
31 employee = commissionWorker
32 output &= GetString(employee) & _
33 commissionWorker.ToString() & " earned " & _
34 commissionWorker.Earnings.ToString("C") & vbCrLf & vbCrLf
35
36 ' employee reference to a CPieceWorker
37 employee = pieceWorker
38 output &= GetString(employee) & pieceWorker.ToString() & _
39 " earned " & pieceWorker.Earnings.ToString("C") _
40 & vbCrLf & vbCrLf
41
42 ' employee reference to a CHourlyWorker
43 employee = hourlyWorker
44 output &= GetString(employee) & _
45 hourlyWorker.ToString() & " earned " & _
46 hourlyWorker.Earnings.ToString("C") & vbCrLf & vbCrLf
47
48 MessageBox.Show(output, "Demonstrating Polymorphism", _
49 MessageBoxButtons.OK, MessageBoxIcon.Information)
50 End Sub ' Main
51
52 ' return String containing employee information
53 Shared Function GetString(ByVal worker As CEmployee) As String
54 Return worker.ToString() & " earned " & _
55 worker.Earnings.ToString("C") & vbCrLf
56 End Function ' GetString
57
58 End Class ' CTest
Fig. 10.14 CTest class tests the CEmployee class hierarchy (part 2 of 2).
Line 12 assigns to CBoss reference boss a CBoss object and passes to its constructor
the boss’s first name (“John”), last name (“Smith”) and fixed weekly salary
(800). Line 26 assigns the derived-class reference boss to the base-class CEmployee