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From Form1
objNew = Intern.Constructor()
Intern.setFirstName objNew, txtInternFirstName.Text
Intern.setLastName objNew, txtInternLastName.Text
Intern.setHourlyWage objNew, txtInternHourlyWage.Text
ccolInterns.Add (objNew)
From Intern
Public Function setLastName(objIntern,
sLastName)
Call Employee.setLastName(objIntern, sLastName)
End Function
Public Function setHourlyWage(objIntern,
iHourlyWage)
Dim iID
If (IsIntern(objIntern)) Then
iID = getID(objIntern)
If Not (iID = -1) Then
ccolHourlyWage.Remove (CStr(iID))
ccolHourlyWage.Add iHourlyWage, CStr(iID)
Call Employee.setAnnualIncome(objIntern, (iHourlyWage *
52 * 40))
Else
MsgBox "Intern::setHourlyWage was passed an object
with an invalid ID."
End If
Else
MsgBox "Intern::setHourlyWage was passed an invalid
object."
End If
End Function
Now, when we call methods of any Intern
that are inherited from Employee, all we have to do is pass
down the parameters to Employee as shown in the function
setLastName. When we are setting a value for a new
parameter such as HourlyWage, we use the same type
of functions to enter the value into the correct Key
in the collection. In addition for the setHourlyWage
function, we use the employees hourly wage to determine
their AnnualIncome, and pass that along to Employee as well.
By making sure all descendants of Employee have an AnnualIncome
property, we will be able to use polymorphism later in this
article.
Lets head back to our program. Our executives
need to cut costs on the go, so we have been asked to add
a method to the Intern class that will allow executives
to cut their hourly rate whenever and wherever they want!
So inside the Intern class we add a new method called GivePayCut:
Public Sub GivePayCut(objIntern, iHourlyPayCut)
Dim iNewHourlyWage As Integer
Dim iOldHourlyWage As Integer
Dim iID As Integer
If (IsIntern(objIntern)) Then
iID = getID(objIntern)
If Not (iID = -1) Then
iOldHourlyWage = Intern.getHourlyWage(objIntern)
If iOldHourlyWage > 0 Then
iNewHourlyWage = iOldHourlyWage - iHourlyPayCut
If (iHourlyPayCut > 0) And (iNewHourlyWage >= 0) Then
Call Intern.setHourlyWage(objIntern, iNewHourlyWage)
Else
MsgBox "Error. Intern::GivePayCut was passed iHourlyPayCut="
& iHourlyPayCut
End If
End If
Else
MsgBox "Intern::setHourlyWage was passed an object
with an invalid ID."
End If
Else
MsgBox "Intern::GivePayCut was passed an invalid object."
End If
End Sub
Lets see the new method in action. After
adding all our employees inside the program, we click on
“Cut Costs” which populates a list with all Interns
from the ccolInterns collection.
The intern that is making the most money
is given a $1.50 pay cut by clicking on the “Reduce
Hourly Wage” button.
Private Sub cmdReduceWage_Click()
If Len(Me.txtWageReduction.Text) > 0 Then
If (lstInterns.ListIndex >= 0) Then
Call Intern.GivePayCut(ccolInterns.Item(lstInterns.ListIndex
+ 1), CDbl(Me.txtWageReduction))
Call cmdDisplayAnnualIncome_Click
Else
MsgBox "Please select an intern."
End If
Else
MsgBox "Please enter a dollar amount."
End If
Me.txtWageReduction.Text = ""
End Sub
When we look again, we see that indeed,
the company is now saving an extra $1.50 for every hour
that James Blake works.
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