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Tenatively laying out an application structure

by | Nov 21, 2024 | Blogging, MS Access, MS Access Forms, MS Access Tables, MS Access VBA Coding | 0 comments

Now I have some code.

Here’s what my form looks like so far:

That contains the following module:

'Form_frmAccounts
Option Compare Database
Option Explicit

Private InternalAccount As AccountInterface

Private Function Acct() As AccountInterface
    If InternalAccount Is Nothing Then Set InternalAccount = New AccountCreditCard
    Set Acct = InternalAccount
End Function

Private Sub Form_Current()
    If Not IsNull(CurrentBalance) And Not IsNull(Me.MinimumPayment) And Not IsNull(Me.InterestRate) Then
        Me.txtMonthsToPayOff = Acct.MonthsToPayoff(Me.CurrentBalance, Me.MinimumPayment, Me.InterestRate)
    End If
End Sub
Visual Basic

And that is currently using both the interface and an object based on the interface. Class AccountInterface and Class AccountCreditCard. Here are each of those classes:

'Class AccountInterface
Option Compare Database
Option Explicit

Public Function MonthsToPayoff(CurrentBalance As Currency, MinimumPayment As Currency, InterestRate As Single) As Long: End Function
Visual Basic
'Class AccountCreditCard
Option Compare Database
Option Explicit

Implements AccountInterface

Private Function AccountInterface_MonthsToPayoff(CurrentBalance As Currency, MinimumPayment As Currency, InterestRate As Single) As Long
    Dim retVal As Long
    retVal = CurrentBalance / MinimumPayment
    AccountInterface_MonthsToPayoff = retVal
End Function
Visual Basic

My thought is that there will be one interface but different calculations for the same function across different account types like a credit card vs a car loan.

I also have put some validation already into the user form. I don’t really want to do that. I’m just sort of testing out my thought process so far and will adjust as needed.

Note that the Interface is just a definition of what a class that implements that interface should contain.

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