I would like to know if there is some way to add your own methods/properties to an existing VBA class (such Range, Charts, etc).
An example:
I would like the currently VBA class Worksheet have a specific method done by myself, something like:
'Worksheet methods
Public Sub LookFor (ByVal Value as String)
'My code
End Sub
Then I can call from any declared Worksheet class this function.
In class MyClass:
'MyClass members
Private pWS1 as Worksheet
Private pWS2 as Worksheet
Private pWS3 as Worksheet
'MyClass methods
Private Sub Class_Initialization()
Set pWS1 = Worksheets("WS1")
Set pWS2 = Worksheets("WS2")
Set pWS3 = Worksheets("WS3")
End Sub
Public Sub Example()
pWS1.LookFor("abc")
pWS2.LookFor("123")
pWS3.LookFor("def")
End Sub
Thanks!
There is no direct way to do this in VBA.
Best you can do is create a “wrapper” class which has a private Worksheet member, and expose that via a Sheet property. Add your “extension” methods to the class and have them operate on m_sheet.
Initialize your class by creating an instance of it and assigning a worksheet object to its Sheet property.
You can call your “extension” methods directly on the object, and any existing methods you’d access via the Sheet property.
Class MySheet:
Private m_sht As Worksheet
Public Property Set Sheet(ws As Worksheet)
Set m_sht = ws
End Property
Public Property Get Sheet() As Worksheet
Set Sheet = m_sht
End Property
Public Property Get CountHellos() As Long
CountHellos = Application.CountIf(m_sht.Cells, "Hello")
End Property
Test sub:
Sub Tester()
Dim sht As MySheet
Set sht = New MySheet
Set sht.Sheet = ActiveSheet
MsgBox sht.CountHellos '<< "extension" method
MsgBox sht.Sheet.Rows.Count '<< built-in object property
End Sub
Edit: you might be able to make the Sheet property the default for your class by following the steps outlined by Chip here: http://www.cpearson.com/excel/DefaultMember.aspx
May work to allow you to skip the Sheet property when working with instances of your class (but I’ve not tested this)
Answer：
What you are looking for is called “Extension” methods in tradition Object Oriented Programming Languages.
See MSDN: Extension Methods (Visual Basic)
AFAIK, what you are looking for is not supported / available in traditional Visual Basic for Applications (VBA).
Here’s an example of doing extension methods in Visual Basic .Net (VB.Net) from the MSDN source.
Step 1. Declare Extension method like so…
Step 2. Call extension method like so…
Tags: class, excelexcel, vba
