Classes in Visual Basic 6 (VBA)
Class is a fundamental concept of Object Oriented Programming (OOP). Class can be considered as repository for storing data in class level variables, and providing functions, properties and exposing events.
Classes are created in the class modules
Classes must have a unique name which can be defined in the Visual Basic Editor
MyClass Class Module
Public Var1 As String Public Var2 As Double Public Sub Foo() End Sub
Dim cl1 As MyClass Dim cl2 As MyClass Set cl1 = New MyClass Set cl2 = New MyClass cl1.Var1 = "A" cl2.Var1 = "B" cl1.Var2 = 1 cl2.Var2 = 2
Classes are similar to modules, but there are several differences:
- It is required to create an instance of a class using new keyword
- All the data associated with this class wil be stored within its instance, which means that different instances of the same class may have different data.
- Classes allow to handle and expose events