I have an interface IValidator, and I want classes that implement IValidator to have access to a shared set of properties and methods, but it seems VBA doesn't have true implementation inheritance, so instead I have a class BaseValidator with the shared resources, which is used as a delegate in the subclasses.
Interface:
'IValidator
Public Function isValid(columnName As String) As Boolean
End Function
'used for initializing delegate
Public Sub setup(fieldsDict As Dictionary)
End Sub
Base class:
'BaseValidator
Public fieldsDict As Dictionary
Public Sub setup(fieldsDict As Dictionary)
Set Me.fieldsDict = fieldsDict
End Sub
Public Function doSomethingWithFieldsDict(columnName as string) as variant
'do something
End Function
Example implementation:
'Validator_FeatureNumber
Private bv As New BaseValidator
Implements IValidator
Public Sub IValidator_setup(fieldsDict As Dictionary)
bv.setup fieldsDict
End Sub
Function IValidator_isValid(columnName As String) As Boolean
IValidator_isValid = IsNumeric(bv.doSomethingWithFieldsDict(columnName))
End Function
This works, but it means I have to duplicate the IValidator_setup() code block in every implementation, which seems like a bad idea for code maintainability. Is there any way to have a subclass inherit methods from a superclass in VBA?
