Microsoft Access 2010 Bible

Chapter 28: Object-Oriented Programming with VBA

991

Definitions of property procedures for the same property are

inconsistent, or property procedure has an optional parameter, a

ParamArray, or an invalid Set final parameter.

FIGURE 28.9

The property variable data type must coincide with the property’s data type.

Class Module

Private m_ProductID As Long

Public Property Let ProductID (Value As Long)

Public Property Get ProductID() As Long

A

m_Product ID= Value

End Property

End Product

C

D

ProductID = m_ProductID E

B

Caution
Although you can use an incorrectly typed private variable for your property procedures, you’ll encounter
side-effect bugs if the variable doesn’t match the data type used for the property procedures.

Modifying the Product Class

Earlier in this chapter, I built a simple product class representing a Northwind product. The initial

class is included in the Access .accdb file accompanying this chapter as the clsProduct1 class

module. In this section, I extend the initial class (as the clsProduct2 class module) by making

its properties more intelligent and useful.

Specifically, this section extends the property procedures within the Product class module, and

adds methods to the module. I also expand the basic application by adding a few other classes

needed to support the Northwind Traders application.

The example application accompanying this chapter includes a form named Products_OOP,

which is based on the Products form included with Northwind Traders (see Figure 28.10). This

form utilizes the majority of OOP techniques described in this chapter and can serve as a model for

your OOP endeavors.