ArcGIS Engine Developer Guide

THE V ISUAL BASIC 6 ENVIRONMENT
For instance, you might have decided that a variable has a valid range of 1–100.
If you were to allow other developers direct access to that variable, they could
set the value to an illegal value. The only way of coping with these illegal values
is to check them before they get used. This is both error prone and tiresome to
program. The technique of declaring all variables as private member variables of
the class and providing accessor and mutator functions for manipulating these
variables will solve this problem.
In the example below, these properties are added to the default interface of the
class. Notice the technique used to raise an error to the client.
Private m_lPercentage As Long
Public Property Get Percentage() As Long
Percentage = m_lPercentage
End Property
Public Property Let Percentage(ByVal lNewValue As Long)
If (lNewValue >= 0) And (lNewValue