Choosing Between Methods or Properties

As you may pointed our earlier.  Properties is like a function.  So how can we know when we must implement property or a function.  To tell you honestly, their is no universal rule concerning this scenario, but usually programmer implement a properties when a routine serves mostly to return a value stored inside the class and can be quickly and easily reevaluated.  When the routine servers mostly to evaluate a complex value, they use function. If programmer thinks that in the future the value returned by the routine could be assigned to, they use Property Get procedure and gives them a chance to add a Property Let when its time to implement one.

Let's make an example. Earlier we implement a Property Get procedure for our class member FullName.  How can we make our class more useable in a long run by providing a Property Let.  This way we can have two way of assign a value to FirstName and LastName property.  A possible solution might look like this:

Property Let FullName(ByVal strNewValue As String)
' Return the full name of Student object
    Dim aStrName() As String
    ' Split the argument pass (strNewValue)
    aStrName() = Split(strNewValue)
    ' Raise an error if an FirstName or LastName is empty
    If UBound(aStrName) = 0 Then Err.Raise 5
    FirstName = aStrName(0)
    LastName = aStrName(1)
End Property

You can directly assign a value to FirstName and LastName property as shown below:

objStudent.FullName = "Cathrina Anniversario"
'try getting the Student property FirstName and LastName
MsgBox objStudent.FirstName  'Invoke Property Get FirstName
MsgBox objStudent.LastName   'Invoke Property Get LastName

As you can see, even if we didn't assign a value to the Student FirstName and LastName property explicitly, our new FullName property does the job.  This is other nice thing you can do with class property