After you have instantiated your Class object, manipulating the object's properties
and methods becomes quite straightforward: You use exactly the same techniques
and syntax as you would use to manipulate VB's standard objects.
You manipulate a Class object's properties with the Object.Property syntax,
as in the following example:
objMy.Name = "Vergilio"
You manipulate a Class object's methods with the Object.Method syntax, as
in the examples in Listing 12.11.
CALLING CUSTOM METHODS IN CONTROLLING CODE
'Method without argument or return value
'Method with argument
'Method with return value
strDir = objName.FindFile("VB.EXE")
Handling a Class Event
You handle a Class object's event just as you would handle events for a VB
control: by writing code in the predefined stub of its event procedure.
To make the object's event procedure available in a form or another class module,
you must declare the object variable with the special WithEvents keyword in the
General Declarations section, as in the following example:
Private WithEvents FF As FileFind
where FF will be the name of the object variable, and FileFind is the name
of its class.
After you insert this declaration in your code, you will be able to see the
object variable in the Objects list box at the upper-left corner of the code window
of the file (Form or Class) where you put the declaration. When you choose the
object from this list, you will then be able to see the object's events in the
Events list box at the upper-right corner of the code window. If you use the Events
list box to navigate to the event you are interested in, you will find your cursor
blinking inside the predefined event procedure stub for that event, just as you
would for any control you had placed on a VB form (see Figure 12.5).
At this point, all you need to do is to write code in the event procedure,
as in Listing 12.12. If the event procedure furnishes parameters, you can use
them and, if appropriate, change them. The event procedure in Listing 12.12 takes
three parameters. The first two are informational, and the third (Cancel) could
be changed to True to tell the object to stop the process that is generating these
events (in this case, a file search process).
EVENT-HANDLING CODE FOR A CUSTOM OBJECT NAMED FF
Private Sub FF_FileFound _
(strFileName As String, _
strFilePath As String, _
Cancel As Boolean)
iFilesFound = iFilesFound + 1
If iFilesFound [me] 20 Then
'tell object to stop processing
'we found the maximum number
Cancel = True
FIGURE 12.5 Navigating to the event procedure for a custom object's event.
WARNING - Can't Use As New in WithEvents: Declaration
When you declare an object using the WithEvents keyword, you can't instantiate
it at the same time with the New keyword. You must instantiate the object later
in your code.