| Rick gave a presentation in December 1998 and
January 1999 for the Atlanta Visual Basic Study
Group on using Events with Class modules. Here are all the files, with additional
documentation. There are numerous comments in the source code for each Visual Basic
project. Everything was done in Visual Basic 5.0, with Service Pack 3. I did something wrong when I previously set up the compiled version of the Event5_2 project. Even though I compiled both the in process and out of process ActiveX Servers, I did not compile the client side of the application. Unfortunately, when you run VB projects in the Visual Basic IDE, it forces you to have a single thread of execution. See below for the solution! |
|
|---|---|
File |
Description |
| Events.ZIP | EZ Download - This Zip includes all the other Zip files. |
| EventPPT.ZIP | Zip file of Powerpoint slides, in MS PowerPoint 97 format. |
| MSIE.ZIP | Powerpoint Slide: Client Side This project has a reference to the Microsoft Internet Controls.You can change the variable declaration to include the word WithEvents. When you do that, the object itself will appear in the drop down list of objects at the upper left of the VB code window. Then you will see all the available events appear in the drop-down list of events at the upper right of the VB code window. |
| Event4.ZIP | Powerpoint Slide: Server Side This project is basically Warren Bedell's original example of using Events with Class modules. It shows how the client (code in the VB Form) and the server (code in the Class module) can communicate. By declaring an instance of the Class module WithEvents in the Form, you can place code in its event routine. This code is executed each time that the Event is raised in the Class module. The event and its parameters are declared at the top of the Class module. The event is called with the RaiseEvent statement from within the Class module, which then executes the code in the Form module. |
| Timer.ZIP | Powerpoint Slide: Timer API calls This project is based on a White paper that Dan Appleman wrote called "It's About Time". This discusses a disadvantage of VB's Timer control, which is that it may not fire when YOU want it to. |
| Callbck2.ZIP | Powerpoint Slide: Timer API calls This slide discusses the alternative to using VB's Timer control. This project shows how to call the Windows API functions SetTimer and KillTimer to create your own timer object. This eliminates the need for a Form and a timer control in the Class module. |
| SimpCall.ZIP | Powerpoint Slide: Callbacks versus Events This project is an extremely oversimplified demonstration of how you can achieve the same functionality that Events provide by using Callbacks. I modified the project from Event4.vbp to pass a reference from the Form object to the Class module. Instead of declaring and raising an event in the class module, it invokes a method on the calling object. |
Each of the links above allows you to download a ZIP file which contains the files for the presentation.
| Supplementary projects We did not have time to go through several additional Visual Basic projects related to Events. The links below take you to separate pages for each Visual Basic project. |
|
| Event4_1 | Multiple Objects - Example 1 |
| Event4_2 | Multiple Objects - Example 2 |
| Event4_3 | Multiple Objects - Example 3 |
| Event5_1 | Asynchronous Execution - Example 1 |
| Event5_2 |
 Asynchronous Execution - NOT! |
| Event5_3 |
Asynchronous Execution - YES!! |
