AP: The Power of Sub Classes in VBA with Kent Gorrell

Overview: Introduction to Form and Control Sub Classes
Examples of how to create a consistent User Experience with very little code.
These examples should get you thinking about what else you could do in your applications.
Longer Version: Exploration of the Form and Control Sub Classes
Implementing Form and Control Sub Classing examples to make your applications consistent with very little code. You’ll learn about the following.
Raising Events to enable and disable buttons like Save and Undo when you edit or save a record
Using a Button class to do the saving and undoing with no code behind your button or form
Text Box Class to highlight the current control without using Format Conditions
Change the on focus background color for you entire application in just one place
Use a different on focus background color for locked or unlocked controls
Prevent illegal characters like a-z in date controls
And plenty more
And all with as little as 3 lines of code behind each form
The sample application is available for download; it’s yours to download and keep. You'll find it on the Member Dashboard at AUG Pacific: accessusergroups.org/pacific/...
Table of Contents:
00:00 - Introduction
00:29 - Intro Kent Gorrell, The Power of VBA subclassing
00:35 - Building on John Colby's original work on classes
01:01 - Reference to Eric Blomquist's discussion of Access classes
01:18 - Make ALL of your forms consistent and easily maintained with Classes
02:09 - Subclassing makes for easier maintenance and enhancement
02:32 - Raise events in the subclass and let the subclass handle them all the same way
03:16 - Q: What is a Subclass? (explanation deferred)
03:37 - 1st Demo of a basic Customer Form with subclasses
04:00 - Labels on control buttons respond to changes in the form
04:25 - Code review and walk through
04:49 - What is a subclass explained
04:52 - The Form itself Is a class. Class code invoked there is its subclass
05:00 - The form declares and calls a sub class with extended events
05:17 - Subclassing can also apply to controls
05:31 - Form subclass in turn instantiates control subclass for controls on that form
06:06 - 2nd Demo of a form with control subclasses
12:10 - Revisit explanation of subclasses
12:39 - Create a separate instance of each class
12:45 - A standard module code is shared by all forms, each subclass instance is unique to that form
13:11 - How Control subclasses work
14:09 - A form's Property Sheet shows [Event Procedure] when an event has been added for it
14:25 - Demo and walk through of a control subclass
14:33 - Create one instance of each control for each form on which the control is used
14:58 - 3rd Demo of the button subclass
16:31 - Subclass events run in addition to any events defined in the form's class
16:43 - If an event already exists in the control's event, both are run
17:42 - The beauty of the class is one place to update or enhance all forms
19:03 - 4th Demo of subclasses for text & combo box controls
19:24 - Better than conditional formatting because changes are made once, in one place in the code
20:11 - Use combo box .ListCount to fully populate the records shown
21:33 - Highlight for control's labels when controls don't have their own background color
24:13 - Identifying and using data typing in subclasses
26:02 - Reusable code is one line
26:50 - Audience question & answer about listbox subclass
27:16 - We want consistent behavior in all similar forms; classes enable that
29:30 - New controls pick up existing subclass behavior simply by being on the form
32:00 - Code to throw away invalid characters in a control (such as a date)
34:49 - New controls acquire existing functionality when added
35:40 - Managing "Form" Background color using a subclass and a textbox conrol
37:27 - Use a class to toggle Dev/runtime features
37:30 - Controls with Tag "Dev" follow State selected (dev or runtime)
37:55 - Late binding for sub forms in subclasses
40:09 - Summary of presentation and overview of possible uses
40:29 - Using the CodeContextObject
42:42 - Additional points relevant to using subforms on tab controls
47:03 - Adding highlighting to continuous forms
52:47 - Replace delete with active/inactive using a pair of fields and a subclass
55:52 - Summary of VBA Subclassing in this presentation
56:42 - The bottom line: consistent, but easily updateable behavior across an application or suite of applications

[@LearnAccessByCrystal]

thanks, Kent! Great presentation :)

[@gregoryregan3000]

Very helpful presentation. Thanks, Kent.

[@AccessUserGroups]

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