[AccessD] Classes and Withevents

[Jim Dettman]

<< I find it amusing that a progmmer says I don't use classes because they
are
not inheritable>>

 Guess I'm just an OOP snob then.

Jim.

-----Original Message-----
From: AccessD On Behalf Of John Colby
Sent: Monday, August 31, 2020 1:33 AM
To: Access Developers discussion and problem solving
<accessd at databaseadvisors.com>
Subject: Re: [AccessD] Classes and Withevents

I find it amusing that a progmmer says I don't use classes because they are
not inheritable and then happily uses combos, text boxes, forms, reports,
recordsets etc which are all classes and are not inheritable.

An access class is every bit as powerful and useful as any other class in
access, and are a paradigm shift once used.

So no, I obviously am not preaching to the choir.

On Sun, Aug 30, 2020, 16:50 Jim Dettman via AccessD <
accessd at databaseadvisors.com> wrote:

> John,
>
>  You are preaching to the choir so to speak.
>
>  I know what classes are, how to use them, and use them all the time when
> doing C# or VFP.
>
>  But when it comes to Access, lacking full inheritance, I just don't find
> them overly useful or worth the overhead for the most part, and this is a
> conversation we've had several times in the past that I don't care to
> repeat.
>
>  All I was offering was that since you've been out of Access for a while,
> was letting you know that nothing fundamentally has changed, so if there
> were issues you were running into, expect them still to exist.  In fact,
> recently the stability of Access has gotten worse.  Microsoft has
> introduced
> more than a few killer bugs over the past couple of years, one of which is
> now over two years old and a fix nowhere in sight.  To be fair, it's the
> Windows group that introduced the bug, but we're still left to deal with
> it.
>
>  The other part was that even to this day, classes are still not widely
> used
> in Access and I would not be shocked if you ran into new issues.  A lot
has
> happened with Access since you stopped using it.
>
>  As I said, FWIW.
>
> Jim.
>
>
> -----Original Message-----
> From: AccessD On Behalf Of John Colby
> Sent: Sunday, August 30, 2020 1:34 PM
> To: Access Developers discussion and problem solving
> <accessd at databaseadvisors.com>
> Subject: [AccessD] Classes and Withevents
>
> Jim, you have to understand that in the framework and app I wrote I would
> instantiate literally thousands of wrapper classes, sink events in those
> classes, tear them back down etc.  Thousands every single day for every
> single user.  And I didn't have issues.  Shamile got out long before the
> last two service packs were issued.
>
> I quite understand that Microsoft isn't actively doing anything with it.
> Any remaining bugs will never be fixed.  Yep, got it.  On the other hand
by
> 2005 or whenever SP3 came out, Access was 15 years old and they had been
> working on it up to  that time.  It is my opinion that it is remarkably
> stable.  It is also my opinion that there is no other DB FE RAD in
> existence even close to it in pure data integration and OO integration. It
> is a remarkable piece of engineering IMHO.
>
> Maybe I should offer MS a dollar to sell it to me?  :)
>
> >>>There has been very little work done with classes in Access.   Yes, I
> know forms and reports in Access are classes, but that's a very different
> thing from using classes in VBA.
>
> As for the classes, AFAIK the classes behind reports and forms are the
> exact same thing as the classes that you can use if you so desire.  And to
> say that little work has been done with them ignores the fact that
> everything in Access is a class.  All the controls come from a base
control
> class.  The DAO engine and everything in it is a class,  AFAICT even the
> properties of objects are classes.  All the controls, forms and reports
> know how to raise events.
>
> All classes can sink events.  And they can sink events from ANYTHING
passed
> in to them that is saved "WithEvents".  Every Access developer who uses
> event sinks in a form or report class for handling the events from
controls
> is already sinking events.  It is a miniscule jump to opening your own
> class, passing in an object (control for instance), storing a pointer to
> that "WithEvents" in the header of that class, and then sinking events
from
> that control inside of the class you just created.  Trivial.
>
> And... the class itself can raise its own events.  And, any class can take
> a pointer to another class, store a pointer to that passed in class
> "withevents" and sink the events from that class.  And... anything that
can
> raise events can be saved in multiple locations and the events sunk in
> every class where a pointer to the object is stored "WithEvents".  So a
> combo GotFocus event can be sunk in one or a thousand different classes.
> Pass a pointer to a combo into a function in the class behind form of 10
> other forms, save a pointer to that combo "WithEvents" in the header of
> that class, and each of those forms can sink the events from that combo.
>
> And... There are controls at the top of the class which display any
objects
> saved "WithEvents" in the top of the class, as well as all of the events
of
> said object.  Selecting such an object and an event will stub out the
event
> sink for you.
>
> And... all this stuff ALSO works in Excel, Word, Power Point and so forth.
>
> This is precisely the same technology that C# provides.  The syntax for
> doing it is different of course but the capability is there.  It is just
> that the "average programmer" in Access vba has no clue. But I have a
clue.
>
> Access is, from top to bottom, an object oriented design.  At the risk of
> repeating myself,  It is a remarkable piece of engineering IMHO.
>
> --
> John W. Colby
> Colby Consulting
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