[AccessD] Classes and Withevents

[John Colby]

Yeah

On Mon, Aug 31, 2020, 09:30 Jim Dettman via AccessD <
accessd at databaseadvisors.com> wrote:

> << 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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> > Website: http://www.databaseadvisors.com
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