Shamil Salakhetdinov
shamil at smsconsulting.spb.ru
Sat Jun 7 06:04:52 CDT 2003
> Please have a look here/dowload:
> http://smsconsulting.spb.ru/samples/exposed.jpg (137 244 bytes)
I uploaded another picture with the same URL:
http://smsconsulting.spb.ru/samples/exposed.jpg and it has more details on
subj and it's now 202 984 bytes in size.
Shamil
----- Original Message -----
From: "Shamil Salakhetdinov" <shamil at smsconsulting.spb.ru>
To: "AccessD" <AccessD at databaseadvisors.com>
Sent: Saturday, June 07, 2003 2:06 PM
Subject: Re: [AccessD] Where does WithEvents go?
> <<<
> > None of the properties that are exposed when
> > the class is exported to a text
> > file is visible from within Access.
> >>>
> John,
>
> Please have a look here/dowload:
> http://smsconsulting.spb.ru/samples/exposed.jpg (137 244 bytes)
> I follow the principle that "one good picture is better that thousand
> words" - and this good IMO picture referenced above shows that VB_Exposed
> property of MS Access 2000/XP/... VBA modules can be set from within MS
> Access...
>
> > why you wouldn't simply set both of
> > the properties I discussed to true
> This is not standard functionality and I can't recommend that because MS
can
> well close this "backdoor" in the future - then all your coding will have
to
> be changed.
> VB_Exposed is standard for MS Access 2000 and up - so it is safe to use
with
> wrapper class factory functions, subs, custom classes...
>
> In general I don't like to use New keyword with custom classes here and
> there because as I said this makes the coding unorganized - when you've a
> special class factory code then you can control custom classes' instances
> creation in the sense that you can concentrate all this code in one-two
> modules etc.
>
> There is also a technical reason of avoiding to use
>
> Dim obj as New MyClass
>
> This code above AFAIK uses 'just in time custom class instance creation
> (JITCCIC)' technique - and therefore it may generate a lot of additional
> support code on compilation...
>
> Dim obj as MyClass
> set obj=new MyClass
>
> shouldn't use JITCCIC but to avoid temptation of using shorter code
>
> Dim obj as New MyClass
>
> I don't use it too :) - speaking seriously:
>
> Dim obj as MyClass
> set obj = MyClassFactoryCreateObject("MyClass")
>
> IMO gives a developer much more freedom for future extensions and
safety...
> E.g. using this approach you can well make your class MyClass an Interface
> Definition Class in the future WITHOUT breaking any of your
functionality -
> etc...
>
> Well, all that are my preferences and of course they can be argued... -
this
> message isn't an invitation to such a discussion - I made my choice
several
> years ago :)
>
> > What does the wrapper buy you? It seems like extra work, an extra layer
> > that things have to go through, as well as an extra layer that I have to
> > write (the helper function). We don't do that with the libs that MS
> > publishes do we?
> Yes, some more work but without breaking "MS fences" - they didn't give us
> an opportunity to set VB_Creatable = True from within VBA editor - in the
> future they may well introduce this functionality as standard or drop it
> completely by closing "backdoor" of exporting/manually setting
> VB_Creatable=True/importing back custom class module. And I don't think
> they can drop standard (MS Access 2000, 2002,...) functionality of
> VB_Exposed=true - then they will break versions compatibility...
> Yes, MS allows to use New with their libraries but they use C++ or VB to
> write these libraries , where this is a STANDARD (COM-)functionality
> when these libraries expose their CREATABLE public objects...
>
> > > And yes, the ClassExposer add-in would be nice.
> I will try to make conversion in the near future - it wasn't
straightforward
> "convert to Acc2000" when I tried to make it first time in the past..
> And then I also found that MS Acces 2000 has setting VB_Exposed as
> standard functionality...
>
> Shamil
>
> ----- Original Message -----
> From: "John Colby" <jcolby at colbyconsulting.com>
> To: <accessd at databaseadvisors.com>
> Sent: Saturday, June 07, 2003 3:14 AM
> Subject: RE: [AccessD] Where does WithEvents go?
>
>
> > Shamil,
> >
> > None of the properties that are exposed when the class is exported to a
> text
> > file is visible from within Access. What I don't quite understand is
why
> > you wouldn't simply set both of the properties I discussed to true and
> > directly see the classes from any database referencing the library.
Doing
> > this allows seeing all of the class properties, functions etc, as well
as
> > directly dimensioning a class variable.
> >
> > What does the wrapper buy you? It seems like extra work, an extra layer
> > that things have to go through, as well as an extra layer that I have to
> > write (the helper function). We don't do that with the libs that MS
> > publishes do we?
> >
> > And yes, the ClassExposer add-in would be nice. It appears that the
> object
> > on your site is compiled - I can't open or convert it in A2K. I could
> > certainly write my own if I need to.
> >
> > John W. Colby
> > www.colbyconsulting.com
> >
> > -----Original Message-----
> > From: accessd-bounces at databaseadvisors.com
> > [mailto:accessd-bounces at databaseadvisors.com]On Behalf Of Shamil
> > Salakhetdinov
> > Sent: Friday, June 06, 2003 6:50 PM
> > To: AccessD
> > Subject: Re: [AccessD] Where does WithEvents go?
> >
> >
> > <<<
> > > If MyClass is in a lib, then this dim statement doesn't work since
> MyClass
> > > isn't exposed.
> > >>>
> > John,
> >
> > But you can dimension the class specifically as that class type if this
> > custom class's Instancing property is set to PublicNotCreatable. Then
you
> > create instance of this class using wrapper/helper function. And you can
> > sink an event of this class declared as public.
> >
> > Instancng is a standard property for custom class modules in MS Access
> 2000
> > and XP.
> >
> > Are we talking about different things?
> >
> > Shamil
> >
> > P.S. Unfortunately I don't see Instancing property for Forms' and
Reports'
> > modules (am I missing it?) - so maybe ClassExposer Add-In for MS
> > Access2000/XP to expose forms' and reports' modules isn't a totally
crazy
> > idea....
> >
> > ----- Original Message -----
> > From: "John Colby" <jcolby at colbyconsulting.com>
> > To: <accessd at databaseadvisors.com>
> > Sent: Saturday, June 07, 2003 12:10 AM
> > Subject: RE: [AccessD] Where does WithEvents go?
> >
> >
> > > Shamil,
> > >
> > > I don't understand how to sink an sourced from a class in a library
> > without
> > > being able to dimension the class specifically as that class type
> > >
> > > dim withevents SomeCls as MyClass
> > >
> > > If MyClass is in a lib, then this dim statement doesn't work since
> MyClass
> > > isn't exposed.
> > >
> > > John W. Colby
> > > www.colbyconsulting.com
> >
> >
> > _______________________________________________
> > AccessD mailing list
> > AccessD at databaseadvisors.com
> > http://databaseadvisors.com/mailman/listinfo/accessd
> > Website: http://www.databaseadvisors.com
>
>
>
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