Code DataBases and Class Modules
Lyle Fairfield
of it in class modules, of course. Now I want to emulate that with a code
database, and for the most part can just copy and paste the code. Great so
far.
But, the database with the reference to the code database can't see the
class modules, just the regular modules.
What am I doing wrong?
--
Lyle
Terry Kreft
You're not doing anything wrong, Access class modules are not Public
createable.
There are two ways around this.
One is to create a function in your Library database which returns an
instance of your class object, the other is to export the class module to a
file, edit the file and change the
Attribute VB_Exposed = False
line to
Attribute VB_Exposed = True
and then insert the file into a new class module.
Lyle Fairfield <lyle...@cgocable.net> wrote in message
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Lyle Fairfield
I have this working now and thought that I had followed you instructions,
but in writing this I see that I did not.
I used the Application.SaveAsText to make a text copy of the class module.
At the top of the text file I found:
Attribute VB_Creatable = True
Thinking that was the attribute you named I changed it to:
Attribute VB_Creatable = False
Then I used Application.LoadFromText to recreate the class module.
And now the object browser shows the class.
So ...
I wonder why this worked, and where I can find a description of these
attributes (probably MSDN library?) and how they work.
VB_Exposed seems more pertinent to the problem.
--
Lyle
Terry Kreft <terry...@mps.co.uk> wrote in message
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Michael S. Kaplan
so they won't do much good. Access 97 class modules are not public, ever. In
Access 2000 they are public non-createable, which still means the instance
must be created in the referenced db, non in the referencee.
Michael
Lyle Fairfield <lyle...@cgocable.net> wrote in message
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Lyle Fairfield
object browser?
--
Lyle
Michael S. Kaplan <mic...@nospam.trigeminal.com> wrote in message
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Michael S. Kaplan
the referencer db?
Michael
Lyle Fairfield <lyle...@cgocable.net> wrote in message
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Lyle Fairfield
I'm in the main database, the front end, the database that has the reference
to the code database.
I closed that database, closed Access, cold booted ... everything is as
before.
BUT ... I cannot create a new instance of the class. I can use it however in
what I suppose is its default instance:
clsThisClass.pType = DbText
etc.
So, I suppose that one of the great strengths of Classes, multiple
instances, is taken away from me?
Maybe it's back to DLLs.
Lyle
--
Lyle
Michael S. Kaplan <mic...@nospam.trigeminal.com> wrote in message
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Michael S. Kaplan
but its easy to create a function that does this, something like
Public Function QIClass1() As Class1
Set QIClass1 = New QIClass1
End Function
in a standard module.
Michael
Lyle Fairfield <lyle...@cgocable.net> wrote in message
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Terry Kreft
I'm sorry, it is creatable outside of the project.
Hi Lyle,
You seem to have misread my post, you need to change
Attribute VB_Exposed = False
to
Attribute VB_Exposed = True
not the VB_Creatable attribute.
Michael S. Kaplan <mic...@nospam.trigeminal.com> wrote in message
news:#SuOl1kI#GA.190@upnetnews03...
Lyle Fairfield
I tried "ATTRIBUTE VB_Exposed = True", although I had to enter the line
(there was no exisitng "ATTRIBUTE VB_Exposed = False" line), but I did not
find that it made the class visible in the "referencer" database. I did find
a line "ATTRIBUTE VB_Creatable = True" and when I changed it to "ATTRIBUTE
VB_Creatable = False" the class did become visible but I was still not
allowed to create multiple copies of the class. I also found that the
visibility of the Class seemed erratic; Now you see me; Now you don't!
I also tried using a function in the code DB to return an reference to the
Class. I found that if the Class was invisible then the function was
invisible.
I think I am not going to use Classes in Code DBs.
I am now deciding among:
1. rewriting the classes as ordinary modules;
2. leaving them in the referencer MDB;
3. returning to the DLL idea.
Thanks for your help.
Lyle
--
Lyle
Terry Kreft <terry...@mps.co.uk> wrote in message
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Dev Ashish
FWIW, SaveAsText or File/Save As Text do not put that line in the exported
file. Try closing the module and doing a File/SaveAs/Export to a text file.
This created the following header for me.
Attribute VB_Name = "cDirty"
Attribute VB_Creatable = True
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Similarly, you have to import the file I believe for things to work
properly.
-- Dev
Lyle Fairfield wrote in message <74jsku$dt2$1...@usenet41.supernews.com>...
:Terry
:
:I tried "ATTRIBUTE VB_Exposed = True", although I had to enter the line
:(there was no exisitng "ATTRIBUTE VB_Exposed = False" line), but I did not
:find that it made the class visible in the "referencer" database.
<<snip>>
Terry Kreft
The exact steps are as follows:
1) Select the Class module in the DB window
2) Choose the "File, Save As/Export..." menu item
3) Choose "To an External File or database" from the dialog and click OK
(Should be the default anyway)
4) Change the Save as type to "Text Files ..." and click export
5) Locate the file you have saved and open it in a text editor
At the top of the file you will find the following line
Attribute VB_Exposed = False
Change this to
Attribute VB_Exposed = True
and save the file
6) Rename your Class module
7) Create a new empty class module with the old name
8) In design view for the new Class module -
Go to the "Insert, File..." menu item and select the amended text
file
That is it, you now have an externally creatable class.
Lyle Fairfield <lyle...@cgocable.net> wrote in message
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Michael S. Kaplan
you without warning (the hazards of unsupportable behavior).
Michael
Terry Kreft <terry...@mps.co.uk> wrote in message
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Lyle Fairfield
and I've rewritten the Class Modules as Standard Modules, so there's no
hurry to do so; I'll have a go and that in the next week or so.
But, what do you mean by "set it back on you without warning"?
That future versions of VBA and Access may not support this?
Or
It may behave erratically, something I found (which was totally my fault as
I did not follow Terry and Dev's instructions exactly.)
While I have your attention, or anyone else's, I note MS says about DLLs:
"Components you author with Visual Basic will always support vtable
binding."
and
"In the fastest form of early binding, vtable binding, Visual Basic uses an
offset into a virtual function table, or vtable. Visual Basic use vtable
binding whenever possible."
So, I'm wondering and can't find:
What kind of binding do I get for Classes in Code dbs? ... the same, faster,
slower?
Do DLL's have any natural advantage over Code dbs other than having the
richer function set of VB available to them?
Lyle
--
Lyle
Michael S. Kaplan <mic...@nospam.trigeminal.com> wrote in message
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Michael S. Kaplan
supports... ao if your app sudenly breaks, don't say I didn't warn you. I
was not making comments about future versions, I am staying rooted in the
present.
Not sure I understand the question... VB does not have a richer function set
than any Office app, its all a matter of what you reference.... and VBA
supports early binding just as VB does.
Michael
Lyle Fairfield <lyle...@cgocable.net> wrote in message
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