[AccessD] Any limits on what can be passed as an argument?

Here is what I think is a pretty good example of this in a nutshell Arthur:

Sub testcol()
Dim c1 As Collection
Dim c2 As Collection
Set c1 = New Collection
Set c2 = c1
c1.Add "Bill"
Debug.Print "c1 count = " & c1.Count
Debug.Print "c2 count = " & c2.Count

AddAnItemToC1 c1
Debug.Print "c1 count = " & c1.Count
Debug.Print "c2 count = " & c2.Count

End Sub


Sub AddAnItemToC1(ByRef SomeCol As Collection)
SomeCol.Add "Benson"

End Sub


-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Arthur Fuller
Sent: Monday, March 11, 2013 2:13 PM
To: Access Developers discussion and problem solving
Subject: [AccessD] Any limits on what can be passed as an argument?

I suppose that I could whip up a few test harnesses and discover this
myself, but hell, why bother in a list full of experts? :)

I'm wondering whether virtually *anything* can be passed as an argument.
Can I, for example, pass a QueryDef or TableDef?

I'm also wondering exactly what happens in the following (pseudo-code)
example.

<vba>
Dim qd as QueryDef
Dim qd1 as QueryDef
Set qd = QueryDefs("myDef")
Set qd1 = qd
... make some changes to qd, such as changing the sql property </vba>

1. Are changes to qd relfected in qd1? (My guess is Yes, that it's just a
pointer).
2. If Yes, is there a method such as Clone which would NOT change qd1?
3. Can I pass qd around like any other parameter?

And finally, for reasons I won't go into, I declare a qd in the Declarations
of a form. In the FormOpen event, I retrieve the particular QueryDef of
interest and assign it to qd. In various other form events, I manipulate qd.
Then in the spirit of good housekeeping, I close it and set it to Nothing.
I've tried this code in both the Close and Unload events, but in each place,
Access tells me that there is no object qd. I'm not sure where it's
disappearing but it is. I thought that declaring qd at the top would mean
that it's alive until I close the form, but apparently I was wrong. I don't
really understand what is occurring.

Any ideas?

Oh, before I close this, if I assign qd to qd1 as above, and then attempt to
close qd, am I correct in assuming that this will fail, since there is a
reference to qd (qd1)?

Finally, if I can pass a QueryDef as a parameter, does this mean that I
could pass it to a static function of the standard get/set type, and
therefore that it would live until I specifically killed it?

(Which reminds me of something I heard in a Q&A session years ago:
Q: Do static functions continue to hold their values even if I turn the
computer off?
A: Well yes, but turning it back on wipes them out.

--
Arthur
Cell: 647.710.1314

Prediction is difficult, especially of the future.
  -- Niels Bohr
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