[AccessD] Closing & Destroying Objects

Always welcome!


John W. Colby
Colby Consulting
www.ColbyConsulting.com 
-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Robert
Sent: Saturday, March 22, 2008 9:14 AM
To: 'Access Developers discussion and problem solving'
Subject: Re: [AccessD] Closing & Destroying Objects

John,
 Thank you, I'm, generally very careful about closing and destroying created
objects, but I got lazy or absent minded and end up with a very well hidden
un-destroyed class holding the main class open. I finally found it...


Again Thanks for your help....


WBR
Robert

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: Friday, March 21, 2008 10:16 PM
To: 'Access Developers discussion and problem solving'
Subject: Re: [AccessD] Closing & Destroying Objects

Class_Terminate not running means the class is not closing.  The class does
not close because there is still a reference to the class somewhere.  The
last reference to the class being set to nothing causes the VBA garbage
collector to shut it down and destroy the instance, returning the memory to
the pool.

The only time I have ever seen something inside the class from preventing
shutdown is when the class references itself.  This technique is used to
hold an instance open without an external pointer to the class, and this is
usually only used for multiple instances of forms.  If a class references
itself (holds itself open) then it has to be capable of setting its self
reference to nothing.  Something has to trigger that or the class will never
close.  Again this is very rare though.

More than likely you have several pointers to the class and one of them is
not being set to nothing.  Every single pointer to the class has to be set
to nothing.  The _Terminate will fire whenever that last pointer is set to
nothing.


John W. Colby
Colby Consulting
www.ColbyConsulting.com
-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Robert
Sent: Friday, March 21, 2008 8:48 PM
To: 'Access Developers discussion and problem solving'
Subject: Re: [AccessD] Closing & Destroying Objects

John,
 Thank you...
   How do you find the cause of setting a class to nothing, and the
Class_Terminate sub not running.. I'm assuming something is still open
within the class, but just can't see it..
  
Set qbc = Nothing

Does not cause the Class_Terminate() sub to run..

Thanks Again.

WBR
Robert

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: Friday, March 21, 2008 7:12 PM
To: 'Access Developers discussion and problem solving'
Subject: Re: [AccessD] Closing & Destroying Objects

You need to set pointers to nothing EVERYWHERE.  You need to close before
setting pointers to nothing in the last place that the recordset is used. 


John W. Colby
Colby Consulting
www.ColbyConsulting.com
-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Robert
Sent: Friday, March 21, 2008 6:09 PM
To: 'Access Developers discussion and problem solving'
Subject: [AccessD] Closing & Destroying Objects

Hello Group,
 I have a question about how to close an object correctly..

Dim rstWOS              As DAO.Recordset

Set rstWOS = db.OpenRecordset("qryServicesNavigator", dbOpenDynaset,
dbInconsistent)

 I do a findfirst on rstWOS which I pass to another form. Like such..


            DoCmd.OpenForm "frmMsgboxWODelete", , , , , acHidden
            With Form_frmMsgboxWODelete
             .CallingForm = "Calander"
             .RN = EventRN
              Set .rst = rstWOS
              .Visible = True
            End With

In the form it's a property 

Private m_objRst            As DAO.Recordset

Public Property Set rst(objRst As DAO.Recordset)
    Set m_objRst = objRst
End Property


Where do I Properly close and destroy the recordset, in the first or the
second or both?

I'm thinking that I need to destroy it on the first, as if I destroy it on
second via:

Private Sub Form_Unload(Cancel As Integer) If Not m_objRst Is Nothing Then
m_objRst.Close  Set m_objRst = Nothing End If End Sub

Then I get some very strange problems trying to destroy in on the first..
Like and Error 3420 Oject Invalid or No Longer Set Via: (because the
recordset is already closed??)


If Not rstWOS Is Nothing Then
 rstWOS.Close
 Set rstWOS = Nothing
End If

TIA...

WBR
Robert



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