I have just started to migrate some code from VBA to VB.Net. So I am an absolute beginner in VB.Net – but I want to do things right. Maybe some of my questions are stupid but I guess that is because I am a beginner.
So as a first exercise I have developed my first piece of code (see below). Now I thought I have to release ALL COM objects again. Two of them throw errors already while writing the code. And others throw errors at runtime.
But the funny thing is: Weather I release the rest of the COM objects or not (by making the relevant not yet commented lines of Marshal.Release to comments as well – then all lines starting with Marshal.Release are comment lines) the behavior of the code is absolutely the same to my eyes.
Can anybody tell me where I can see/find the difference?
The internet tells me that there must be a difference?
But I guess I just don’t understand (till now).
Besides this many more questions are in my head:
Does every “Dim” statement create a COM Object - that has to be released later on?
If not how do I detect whether a COM object has been created or not? Which “Dim” statements create COM object and which don't?
In this example: Dim ActiveWindow As Object = Nothing Try ActiveWindow = Me.HostApplication.ActiveWindow() Catch End Try
Is
Marshal.ReleaseComObject(ActiveWindow)
identical to
Marshal.ReleaseComObject(Me.HostApplication.ActiveWindow())?
According to this:
http://www.codeproject.com/Tips/235230/Proper-Way-of-Releasing-COM-Objects-in-NET
Would it not be better to release each "level" separately like this:
Marshal.ReleaseComObject(Me.HostApplication.ActiveWindow())
Marshal.ReleaseComObject(Me.HostApplication)
Marshal.ReleaseComObject(Me)
Overall: Am I trying to release too much? Or is it correct / good practie?
And what does "GC.Collect()" and "… = Null" have to do with all this? I have not used it at all. Should I better use it? Why? ( "... = Null" I have seen here:
http://www.codeproject.com/Tips/162691/Proper-Way-of-Releasing-COM-Objects-in-NET)
Why do I get “ShapeCount was not declared …” - Error if I try to do “Marshal.ReleaseComObject(ShapeCount)”? The same with “ShRange”. I think these are COM objects as well?!?
How do I notice when is the best time to release the COM object again? When I process/debug my code step by step with F11 will it be possible for me to determine the best (soonest) point of release? So far I have no “feeling” about when the COM object is not needed anymore and I can release it.
Any help and explanations very welcome.
Here is the code I am talking about:
Imports System.Runtime.InteropServices
Imports System.ComponentModel
Imports System.Windows.Forms
Imports AddinExpress.MSO
Imports PowerPoint = Microsoft.Office.Interop.PowerPoint
'Add-in Express Add-in Module
<GuidAttribute("D75C609E-7632-400F-8A6F-6A6E6E744E75"),
ProgIdAttribute("MyAddin8.AddinModule")> _
Public Class AddinModule
Inherits AddinExpress.MSO.ADXAddinModule
#Region " Add-in Express automatic code "
[…]
#End Region
Public Shared Shadows ReadOnly Property CurrentInstance() As AddinModule
Get
Return CType(AddinExpress.MSO.ADXAddinModule.CurrentInstance, AddinModule)
End Get
End Property
Public ReadOnly Property PowerPointApp() As PowerPoint._Application
Get
Return CType(HostApplication, PowerPoint._Application)
End Get
End Property
Private Sub AdxRibbonButton2_OnClick(sender As Object, control As IRibbonControl, pressed As Boolean) Handles AdxRibbonButton2.OnClick
MsgBox(GetInfoString2())
End Sub
Friend Function GetInfoString2() As String
Dim ActiveWindow As Object = Nothing
Try
ActiveWindow = Me.HostApplication.ActiveWindow()
Catch
End Try
Dim Result As String = "No document window found!"
If Not ActiveWindow Is Nothing Then
Select Case Me.HostType
Case ADXOfficeHostApp.ohaPowerPoint
Dim Selection As PowerPoint.Selection =
CType(ActiveWindow, PowerPoint.DocumentWindow).Selection
Dim WindowViewType As PowerPoint.PpViewType = PowerPoint.PpViewType.ppViewNormal
Dim SlideRange As PowerPoint.SlideRange = Selection.SlideRange
Dim SlideCountString = SlideRange.Count.ToString()
If WindowViewType = 9 And SlideCountString < 2 Then
Dim ShRange As PowerPoint.ShapeRange = Nothing
Try
ShRange = Selection.ShapeRange
Catch
End Try
If Not ShRange Is Nothing Then
Dim ShapeCount = ShRange.Count.ToString()
Result = "You have " + ShapeCount _
+ " shapes selected."
Else
Result = "You have 0 shapes selected."
End If
End If
'Marshal.ReleaseComObject(ShapeCount)
'Marshal.ReleaseComObject(ShRange)
'Marshal.ReleaseComObject(WindowViewType)
'Marshal.ReleaseComObject(SlideCountString)
Marshal.ReleaseComObject(SlideRange)
Marshal.ReleaseComObject(Selection)
Case Else
Result = AddinName + " doesn't support " + HostName
End Select
'Marshal.ReleaseComObject(Me.HostType)
'Marshal.ReleaseComObject(Result)
Marshal.ReleaseComObject(Me.HostApplication.ActiveWindow())
Marshal.ReleaseComObject(Me.HostApplication)
'Marshal.ReleaseComObject(Me)
End If
Return Result
End Function
End Class
The ReleaseComObject method of the Marshal class decrements the reference count of the specified Runtime Callable Wrapper (RCW) associated with the specified COM object, it doesn't release an object. It comes from the COM nature.
Typically you need to release every object returned from the Office (PowerPoint in your case) object model. Exceptions are objects passed to event handlers as parameters.
You may read more about that and find answers to your multiple questions in the When to release COM objects in Office add-ins developed in .NET article.
FinalReleaseComObject calls ReleaseComObject til it returns 0 which means release of COM object. Calling them in reverse order as in Excel objects(Application, Workbook, Worksheet) is the proper way to dispose of COM objects that are related.
Exception Condition
ArgumentException
o is not a valid COM object.
ArgumentNullException
o is null.
Related
Anyone else finding that their Terminate() method in Access isn't being called?
Here's my code for my cBusyPointer class with the comments removed for brevity:
Option Compare Database ' Use database order for string comparisons
Option Explicit ' Declare EVERYTHING!
Option Base 1 ' Arrays start at 1
Public Sub show()
DoCmd.hourGlass True
End Sub
Private Sub Class_Terminate()
DoCmd.hourGlass False
End Sub
Typical usage is:
Sub doTehThings()
Dim hourGlass As New cBusyPointer
hourGlass.show()
' Do all teh things
End Sub
In previous versions, this class would restore the hourglass whenever the object went out of scope and was destroyed.
I even tried to manually destroy my hourglass object:
Sub doTehThings()
Dim hourGlass As cBusyPointer
Set hourGlass = New cBusyPointer
hourGlass.show()
' Do all teh things
Set hourGlass = Nothing
End Sub
The only way to fix this is to add a hide() method and call that.
Has anyone else encountered this problem?
I cannot replicate the issue. The Terminate() method is called upon reaching the Set hourGlass = Nothing.
A couple of points:
Dim hourGlass As New cBusyPointer
This will create a new instance every time you call the hourGlass variable even to set it to Nothing. See the answer in the link below for additional info:
What's the difference between Dim As New vs Dim / Set
You should always use Dim/Set when working with objects.
hourGlass.show()
This does not even compile in VBA. Subs do not accept parentheses even when arguments are being expected, unless they are preceded with the Call keyword.
Lastly, the cleanest way to reference an object is to access it using the With statement which ensures the object is terminated when the End With statement is reached.
With New cBusyPointer
.show
End With
So, here it goes. To start, A disclaimer, I understand that MS Access is not built for this kind of work. It is my only option at this time.
I have done just a bit of Automation using UIAutomationClient and I have successfully used its other features, however I cannot for the life of me get it to subscribe to events.
Normally, it is supposed to be a bit like this:
Dim CUI as new CUIAutomation
Dim FocusHandler as IUIAutomationFocusChangedEventHandler
Set FocusHandler = new IUIAutomationFocusChangedEventHandler(onFocusChanged)
C.AddFocusChangedEventHandler(Element,TreeScope_Children, null, FocusHandler)
end function
'
'
Function onFocusChanged(src as Object, args as AutomationEventArgs)
''my code here
end function
Yet when I attempt this, I get the error "expected end of statement" on the line:
FocusHandler = new IUIAutomationFocusChangedEventHandler(onFocusChanged)
additionally, if I leave off the (onFocusChanged) I get the error "Invalid use of new Keyword".
It seems like I am missing a reference somewhere. The usual drop down when using "new" does not contain the IUI handler classes though they are in the object library.
I am not sure if there is just some piece I am not accounting for in the code since I am using vba, but all examples seem to be for .net or C#/C++. Any help would be appreciated.
Additionally, I have no problem finding the element in question and all other pieces work fine. If you need any other pieces of the code let me know.
Edit: added set to line 3. No change in the problem though.
After two years this probably isn't relevant any more, but perhaps somebody else encounters this problem... The answer is to create a new class that implements the HandleAutomationEvent method.
Here I created a class named clsInvokeEventHandler and (importantly) set the Instancing property to PublicNotCreatable:
Option Explicit
Implements IUIAutomationEventHandler
Private Sub IUIAutomationEventHandler_HandleAutomationEvent(ByVal sender As UIAutomationClient.IUIAutomationElement, ByVal eventId As Long)
Debug.Print sender.CurrentName
End Sub
And to use it:
Sub StartInvokeHandler()
Dim oUIA As New CUIAutomation8
Dim oRoot As IUIAutomationElement
Dim InvokeHandler As clsInvokeEventHandler
Set InvokeHandler = New clsInvokeEventHandler
Set oRoot = oUIA.GetRootElement
oUIA.AddAutomationEventHandler UIA_Invoke_InvokedEventId, oRoot, TreeScope_Descendants, Nothing, InvokeHandler
End Sub
I am getting an error trying to arrange asynchronous loading and parsing of an XML document in VBA using a wrapper class.
Following the ideas described in this msdn article and this tutorial which have worked perfectly for asynchronous handling of MSXML2.XMLHTTP40.send method I attempted to do a similar thing for DOMDocument.loadXML.
Here is the code from the wrapper class DOMMonitor
Private domDoc As MSXML2.DOMDocument
Public Event onXmlLoadComplete(d As MSXML2.DOMDocument)
Public Sub loadXML(XmlFilePath As String)
Set domDoc = CreateObject("MSXML2.DOMDocument")
domDoc.async = True
domDoc.onreadystatechange = Me ' error occurs here
domDoc.Load XmlFilePath
End Sub
Public Sub onLoadComplete()
If domDoc.readyState = "4" Then
RaiseEvent onXmlLoadComplete(domDoc)
End If
End Sub
I have made onLoadComplete the default method by setting VB_UserMemId = 0, so it is supposed to be invoked when domDoc fires onreadystatechange .
However when I invoke loadXML
Dim dm As DomMonitor
Set dm = New DomMonitor
dm.loadXML txtXMLData
i get the following runtime error in this line:
domDoc.onreadystatechange = Me
This object cannot sink the 'onreadystatechange' event. An error occurred marshalling the object's IDispatch interface
What am I doing wrong and is there a good workaround here?
Thanks in advance.
P.S. The reason I am republishing the event is that I do not necessarily want use the default method of the final subscriber for this purpose. However, as things stand now I do not even get to that stage.
The way I read that msdn article is that to assign a wrapper class to the readystatechange, the object has to be either an IXMLHTTPRequest or an IServerXMLHTTPRequest object (bullet 3). Since your object is a DOMDocument, readystatechange doesn't accept an object.
However, you can instantiate a DOMDocument WithEvents (bullet 2), making the other way redundant, I guess. I don't have an xml file large enough to test, but I think this should work. I assume that if the class loses scope, all bets are off, so I made it a global variable.
In a standard module
Public clsDOMMonitor As CDOMMonitor
Sub test()
Set clsDOMMonitor = New CDOMMonitor
clsDOMMonitor.loadXML "C:\Users\dkusleika\Downloads\wurfl-2.3.xml"
End Sub
In CDOMMonitor class
Private WithEvents mDoc As MSXML2.DOMDocument
Private Sub mDoc_onreadystatechange()
If mDoc.readyState = 4 Then
MsgBox "second"
End If
End Sub
Public Sub loadXML(XmlFilePath As String)
Set mDoc = New MSXML2.DOMDocument
mDoc.async = True
mDoc.Load XmlFilePath
MsgBox "first"
End Sub
I assume that setting async to True is all that is needed for this to work properly. My 100k xml file is probably done so fast that that the event never gives up control. But if you had a sufficiently large xml file, I think you would get "first" before "second".
Change the class' Instancing property from Private to PublicNotCreatable when late binding, whilst also applying the tweak which you have mentioned.
Use the above example when early binding (as in your case).
I have a crash file where I can see that one of my own VB6 user controls is responsible for the crash; i.e. one of its methods is part of the stack trace and I can see the line responsible.
From here, I'd like to inspect the state of its member variables. How do I do this?
Note: I also have the private symbols for my controls. The problem is being able to inspect "Me". The command !object address_of_Me doesn't seem to do the trick and so I'm at a loss.
Thank you.
It's been 10 years since I had to do this in VB6, but I remember a lot of Printer.Print statements in my past life :)
I used to do things like this for debugging (but not for release code)
Sub MySub
On Error Goto ErrorTrap
Dim intX as integer
Dim intY as integer
' do some horrible error here
Exit Sub
ErrorTrap:
Printer.Print "Error"
Printer.Print intX
Printer.Print intY
Printer.Print ...
End Sub
well, codeSMART have one option install global handle on your application first call to SetUnhandledExceptionFilter (win api) is should be installed when load your module main or master form when is closing the program so call to SetUnhandledExceptionFilter.
The code is little long so copy methods names y api calls
Public Sub InstallGlobalHandler()
On Error Resume Next
If Not lnFilterInstalled Then
Call SetUnhandledExceptionFilter(AddressOf GlobalExceptionHandler)
lnFilterInstalled = True
End If
End Sub
Public Sub UninstallGlobalExceptionHandler()
On Error Resume Next
If lnFilterInstalled Then
Call SetUnhandledExceptionFilter(0&)
lnFilterInstalled = False
End If
End Sub
Also here is Record Structure y apis declarations for the module
- CopyMemory
- SetUnhandledExceptionFilter
- RaiseException
' Public enums
-EExceptionType
-EExceptionHandlerReturn
-Private Const EXCEPTION_MAXIMUM_PARAMETERS = 15
' Private record structure
-Private Type CONTEXT
'Structure that describes an exception.
-Private Type EXCEPTION_RECORD
'Structure that contains exception information that can be used by a debugger.
-Private Type EXCEPTION_DEBUG_INFO
-Private Type EXCEPTION_POINTERS
Take a revised that How to route the exe exception back to VB6 app?
I have a collection inside a class module. I'd like to restrict the object type that is "addable" to this collection, i.e. collection should only ever accept objects of one given type and nothing else.
Is there any way to enforce the type of objects added to a collection?
From what I can tell, there is no built-in way to do this. Is the solution then to make this collection private, and build wrapper functions for the methods usually accessible for Collections, i.e. Add, Remove, Item, and Count?
I kinda hate having to write 3 wrapper functions that add no functionality, just to be able to add some type enforcement to the Add method. But if that's the only way, then that's the only way.
There is no way to avoid wrapper functions. That's just inherent in the "specialization through containment/delegation" model that VBA uses.
You can build a "custom collection class", though. You can even make it iterable with For...Each, but that requires leaving the VBA IDE and editing source files directly.
First, see the "Creating Your Own Collection Classes" section of the old Visual Basic 6.0 Programmer's Guide:
http://msdn.microsoft.com/en-us/library/aa262340(v=VS.60).aspx
There is also an answer here on stackoverflow that describes the same thing:
vb6 equivalent to list<someclass>
However, those are written for VB6, not VBA. In VBA you can't do the "procedure attributes" part in the IDE. You have to export the class module as text and add it in with a text editor. Dick Kusleika's website Daily Dose of Excel (Dick is a regular stackoverflow contributer as you probably know) has a post from Rob van Gelder showing how to do this:
http://www.dailydoseofexcel.com/archives/2010/07/04/custom-collection-class/
In your case, going to all that trouble - each "custom collection" class needs its own module - might not be worth it. (If you only have one use for this and it is buried in another class, you might find that you don't want to expose all of the functionality of Collection anyway.)
This is what I did. I liked Rob van Gelder's example, as pointed to by #jtolle, but why should I be content with making a "custom collection class" that will only accept one specific object type (e.g. People), forever? As #jtolle points out, this is super annoying.
Instead, I generalized the idea and made a new class called UniformCollection that can contain any data type -- as long as all items are of the same type in any given instance of UniformCollection.
I added a private Variant that is a placeholder for the data type that a given instance of UniformCollection can contain.
Private mvarPrototype As Variant
After making an instance of UniformCollection and before using it, it must be initialized by specifying which data type it will contain.
Public Sub Initialize(Prototype As Variant)
If VarType(Prototype) = vbEmpty Or VarType(Prototype) = vbNull Then
Err.Raise Number:=ERR__CANT_INITIALIZE, _
Source:=TypeName(Me), _
Description:=ErrorDescription(ERR__CANT_INITIALIZE) & _
TypeName(Prototype)
End If
' Clear anything already in collection.
Set mUniformCollection = New Collection
If VarType(Prototype) = vbObject Or VarType(Prototype) = vbDataObject Then
' It's an object. Need Set.
Set mvarPrototype = Prototype
Else
' It's not an object.
mvarPrototype = Prototype
End If
' Collection will now accept only items of same type as Prototype.
End Sub
The Add method will then only accept new items that are of the same type as Prototype (be it an object or a primitive variable... haven't tested with UDTs yet).
Public Sub Add(NewItem As Variant)
If VarType(mvarPrototype) = vbEmpty Then
Err.Raise Number:=ERR__NOT_INITIALIZED, _
Source:=TypeName(Me), _
Description:=ErrorDescription(ERR__NOT_INITIALIZED)
ElseIf Not TypeName(NewItem) = TypeName(mvarPrototype) Then
Err.Raise Number:=ERR__INVALID_TYPE, _
Source:=TypeName(Me), _
Description:=ErrorDescription(ERR__INVALID_TYPE) & _
TypeName(mvarPrototype) & "."
Else
' Object is of correct type. Accept it.
' Do nothing.
End If
mUniformCollection.Add NewItem
End Sub
The rest is pretty much the same as in the example (plus some error handling). Too bad RvG didn't go the whole way! Even more too bad that Microsoft didn't include this kind of thing as a built-in feature...
I did almost the same code of Jean-François Corbett, but I adapted because for some reason wasn't working.
Option Explicit
Public pParametro As String
Private pColecao As New Collection
Public Sub Inicializar(ByVal parametro As String)
pParametro = parametro
End Sub
Public Sub Add(NewItem As Object)
If TypeName(NewItem) <> pParametro Then
MsgBox "Classe do objeto não é compatível à coleção"
Else
pColecao.Add NewItem
End If
End Sub
Public Property Get Count() As Long
Count = pColecao.Count
End Property
Public Property Get Item(NameOrNumber As Variant) As Variant
Set Item = pColecao(NameOrNumber)
End Property
Sub Remove(NameOrNumber As Variant)
pColecao.Remove NameOrNumber
End Sub
Then, when i want to create an instance from CCollection I make like the code bellow:
Set pFornecedores = New CCollection
pFornecedores.Inicializar ("CEmpresa")
Where CEmpresa is the class type from the object I want
Yes. The solution is to make your collection private and then make public wrapper functions to add, remove, getitem and count etc.
It may seem like hassle to write the additional code but it is a more robust solution to encapsulate the collection like this.