Visual Basic

carlos_rocha20-Dec-04 6:50

20-Dec-04 6:50

Hi! Thanks for you reply.I made a little example using the AsyncCallBack class and BeginInvoke() but i reached a result that i didn't expected.I ran the beginInvoke in a different thread and the callback function is located at the form(main thread).After the beginInvoke() my code proceeded(as expected).Then the execution passed to the callback function(in the form) but it wasn´t running neither on the thread or form context, it was in a completly different thread.Strange?For me it was because i was hopping that the callback executed in the form's context.Am i doing anything wrong or is this correct?

Nicholas Cardi20-Dec-04 7:16

20-Dec-04 7:16

This is the normal behavoir of the AsyncCallBack class. However, you should not let this tread modify any of the forms controls. This is an Windows UI rule and if you violate it you will pay the price Smile | :)

. If you need to modify the forms controls during the call back do the following in the call back function.

Private Sub MyFunct() 'This is your callback function.
If Me.InvokeRequired = True Then
Me.Invoke("Your Delegate here") 'You can create a delegate that matches the call back
'and pass that in. After the invoke the function will be recalled and you will
'end up in the else part of this block
Else
'Do your work here this code is now executing on the UI thread.
End If
End Sub

Forever Developing

carlos_rocha20-Dec-04 7:29

20-Dec-04 7:29

Ok! I made that last question because i have and app that raises an event in a thread and the handler is in the main form. The context of the handler is the thread which fired the event but this isn't happening with the async. Callback, thus my confusion. When i raise and event and check out the name of the current thread it gives me the thread that fired the event, if i check the name with the callback the name isn't from the thread that executed the beginInvoke().But if you say that this is the normal procedure fine by me Big Grin | :-D

One less problem for me to handle. But just to know, in what thread is it running? Is it a thread from the thread pool?A system thread?Just out of curiosity...

PS:Ye, i know that is a mistake to modify the UI from another thread.I found out the hard way Big Grin | :-D

Thanks for your concerne.

Nicholas Cardi20-Dec-04 7:47

20-Dec-04 7:47

OK, this is what I belive is happing. The AsyncCallback is creating a new thread to do the work. I am not sure where this tread comes from but I belive it is from the thread pool Dot Net creates on startup. When you call BeginInvoke that tread starts on the function you have told it to execute. When it is finished it will call your finshed call back.

Forever Developing

carlos_rocha20-Dec-04 21:58

How to build a COM or Win32 in .NET IDE

20-Dec-04 21:58

Thanks a bunch.
That was what i though.

kmaclean20-Dec-04 6:48

kmaclean

20-Dec-04 6:48

Help!

We're getting ready to deploy and I'm trying to build a Launcher application that will run on non-.NET platforms (COM or Win32).

Is there any way to build or compile a VB .NET application to output COM or Win32 code, or do I have to re-write this thing in Visual Studio 6 or InstallShield?

We're shipping tomorrow! Please help!

Re: How to build a COM or Win32 in .NET IDE

Nicholas Cardi20-Dec-04 7:24

Excel Interop with Existing File?

20-Dec-04 7:24

This depends on the Level of the Visual Studio Dot Net you have installed. If you have the ability to create C++ applications then you can create byte code exe's "Win32" in C++. If you are asking if a VB.Net application can be compiled as byte code, the answer to that is NO. If you use VB 6.0 then you will get semi-byte code but you will still need the vb runtime. The vb 6 runtime is installed by default for Windows 2000 and greater.

For a very simple launch I would create a native C++ program.

For a more complicated on I would probably use InstallShield. However, I am not sure what you mean by Launcher since InstallShield is a installer application.

Best of Luck

Forever Developing

halhamilton20-Dec-04 3:59

halhamilton

20-Dec-04 3:59

I've found numerous examples on doing interop by creating a NEW Excel file, but would like to open an existing Excel file from VB.NET and interop with that. I've tried "guessing" how to modify the examples, but with no luck. Can anyone point me to an example of how to open an existing Excel file in VB.NET so I can interop with it?

Thanks for any help on this... Confused | :confused:

Hal in AZ

Re: Excel Interop with Existing File?

Jim Matthews20-Dec-04 6:30

Jim Matthews

20-Dec-04 6:30

hey hal,

try...

myExcel.Workbooks.Open(pathToFile)

hope this helps

-jim

Re: Excel Interop with Existing File?

halhamilton22-Dec-04 6:15

halhamilton

22-Dec-04 6:15

Jim,
Worked fine. Thanks very much! Funny that out of 3 different books no one mentioned this.

Thanks again,
Hal

Hal in AZ

how to treat events async.?

carlos_rocha20-Dec-04 3:17

20-Dec-04 3:17

Hi!

I have a doubt about how to handle an event asynchronously.I have an event and a handler for that event, but after the raiseevent instruction the handler runs synchronously and my thread has to wait for the handler to terminate it's code.How can i treat this event asynchronously using the raisevent instruction? And what about delegates?Is it easier to perform with delegates?

Nicholas Cardi20-Dec-04 5:24

Add filenames to list box

20-Dec-04 5:24

I am not sure but I don't think you can accomplish this with RaiseEvent. However, you can use the
AsyncCallback class. Check your local help files for more information on how to use this class.

Best of Luck

Forever Developing

johnjsm20-Dec-04 2:07

20-Dec-04 2:07

Hi,
Is there a way to add file names from a folder on the hard drive to a list box and only show two types of file extensions ie txt and dat files using vb6.

Thanks

Nicholas Cardi20-Dec-04 5:54

20-Dec-04 5:54

Here you go.

1) You need to add a referance to the Microsoft Scripting Runtime.
2) Add a Command Button to the form
3) Add a ListBox to the form
4) Have Fun

'///BEGIN CODE///

Private Sub Command1_Click()

Dim fso As New FileSystemObject
Dim fld As Folder
Dim fi As File
Dim I As Long

Set fld = fso.GetFolder("C:\")

For Each fi In fld.Files
If MatchesExtension("txt", fi.Name) Then
List1.AddItem fi.Name
End If
Next

End Sub

'Takes a filename and a file extension to match
'Works in reverse on the file name looking for the last
'period character. Once found the string is then compared to the
'passed in sFileExtension parameter.
Private Function MatchesExtension(sFileExtension As String, sFileName As String) As Boolean
Dim sChar As String
Dim sTemp As String
Dim I As Long

MatchesExtension = False

For I = Len(sFileName) To 1 Step -1
sChar = Mid(sFileName, I, 1)
If sChar = "." Then
If sTemp = sFileExtension Then
MatchesExtension = True
Else
MatchesExtension = False
End If
Exit For
End If
sTemp = sTemp & sChar
Next I

End Function

'///END CODE///'

Forever Developing

johnjsm20-Dec-04 22:09

20-Dec-04 22:09

Thank you so much for this code. One question. Does this only wory for txt files or can other extensions be used. The two file extensions i'm trying to display is .cdimage and .dvdimage
I tried changing the "txt" in the code you gave me but it did not work.
Any ideas.
Once again Thank you for the code

Nicholas Cardi21-Dec-04 4:14

21-Dec-04 4:14

Sorry about that. There is a small bug. I tested it with txt files.

Here is the fix you need to make.

In the MatchesExtension Function change

sTemp = sTemp & sChar

TO

sTemp = sChar & sTemp

if you want to add different/more file types you can do some thing like this in the
commandbutton click event

For Each fi In fld.Files
If MatchesExtension("cdimage", fi.Name) Then
List1.AddItem fi.Name
End If
If MatchesExtension("dvdimage", fi.Name) Then
List1.AddItem fi.Name
End If
'Keep adding file extensions. by duplicating the code above
Next

Forever Developing

johnjsm21-Dec-04 4:56

21-Dec-04 4:56

Thank you so much. You the man
I'm wondering if i could ask you one more thing.
I was trying to change your code so that I could get it to do the following.

i need to separate the file name eg 50678.cdimage. so that the 50678 goes into one text box and the .cdimage goes into another text box. would you be able to help on this.
Thanks

johnjsm22-Dec-04 0:25

22-Dec-04 0:25

johnjsm22-Dec-04 0:24

22-Dec-04 0:24

Nicholas Cardi22-Dec-04 5:04

22-Dec-04 5:04

I am not sure what you are asking for here.

You want to enter a file name in a text box and have the name and extension split into to differnet text boxes?

Forever Developing

johnjsm22-Dec-04 5:35

22-Dec-04 5:35

You hit the nail on the head. I was trying with your code but with no success. Is this possible. If you could help I would be so greatful. This will make the program i'm working on work perfectly.

Nicholas Cardi22-Dec-04 5:51

22-Dec-04 5:51

Add a command button.
Name it cmdSplit called split

Add 3 text boxes.
Name the first one txtFileName
Name the second one txtFile
Name the third one txtExtension

Private Sub cmdSplit_Click()

SplitFileNameOnDot (txtFileName.Text)

End Sub

Private Function SplitFileNameOnDot(sFileName As String)
Dim sChar As String
Dim sTemp As String
Dim sName As String
Dim sExtension As String
Dim bGotExtension As Boolean
Dim I As Long

For I = Len(sFileName) To 1 Step -1
sChar = Mid(sFileName, I, 1)

If bGotExtension = False Then
sExtension = sChar & sExtension
Else
sName = sChar & sName
End If

If sChar = "." Then
bGotExtension = True
End If
Next I

txtExtension.Text = sExtension
txtFile.Text = sName

End Function

Forever Developing

johnjsm22-Dec-04 6:18