Re: Problem with Remove/AddHandle
- From: "Lloyd Sheen" <a@xxx>
- Date: Sat, 27 Dec 2008 16:50:07 -0500
"Cor Ligthert[MVP]" <Notmyfirstname@xxxxxxxxx> wrote in message news:OLTWhyFaJHA.5488@xxxxxxxxxxxxxxxxxxxxxxx
Lloyd,
One last thing. The Textbox is in a usercontrol, hosted in a tabpage, hosted on the mainform. I have had many problems with tabs including docking where I have had to code the docking in the maninform load event.
Afaik is the tabpage doing a kind of initializing everytime it is from not showed to showed. (Herfried knows this much better then I)
Therefore can you first delete the add handler from your load and simple set it in the event sub in VB style (or just for testing set a boolean before that initial load.)
Cor
"Lloyd Sheen" <a@xxx> wrote in message news:eX%23JNUFaJHA.4852@xxxxxxxxxxxxxxxxxxxxxxx
"Cor Ligthert[MVP]" <Notmyfirstname@xxxxxxxxx> wrote in message news:uxL9nIFaJHA.3908@xxxxxxxxxxxxxxxxxxxxxxxLloyd,
I was currious to your problem, I made this piece of code, the only difference I see that I did add the handler by using the VB extention for that.
I did not have the problem you told. Can it be that your addhandler what you asume is the load is executed more times?
\\\
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles TextBox1.TextChanged
Static x As Integer = 0
x += 1
Label1.Text = "I am changed for the " & x.ToString & " time"
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button1.Click
RemoveHandler TextBox1.TextChanged, AddressOf TextBox1_TextChanged
Label1.Text = "I am reset"
TextBox1.Text = ""
AddHandler TextBox1.TextChanged, AddressOf TextBox1_TextChanged
End Sub
///
Cor
"Lloyd Sheen" <a@xxx> wrote in message news:uNBycwEaJHA.6036@xxxxxxxxxxxxxxxxxxxxxxxI am trying to do the "Dot.Net" way of handling the following situation.
I have a handler for a textbox for changes in the text box. On the load of the usercontrol containing the textbox I have the following code:
AddHandler ArtistName.TextChanged, AddressOf ArtistName_TextChanged
This works just fine. The problem is that in several occasions I want to directly set the contents of the textbox and not have the event fire. In the code to do this I have the following code:
RemoveHandler ArtistName.TextChanged, AddressOf ArtistName_TextChanged
Me.ArtistName.Text = inArtistName
AddHandler ArtistName.TextChanged, AddressOf ArtistName_TextChanged
This should first remove the handler such that the next line which sets the text will not cause an event and then the handler is reinstated so that any further keystrokes in the textbox will cause the event.
What happens is that on the first occurrence of the programmatic set of the text there is no problem, the event does not happen but on each of the next attempts the event is fired. I have verified this with the call stack.
Brand New Music Console.exe!New_Music_Console.CDByArtistUC.ArtistName_TextChanged(Object sender = {Text = "Laura Nyro"}, System.EventArgs e = {System.EventArgs}) Line 102 Basic
[External Code]Brand New Music Console.exe!New_Music_Console.CDByArtistUC.setItems(String inArtistName = "Laura Nyro") Line 96 + 0x25 bytes BasicBrand New Music Console.exe!New_Music_Console.MainForm.SongViewUC1_ShowArtistAlbums(String artist = "Laura Nyro") Line 907 + 0x1b bytes Basic
I really don't want to create a Boolean to short-circuit the handler as I want to use this technique in cases where the code is not necessarily in the same code file.
LS
Cor,
Could you add the code to your sample and see what you get. It uses linq for the search so if you are not using VS 2008 you will have to change the query to a loop.
You will need -
Imports System.ComponentModel
Imports System.Reflection
Imports System.Data.Linq
Public Function GetEventSubscribers(ByVal target As Object, ByVal eventName As String) As [Delegate]()
Dim t As Type = target.GetType
Dim fia As FieldInfo() = t.GetFields((BindingFlags.NonPublic Or (BindingFlags.Static Or BindingFlags.Instance)))
For Each f As FieldInfo In fia
Debug.WriteLine(f.Name)
Next
Dim q() As FieldInfo = (From fif In fia Where fif.Name.Contains(eventName.ToUpper) Select fif).ToArray
If q.Count > 0 Then
Dim fi As FieldInfo
Dim d As [Delegate]
fi = q(0)
d = TryCast(fi.GetValue(target), [Delegate])
If (Not d Is Nothing) Then
Return d.GetInvocationList
End If
End If
Return New [Delegate](0 - 1) {}
End Function
When I use this with my TextBox (see below) it does not find the TextChange event. I have tried other controls and they seem to find all the events.
Dim tmpDelegates() As [Delegate]
tmpDelegates = GetEventSubscribers(Me.ArtistName, "TextChange")
One last thing. The Textbox is in a usercontrol, hosted in a tabpage, hosted on the mainform. I have had many problems with tabs including docking where I have had to code the docking in the maninform load event.
Thanks
LS
Cor,
The tabpage is loaded on form load, the user control I use has only one occurence of the load and that is where I set the handler. I have done a bunch of testing using reflection and it really appears that the textbox does not in any way I can see follow the rules as do other controls. I may be my understanding (or lack of) of reflection but I had to create a Type object of the base type to see the events and fields for the TextBox object. This may be why.
I guess the boolean will have to do for now and I will have to create a property to tell the usercontrol not to handle the event.
Oh well. I will create a simple C# app to see what I see there.
Thanks
LS
.
- References:
- Problem with Remove/AddHandle
- From: Lloyd Sheen
- Re: Problem with Remove/AddHandle
- From: Cor Ligthert[MVP]
- Re: Problem with Remove/AddHandle
- From: Lloyd Sheen
- Re: Problem with Remove/AddHandle
- From: Cor Ligthert[MVP]
- Problem with Remove/AddHandle
- Prev by Date: Re: Destroy Objects How ?
- Next by Date: Re: Destroy Objects How ?
- Previous by thread: Re: Problem with Remove/AddHandle
- Index(es):
Relevant Pages
|
