Clear All WithEvents Fields Via One Command?
Oct 15, 2010
The vb.net "WithEvents" syntax is very useful, but if a WithEvents field which references a long-lived object is not nulled out, it will often constitute a memory leak.Is there any easy way for a Dispose routine to have vb.net automatically clear out all WithEvents fields and unsubscribe them?
I've figured out a nice way to wrap the creation of disposable fields so that they will be automatically Disposed when the containing object is disposed, without having to individually list such objects. Is there any way to take care of WithEvents fields without having to manually null them out in the Dispose routine?
EDIT:Since there was no response indicating a built-in way to do it without reflection, is there any built-in means of using reflection to determine whether a particular property is a VB automatic implementation of a WithEvents "field"? I know that a WithEvents "field" called "foo" is implemented as a property called "foo" and a field called "_foo", but that's such a common naming pattern that I wouldn't count on it. Is there some attribute that could be used to determine which properties need to be auto-nulled?
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Feb 24, 2010
Is it necessary to set to Nothing(in Dispose()) all WithEvents fields?
Apparently Handles keyword adds handlers to such fields, but does not remove it until this field is not Nothing, and this can generate memory leaks?!.
This should be specially actual on cases like
class Foo
{
Private WithEvents _bar as Bar
[Code].....
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Jan 22, 2012
a simple question. Given the following code:
Public Class MyClass
Private WithEvents pPerClass As PersistableClass
Public Overridable Property PerClass() As PersistableClass
Get
Return pPerClass
[Code]...
the first being a duplication of the second key, strangely obtained from a private field.
If you remove the WithEvents keyword, the pPerClass_PersistableClassID key is not created.
I am new to EF but it seems to me a strange behaviour.
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Aug 21, 2011
User need to select their prefferable data to show in report. What i did is i have a clear command first to delete the temporary table. The temporary table is basically a table to stored user selection parameter data. After the clear command, i have
a insert command to insert user selection data into the temporary table. What happened now is when i run the program exe, first run of the report is work fined, but not the second and the following times of execution. It will return null or blank report. The weird thing is when i execute it from development environment, it seem like the report is able to pick up user selection parameter and run the report for the first times and the subsequent execution.
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Aug 5, 2009
I have the aplication which requires name fields... and i wan tto clear these fields whenever i closed the application using close(X) button. i dont want to use 'clear' button.
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Apr 7, 2012
I have a web page that has a few text fields, and a reset and submit button. I'm having trouble getting the reset button to work to clear the text fields because the required field validators and regular expression validators are blocking any code in the reset button's click event from occurring. how to get the validators to not activate when the reset button is clicked? One method I tried was to set the enabled property of all the validators to false in the reset button's code block but no luck.
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Feb 27, 2011
I am building a vb.net application for a client, and there is a problem. I am connecting to a mySQL server, and using the UPDATE command to update certain fields to the specified values, however, once I run this code, the fields on the mySQL server turn EMPTY. Here is my code :
Sub updateresidents()
'MAKES NO SENSE; UPDATES EMPTY FIELDS ON mySQL SIDE??!!!!!!!!!!!!!!!!!!
Dim connection As MySqlConnection
[Code]....
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Dec 13, 2011
this is currently my code to clear my 5 textboxes
Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
TextBox1.Clear()
TextBox2.Clear()
TextBox3.Clear()
TextBox4.Clear()
TextBox5.Clear()
End Sub
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May 17, 2009
I have a timer that runs every time by itself, and for the code the runs in it I would like to have it clear the dataset before it does anything, the timer runs every 10 seconds, so I tried to do dataset.clear but it would crash if the dataset had no values
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Nov 14, 2011
I'm currently refactoring an old Visual Basic DLL (VB.Net), which stores all of its data in one module called Globaldefinitions as public fields. There are about 200 fields, referenced thousands of times all around the code:
Public Module Globaldefinitons
Public a As Short
...
Public zz10 As Double
[Code]...
I need to change the module into a class with non-shared fields. This means, each and every of these thousands of references needs to reference the instance of that class:
globalDefinitionsInstance.a = 5
How do I go about this efficiently?
Regular expressions operating on the source fall flat. Refactoring tools like Re-Sharper or CodeRush don't seem to offer this functionality. Visual Studio 2010 cannot do it automatically either.
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Jun 19, 2011
Class Foo
ReadOnly name As String
Public Sub New(name As String, dependentUpon As Foo)
Me.name = name
[code]....
The output of New Bar() is:
Dependent created. Dependent upon nothing.
Independent created. Dependent upon nothing.
It seems fields are initialized in the same order as they appear in the source code, which (a) leads to an unexpected result, and (b) seems a little puzzling, given that one is normally not permitted to read from uninitialized variables in .NET, yet that seems to be working fine above.I would've expected VB.NET to be smart enough to initialize referenced fields first, and only then those that reference it; i.e. I'd have liked to see this output instead:
Independent created. Dependent upon nothing.
Dependent created. Dependent upon Independent.
how to get VB.NET to behave like that instead, without simply having to swap the declaration order of dependent and independent inside class Bar?
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May 27, 2012
I'm trying to create a table in Word using data from a table in Access. There are four fields in the access table that I need. 3 fields are text which I can populate the Word without any issues. However the fourth field is a memo with >255 characters.I'm struggling to come up with the proper code to allow me to populate the Word field with the memo data that has more than 255 characters. The code I have so far is listed below. But when it hits the memo field, it crashes on the line I marked with **. I know it's not text, but I've tried many different field types, but nothing has worked so far.[code]...
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Jan 14, 2012
My intent is to have the code - on a button.click event - check the Username and Password fields and return an error depending on which is wrong. Or if both are wrong, return a different error message. I've set the username as parts and the password as parts (still learning how to use external authentication). [Code]
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Aug 17, 2010
I have several sqldatasources for my gridview. All of the columns are autogenerated. However they all have some consistent fields and I'd like to make those fields template fields so I can modify the edit template for them such as adding a drop down menu. Is this possible?
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Jun 23, 2011
in hyper teriminal when i press "ctrl+L" is to clear terminal screen how to write the code in vb.net? Hyperterminal is connecting to serial comport.when i try this it work and return line on debug
serialport.writeline ("at+cmgl=1")
i try this but not work and it still show some lines on debug
serialport.writeline (vbcrtl +"L")
serialport.WriteLine("vbCrLf + l")
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Apr 30, 2010
First let me say that I am not sure whether or not this should go in this section or the API section, and if it needs to be moved I apologize. My issue is fairly straight forward, but for some reason I cannot get it to work.
I am trying to send a command to a command line and then submit the command. I have been trying without success to get this to work in v2008 Express and v2010 Express, Here is the code I am trying to us:
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" ( _
ByVal lpClassName As String, _
ByVal lpWindowName As String _
[Code].....
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Sep 20, 2010
way to clear textboxes in VB.Net and what is the difference between the two methods? I have also seen people be critical of folk using clear objects on their forms and i can see why but in this case, i am only learning.
txtbox1.Clear()
or
txtbox1.Text = ""
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Jul 15, 2009
wan to ask about anyone know the code about how to clear all the data inside the data grid view without clear the binding source...
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Sep 3, 2009
experience on how to create an engine using C# (VB.NET is okay too) that is generic enough to handle most cases of MS Word text fields I need to fill with data I'm getting from a database? In short, I'm about to embark on this little Office automation excursion and I'm hoping a little bit of feedback here.
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Dec 17, 2009
Who knows, why in vb.net WinForm projects the designer by default use the Friend WithEvents attributes and in C# - private ones.
By ex, in a form.designer.
.cs
private Label Label1;
.vb
Friend WithEvents Label1 as Label;
For WithEvents is more or less clear(for using Handles, apparently). But why Friend in VB and private in C#...
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Jul 11, 2011
i have the folowing co
For x = 0 To 7 Step 1
For i = 0 To 7 Step 1
Dim rectangleShape1 As New Microsoft.VisualBasic.PowerPacks.RectangleShape() 'create a new object to assign to the array location
board(x, i) = New Microsoft.VisualBasic.PowerPacks.RectangleShape() 'create the new object in the array
[code].....
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Feb 11, 2010
When you declare an object 'WithEvents' and then utilize the "Handles" clause at the end of your event methods, how does Visual Basic manage a reference change for the object? In other words, if the withevents var is set to ObjectA, then later I switch it to ObjectB (or nothing), does Visual Basic automatically both remove those handler methods from ObjectA, and attach them to ObjectB? Or do I still have a ObjectA's events being handled behind the scenes?
I ask this because if instead you use AddHandler for an object, and then switch your reference, unless you removed the handler before switching, your original object is still handled (at least I'm pretty sure that's how it works).
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Apr 21, 2010
I have the following classes: Public Class Email
[Code]...
If a create a wrong email lets say "email" the exception is correctly cached and a message is showed however is i input a valid email the event is not raised, the object is being created but no message is shown and no error or exception is thrown i suspect it has something to do with using "myemail = new Email(email)" but i have seen examples of using new with withevents with no problem.
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May 17, 2010
Does anyone know why a local variable cannot be declared WithEvents?T
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Jun 9, 2011
I'm trying to create multiple instances of a child form. This form has an event that feeds a string variable back to the parent so I'm declaring it with WithEvents which is declared outside of the Sub - meaning multiple clicks will not open multiple forms.
another method of doing this while keeping the event?:
Dim WithEvents FRestoreDB As New FormRestoreDB()
Private Sub BtnOpenDB_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnOpenDB.Click
[Code].....
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Feb 24, 2010
Protected WithEvents gel As New TabPage
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
TabControl1.TabPages.Add(gel)
gel.Text = ("Gel")
Private Sub Gel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles gel.Click
MsgBox("test") So my problem is that if I click on the tabpage gel, nothing happens.
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Sep 7, 2011
I have an application that performs a lot of busy work. All of the work is performed using a BackgroundWorker and the point of execution is the DoWork Event of the BackgroundWorker.On the UI thread, before the workload begins, I display a PictureBox that contains an animated GIF that illustrates progress; for the most part this works fine and the UI thread is not paused or slowed while the BackgroundWorker does its job. There is however, one instance where the UI thread is impacted by the work being done and it defeats the whole purpose of putting this work in a separate thread. In this application, the user must wait until the work completes before they can move to the next step, so my sole reason for moving this all to a BackgroundWorker was so that I could display a smooth, uninterrupted progress indicator on the UI thread while this work was being done, so that the user could see that something was happening.
The case where the work being done is impacting the UI thread (pausing/delaying the PictureBox animation) deals with a referenced COM object.
[Code]...
All of the COM object event handlers and subsequent functions are appropriately using Delegates, but I am not sure why the ProcessFiles method would cause the UI thread to hang while the work completes; I thought that was the whole purpose of the BackgroundWorker.
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Dec 14, 2010
I'd like to create an array of objects with events. Where do I need to put the "WithEvents"? Should it be placed in the ReDim line or the next one?I'm trying to use a "global" event, like objects of people that recieve a time-event to get older.
[Code]...
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Apr 8, 2012
I have a table which contains a list of products for a company. They input data about how much stock they have and also the level at which they want to be reminded that they need to order new stock.
[Code]...
I want to list all the true results in a form which the user is then able to navigate through. What would be the best way to go about doing this?
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Mar 5, 2010
What is the optimal approach to a WithEvents Collection - VB.NET?Have you any remarks on the code bellow (skipping the Nothing verifications)?The problem is when I obtain the LinkedListNode(Of Foo) in a For Each block I can set myNode.Value = something, and here is a handlers leak...
-Could I override the FooCollection's GetEnumerator in this case?
-No. :( cause NotInheritable Class LinkedListNode(Of T)
Class Foo
[code]....
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