In VB.NET, I can't seem to figure out how to do a similar thing.
This doesn't work:
Dim handler As EventHandler = Me.SomeEvent
...due to the following error:
Public Event SomeEvent(sender As
Object, e As EventArgs)' is an event,
and cannot be called directly. Use a
'RaiseEvent' statement to raise an
event.
But this doesn't work either: [Code] So how can I actually get an EventHandler from an event in VB.NET? The only idea that's immediately coming to mind is to use reflection, but that seems pretty ridiculous.
I have a Dialog Box that creates a Link Label for each item in a list.When one of those LinkLabels is clicked the DialogBox raises a LinkClicked event.Before, I was using code like this in the Form that was instantiating the Dialog:[code]But I don't like that for several reasons.What I want to do, and what I thought would be straight forward, was to pass the AddressOf the UserClicked PoLink Method into the ShowClickableLinksDialog Constructor and do an AddHandler within the constructor and also assign the Delegate to a Property on the Dialog so as to RemoveHandler when the Dialog is Disposed.[code]But I get a squiggly on the tempLinkClickedEventHandler after the AddressOf Operator saying: "AddressOf operand must be the name of a method (without parenthesis)"I don't get it.I've played around with a number of permutations and can't get what I feel ought to work, to work.
D is a dictionary whose entry values are of Type T..What I'm attempting to do is have a delegate like "Serializer" below that I can invoke on an instance of T, such as "Entry.Value" below.Please see the "return Entry..." line below for my wishful thinking.[code]
Ran into this while converting a VB.NET interface to C#; the VB version defines an event which doesn't conform to the typical (object sender, EventArgs e) signature:
I do have a customized treeview which inherits from treeview. The customized treeview offers - amongst other - the functionality to automatically check/uncheck the child and parent nodes according to the selected node.To do so, I use (or mabye abuse?) the AfterCheck-event of the treeview in the class where the inherited treeview is customized. Code looks like that (Submethods not included):
[code]...
I temporarily remove the AfterCheck-Event in the event-procedure to avoid it getting fired when I programmatically check/uncheck the checkboxes of the treeview. Works fine so far, only problem I see: if another programmer wants to use the customized tree view and tries to make use of the After-Check-Event, he'll get caught in an infinit loop, because his own After-Check-Event (he added himself to the treeview) was not removed and keeps on firing every time a checkbox is automatically checked/unchecked.
How can I remove ALL methods linked to AfterCheck-Event without knowing which method someone added to the treeview-control? My guess is to use reflection and to get the underlying delegate of the AfterCheck-Event by using the .GetInvocationList somehow - but I was not able to make it work. Feraud
I'm trying to search a generic list of 'User' business objects which has a property called 'Username': If (From u In colUsers Select u.Username Where Username.Equals(strUsername)).Count > 0 ThenI keep getting:Delegate to an instance method cannot have null 'this'.
Correct me if i'm wrong, but i believe most (if not all) classes in the CLR that raise events raise those events from protected methods, for example Form.OnMouseDown... so... In a subclass, when would you want to override the "OnXyzMethod" instead of simple adding an event handler like Visual Studio does by default when you want to handle a controls event?
may i know how to implement a delegate method into my project> currently i am using the serial port polling method by using a timer to read from the serial port, but now i am changing the method to delegate part.i have the code for the delegate part updating to the text box control but how do i modify it to update the mainform with my program codes.
The part for the delegate code is here
'---Event handler for the DataReceived event--- Private Sub DataReceived( _ ByVal sender As Object, _ ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) _
So I'm using a Open Source DLL file.The DLL-file got a "Public Custom Event" named: Hashed and I don't really know how to use it.The example is as follow: (C# Language)
c.Hashed += delegate (object o, TorrentCreatorEventArgs e) { Console.WriteLine("Current File is {0}% hashed", e.FileCompletion); Console.WriteLine("Overall {0}% hashed", e.OverallCompletion); Console.WriteLine("Total data to hash: {0}", e.OverallSize); };
I've tried to convert it to VB.NET but it doesn't work.How can I get that code above working?
from the documentation we have this: Multicast Delegate: Represents a multicast delegate; that is, a delegate that can have more than one element in its invocation list.
so am i right to say that Multicast delegate is no different from a normal delegate other than the fact that it has arguments. so System.Action is a 'normal' delegate whereas System.Action(T)(Byval obj as T) is a multicast delegate?
I have a class that is in an assembly due to being required for other projects that I'm currently working on. One class lets call it Class Factory, creates a group of controls which require click event handlers to be attached, I have algorithms which determine polymorphic behavior based on certain features but that is relatively irrelevant.
Due to the event handler having to open up a specific form that isn't part of my assembly, and that form requiring this "Factory" class. Without creating circular reference is there any way I can essentially "delegate" the handler event for the form to define? As a simple work around I have had to maintain two separate classes, one in the project with the form and one in the assembly.
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Me.Width = 1500 Dim panel As New Panel panel.Location = New Point(0, 0) panel.Size = New Size(1000, 200) [Code] .....
I'm having problems with a program where I've got some multi threaded activities addressing the states of check boxes, which in turn are created by a user definable interface To achieve this I'm using the code below, which works on some occasions and crashes on other occasions when it stops with the following error NullReferenceException was unhandled Object reference not set to an instance of an object.Delegate Sub CBSetCallback(ByVal cb As CheckBox, ByVal value As Boolean)
Private Sub SetCheckBox(ByVal cb As CheckBox, ByVal state As Boolean) If cb.InvokeRequired Then Dim d As New CBSetCallback(AddressOf CBset) Invoke(d, New Object() {cb, state})
In C# adding event handler methods is very easy. You just type "object.event +=" and then press tab twice. Is there anything like this for VB projects? Note: This is for dynamically created controls or controls that are not declared WithEvents.
Code: Public Class SendPings Shared Sub New() AddHandler Post.Saved, AddressOf Post_Saved[code].....
I get a error" Method 'Private Shared Sub Ping(item As BlogEngine.Core.IPublishable, itemUrl As System.Uri)' does not have a signature compatible with delegate 'Delegate Sub WaitCallback(state As Object)'.
I am trying to write a VB.NET alternative to a C# anonymous function.I wish to call Threading.SynchronizationContext.Current.Send which expects a delegate of type Threading.SendOrPostCallback to be passed to it. The background is here, but because I wish to both pass in a string to MessageBox.Show and also capture the DialogResult I need to define another delegate within. I am struggling with the VB.NET syntax, both from the traditional delegate style, and lambda functions.My go at the traditional syntax is below, but I have gut feeling it should be much simpler than this:
Private Sub CollectMesssageBoxResultFromUserAsDelegate(ByVal messageToShow As String, ByRef wasCanceled As Boolean) wasCanceled = False
I'm dynamically adding an event handler on a link button, first when the page is load o create a link button with product category. On clicking the product category it fires an event and passes the product-id IN sender object.
Here is my problem: when i readd the event handler on page load it's giving an error cannot cast sender object
I'm having trouble wrapping my head around Events and their Handlers in general. I was working from some sample code that used them, and I can't understand why use an event rather than simply using a sub. I'm absolutely sure I'm missing the bigger picture here.
[Code]....
The Event allows a class to say 'Do something when this happens' in a very ambiguous way, leaving the class which created the Object to define a Handler; what that action should be. That Handler can, and very likely will, be unique to each instance of the class.
It seems to me that this would likely be achievable (on a basic level) through indexing and enumeration, but that would get messy and become a lot of code to write rather quickly. This is probably a much more flexible and extensible way of handling things. I'm going to post this anyway, in the hopes that I'll get someone to tell me whether I am correct in my observations or totally off base, and that it helps someone else who is having trouble with this concept as they dip their toes into OOP and event driven objects.
I'm using the below to update controls from another thread (works great) How would I call a Sub (Named UpdateList)? The UpdateList updates a listview with a list of databases on a selected SQL instance, requires no arguments.
Private Sub CompleteEventHandler(ByVal sender As Object, ByVal e As Microsoft.SqlServer.Management.Common.ServerMessageEventArgs) SetControlPropertyValue(Label8, "text", e.ToString)
I have found a sample code of something I am trying to complete in VB.Net however the sample is in C++, and I am having a hard time understanding how to translate it.
I have everything basically covered except for the actual EventHandler line.
[Code]....
I would like to know how to translate this easily into VB.Net. I understand i may have to create an Event and a Raise Event, but not sure how.
Back in form1, how can I wire up the Click event for each MenuItem present in the contextmenu? I want to do this as abstract as possible, meaning I don't want to implement the OnClick code inside Form1.
Code: Public Class Form1 Me.ContextMenu = MenuFactory.BuildMeAContextMenu() End Class
Me.SetProgressBars() AddHandler zip.SaveProgress, New EventHandler(Of SaveProgressEventArgs)(AddressOf Me.zip_SaveProgress) zip.Save(target)
Took some snippets from a MSDN page and molded it into my project ... problem is on every run its setting a value of -1 to something and i cant for the life of me figure out what to!
Private Sub zip_SaveProgress(ByVal sender As Object, ByVal e As SaveProgressEventArgs) Select Case e.EventType Case ZipProgressEventType.Saving_AfterWriteEntry
I have 2 classes that Implement 1 EventHandler. Its part of a fingerprint scanner API but I'm having some issue and I'm not sure if it is my fault in how i use the Implements.Is it ok to have 2 different classes Implement the same EventHandler? Each class then uses the events differently within the class but it almost seems like there is some overlap that is causing some issues. I know this is hard to explain without posting code but since i can pinpoint the problem, idk what to post. My main point is, can you have 2 different classes Implement the same Interface?
I wish to check the hard drive space used in a folder on a hard drive. This will happen continuously as a service, so it will be calculating the space used for thousands of folders all the time. I know that this code can be done easily in dotnet, but it seems to take a really long time. Are there any APIs to do this more efficiently, or does the entire looping process have to occur to do this check?
For me it seems like the an event hooking up on an another event?But I have tried everything to translate this into VB.NET code?I have found out that EventHandler management in VB.NET is far from as good it is in C# as many other things.
How can i cancel the eventhandler, i have a problem with tab browser is that:- i have a set of button image to show the forward and back button which are disable or enable (like IE).Inside my program which are deal with the web_CanGoForwardChanged and web_CanGoBackChanged event.my problem is that if i click on other tab faster than the eventhandler done,i got the wrong image shown on button.how can i stop the eventhandler to prevent the wrong image.
Public Function GetBrowser() As WebBrowser If TabControl1.SelectedTab IsNot Nothing Then For Each c As Control In TabControl1.SelectedTab.Controls If TypeOf (c) Is WebBrowser Then
I'm working on a project that will require me to react to 5 separate events generated by an external device and then do something after a certain delay. The events will normally happen one at a time but may occasionally be simultaneous.
Imports System.Windows.Threading Class MainWindow Private TimerList As List(Of DispatcherTimer)
