Shadowing Events In .NET?
Sep 8, 2009
In VB.NET there is a keyword 'shadows'. Let's say I have a base class called 'Jedi' and a derived class called 'Yoda' which inherits from 'Jedi'. If I declare a method in 'Jedi' called 'ForcePush' and shadow that out in 'Yoda' then when calling the method on an instance of the 'Yoda' class, it will ignore the base class implementation and use the derived class' implementation. However if I have an instance of 'Yoda' that was declared originally as of type 'Jedi', i.e. Dim j as Jedi = new Yoda(), and called the 'ForcePush' method on the instance, it will use the Jedi implementation.
Now let's say I have an event that is called 'UsingForce' which is raised when the 'ForcePush' method is called, and I shadow the event out in the derived class (this is because 'Yoda' has an interface 'IForcePowers' that declares this event) and each class raises it's respective event.
If I have an instance of 'Yoda' that is declared as type 'Jedi' (like above) and I put an event handler on the 'UsingForce' event of 'Jedi', and then the 'ForcePush' method is called in the 'Yoda' class, will this event handler be reached?
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May 4, 2011
I have a two windows forms classes, a base class and a derived class. The base class has an event handler which handles ValueChanged on some component. I have also written a different event handler for the same event on the derived class.
When I create an instance of the derived class and fire the event, I find that both event handlers run (the base class one and then the derived class one). But I want only the handler in the derived class to run.
Edit: Here is what the code looks like (can't post the actual code):
Public Class BaseForm
Inherits System.Windows.Forms.UserControl
(Windows Form Designer Generated Code)
[Code].....
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Dec 4, 2011
It works, but doesn't save what I've changed it to. In the designer everything works fine. I can change the text and have it update on my button control. BUT once I run or rebuild in any way, the text property changes back to it's default value, in my case "Button Control"These are what I've tried, and I've tried all with both Shadows and Overrides - both with identical outcomes. So I've just indicated that with Shadows/Overrides.
vbnet
<DefaultValue("Button Control"), Browsable(True)> _ Public Shadows/Overrides Property Text As String Get Return MyBase.Text End Get Set(ByVal value As String) MyBase.Text = value Me.Invalidate() End Set End Property Private _Text As String = "Button Control" <DefaultValue("Button
[code]....
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May 8, 2009
shadowing and delegate method?
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Nov 17, 2009
I have a couple of small classes to represent parts in a search filter. If the searched value equals NonValue the filter is supposed to do nothing. This is defined in a Base Class:
Private Class BaseFilter
Protected NonValue As Object
Protected sQueryStringBase As String = "AND {0} {1} {2} "[code]......
When I then create a StringFilter and check for allowed value:
Dim stf As New StringFilter()
stf.CheckNonValue(MyString)
I get a NullReferenceException (NonValue = Nothing) , when I expected the NonValue object to be String.Empty. Is this a bug in my code, or am I trying to achieve polymorphism in a wrong way?
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Mar 4, 2010
I'm in a project where it's pretty much my first time doing all the architecture myself,and I'm running into a frustrating situation. My architecture for forms seems to be correct from a heuristic perspective, but I don't think its implementation is correct.
My architecture is thus:
Base Class: OrderForm
Child Classes: PurchaseOrder, Invoice, Credit
[code].....
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May 13, 2011
I have created a new usercontrol. My usercontrol contains several other controls like labels, buttons and so on ...When I set the Font property of the usercontrol I want that font property value to propagate down to the child controls.
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Apr 4, 2011
Shadows vs. Overrides in VB.Net.What's the difference between shadowing a function in a base class in a subclass and overriding the same function? There is performance issues involved too?I know how to shadow and how to override in VB.net. My question is about when and why should I shadow a function instead override it and vice-versa.
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Oct 13, 2011
I have been trying to implement the jQuery weekcalendar using .net. What I can't seem to figure out is why weekcalendar states events.events is undefined after I make an ajax call to a webmethod I created which returns JSON. Below is the relevant code:
[Code]...
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Aug 2, 2009
I want to make Keybord events and mouse events for learning and educational Purpose.
1. In Form any object like A "picture box" move by Arrow keys .
2. Picture Box Contain many Picture i want change Picture With next and Previos By Arrow keys.
3. I contain Voice of alphabet in Mp3.When i Press any button in textbox then its work.
4. Mouse Pointer Change My Own.
5. I click any Object or any thing By mouse its noice clicking sound like Tik Tik Tik.... Question No 3 is very hard to do . but not im possible
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Dec 31, 2010
I created a control that has picture box control docked within it. This control allows me to "animate" the image by swapping them out by setting the interval to swap them at. I want to use this control kind of like an animated icon within a application, but because the picture box is docked, the control I created won't respond to the events, MouseHover specifically. [Code]
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Aug 5, 2011
I don't know how to use these events and get the appropriate values out of these events ....here is some code that I have copied from a website...
[code]
Private Function MouseHookProc(ByVal nCode As Integer, ByVal wParam As Integer, ByRef lParam As MSLLHOOKSTRUCT) As Integer
Try
If nCode >= 0 Then
Select Case wParam
[code]....
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Dec 16, 2009
is there a difference between shared events and non-shared events?
Private Shared Event EVENT_something_changed()
Private Sub SUB_handles_something_changed() Handles Me.EVENT_something_changed
End Sub
no errors with this code, but how is Me possible since the Event is shared. it seems like there's no errors between switching shared with un-shared and switching Me with Myclass, all 4 combinations seem to work, isn't that weird
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Mar 1, 2011
I'd like to be able to access the events in a C# DLL so I can display a Progress Bar as the file analysis is carried out - the DLL is written by a third party using VB.Net.
Details
C# FileAnaysis.DLL
Contains a public class FileManager which contains 2 public subs
public void ProgAnalysis(string fileName)
public void ProgAnalysis(string fileName, ProgressChangedEventHandler progressChangedEventHandler, RunWorkerCompletedEventHandler runWorkerCompletedEventHandler)
How do I access the events generated by second sub in Vb.Net?
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Jun 17, 2010
I find that I write a lot of code within my classes to keep properties in sync with each other. I've read about Events in Classes, but have not been able to wrap my head around how to make them work for what I'm looking for.For example, in this one I always want to keep myColor up to date with any change whatsoever in any or all of the Red, Green or Blue properties.
Class myColors
Private Property Red As Byte
Private Property Green As Byte
[code]....
If one or more of those changes, I want myColor to be updated. Easy enough as above, but is there a way to work with events that would automatically do this so I don't have to put myColor = Color.FromArgb(Red, Green, Blue) in every sub routine?
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Mar 14, 2012
So, I'm at the stage where I have created checkboxes through the codes.Not through the toolbox.
They are added correctly to the form when I test it.Checkboxes can be checked or unchecked correctly.
But my problem is this:I want to use events mouseclick or mousehover with those checkboxes.
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Apr 24, 2009
I don't have a lighting bolt at the top like I normally do to add events.How do I add events in .NET 1.1 for Visual basic 2002?
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Dec 22, 2010
Is it possible to get an asp.net code (preferably vb.net) to query a sql server for results, but for it to somehow wait for a response from the server when a change is found in the records without resorting to server intensive loops?For example, I want to write a query which checks the date of a record, if the date is different from last known date, only then should the query return the results.
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Feb 15, 2010
Is there a way to translate this code in VB? Most of it is easy, but I can't figure out a way to override the event handler.
public class MTObservableCollection<T> : ObservableCollection<T>
{
public MTObservableCollection()
{
[code]....
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Oct 14, 2011
i want to know how i can create events for IE. i use with this code:
Imports mshtml
Imports SHDocVw
Dim myDoc As mshtml.HTMLDocument
[Code].....
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Mar 30, 2010
I am a VB programmer working my way into C#. I learned how to create and raise events in vb and am finding that it isnt done the same way in C#. Has anybody come across an article that will help me to understand how to do events in C# and maybe explain why it is different in VB.
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Oct 14, 2011
In C#, I can do this:
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)[code]....
Notice the line int i = c1.GetInt();. I can't seem to get VB.NET 4.0 to do something similiar.
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Jun 7, 2009
I'm calling the SQLDMO 8.0 COM library from VB.NET (using a PIA I generated with tlbimp) in order to backup a database with percentage completion notification:
Dim server As SQLDMO.SQLServer = Nothing
Dim backup As SQLDMO.Backup = Nothing
Dim restore As SQLDMO.Restore = Nothing
Dim backupAbortable As Boolean
Dim restoreAbortable As Boolean
[Code]...
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Jan 22, 2009
I have a component written in C# which exposes an event which the clients can Handle. I would like know how to handle this event in VB.Net?
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Sep 23, 2011
im using webbrowser control and html code in my project my question is how to see other invokemember events like ("Click") is there any complete list of events,
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Aug 11, 2011
i'm looking for a solution to get the last 10 eventlogs by date From the windows eventlog (ofcourse)This is what i have now:
Dim eventLogApp As New System.Diagnostics.EventLog("Application")
Dim eventLogEntry As System.Diagnostics.EventLogEntry
Dim ev
[code].....
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Jul 29, 2009
i created a motion detection project and i would like to save in a notepad the date and the time that a motion detected?
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Apr 8, 2009
I'm wondering if is it possible that the events for a certain object will be executed by another events under a different object?For example.I have a button named Button1, and I have a ListView named lstView. What I want is that when I click on Button1, the events that will be executed will be the one under lstView.
Here are my codes:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
lstView_KeyPress(Button1, e) 'This is the part where I don't know what to do.
End Sub
[code]....
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Jul 22, 2009
I have a windows application which raises a particular event.I need to create a COM callable class whic will allow VB 6.0 to subscribe to this event.I have done a fair amount of research on this and am confused as hell.
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May 16, 2011
It looks like theres a bunch of threads with these issues. Mine has to do with events and event handing in an add-in...so its a bit complicated for me.I'm trying to rewrite this C# code
#region Event Handling
/// <summary>
/// Wires up events from xWeb and this plugin
/// </summary>
[code]....
I have no idea where the type AddinActiveDocumentChanged and the type DocumentEventHandler is coming from. Intellisense doesn't have these. So both of those sub routines I'm stopped at.
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