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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Shadowing An Event Handler?

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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Shadowing The Text Property?

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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Using The Shadowing And Delegate Methods?

May 8, 2009

shadowing and delegate method?

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Polymorphism And Shadowing Inherited Members?

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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Prevent Massive Shadowing Of Methods?

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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VS 2010 Understand Shadowing Properties?

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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[Code]...

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4. Mouse Pointer Change My Own.

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Use These Events And Get The Appropriate Values Out Of These Events?

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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Difference Between Shared Events And Non-shared Events?

Dec 16, 2009

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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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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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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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Add Created Cb Into Events/

Mar 14, 2012

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public class MTObservableCollection<T> : ObservableCollection<T>
{
public MTObservableCollection()
{

[code]....

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Imports mshtml
Imports SHDocVw
Dim myDoc As mshtml.HTMLDocument

[Code].....

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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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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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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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Handling Events In .Net?

Jan 22, 2009

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Sep 23, 2011

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Dim eventLogApp As New System.Diagnostics.EventLog("Application")
Dim eventLogEntry As System.Diagnostics.EventLogEntry
Dim ev

[code].....

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Jul 29, 2009

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Passing Events To Another Sub?

Apr 8, 2009

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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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Raising Events And COM?

Jul 22, 2009

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Rewriting C# Into .NET With Events?

May 16, 2011

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#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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