VB Syntax Overridable/Virtual Event?
Oct 26, 2010
Since VB2005 I have been struggling with the limitaion of VB of defining an Overridable Event. This is essential for having a class which implements the NotifyPropertyChanged event (or other events) and needs to be used as an NHibernate proxy class loading). The .NET 2.0 framework itself has no problem with this whatsoever since it is supported in C#. Now I have to always include a C# base class for any VB class that needs to implement events.
Can somebody explain to me why the VB is in this case so incompatible with the C# and .NET language? Was expecting to see this implemented in VB 2008 or 2010 but neither seems to have given this (small?) syntax/compiler change any thought.
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Nov 26, 2009
Well its simple here you have my vb.net code:
Public Class Class1
Public Overridable ReadOnly Property Name() As String
Get
Return Nothing
[Code]....
(It dosent print nothing it just prints an empty line) Why does vb.net go for the base class implementation when its overriden?
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Sep 8, 2011
Using the walkthrough from [URL], I implemented a DatagridView in virtual mode, totally unbound, in VB 10 Express (we are talking WinForms).
I understand that CommitEdit (DataGridViewDataErrorContexts.Commit) commits the current cell's contents to the data cache.
The example uses row-level commit, i.e. it pushes the values into a row buffer until the current row is left. Only then the row is added to (or updated in) the data store. That's exactly what I do, too.
Question -- how can I commit the current row programmatically without leaving it? (I want to commit the whole row, not just the current cell.)
If the user leaves the row, there is a RowValidating, RowValidated, RowEnter event sequence where the datastore update is taken care of. So one idea (currently my only one) was to simply re-set CurrentCell to Nothing, for example.
But I cannot just set the DataGridView's CurrentCell property to Nothing (or any cell outside of the current row) since I want to commit from within an event handler of a custom edit control created by a custom column, and I see an System.InvalidOperationException exception when setting CurrentCell there.
In fact, it is a tiny button right to a combo box, i.e. I create a DataGridViewComboBoxCell descendant which is a DataGridViewComboBoxColumn descendant's edit control. My special ComboBox cell adds a tiny button which should commit the current row. Unfortunately, that button's _Click event handler cannot change CurrentCell since DetachEditingControl throws the exception then.
Obviously, I must delay the CurrentCell re-assignment until the whole _Click event has been processed. Or what? How would I do that -- register a custom Windows message, SendMessage that one to me, and override the windows procedure of the form so it re-sets CurrentCell when this message is received? (Hello?)
There should be a rather easy way to let DataGridView commit all changes by firing the events that I handle to perform the datastore update, no?
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Feb 12, 2010
I am facing issue in following code syntax...
Protected Overridable Sub OnHeaderClicked(ByVal args As ItemSelectedEventArgs)
If ItemSelected IsNot Nothing Then
RaiseEvent ItemSelected(Me, args)
[CODE]...
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Jan 12, 2010
In a base class object, I have an overridable subroutine that I would like all derived objects to have the ability to include. However, they don't have to, and if it's not necessary for them to use it, I don't want them to be forced to declare it. To enforce this, I've left the default behavior empty. For example, here's my whole sub:
Protected Overridable Sub MySubroutine(ByVal someObject As Object)
End Sub
Is this bad practice? I don't want to declare it as MustOverride, but I don't want default behavior. Is there a "better" way of doing this, or is this perfectly acceptable? I don't want to be that hack programmer...
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Oct 28, 2009
Difference between overloads, overridable and overrides .
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Mar 27, 2009
I need to pass a parameter to the event PrintPage of the PrintDocument relative to my PrintPreviewDialog in some way.I tought to inherit PrintDocument class adding to it a property with the parameter I need, creating MyPrintDocument class. Then, I would like to create MyPrintPreviewDialog class, in which I could override the Document property declaring it of MyPrintDocument type.The problem is that the Document property is not overridable and if I declare it Shadows the PrintPageEvent doesn't raise.
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Jan 9, 2012
I've removed the properties completely with a controlDesigner class, but I'm getting warnings + trying to do it properly to remove those warnings.
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Aug 5, 2010
I have a base class foo that will be used in multiple child classes of similar but slightly different function:
Public MustInherit Class foo
Public Function bar1() as Something
''// Perfectly OK to change what this method does
[code]....
How do I get the compiler to generate an error when bar2() is overridden by a child class?
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Jan 18, 2010
when we have a method of a derived class implementing a method of an interface which is already implemented in the base class, the compiler throws a warning (by default). when i see a warning i will try to erase it and the only way to erase this warning is to mess with the settings of the compiler hence i hope that there is a way to declare "how" a method implements an interface's method. by this i meant that we should be able to declare overridable, overrides and shadows for the implements keyword. hence if we declare overridable-implement for a method of a base class implementing an interface's method, the compiler should give no warnings when we override this implementation (re-implementing in a derived class). Similarly, if the method of the base class implementing an itnerface's method was not declared as ovveridable-implement, the derived class should be able to Shadow the implementation example code which flags unnecessary warning:
[Code]...
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Feb 7, 2010
I am trying to load a movie from openfiledialog.filename, but i keep on getting an error. Here are the 2 things ive tried
1) AxShockwaveFlash1.LoadMovie(OpenFileDialog1.FileName)
2) Call AxShockwaveFlash1.LoadMovie(OpenFileDialog1.FileName)
Both of the codes get the same error that looks like this
Argument not specified for parameter 'url' of 'Public Overridable Sub LoadMovie(layer As Integer, url As String)And here is the URL it goes to when you click "Show Error Help" http:msdn.microsof...f0a(VS.85).aspx
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Jun 2, 2009
i'm accessing an access database and want to execute the following query
INSERT INTO sometable
(date, field1, field2)
SELECT ( ? AS Expr1, field1, field2)
FROM othertable
? is a date i generate in code and field1,field2 belong to othertable i put it in a tableadapter and execute it by me.tableadapter.queryname(calculated date) but i get the error : Too many arguments to 'Public Overridable Overloads Function queryname() As Integer' Also if i try to generate the date in the query builder in the form dateserial(year(now),month(now),1-1)the query builder does not accept it?
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May 14, 2009
I'm following this tutorial: [URL]..except I'm connecting to my own data source - a MS Access database.This is the query I have setup with the dataset:
SELECT Terminal_ID, SUM(Transaction_Quantity) AS Total
FROM tblTransaction
WHERE TransactionType_ID=3 and Transaction_DateTime>[@fromdate]
GROUP BY Terminal_ID
The debug fails immediately because it needs the extra parameter so I change the code from:
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'tetrisDataSet.tblTransaction' table. You can move, or remove it, as needed.
Me.tblTransactionTableAdapter.Fill(Me.tetrisDataSet.tblTransaction)
[code].....
The error I get on build is:Too many arguments to 'Public Overridable Overloads Function Fill(dataTable As tetrisDataSet.tblTransactionDataTable) As Integer
...I gave it the extra parameter, so what gives? Something special I need to do as it's a datetime field?
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Oct 12, 2011
I am having an issue trying to figure this out. I am writing a script editor that uses tabs (a tab control) and I want to implement syntax highlighting. My issue is that every sample I can find on syntax highlighting uses
Private Sub RichTextBox_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RichTextBox1.TextChanged
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Dec 16, 2009
Can any one translate the following syntax to vb.net.
m_TextBox.Loaded += TextBoxLoaded
m_TextBox.Loaded -= TextBoxLoaded;
private void TextBoxLoaded(object sender, RoutedEventArgs e)[code].....
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Aug 6, 2009
I am using the following function to return the primay ip address with out problem until I ran it on a virtual server. It returned the ip of the physical server not the virtual server.
Public Function fnGetIPAddress() As String
Dim IPAddress As String = My.Computer.Name
Try
[code]......
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Jan 7, 2011
i want to make a custom CMD i can try it to make it in notepad and save it as a .bat file en then say, [Code]
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Mar 31, 2009
I using 2 virtual PC on may Computer. Can I re-use an existing for a new virtual PC?
Because, A Virtual PC have many space on HDD.
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Sep 4, 2009
I have created a WFA that has 5 projects in it. One of the projects runs against 600 + servers and queries each server for local administrator accounts and then dumps that into an excel file. It will also check to see if the account that is in a local administrator group is disabled in AD. The problem that I have is that when I run the particular project I will run out of virtual memory. I have 4 gig on my computer. Is there a way to control this?[code]...
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Apr 3, 2009
Does VB.NET supports virtual events?
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May 26, 2010
I need to define Virtual IP programmatically (Perl or VB or CMD or java).I need it for temporary use, I can't use any actual IP address and I don't care if it will be accessible only from local machine.
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Oct 4, 2011
I want to create virtual directory using vb.net. But while creating permission denied error occurs.If im manually creating virtual directory no error..
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Jul 8, 2010
I'm trying to create a custom keyboard for my accounting firm. I have all the buttons and button events sorted out.How can I make it so that when buttons a pressed, the text is input into where the cursor is? Currently i put the cursor for instance in an excel cell, then click the key on the virtual keyboard and nothing is inputted into the cell, i assume because it selects the keyboard window when i click the button. For some keys I'm also simply using:SendKeys.Send("q") for example.
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Jul 12, 2010
i am trying to make a virtual piano.in that i am also playing music files which is recorded through the above said piano.but how can i understand when this music playback ends.i need to invoke another function when the plyback ends.so how can i understand when the playback end.
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Jan 28, 2010
I am trying to use fluent nhibernate in a MVC project. It seems the entities should have properties that are virtual and the set should be private for IDs. I use vb language. So tried using overrideable. It gives an error...
Public Overridable Property DesignId() As Integer
Get
End Get
Private Set(ByVal value As Integer)
End Set
End Property
It says property cannot be overrideable because it has a private accessor.
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Jun 13, 2010
Is it possible to make a virtual interface represents the value of an input? For example, if we have a program shows the level of a liquid in a tank and we want to represent the level virtually: as the calculated value of the level increases, the level (and color) filled in the tank shown, increases as well. Example: If the value is 100, the tank ( a rectangular ) will be shown full and green. If it is 0, will be shown empty and red.
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Dec 17, 2004
Im creating a Virtual Keyboard for a touchscreen application and I was wondering if there is a way to know whenever a control gets focus, what type of control it is, basically either another thread or a watch function or something that raises an event when a control gets focus.GLOBALLY, not just one control or one form, but any control on any form in the whole program..Basically i want a keyboard icon to appear whenever the control is of Textbox type.
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Sep 5, 2011
i have this code:Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[Code]...
Error 1: Option Strict On disallows late binding.Im using visual basic 2010 express on a gateway laptop thats running Windows 7 OS How do i resolve this error?
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Apr 9, 2009
I have a listbox and it it I am showing numbers.It should look like this (line by line) 1,2,3,4,5,6,7,8,9,10,11.....but is is showing it like this 1,10,11,...2,20,21...3,30...ow can I make it that it will show it in number order 1,2,3,4,5......
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Oct 21, 2009
I want to select some rows from a sql express 2005 table. I am using this expression: "Starttime >= " & dtpStart.Value dtpStart is a DateTimePicker But I am getting this error: Syntax error: Missing operand after '14' operator.
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