When editing vb.net forms code in vs2008, how do I select base class events that I want to override? In vs2003 there was a list of overridables in the drop down list but now that list is missing?
View 4 RepliesI have a base class, with a const giving its name. If I inherit that class, how can I override the const to give the name of the new class?E.g. (and I know this won't compile!)
Public MustInherit Class BaseClass
Const ClassName="BaseClass"
Public Sub DisplayName
MsgBox(ClassName)
[code]....
What I want is for class One to display its own name, not that of the base class.
Consider:
Public MustInherit Class Column
Public ReadOnly Property ReturnSomethingUseful() As Object
Get
'return something useful
[code]....
But this gives the following error:
Public Overrides Function ParseValue(sValue As String) As Boolean'
cannot override 'Public Overridable Function ParseValue(sValue As String) As Object'
because they differ by their return types.
I accept that you can't do this, but I'd like to be able to preserve the semantics of what I'm. trying to do, which is to have an untyped version that deals with Object, but a typed version in derived classes that knows about the specific type T.
At the moment I have the following Command class:
Public Class SubscribeCommand
Implements ICommand
Private ReadOnly _vm As MainWindowViewModel
Public Sub New(ByVal vm As MainWindowViewModel)
_vm = vm
End Sub
[Code]...
In a tutorial i read, you have to implement add {} and remove {} for the canExecuteChanged-Event. But how can i do that, with vb.net?
I am just curious, if there is some way to attach handler to my derived classes base event, if I know EventInfo and I have Delegate to handler function. I have tried MyEvent.AddHandler(CType(Me, BaseClassType), MyDelegate) already, but no positive result at all. Consider being in need of attaching handler to custom event at runtime, while derived class possibly shadows this event.
View 2 RepliesWhen i use my UserControl in a project my Mouse Enter & Leave events aren't firing, i assume i fix this with a raiseevents in my usercontrol. However when i try to do this it says something about "cannot raise base event from derived class".
View 7 RepliesI'm trying to validate a few things in a form I'm building. It has a datagrid with clients info (taken from an access database) and a few textboxes where the user can type some search criteria. The thing is that those same textboxes are used to add new clients to the database and to modify a client's information if one from the datagrid is selected, so I made it that the buttons to insert and modify clients are disabled on load and thenevery time the text on a textbox changes ("TextChanged" event) they become enabled. So far so good. But then I wanted to make it so when a client from the datagrid is selected both buttons become disabled again until the text on a textbox changes (to make sure they're adding a different client and not the same one that was
selected).
I tried using the CellClick event from the datagrid to disable the buttons, but since every time a client is selected from the datagrid the info is shown on the textboxes, this triggers the TextChanged event too, and the buttons become available.So, is there a way I can tell the TextChanged event not to be triggered when the CellClick event occurs?
When I do this
Public Class cInherits : Inherits Panel
I get this: Base class 'System.Windows.Forms.Panel' specified for class 'MenuButton' cannot be different from the base class 'System.Windows.Forms.UserControl' of one of its other partial types.
How do I inherit?
I have put this code in the global form Inherits System.Windows.Forms.Form. And then in the form that will inherit this from the global Inherits MenuStrip. "MenuStrip" is what the global form is called. But keep getting this error: Error1Base class 'MenuStrip' specified for class 'Lesson2' cannot be different from the base class 'System.Windows.Forms.Form' of one of its other partial types.
View 5 RepliesWhat does this error mean? I havent modified anything in the designer code, but its giving me an error? WithEvents variable 'Move' conflicts with event 'Move' in the base class 'Control' and should be declared 'Shadows'. The error relates to Friend WithEvents Move As System.Windows.Forms.DataGridViewCheckBoxColumn
View 1 RepliesI've been creating short test apps repeatedly to try to understand some of the concepts in VB.NET.For the most part it has been illuminating.I read Bucky's .NET knowlegebase tutorial on passing objects as parameters to newly created forms. He shows how to create a new class that inherits from the base form class and define a New() method with parameters Extending the concept I thought about doing the same thing with a form that was created at design-time (In this case Form2).
[Code]...
Base class has one field to hold numeric balance value. With 2 methods that accept arguments for adding and subtracting the new input calculating new balance. Sub class has four fields dates, transaction, memo and amount.I have a deposit form, and withdraw form. Each time one transaction is entered it creates an object with sub class fields, then adds to the account collection. My problem is not understanding how to call the deposit/withdraw method and pass the current transaction amount back to the base class to alculate the new balance. Does anyone have any links to information/tutorials on how to perform something like this? As you can see with my code I have tried various different approaches without any success.
[Code]...
I have a WinForms application (OwnerForm) with some UserControl. When textbox of UserControl is changed, I want to filter content of a OwnerForm. But how can I make it? I don't want to specify OwnerForm inside the user control. I know a solution to add manually handlers for MyUserControl.tb.TextChanged to some functions on a owner form, but I think it's bad way. I'll prefer to have overridable functions, but I can't imagine how to do it.
View 5 RepliesI would like to shadow/override an event in VB.NET v2
I need to do it, because I need to implement a interface, let's name it IVisibleChanged, on the custom objects that does not have defined this event, and on the objects that already have defined this event (custom Button, by eg.)[code]...
I would like to shadow/override an event in VB.NET. I do it only because I have to implement in this object an interface, that contains the same event like the base object itself, and I need to keep this base event as is it without modification nor supplementary event additions.How can I do it?
Public Shadows Event VisibleChanged As EventHandler Implements IVisibleChanged
So, I would like to implement a interface that contains VisibleChanged event, but to keep functional the myBase VisibleChanged event too.
[code].....
Supose a base class
Public Class airplane
Private var_num_seats As Integer
Private var_num_engines As Integer
[code]....
Obviously, I don't wish that the class Glider has the method "start_engines" neither the property "num_engines". Otherwise, other child classes may have. How can I supress these property and method in child class, not just ignoring (if I can)?
I am trying to create a class in VB.NET which inherits a base abstract class and also implements an interface. The interface declares a string property called Description. The base class contains a string property called Description. The main class inherits the base class and implements the interface. The existence of the Description property in the base class fulfills the interface requirements. This works fine in C# but causes issues in VB.NET.
[Code]...
This is another one of my "I think it's not possible but I need confirmation" questions.I have a base class for a bunch of child classes. Right now, this base class has a few common properties the children use, like Name. The base is an abstract class (MustInherit)Technically, this means that everytime a child class is instantiated, it lugs around, in memory, its own copy of Name. The thing is, Name is going to be a fixed value for all instances of a given child. I.e., Child1.Name will return "child_object1", and Child2.Name will return "child_object2".
View 1 RepliesSuppose I have piece of code like this:
Public Interface ISomething
....
End Interface
[code]....
I suspect I am being very silly here but I have the following setup
Class MustInherit myBaseClass
'some stuff
End Class
Class myInheritedClassA
[code]....
Running this results in the following error
Unhandled Exception: System.InvalidOperationException:
There was an error generating the XML document. --->
System.InvalidOperationException:
[code]....
is there any way of 'Widening' the inherited class to the base class so this would work?
EDIT:regarding XmlInclude(typeof inheritedClass), currently this method could potentially return a number of types of inherited class (i.e myInheritedClassA and myInheritedClassB) is it case of simply having to add each of the inheritedTypes in this tag?
How do I access the base class inside a derived class?
View 1 RepliesIf we are within the derived class then ofcource we can use MyBase keyword to access base class's object reference . That's fine , how can we take that base class's object reference outside that derived class's definition.My following code will explain what i want . Actually that is giving error right now, but it is explaining my requirement .
Public Class Base
Public x As String
End Class
[code]....
Actually there is error in ReadOnly Property BaseReference's Getter . Error is "Error 1 'MyBase' must be followed by '.' and an identifier. " how can i get base class object reference in Main method ?
I have this code that's suppose to override the form closing event, It fires off sucessfully however doesn't prevent the form from closing.
Private Sub Form_Close(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
Me.Hide()
e.Cancel = True
End Sub
short question: What's better?
Form KeyDown event vb Private Sub MainForm_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown End Sub
Override OnKeyDown
vb Protected Overrides Sub OnKeyDown(ByVal e As System.Windows.Forms.KeyEventArgs) MyBase.OnKeyDown(e) End Sub
Ok, I've been searching all over the web for an answer to this and I'm getting nowhere. I've found several examples and tried code translators, but they either fail to compile at all (syntax is wrong) or fail to solve the problem. Here is what I am up against:
I am trying to implement a service object class for the POS for .NET library using VB9. Specifically, the BillDispenser class. I define my class and inherit from Microsoft.PointOfService.BillDispenser. As normal, it creates stubs for all the MustOverride (abstract) properties and methods that I need to override (I love that), EXCEPT for the DirectIOEvent. Apparently this event is defined as abstract in the POSCommon base class, but VB doesn't generate a stub for it.
No compile errors are generated from not defining it, but I get the following runtime error as soon as my unit test attempts to load the dll[code]...
I have a listview but I would like to add 3 properties (for example one of them is "image") to the listviewitems in it. I was fine with making a custom class with the 3 properties and just inheriting ListViewItem but now I need to use MultiSelect, so it means doing things like(in For Each loops):
ListView1.SelectedItems.Item(i).Image don't work because it returns a ListViewItem not my CustomClass. I could always do : Ctype(ListView1.selectedItems(i), MyCustomClass).Image
But using that over and over again seems like a waste/wrong way to do it?
I'm trying to create a generic Controller Class for generic events. But these these events still need to access their class variable. So my idea is to create the Base Controller Class with a ModelBaseclass variable as _ClassVar, which is inherited by all of the other class Controller classes will derive from. But I want the derived controller classes to override the _ClassVar with whichever one they need.
I want to do this, so the ControllerBaseClass can have all the generic functions that all the Derived Classes would use.
Model :
Public Class ModelBaseClass
Public Overridable Function Foo() As String
Return "Name"
[Code].....
I'm using ASP.Net 2.0. I have a custom control that is inherits from a 3rd-party vendor's control. I'm trying to override the Render method. [code] What I need is that under certain situations I want to be able to render a Button instead of the original control.But I want the Button to have the same client Id as the control so that I can use javascript to manipulate it.How do I assign a clientid to the button?
View 1 RepliesI have to two forms. Form one has several check boxes and when a button is pressed, a second form is opened and certain functions are ran based on which check boxes are selected.The problem is that the second form doesn't show until all of the functions are done.I decided to use the Form's Activated event, which works fine. However, the event fires every time the form comes into focus.Is there anyway to override the event and make it only fire once?
View 1 RepliesBasically, what I want to do is create a new control called EncryptedPictureBox. The image path I would be loading into ImageLocation would be the path of a 512 bit encrypted image. Normally if I load this type of file, it will not display. So I want to override Load() so that I can write the encrypted image to a stream, decrypt it, and then display the stream. I'm trying to save processing time so I don't have to grab the encrypted image, save it to disk as a decrypted image, then display it, then when done, delete the decrypted image from disk.
View 11 Replies