I 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.
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 RepliesConsider:
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.
I need to write a program that uses constants to establish the base pay, the quota, and the commission rate. The Pay menu item calculates and displays the commission and the total pay for that person. However, if there is no commission, do not display the commission amount (do not display a zero-commission amount).
Write a function procedure to calculate the commission. The function must compare sales to the quota. when the sales are equal to or greater than the quota, calculate the commission by multiplying sales by the commission rate. Format the dollar amounts to two decimal places; do not display a dollar sign.
The summary menu item displays a message box that holds total sales, total commission, and total pay for all salesperson. Display the number with two decimal places and dollar signs.
the Clear menu item clears the name, sales, and pay for the current employee and then resets the focus.
The Color and Font menu items should change the color and font of the information displayed in the total pay text box. Use a message box to display the program name and your name as programmer for the about option on the Help menu.
[code...]
So the issue is when I push calculate and summary, the total sales comes up, but not the total commission or total pay. Also, the color only changes to blue and that is it. I am not sure how to get the color or the font menu choices to be able to be choosen by the user. Is that possibile?
[code...]
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 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 have an API that I created and currently utilize successfully in C#. I am trying to create an example of interacting with the API in VB.NET (so that the QA without C# experience can still utilize it for creating automated tests).
In C# I do the following
[TestingForm(FormName= "Land Lines", CaseType= _caseType
, Application= ApplicationNameCodes.WinRDECode, HasActions= true)]
public class LandLines : RDEMainForm
[Code]....
This gives me a compile time error because it claims that FORM_NAME and CASE_TYPE is not defined, even though the class has it defined inside.
How can I use the defined constants inside the class in the class attributes?
I have a class in VB with some constants that represent the string name of my security roles. I need to be able to call a function to return to me a string array(or collection, or whatever) of the values of each of these constants. I will be using it to make sure that my databases Roles table has the same roles as coded into the application.
[Code]...
I'm looking to run a function, i.e. ClassConstantsToStringArray(gettype(Roles)) that will return to me "Administrator","Basic User","Power User" I'm know reflection is the way to go, I just don't know enough about using it yet to get what I want. I found a function on the net that would return to me the constant names in a FieldInfo array but still don't have enough smarts to make that work for me.
I'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]...
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 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].....
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?
[code]The reason that this is a problem is that this is a collection of EventBase objects, but I'm trying to populate it with child classes instead. For example, I might have a JumpEvent class that inherits EventBase, and this is being put into the EventBaseCollection. That means that value.GetType() returns the type of JumpEvent, which as you might guess does not equal the type of EventBase.The goal of course is to simply loop through all of the various events without having to know anything about the sub-classes. Is there a way to determine the type of the base class so that the OnValidate call will work? Or is this just the wrong way to go about it altogether?
View 2 RepliesI understand that inherited classes can't be converted from base classes. But is there any way to write a conversion sub, so that the base class gets assigned to MyBase, then extra properties are added?[code]...
View 7 RepliesCan we override a Public Shared method in derived class? If not why?
View 2 RepliesI am using Linq to Sql that generated a data contract for a table. I have a date field in that table which is a non-nullable field. I need to override the auto generated property of the date field to return a specific value, something like [code]Is it possible to override an autogenerated property in the designer.vb file using a partial class? I dont want to create a new property as it is currently being accessed in n number of places and I dont want to change it in every place.
View 1 Repliesbare with me during this silly example. :-) Let's say I have a class like this:
Public Class Animal
Public iLegs as int32 ' Number of legs
Public bWings as Boolean ' Wings? Yes/No
End Class
And another class that inherits the "Animal" class and adds one more property:
Public Class ScaryAnimal
Inherits Animal
Public iScariness as int32 ' 0-100, how scary is it?
End Class
Now, if I have an instance of "Animal" with some values in it, and I decide I want to cast it to a ScaryAnimal for some reason, how do I do that without having to create a new instance of "ScaryAnimal" and copy each property value?Basically I'm looking for a way to do this, without having to write the lines marked with '*** below:
[Code]...
I have a base class called PageBase and then a derived class TestPage that inherits from PageBase. In PageBase I have overridden the OnInit() and when it is called and I inspect the value of 'Me', it is of the type of the derived class and not the base class. My question is how does inheritance really work? For instance, when instantiating TestPage does an instance of PageBase get created too?
Here is my code;
Partial Public Class TestPage
Inherits PageBase
Public Sub New()
[code]...
What is the base class of .NET?
View 2 RepliesWhen referencing a method's address, should we take into account the overriding or not?
Class B
Inherits A
Overrides Sub Foo
[code].....
When you create a webpage in ASP.net, the codebase inherits System.Web.UI.Page Now when I extend the page object to check for SessionExpired for example, I create a new class and inherit from system.web.ui.page, and overwrite some functions. The problem then is that on each page, I have to replace system.web.ui.page with my custompage class. Is there a way to extend a class by adding methods or modifying its methods directly (e.g. add the sessionExpired check to System.Web.UI.Page) ?I'm using .NET 2.0
View 2 Replies