suppose I have the following hirarchy:
Public Class PrimalClass
Public Event SomeEvent()
End Class
Public Class BaseClass
[code]....
this code compiles and runs.what I want to do, is remove the event SomeEvent in BaseClass so that DerivedClass won't be able to register a handler to it.
Consider the following objects:
Public MustInherit Class FileRepository
Public MustOverride Sub SaveStringToFile(ByVal FileText As String, ByVal FilePath As String)
Public Event FileSaved(ByRef sender As Object, ByVal EventArgs As EventArgs)
[code]....
I want my base class to raise the FileSaved event in it's implentation of SaveStringToFile once it's saved the file. However in VB.NET you can't have a derived class raise a base classes event. I suppose I can treat XMLFileRepository_FileSaved as a standard function call and have my SaveStringToFile implementation call it directly?
When 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 RepliesWhen 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?
Trying to implement some sort of commit/rollback functionality in my base objects. I have it working with some help from google. However, I have a question My Base Class has a BeginEdit as shown below -
[Code]...
Now, what I'm confused about is if I create another class, Class1, that inherits the base class. I add some properties such as Name, Age, Location, etc. to Class1.When I do Class1.BeginEdit, wouldn't "Me.memberwiseclone" make a copy of Class1, then CType try to cast it from Class1 to the BaseObject class? How does that work if Class1 has additional properties like the Name, Age..blah blah? Where do those gets stored in the Base class? I'm having a hard time wrapping my head around the concept...
I'm struggling here.. I know I can disable the warning manually. However I'm not sure if this would be the right way to go about this.
Here's my interface..vbnet Public Interface IPopulatingClassBase Property Identity() As Int64 ReadOnly Property Dirty() As Boolean Sub Populate_Class(ByVal RecordID As Int64) Sub Save_Class() Sub Reset_Class()End Interface
[Code]...
PS In my example think of it as classes that populate with data from a database. The parent class would be an organization, and the derived class a location. Both populate and have similar functionality. The only difference is locations are an entity of an organization(the data record for a location constraints it to an organization) upon loading location data I also populate the organization class. This is a real example of what my project does.. so having said I just want to know how I can get around this warning, and if not would it have any consequences if I left it as-is.
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 Repliesi've finally got round to learning about classes and inheritance, but i'm not sure how to proceed. i have a base class Employee, which is inherited by 2 derived classes. how do i use the same Employee class in both derived classes? obviously if i write a sub new for both of them + declare a new Employee class, they won't be using the same class. heres my Employee class:
[Code]....
I've searched on the Internet and I can't find a solution to this simple problem. I've also looked on Microsoft's MUCH improved MSDN site and haven't found a solution, so here it goes. I'm trying to remove an entry from a list of class and it doesn't get removed. Here's a sample of the code I'm trying: (I renamed the class and variable names to make it a simple example)
Dim lstClass As New List(Of TheClass)
Dim mClass As TheClass
I tried this first
mClass.filename = "The Entry to Delete"
lstClass.Remove(mClass)
[Code]...
i have a base class which declares the event StatusTextChanged. My child class, of course cannot directly raise this event.
[Code]...
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.
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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 am migrating my code from vb.net 1.1 framework to vb.net 3.5In my windows application, the base window has some buttons and events are written for the same.I have shortcuts defined for these buttons also, for example: ctrl+d, DEL (keyboard) etc.Now i open a property Grid form on top of my base window for a selected object.Even when the focus is on this property grid, i am noticing that my base window events are firing on pressing those shortcuts.
example:I select some text in my property grid and hit delete button from keyboard. The delete event that i have written for the selected object gets fired and the text is not deleting.I fail to understand why is it happening. It wasnt behaving like this in .net 1.1.In .net 1.1 it would delete the text and only when the focus is back on the base window, hitting Delete would call the event.How do i control such a behavior? Is there some property that i need to set for property grid in .net 3.5 to prevent base window events from firing till the time focus is on property grid form?
I've an app that starts to work from a module wich should load a form an do other things with a class library who raise an event an the form shoud cath it. The problem is that applicarion.run(frmMain) displays the form in the same thread the the code stops work while the form is open. And I need that the app works in this way because the user need to send files to the app using args and this avoid that the app init another instance of it (in other code) and update the form with the info when the event is raised.
[Code]....
[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 RepliesI am auto generating data grid and I am using check box in Data grid View,Now i am invoking check box state changed event but it produces the following error Handles clause requires a With Events variable defined in the containing type or one of its base types.
Here the code
Private Sub PRNT_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles PRNT.CheckedChanged
Some Stuff.
End Sub
bare 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 RepliesAny best practices on how to deal with different versions of base classes.We have made significant changes to the base class but still have lots of code inheriting from the old base class. Could you recommend how we introduce new base class.We'd like all new code to use the new base class. But, we would like the option to have old code still inherit from old base class so we have time to switch and test old classes with new base class.
View 11 Replies
