Create A New Class That Inherits From The Base Form Class And Define A New() Method With Parameters?
Oct 1, 2008
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).
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.
I'm developing a software that handles very specific regional standards. In one part of the country they have different standards for entering this data than they do in other parts of the country. In fact there are hundreds or thousands of possible configurations that would be best in various regions.
The solution I've come up with is to write a program that can load different control configurations with the supporting code to its main form at runtime. I do not know how to accomplish this. Would I use visual inheritance at runtime? Would I use a plugin system? I just need to potentially allow a power user to design thier own interface or to modify an existing interface to better suit thier needs.
Edit: Is there a way to define the base class of a form at runtime? Could I create user controls in a plugin and pass them in to the host program?
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?
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.
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.
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)?
Consider a MyForm class that contains a shadowed implementation of Show(). It also contains a CreateForm() method, which accepts an instance of the form and calls the shadowed sub:
If Class X is within the scope of Class Y, is X a subclass of Y?If Class A is a sub Class of B, then is Class B considered a super class of A?if Class C inherits Class D is Class D a superclass or parent of Class C?if Class E extends Class F then we can consider Class E a child of F?if Class G inherits Class H and is within the scope of Class I then who is the parent of Class G? Classes that inherits Class J and classes that are within Class J are all sub classes of Class J?
I was just practicing some coding and noticed that I was able to use class instead of Module in VB .NET. So I replaced my module to class and I got this error message:No accessible 'Main' method with an appropriate signature was found in 'practicevb'.practicevb
I made sure that the startup object was set correctly in Properties > Application > Startup Objects.The error message disappears if I change it back to Module but I would like to keep it class since the other parts of my code I changed to class and didn't return and error messages.
Class Atic Sub Main() Console.WriteLine("Hello, this proram will calcaulate the quadratic forumla ax^2 + bx + c") Dim Quads As New Quads
If I have a class that inherits another class in which there are objects that are disposed in the dispose() procedure, do I use mybase.dispose? ex Class A inherits Class B. [code]
REF: http:[url].....The above reference is where I got the code below.This code adds buttons to Form1. When a button is clicked a messagebox appears stating what button was clicked. I want to have the ClickHandler fill a RichTextBox on Form1 (I added a RTB to Form1). My problem is I can't do a Dim xForm As New Form1 to fill the RTB from the ButtonArray Class. I can place my file's text in a MessageBox so I know the code I added is correct. I also tried placing a Property method on Form1 and using a Accessor to fill the RTB, however it also requires Dim xForm As New Form1. How can I get my data from files to the RichTextBox on Form1 from the ClickHandler in the ButtonArray Class? See ButtonArray Class Below.
Under Visual Basic 2010, I am trying to define a specific instance of a static method that was created as a Java class. I have a vendor supplied dll added in as a reference.[code]...
But, I can't seem to define a specific instance of this method. Using "IntegrationMethod.getIntegrationMode()"always returns a value of zero.
There doesn't appear to be any way to "setIntegrationMode" to a specific value.
The documentatoin for this Class as provided by the vendor are shown below.
When I asked the vendor for assistance, their response was: "
Our javadocs for the IntegrationMethod class show that we provide three predefined instances of the IntegrationMethod class[code]...
I would like to inherit from the Data.DataColumn in order to produce a DataTextColumn. That means that in the derived class, I dont want to see the non-applicable AutoIncrement property and the like - all I want to see are properties that apply to string types.[code]...
A friend in work suggested the use on classe to store the parameters BEFORE call a method. He's said this is called "Abstract Class". My "know how" of VB.NET is small... so, I want to know of you what mode is the best way: Call a function/sub like that:
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.
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".
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?
1) VB Allows non-type template parameters2) VB supports explicit specialization 3) VB allows the type parameters to be used as the base class for the generic type4) VB allows a generic type parameter itself to to be a generic 5) VB enforces that all codes are valid for all types of parametrs
If 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 ?
[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?
I 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]...
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 happen to have these common procedures which I want to be used in my forms and usercontrols, with the form I can put those procedures in the base form which is being inherited but I happen to have a need to use those same procedures in my usercontrols, is there a way that I can have a common base class that I can use both for my form and usercontrol? I haven't used yet a base usercontrol since my usercontrols will not look the same so I have to put those procedures in each one of them and I find it rather cumbersome.
I am making a TabStrip control to hold a number of tabs just like TabControl, but only with the tabs, no page. The control has a "Tabs Collection", which stores a list of "Tab" class. "Tab" is not inherited from Control, but each tab has its events. So when the user add a "Tab" in the "Tabs Collection", each "Tab" instance should have a (Name) identifier, which user can access it in the code, and with WithEvents keyword so users can add event handlers to each "Tab". The expected out come should similar to this:
Friend TabStrip1 As TabStrip Friend WithEvents t1 As Tab ... Me.TabStrip1.Tabs.Add(t1)
