DataBinding Inheritance And Typeconverters?
Jan 19, 2010
I have the following code; now i set a propertygrid.selectedobject to the Square object, and start changing the Squares properties. If i change the [Position.x] or [position.y] values in the propertygrid the [Position] and [center] properties update correctly, however when i change the [Center] property, neither [Position] or [Position.x] or [Position.y] update. Is there something else i must do to get this to work both ways. Maybe something is lacking in PointFConverter?
Imports System
Imports System.Collections
Imports System.Drawing
[code]....
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Apr 22, 2012
i am just trying to apply inheritance ..Below is my Code ... on which i am not getting the output on my Text_Box ... when in write it in a Child Class
Imports System
Imports System.Windows
Imports System.Windows.Forms
[code]....
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Jul 14, 2011
Has someone a hint what I'm doing wrong in VB.Net?
Module Module1
Interface ISearch(Of T As ISearchResult)
Function ids() As List(Of T)
End Interface
[CODE]...
The third cast isn't working. Why? did I miss a oop lesson?
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Mar 2, 2011
What's the choice design that microsoft do that? Of course, as of me, I don't use inheritance a lot, or at all.
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Oct 21, 2011
we have 3 classes:Class S, class A, class B / A and B inherits S.A has a property A1 and B has a property B1.we also have a collection of objects that has A and B objects.ex.
Dim c as Collection = new Collection
c.add(new A)
c.add(new B)
Now we want to make a general object that will read from the collection.
ex .
Dim obj as S
how can we cast obj in order to see properties A1 or B1 according to the class;
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Apr 20, 2011
Form1
Public Class Form1
Private Sub But_Bell_Click(sender As System.Object, e As System.EventArgs) Handles But_Bell.Click
MessageBox.Show("Ding a ling")
End Sub
[code]....
Where has the whistle button gone? The class part of the inheritance has works because you can access it via code.
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Jun 29, 2010
Why VB.NET (vs C#) does not "inherit" the constructors with parameters?
Public Class StopLine
Inherits Microsoft.VisualBasic.PowerPacks.LineShape
Public Sub New()
MyBase.New()
[code]....
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Apr 15, 2011
I'm facing a problem regarding multiple inheritance in VB.net:As far as I know VB.net does not support multiple inheritance in general but you can reach a kind of multiple inheritance by working with interfaces (using "Implements" instead of "Inherits"):
Public Class ClassName
Implements BaseInterface1, BaseInterface2
End Class
That works fine for classes but I'd like to have an interface inheriting some base interfaces. Something like that:
[Code]...
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Apr 28, 2009
What are the situations and their associated benefits of using Generics over Inheritance and vice-versa, and how should they be best combined?I'm going to try to state the motivation for this question as best I can:I have a class as shown below:
[Code]...
Now suppose I have a repository that takes an InformationReturn argument, that has to strore different fields in a DB depending on the type of Info object T is. Is it better to create different repositories each for the type T is; one repository that uses reflection to determine the type; or is there a better way using inheritance capabilities over/with generics?
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Jul 19, 2010
I have a base class ("MyBaseClass") in a project called "BaseFramework" which is included in several solutions within the company. There are several derived class's in various projects throughout the company that inherit from "MyBaseClass". If I then create a List and add derived class's to it, it will not serialize. I realise that if I were attempting to serialize this list, and the base class and derived class were in the same project, I could simply apply the "XmlInclude" attribute to the base class and include all of the derived class's. This is however not possible across projects, because that would require a circular dependency.
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Jun 23, 2011
I searched quickly and not find an explicit answer at the following question:Why VB.NET (vs C#) does not "inherit" the constructors with parameters?
Public Class StopLine
Inherits Microsoft.VisualBasic.PowerPacks.LineShape
Public Sub New()
[code].....
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Jan 6, 2012
How can I convert following code to VB.NET?
class A
{
public int NumberA { get; set; }
}
[code]....
In VB.NET there is problem with Implements keyword after property declaration. So I need to do something like this:
Class B
Inherits A
Implements IC
[code]....
But there is duplicit misleading property NumberA1.
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Dec 14, 2011
Suppose I want to inherit from System.Data.SqlClient.SqlTransaction which is sealed. Supose I want to just put a wrapper around SqlTransaction and always use MyTransaction instead of SqlTransaction. Is there a way I could potentially cast MyTransaction to SqlTransaction using an Implicit/Widening operator?
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Aug 24, 2009
I have a parent class and many children class, right now it look like this:
Public Class Parent
Public Property ID as String
End Class
[Code].....
What I need is a strongly type list List(Of Child) that Inherits from ListOfParent (I need the FindByID method) but I can't find the right syntax.
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Nov 5, 2009
get around lack of multiple inheritance
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Aug 24, 2010
I am currently working on a framework for applications developed by my company, my boss wants to have a switchboard and a MenuStrip, where the entries and their actions are controlled by a database.
Now I've dealt with all the code to get them working. But the problem that I am facing is that I have duplicated code because each of the classes have the code that deals with ensuring the user has the right privileges and the code to deal with when a user clicks on an item.
Normally I would move this code out into a class and then have each of the classes inherit from the class, but because the switchboard already inherits from the Form class and the customised MenuStrip inherits from the MenuStrip class.After doing some Googling the only answer I have been able to find it using an interface for the functionality, which is obviously not exactly what I want.
Anyway I was just wondering whether any one had any suggestions on what I could do to deal with this problem, as I would like to avoid having duplicate code as much as possible.
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Sep 1, 2011
I have a library of graphical controls used to display values from a remote device. The controls are typically graphical objects such as a digital meter, analog meter, vertical bar, etc. I first create these controls with a value property. The control will display the value property, e.g. the meter needle will move to the position representing the value.
The next thing I do is to create a new control that inherits the previous discussed control. The new control adds properties that allows the value to be set from values retreived through a communication component. My code that does this is 99% the same for all of the controls. Since I already inherit the graphical control, I can not inherit the class that retreives the values from the communication component.
[Code]....
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Sep 14, 2011
I was wondering if it is possible to have dependent types in VB.Net 4, or alternatively, if it is possible to construct inherited objects based on the base class' constructor's parameter(s). For example,
[Code]...
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Sep 12, 2010
I'm writing some code in VB.Net which I hope demonstrate to colleagues (not to say familiarise myself a little more) with various design patterns - and I'm having an issue with the FactoryMethod Pattern.
[Code]...
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Dec 3, 2009
working on an implementation of a list control for a card game. The catch is the deck control object. I want it to be reusable for different types of cards, which is wheretuck since I seem to be having some issues.First: The basic card object
Public Class BaseCard
'Properties
Private _Id As Integer
[code]....
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Sep 21, 2011
I have two Forms, which have similar Functionality (i.e. an amount of similar Controls) but complete different Layout. So the normal inheritedForm (which VS2010 provides) wont work here.
I have tried following:
Public Class BaseForm
Inherits System.Windows.Forms.Form
Friend WithEvents Button1 As System.Windows.Forms.Button
[Code].....
So it looks like, the Designer only tries to guess how the Form looks like by inspecting the top-most Class, without compiling the full inheritance-Tree...
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Mar 16, 2010
I would like to create an user control that has a panel and a button. The user control should set font color, size, font type, and other properties but when I place the user control on a form I would like to be able to modify the text for the button.
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Aug 6, 2009
I am rather new to OOP and I have, what may be, a simple question. I am developing an architecture for a project that includes some object inheritence trees. I have been running into a bunch of narrowing conversion issues (the old 'Unable to cast object of type x to x' error). I understand the limitations of narrowing conversions and why this error exists, but I'm not quite sure how to get around it architecturally. Here is an analogous problem to mine...
[Code]...
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Jul 8, 2009
I have a base object, with a event that can be triggered by multiple methods.Then I created a child object that inherits that base object. I want to be able to trigger that event in the new object; but I can't use RaiseEvent to raise a base-object's event.To get around this, I created a small method in the base object that takes the argument for the event and I just use it to trigger the event. Is this the proper way to handle this situation? Similarly, I could Shadow the event with a duplicate one in the child object.Is there a standard way to handle events across inheritance?
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Dec 15, 2009
I've not played with inheritance myself much as I've never really had a need to, but now I have a situation which to me seems the ideal time to learn. I'll explain:
This is a WPF application but that shouldnt make any difference to this question. Basically, I have asearch window that retrieves data from a database - I want this one search window to be able to retrieve any item (business object might be a better word than item) from the database and display the relevant data, rather than having a separate window for each 'type' of item in my program. So I have got 3 classes at the moment, ComputerAudit, ConnectionAudit, and SoftwareAudit and I want my one search window to be able to display any of these items in the listbox. Obviously there would only be one type of item displayed at once, so there wouldnt be a computeraudit item and a connectionaudit item displayed in the list at the same time, but there could be several computeraudit items displayed.
So I thought I could create a base class just named Audit and have those 3 classes I mentioned inherit from that, then I can specify the arguments to methods I am using as just being of type Audit (rather than using a specific type like ComputerAudit or SoftwareAudit) because then I should be able to pass around any of these items which inherit from Audit right? Well that doesnt seem to be the case so I'm wondering if I have misunderstood inheritance.
The problem I'm having specifically is that I have some methods which need to be able to accept any of my Audit subclasses but if I specify a generic List(Of Audit) then it wont let me pass in a List(Of ComputerAudit) for example. Is this because I'm using a List or am I just doing something fundamentally wrong?
EDIT: Found this page which confirms my suspicions that this is more to do with the List than general inheritance:[URL]...
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Nov 26, 2009
What I need to know is how to archive UserControl inheritance with VB. I found some samples how to do this with C# and all of them work fine with C#. But when I try to translate this in VB I get an error (namespace not found) in my UserControl-XAML.
E.g. This link, Variant 1: [URL]
It seems to be easy in C# and impossible with VB.
This is my approach:
1) the class "TestBaseCtrl.vb"
Code:
Imports System.Windows.Data
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
[Code] .....
Error message:
"The local.TestBastCtrl-type was not found. All assembly references have to exist and all assemblies, that are referenced, have to be built."
It seems to me that the compiler does not find the class in my namespace but I can assure that the namespace is as correct as it is in the C#-project. I need a UserControl to inherit from, there are several functions that should be integrated in all of my forms and I do not want to implement them in every form I want to create. If I get this working, I hope that this kind of UserControls will still be working within the CAL (Composite Application Libary)-Framework, but this will be another story for another day...
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Oct 19, 2007
I am trying to serialize and object which inherits from another object and uses shadows.
Public MustInherit Class clsGenericField
private moValue as object
public event ValueCha
[code].....
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Jan 8, 2008
The TextBoxBase class is marked MustInherit, but I can't inherit off it. When I try to, I get a squiggly line and the message System.Windows.Forms.TextBoxBase has no accessible Sub New and cannot be inherited.This is kind of pretty inconvenient, as I need to extend this class. (And before you ask, I need to extend this class because TextBox derives from it, and I want to Shadow the TextBox class's TextChanged event - but the TextChanged event is declared in the Control class, not the TextBoxBase class. So there.)
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Feb 15, 2010
I've got an interface inheritance issue that has been vexing me for some time. It doesn't seem to make any sense, and I can only conclude that I'm missing something fundamental.
Overview The code below is from part of a fluent interface for our ORM tool. It provides a SQL-like syntax for pulling data from the database. You don't have to completely grok all the interrelations to understand the problem -- the real issue is the EndClause method.
The EndClause Issue There's a method called EndClause that doesn't show up in one expected spot -- IOrderQueryRoot. As far as I know, it should show up because it inherits from two different interfaces that both have a method called EndClause, but when I consume an object that implements IOrderQueryRoot, EndClause does not pop up in intellisense.
There are some more implementation details below.First though, if you look at IOrderQueryRoot (which contains EndClause), you can see that it inherits IHasOrderLogicalOperators, and also IHasOrderFields (which also contains EndClause).
Public Interface IHasOrderLogicalOperators
Function [And]() As IHasOrderFields
Function [AndNot]() As IHasOrderFields
[code]....
At this point, the interface is working fine -- if I were to remove this method, VS would scream that I have to implement both EndClause methods. The problem is one level down, when the "end developer" is trying to actually write code against the interface.
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Jul 7, 2010
I have a class that I wrote fairly early on in my vb.net programming experience which inherited from another class it really should have composed. The base class is a relatively generic nested dictionary-based collection; let's call the descendant class a "Car".Right now there's a lot of code that does things like 'MyCar!Color.st = "Red"' (I use the generic collection rather than real properties to facilitate data interchange with code written in VB6, and also to facilitate comparisons of cars; given three cars X, Y, Z, I can e.g. detect any changes between X and Y and apply those changes to Z).
Is there any nice way to refactor the code to use composition rather than inheritance?Which properties methods should the "Car" object wrap, and which ones should be accessed through a data-object property? Should a widening conversion be defined between a car and the collection object? Are there any gotchas when doing such refactoring?
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