Getting Around Lack Of Multiple Inheritance?
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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Nov 5, 2009
get around lack of multiple inheritance
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Aug 31, 2010
I have a class, GControl. It's pretty much a Control class clone with some improvements. It doesn't inherit from Control, because that would be a huge mess, and it needs to stay that way. However, to add a GControl to a Form in the first place, it needs to inherit from Control. So, I created a new class, called GForm, that inherits from Control and draws GControls in the OnPaint method. However, it should also inherit GControl, because it needs (1) to be able to be a GControl's Parent and (2) to be able to have a GControlCollection property. The way I've made the GControlCollection is so that it must be created with a GControl as its parent. I could change how GControlCollection works, but not the Parent property. Does anyone know a way to get around that?
Here's what the property looks like:
CODE:
And a few methods (like Invalidate()) need to be called on the control's parent.
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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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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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Dec 18, 2009
I m trying to understand Interfaces so that I can implement them in my programs but I m not able to imagine how should i use them.Also give me some eg of using them with multiple inheritance in C#
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Dec 15, 2011
Can any one explain the usage of interfaces to implement multiple inheritance in VB.NET.
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Nov 7, 2011
Several years ago, I created a nifty data entry form that is called from a main menu. Due to recent user requirements, I had to create another form that is very similar to the data entry form. To prevent duplicate coding and testing, I created a class to inherit the existing data entry form. The issue is when I leave the class and return to a sub menu, the class is opening the main menu and the sub menu. How do I only return to the sub menu without the main menu appearing? Here is a snippet of my code. You'll have to scroll down to the very bottom to see the section that is causing issues. BTW, I coded the application in such a way that only one form should be open at a time.
frmMenu (main menu). This is nothing more than a bunch of buttons that allows the user to perform various functions.If user clicks button #1, open the data entry form:
Dim objFrm As New frmDataEntry
bolOkToCloseForm = True
Me.Close() '--- close the menu screen
[code]....
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Aug 16, 2009
Where do you put the "main code" for lack of a better description? I can find all sorts of places to put code based on events like button clicks or forms loading. However, I can't seem to find a place to run code without an event (just idling).Basically I'm looking to monitor a file and call a sub when it changes. I can monitor the file fine based on the size but I can't figure out where to put code to call a sub when that changes. Everything seems based on user actions but that doesn't work in this case.
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May 18, 2010
Is there a way to get the IntelliSense for a lack of better term to work like it does for C#? For example, lets say I want to add a MessageBox to my form. With C# as soon as I get around Mess it's already coming up with the rest of the word, and the same with variables and control names. Just wondering if I'm missing a setting or something some place or if this is just another example of how things are different between the enviroments. Using Visual Studio 2005.
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Jun 21, 2010
vb6 used to support both procedure view and full module view. VB.net seems only to support the latter.Why would they do this? Is it perhaps because people generally have bigger screens now (and less need to scroll).I find that I have to scroll down a sub/function very slowly with full module view or else i'll inadvertently end up in a different sub.Is there a plug-in or another way to recreate procedure view?
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Dec 14, 2010
Just tried to create a new Data Source in VB 2010, apparently I don't have permission to connect to the 'Login.mdf' file I recently created in SQL 2008. Does anyone here have any knowledge of how to surpass this problem? I'm the Administrator of my PC and have full permissions and UAC is turned off so that shouldn't be the problem either
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Jun 16, 2010
Why is there such tremendous effort made on microsofts part to hide the fact that you cannot write SurroundsWith code snippets for Visual Basic, and the $end$ and $selected$ reserved words dont work in Visual Basic.
Micro$osft... YOUVE HAD 3 VERSIONS OF VISUAL STUDIO TO GET THIS WORKING... WHY THE H3LL IS IT STILL A STEAMING PILE FOR VISUAL BASIC. I HAVE TO BUY A THIRD PARTY PRODUCT TO ENABLE FUNCTIONALITY THAT YOU REFUSE TO WRITE FOR VISUAL BASIC.
Can you tell this is infuriating? I spent a TON of hours finding out about this sorely lacking functionality that you should have plastered ALL OVER your snippets documentation on MSDN. I hear you're a HORRIBLE company to work for, but should I ever need a job and have to dig at the bottom of the barrel, I think you OWE me a g.d. job now.
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May 4, 2011
I'm trying to make a label transparent. When I set the BackColor to transparent, all it does it take the color of the form it's sitting on, i.e. It's not truly transparent. I've googled it and found this in another thread (from a MSFT MVP)".NET controls do not support true transparency. You can set their BackColor to Transparent (in some but not all cases) and the parent control will show through, but only the parent control. If there is some other control behind that is not the parent it will not show through. That's because the control is not truly transparent. It basically copies its parent in the area behind it and uses that as its background, but that doesn't include sibling controls that may be behind it as well." To me, this is completely unacceptable. Why even include the transparency option when all it does is set the control's backcolor to the form color? I'm trying to add a label over a progress bar to give my user some feedback (because the Visual Studio progress bar doesn't support text, which is also a horrible design shortfall by the way), and have yet to find a way around this.
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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 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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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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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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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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