VS 2008 Casting Subclasses, Base Classes?
Jun 26, 2010I am a VB6 programmer learning VB.Net and am having trouble with the following concept.
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Interacting Classes With SubClasses?
Mar 17, 2009I have a project in Visual Basic 2008 where there is a Main Class and couple of classes inside the Main Class. I want to be able to share variables/objects within the Main Class and SubClasses while those vars/object are instanced.
Ex:
Code:
Public Class clsMain
Public t as New clsSub1
[Code].....
So, can i make var1 be in separate instances per clsMain in the memory while being able to access the var1 in clsSub1?
C# - How To Group Enums Structures And Subclasses In Classes
Aug 21, 2010I've heard bad things about overusing regions but when adding enums to my classes I put them into a #region "Enums" at the end of the class, and do the same with structures and even subclasses.
Is there a better/standard way to go about grouping such elements on classes?
(Note: this is tagged C#/VB but maybe the same situation exists for other languages, like Java)
[2008] Base Class Inherited By 2 Derived Classes
Jan 30, 2009i'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:
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Derived Classes Cannot Raise Base Classes
Jul 10, 2009I m trying to raise Click event of Textbox explictly but I m getting "Derived classes cannot raise base classes" error.[code]....
View 1 RepliesObject Casting - TryCast Statement And Base Class
Jun 17, 2009Here is a test program I wrote to explore a facet of object casting ...
Module Module1
Sub Main()
Dim class1 As MyBaseClass = New MyBaseClass()
Dim class2 As MyInheritedClass = New MyInheritedClass()
Dim class3 As MyBaseClass = Nothing
[Code] .....
The problem comes with the TryCast statement on class3. My intention is that class3 remains as a baseclass, but when the TryCast is applied, class3 morphs itself into an Inherited class which is not what I wanted. So is there a gap in my OOP/VB.NET knowledge and this action is legitimate or should class3 still be regarded as a base class?
.net - Events In Base Classes?
May 19, 2009i have a base class which declares the event StatusTextChanged. My child class, of course cannot directly raise this event.
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C# - Using Many Classes In GUI That Inherit From A Base?
Oct 20, 2010I have classes setup similar to this:
<DataContract()> _
Public MustInherit Class SystemTaskProcessBase
Public MustOverride ReadOnly Property Name() As String
Public MustOverride ReadOnly Property Description() As String
Public MustOverride Property Result() As SystemTaskResult
[Code]...
I need to use these classes on the client system, but also need to be able to create these "tasks" through a management interface. Each class (Task) that inherits the base, could have its own properties that are unique to each class, but at the same time, share the same common base class properties. For example, the above shows a reboot task and a delete file task, the delete file task needs to know which file to delete, so has a property for that. But the reboot task does not need this property. So when the management application is creating these tasks, it shouldn't provide a text box for the file property for the reboot task. There may be more tasks created at a later date with completely different properties.
How would I go about providing the WinForms management application a way to enumerate each class into a ListView for example, and allowing the user to create these tasks and filling in the dynamic properties that each class would have? Desired functionality would be to create a task form that creates dynamic controls available for the properties as needed, depending on the public properties in each class, but at the same time have the base class properties available as well.
Base Classes On Proxy Objects
Sep 25, 2011I have a webservice that is wrapped up by a data access object and is accessed by many different UI controls.
The proxy objects look something like this:
Public Class WebProxyObject1
' Common properties, there are about 10 of these
Public Name As String
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Make Base Interface For Generic Classes?
May 25, 2010I'm trying to create a base interface for a class of mine that uses generics. However, I cannot figure out how to declare a property of the interface when its type won't be defined until the class is initialized.
To clarify, consider List(of T), which according to msdn, implements IList (among other things). Note that IList is not the same as its generic counterpart IList(Of T). So that mean any List(of T) can be converted to IList, which simply returns an object for its items. That's what I want to do with MyClass(of T), be able to cast it as IMyClass regardless of what T is.
But when I try such as:
Interface IMyClass
Prop A as Object
Class MyClass(of T) Implements IMyClass
Prop A as T Implements IMyClass.A
I get a signature error for the last line, even though object is broader than T. What am I doing wrong, or how exactly did Microsoft manage to make List(of T) implement IList?
Specifying Different Page Base Classes For Different Directories In Web.config File?
Mar 17, 2010I have a website (coded in vb.net) with an "admin" section (the admin section being a folder in the actual site)... So in every page of the site I'm using my own custom class as the page base (which has been set in the web.config file) but I want to inherit from different class for the files in the "admin" folder... Is there any way to inherit different classes for pages in different folders using the web.config or some other equally as global method? (meaning some other way than inheriting on a per page basis.)
View 1 RepliesV B 2008 Express Book - Can't Connect To The "Service-Based Data Base" Or To The "Linq To Sql Classes"
Jan 6, 2010I can't connect to the "Service-Based Data Base" or to the "Linq To Sql classes". I tried all that I've read in the Forums for days : ( I removed the VB 2008 and SQL 2205-2208, then upload VB 2008 from my CD only. I'm starting a Web Technology class in 2 weeks, and the complition of the book is my entry requirement.
View 4 RepliesCasting From Base Type To Derived Type
Jun 29, 2010I'm wrestling with this treeview control. I have extended the TreeNode class to attach some extra data to the node. Basically, I added one property:[code]Is there a way to cast from a base type to a derived type?
View 11 RepliesVS 2005 - How To Make Custom Base Classes Available To Future Programs
Oct 22, 2010I have written multiple programs in the past that deal with cad data. Points, lines, arcs, etc. For each program I ended up creating slightly different versions of some really base classes like a class that defines a point:
<Serializable()> Public Class Point
Public x As Double = 0
Public y As Double = 0
Public z As Double = 0
End Class
My question is how would I use that class in such a way that it could be in a namespace and imported into any future project that I write?
Design Patterns - Inheritance - Do All Properties In The Derived Classes Have To Be Declared In The Base Class
Aug 8, 2011Background:I have a base class and several inherited derived classes. The derived classes don't always need to have the same properties. If any properties are shared among the derived classes, those properties would live at the base class level ('Contents', for example).Similarly, GoodDocument below has 'GoodThings' but would not want/need to have 'BadThings'.I want to treat instances of both 'GoodDocument' and 'BadDocument' as type 'Document'
public mustinherit class Document
public property Contents as string
public sub new()...
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VS 2008 Casting An Object?
Sep 30, 2009I've got a project called Service.Inside the project, i've got 2 windows classes.ClassA is the main windows class which opens up when I run the program.On ClassA, I've got a button which, when I click it, opens up ClassB which is the other windows class. Inside the button's eventhandler (click), I've got a string which contains the name of ClassB's class ie "ClassB". I will probably get this from a table. Is it possible to initiate the object ClassB without using if statments to check what the type of object is. In the code below, i've managed to create a o of type object, but i need to new it with the ClassB
vb.net Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
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.net - Shared Variables Among Subclasses?
Jan 18, 2011I have a problem with inherited classes. Have a look at the following VB.NET 2.0 / VS 2005 code:
MustInherit Class templateclass
Public Shared x As String
End Class
Class child1
[code]....
The templateclass has a shared variable x which is of course inherited by the child classes. But I wonder that all child classes share only one x! Until now I thought that shared variables are only shared among the instances of a class, not among all childs. This is very annoying because I have a base class which I need in two slightly different versions and they should not "share the shared" variables. And because the classes have a lot of shared variables, shadowing each in the childs would be very..
.NET Generic Constraints And Subclasses?
Sep 17, 2010Consider the following extension method:
<Extension()> _
Public Function Satisfies(Of T)(ByVal subject As T, ByVal specification As ISpecification(Of T)) As Boolean
Return specification.IsSatisfiedBy(subject)
End Function
This works as expected if subject is the exact class being operated on by the specification. However, if the specification is examining the super-class of T, this extension will not work unless subject is explicitly cast to the super-class. Is there a way I can avoid this? So far, the best I've been able to come up with is:
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Since I (apparently) can't get this to work exactly as I'd like in VB.NET due to limitations in the language itself, is my second attempt the safest/most efficient way to do this?
XML Serialization - Objects With Different Subclasses
Oct 11, 2011I'm want to serialize a list(of Animal) of objects with different subclasses of type "their own type" but getting nowhere as exceptions doesn't give out any useful information. I've set up the serializer method which which serializes individual sublass objects if I declare them with their own type but not if I declared them as a derived (Animal).
Code is below:
Public Sub XMLPersistAnimalList(ByVal filePath As String)
Dim serializer As New XMLSerialization(m_animalList, filePath)
serializer.Serialize(Of List(Of Animal))(filePath, m_animalList) '------doesn't work!
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VS 2008 Object Inheritance And Casting
Mar 23, 2011I have two custom objects.On of them inherits the other one, appends few more properties and methods, ovverides some other.When I try to cast the Parnet Object to Child I receive an error that it could`nt be done.
View 1 Replies[2008] Casting Double To Integer?
Feb 5, 2009I'm trying to write a (WPF) program with Option Strict on, but I have a problem.
I have a Canvas with a background image, and I want to use the coordinates of where the canvas was clicked to determine what should happen next. (Something like this)
Dim p As Point = e.GetPosition(DirectCast(sender, Canvas))
Dim imgColorMap As System.Drawing.Bitmap = My.Resources.ColorMap
Dim c As System.Drawing.Color = imgColorMap.GetPixel(p.X, p.Y)
This gives me the error: "Option Strict disallows implicit conversion of 'Double' to 'Integer'" for p.X and p.Y I have tried several things, like Math.Round but strangely enough that also returns a double.
How do I cast/round these Double values to Integer, so I can use them in my GetPixel method?
Control The Element Names Of Serialized Subclasses?
Jul 5, 2011Let's say I have the following class structure (simplified from my real-world problem):
Public Class PC_People_Container
Private _people_list As New List(Of PL_Person)
Public Sub New()[code].....
If I were to serialize this, I'd get the default assigned node names in my XML. That means my root is named PC_People_Container and each person in the list is marked up as PL_Person. I know I can change the root node using <XmlRoot(ElementName :="PeopleContainer")>. The trouble is doing that for the subclasses. I can't use the <XmlRoot> tag on PL_Person class because there can't be two root elements, and IntelliSense throws a fit when I try to use the <XmlElement> tag on a class like I would on a property. Is it even possible to control what those subclasses are named when they're serialized as child nodes?
VS 2008 Object Casting Error When Clicking On A Web Browser Bookmark?
May 31, 2010Unable to cast object of type 'System.Windows.Forms.ToolStripButton' to type 'System.Windows.Forms.ToolStripMenuItem'.This is the error, when I click on the bookmark(When I add the bookmark, It's a non-clickable menu item; the next time i debug it, it becomes a clickable url(button)
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
...
Call minginimi()
End Sub
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The Input Is Not A Valid Base-64 String As It Contains A Non-base 64 Character, More Than Two Padding Characters
Jun 3, 2011I am getting following error when I am trying to use Convert.FromBase64String "The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or a non-white space character among the padding characters."
Dim payloadBytes = Convert.FromBase64String(payloadBase64)
Basically when my facebook registration form [URL]mphone field has a dash in it and encoded string is posted to other page and I am trying to decode it there which creates this error. Basically I am trying to extract data from Facebook Signed Request.
Handle Base 13 (or Generic Base N)?
Sep 6, 2010I can quickly knock together soem code to xlate base 10 to/from bae 13, but I just wondered if something very easy already exists in VB.NET (or even somethign generic, with base N, but right now I am only looking at base 13)
View 1 RepliesUse LINQ To Filter Collection Of Nested Classes To Yield Dictionary Of Unique Properties Of Those Classes?
Jan 23, 2012I have two classes, one nested in the other. [code]Neither "Name" or "ID" are unique between operations and records.I wish to construct a dictionary using LINQ = Dictionary(Of String, Of List(Of Integer), whereby the keys are uniqe examples of Names in my collection and the values are the collective set of distinct IDs that are associated with those names.
View 2 RepliesVS 2010 Structure Classes So That The User Interfaces Though A Single Class While The Supporting Classes Are Hidden From Their View?
Jun 13, 2012How can I structure my classes so that the user interfaces though a single class while the supporting classes are hidden from their view? I think its best understood in an example:
Public Class MyInterface
Public Economic as EconomicClass
Public Sub New()
MyBase.New()
[code].....
So you might ask why am I even separating them? It's strictly for others who will be working with this interface. I need to funnel them though a logical structure:
interface.Economic.MyMethod
interface.Currency.MyMethod
etc
This way everything is already handled for them in the background and they only need to run the method they need. I don't know if I can have it both ways in VB.NET.
VS 2010 Calling Subs And Functions Within Classes That Are Within Classes?
Oct 24, 2009Here is some example code of what I mean:
vb
Public Class Form1
Private Sub Button1_Click(ByVal sender as Object, e as systemEventArgs) Handles Button1.Click
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VS 2008 Base/Derived Class?
Jan 17, 2010Trying 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 -
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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...
VS 2008 Connecting To SQL Data Base
Jun 16, 2011I am trying to familiarise my self with connecting to SQL and manipulating data and I seem to have fallen at the first hurdle I am trying to programmtically connect to a database and fill a data grid with a dataset.
The problem seems to be with the data provider my code is:
Dim strConnection As String = "Data Source=GARY-LAPTOPSQLEXPRESS;Initial Catalog=OriginalFileLocations;Integrated Security=True;Provider=SQLOLEDB"
Dim cnnOriginalFileLo As OleDbConnection = New OleDbConnection
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