VS 2005 - Inheriting Class Based On Generic Interface
Nov 17, 2009
I want to define a generic interface which will be implemented by an abstract Generic Class. Basically this generic class is a collection class of any class. Interfaces are in a separate project saved as FileReconciliation. Here are the interface definitions
Interfaces
Imports System.Collections
Public Interface ICollectionCommon(Of T As Class)
Inherits IEnumerable
Function Exists(ByVal oKey As Object) As Boolean
[Code] .....
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Jan 21, 2010
I can do this without problem.
Class A
End Class
Class B : Inherit A
End Class
Dim Obj1 As A = New B
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Nov 25, 2011
I am trying to construct a generic interface class with generic functions. My goal was to use this to implement multiple worker classes for database interaction that have the same basic functionality. Each class will deal with different object for example, category, product or supplier but unless the the functions in the interface are generic that this won't work.This is the interface code that I have but I don't know if I have done it correctly. [code]
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Jul 29, 2010
I know that an interface can contain another interface within it.But;can a class contain another class within it?Can an interface contain another interface within it?
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Apr 13, 2012
Consider:
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.
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Apr 17, 2009
In the below mockup, how do I find out, if I am an instance of FooDAL or WeeDAL from within the method DoMagix()?
Public MustInherit Class DataAccessClass
Public Sub DoMagix()
'** LOOK AT ME!!! **
[code].....
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Oct 15, 2011
I seem to be having a problem with controls that I am creating as new classes (not UserControls) inheriting from an existing system control. Everything seems ok while I create the control code, through to the compile (which is successful and adds the control to the toolbox) and dragging the control from the toolbox to the GUI surface. However, when I then debug or compile the project, I get a message such
[Code]...
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Apr 27, 2009
I want to implement a priority queue class. When an item is added at a higher priority it is pushed to the front of the queue instead adding to the end of queue. Simple few lines of code
[Code]...
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Jul 3, 2010
I've created a class called connector. By clicking on project and adding a class.And I want to inherit from that class in the forms But I get this error.
Base class '<baseclassname1>' specified for class '<partialclassname>' cannot be different from the base class '<baseclassname2>' of one of its other partial types`
what do I do?Here's the class named connect.vb:Imports MySql.Data.MySqlClient
[Code]...
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Aug 14, 2010
I have a Journal that records entries for different types: Journal(Of ParentT)
[Code]....
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Dec 19, 2009
I have 2 business classes, user & salutation and 2 DAL classes of the same name.
The business classes both have properties of the data class E.g.
Public Property Data() As Data.Salutation
Get
Return _Data
[Code].....
To access some data, you would do Business.Salutation.Data.SalutationID
Both busines classes inherit from BaseClass which contains all my database access methods.
Is there a way that I can access the Data property of the inheriting classes from the BaseClass?
I assume I will need to use reflection as the property types will always be different.
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Jun 29, 2010
When we can access the public methods via object then why is there need of inheritance.
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Nov 27, 2009
What is neater / better in your opinion? Inheriting a Class with useful methods or a creating a module?
For example:
vb Module Tools_Module
Public Sub Print(ByRef text As String)
Console.WriteLine(text)
End Sub
End Module
[Code]...
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Jan 12, 2010
Most of our code base is in VB.NET. I'm developing a project in C# that uses a lot of the assemblies from the VB.NET code.There are three relevant classes in VB.NET:
[Code]...
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Apr 1, 2010
I have an .exe project with a form in it that I want to use as a base class for other forms in the project. So I try to add a new inherited form to the project, but it says "Warning: No build assemblies contain components to inherit from. Build the current application, or click Browse and select a previously built assembly from another application". My base class is declared public and my exe has been built. I don't understand. Can you only do form inheritance in a dll?
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Jan 17, 2009
I have an interface class (IUser) which is the interface of class User. Now, i want to put these into an IList but am confused as to how i should declare the IList:Dim userList As IList(Of IUser) = New List(Of IUser) Dim userList As IList(Of User) = New List(Of User) Dim userList As IList(Of IUser) = New List(Of User) Dim userList As IList(Of User) = New List(Of IUser) when instantiating should you always use its implementation; and when using it as a type use its interface?
And when im creating a new user should i use: Dim myUser as IUser = new User?
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Mar 16, 2010
Why is .Net so adamant about AutoSize being true? Here's my
Imports System.ComponentModel
Public Class JBButton
Inherits System.Windows.Forms.CheckBox
[code].....
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May 15, 2012
When inheriting class or control e.g. ListView, TreeView, etc..., what is the best way to distinguish between built-in methods/property/events and mine?
Currently, i start my methods/property/events with "aa" in order to make them at the top of auto complete list.
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Aug 12, 2010
I have a Class FileDoc Public Class FileDoc Inherits BaseClass
Public Sub DeleteDoc() dim catId as integer = Cat_ID
[Code]...
My question is, since FileDoc comes from the BaseClass, how can I access values from the BaseClass when I'm coding in the FileDoc Class. Like my example in sub DeleteDoc(), I'm trying to access the Cat_ID of the Base Class which this FileDoc belongs to.Adding an inheritance doesn't transfer the values to the class, only the properties.
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Sep 2, 2009
I have a generic class Class MyTestClass(Of T)where I know that T will only ever be an enum. Is there any way to declare this restriction to the compiler?And a second question: If the answer to my first question is 'no, there isn't', then what's the best way to cast T to a plain integer? Doing that is difficult when the compiler doesn't know that T is always an enum. [code]That certainly works, but it looks nasty as it apparently involves unnecessarily boxing and then unboxing the enum value. Is there a better way of doing it?
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Nov 29, 2011
In our current project I am using a generic interface iService which is inherited by all other service interfaces. For instance IService is inherited by ILogService.
The ILogService interface is then implemented by LogService as below:
Public Interface IService(Of T)
Sub Save(ByVal T As IEntity)
Sub Remove(ByVal T As IEntity)
[Code]....
How can I update the method signature so T is displayed as Log?
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Feb 19, 2010
I am working on a general helper class to sort ListView SubItems. I wrote a base class that has much of the code I need. It includes a MustOverride for the Compare method so that the various inherited classes can implment their own comparisons based upon their type. For the value types, I end up with very similar code such as the following, where x and y are ListViewItems: Public Overloads Overrides Function Compare(ByVal x As Object, ByVal y As Object, ByVal sortColumnIndex As Integer, ByVal sortOrder As System.Windows.Forms.SortOrder) As Integer [code]
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Apr 21, 2010
I'm trying to make a .dll that contains a lot of basic functionality that a program can use. Currently i am trying to use interfaces to make a lot of this functionallity independend of the program using it but i hit a snag. The Basic idea is that a programmer will create his own object using the interface discribed in my .DLL file. Then implements those functions as he likes. He can then instanciate a controller (found in the same DLL) and sends his custom object implementing the interface to that Controller. The controller can then be started and will take over all the work. I do not know what type of object is send to the controller and idealy i want to program it in such a fashion that i shouldn't care as long as the object send implements that interface.In code I am trying to achieve the following: (quite simplyfied)
.Dll:
Code:
Public Interface MyInterface '<----Decleration of the interfaceFunction GetData() As Integer
Function SetData(Data As Integer)
end interface
[code]....
this propperly. I know that the second i set the interface adaptor in the Controller VS comes nagging that it can not be converted to a "MyInterface" Class. Obviously i am doing something wrong. I can change the datatype that the controller expects to the "MyController" type but that would completely ruin the whole idea of flexibillity. I am hoping someone sees what i am trying to do and can point out where i made the thinking error.
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May 25, 2010
I'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?
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Jun 8, 2009
I have a following code which works fine
MsgBox(AddSomething(Of String)("Hello", "World"))
Public Function AddSomething(Of T)(ByVal FirstValue As T, ByVal SecondValue As T) As String
Return FirstValue.ToString + SecondValue.ToString
[code].....
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Jan 2, 2011
i've been trying to toy around with generics in vb.net in an example project. At the moment, it looks like this:
I have an interface called IRow (and a class that implements it as a Datarow).
A second interface is ICanGetByRow, which looks like this:
Public Interface ICanGetByRow(Of T)
Function GetByRow(ByVal Row As IRow) As T
End Interface
The function simply takes an IRow and converts it to T. Thats easy enough. Now, for easier access, i want to implement a function in the IRow interface which takes the row and converts it into said ICanGetByRow.
My interface was enhanced by the following function
Function GetObj(Of T As ICanGetByRow(Of T))() As T
You can probably see the problem. If i implemented it like this:
Public Function GetObj(Of T As ICanGetByRow(Of T))() As T Implements IRow.GetObj
Dim foo As New T
foo.GetByRow(Me)
Return foo
End Function
i wouldn't be allowed to construct a new T, and when i tried to make it work by telling the generic function that my interface has a constructor, he wouldn't let me invoke GetByRow anymore.
Public Function GetObj(Of T As New, ICanGetByRow)() As T Implements IRow.GetObj
Dim foo As New T
foo.GetByRow(Me)
Return foo
End Function
how to tell a generic function that it will get a ICanGetByRow(of T) which has a constructor
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Aug 28, 2009
I'm trying to write a class that will be in charge of persisting application options. Since the options need to be persisted the values that I'm sent must be serialisable.
Initially I thought I've be able to write a method with a signature like this[code]...
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Jun 24, 2011
I have a problem when trying to save a picture box image ( I am using vb2008 express edition)When i load my windows form I create a folder called images and the current date (eg images 24062011) using the following code.
Code:
Dim fold As String = "images" & " " & Format(Now(), "ddMMyyyy")
If My.Computer.FileSystem.DirectoryExists("C:usersmickdesktop" & fold) Then
MsgBox(" file exists")
[code].....
this works fine and creates the folder on my desktop. I then load an image into a picturebox and try to save it using the following code which is where the problem starts.
Code:
Dim filename As String = Format(Now(), "ddMMyyyy")
Dim imagename As String = "image"
Dim fileext As String = Drawing.Imaging.ImageFormat.Bmp.ToString
[code].....
so my problem is why does the 1st statement give me the error as surely as I have declared that fold = the folder name then that path should be correct, as the program is set to save the image automatically, not using the savefiledialogue I don't want to have to manually type in the folder name every time I use the program.
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Sep 17, 2008
I am trying to create bitmap with my text and transformation. I am sure that there is no error in my code. Because this code is worked previously. Here is my code.
[Code]...
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Mar 1, 2010
I need to create unit testing project for my current website. The currentw ebsite si written in VB. All unit testing examples are using interface to create mock object. My current VB class does not implment any interface. Can I add interface and implement it to my current class and functions without affecting or changing codes to any pages in my website that call the functions? For examples my current class is like:
[Code]...
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