Mimic An Interface / Contract For Shared Methods In A Class For Use By Generics?

Nov 15, 2010

So I implemented my own form of Enum static classes so I can associate strings to enumeration values. One of the shared functions in each enum class, GetValue, is used to quickly look up the string value from an internal array via the offset. While all of the enum classes implement the same exact function, the data types of their parameters differ, specific to the enums in each class.

So I come to a point where I want to create a generic class that can use any of the enums by passing it as a generic type parameter. But I cannot find a way to constrain type T in such a way to be able to call each enum's GetValue function. This is where an interface would come in handy, but VB.NET forbids interfaces for shared methods.

I have a base class that I could constrain to, but the base class doesn't implement the GetValue method, and I can't define a generic version of it, because I need to rely on shared properties of each child class in order for GetValue to do its thing.[code]..

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Use Derived Class Shared Variables In Shared Methods Of Base Class?

Jun 4, 2010

I am trying to add shared members in derived classes and use that values in base classes...

I have base

class DBLayer
public shared function GetDetail(byval UIN as integer)
dim StrSql = string.format("select * from {0} where uin = {1}", tablename, uin)
end function
end class

[Code]..

currently there is error using the tablename variable of derived class in base class but i want to use it i dun know other techniques if other solutions are better then u can post it or u can say how can i make it work? confused...

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Derived Class Shared Methods?

Nov 3, 2010

I have a function that 2 derived classes use, but the third doesn't, would it make sense to just leave it in the base class, even though one of the 3 derived classes doesn't use it?The only way I could think of disallowing the third class is to basically create an intermediate class that is derived of the base, then the 2 that use the common function are derived off the second class.

Is it possible to prevent the 3rd class from using the function, while letting the two that are supposed to use it, use it?Does that just seem to go overboard, I mean as long as I don't "try" to call the function from the 3rd class, it shouldn't be a problem, I just was interested if there was a way to prevent it all together without a lot of hassle.

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Shared Class With Generic Methods?

Jan 28, 2010

I have created a Interface and a couple classes that implement this Interface. I am in the process of developing a Shared Class that utilizes the functions that each of the individual classes have, due to the interface implementation.What i need to know is how do i develop this Shared Class so that way each of the methods within it are restricted to a single data type. This single data type needs to be restricted to any class that has implemented the Interface.

Some examples:

Public Interface IVector(Of T)
Sub Add(ByVal v2 as T)

[code]....

As you can see it would allow me to develop one form, since i have standardized the required Subs/Functions for any class the implements the IVector interface. As i am still in developement, i was wondering if my current understanding of the method generics is correct in its current form or what i would have to do to make the Generic Shared Class work in the fashion that i am looking for in the example implementation.

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Calling Shared Methods From .NET Class Library In VB6

Jan 25, 2010

I have the following class in a .NET class library:

Code:
Public Class JasonTest
Sub New()
End Sub

[Code]....

The .AddNumbers call works fine, but the AddStrings call yields the error 'Object doesn't support this property or method'.

Is there any way to call a shared method from .NET in VB6? I was unable to find any documentation on this.

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Purpose Of Using Shared Methods That Return An Instance Of A Class?

Oct 11, 2010

What is the purpose of using shared methods that return an instance of a class, as opposed to a constructor?

ie: in VB.net, the system.drawing.color class has shared method "FromArgb(int, int, int) as color". This is different from java's implementation which simply is a constructor that takes three ints. Why the decision to do one or the other?

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Will Modifying Shared Methods Change The Class That Reference Them

Jun 4, 2011

I'm wondering what will actually change a class, in the sense that serialized objects of this class will no longer be recognized. If the class has reference to shared methods of another class. Will changing such shared methods also change the classes that reference them?

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.net - Why Can't Call Private Shared Methods From A Public Shared Method

Aug 25, 2011

I have a class like this:

[Code]...

It works, when I make getBar methods public, but I don't want to expose these unneccessarily. Why I can't call private shared methods from a public one in the same class is over my head. I'm using .net framework 4.0 in a web application.

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Can The T Of Generics Be An Interface

Jul 17, 2010

In my program I have an interface iGraphable that contains two properties: Abscissa and Ordinate. Then I have an xxxx class (actually more than one) implementing iGraphable and a ListOfxxxx class implementing BindingListView(Of xxxx).To draw graphs I have a Graph class with a property called Data whose type is BindingListView(of iGraphable).Why have I a cast exception when I pass a BindingListView(Of xxxx) to the Data property.

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Interface And Graphics :: Create An Image That Is To Mimic A Single Clock Rotating Hand Within A Square Area?

Aug 20, 2011

I have to create an image that is to mimic a single clock rotating hand within a square area,and the user has to choose the width and speed of the rotation and the direction.i managed to create the square area with a hand inside,with this codes and variables,

(Dim Mygraphics As graphics = e.graphics
mygrqaphics.Draw Rectangle(pens.color x1,x2,y1,y2)

mygraphics draw line(pens.color,x1,x2,y1,y2),now i have to find codes and variables to rotate the hand or line within a square area.one point remaining constant the other moving.

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Enforce "contract" Without Using An Interface?

Oct 13, 2011

I basically have an abstract class that deals heavily with Generics. I need to call a Shared method on the Generic class T. I need to make sure the Shared method is implemented. I could use reflection to check for the implementation and call the method if it exists or throw an exception otherwise. However, since the derived class is not "aware" that it needs to implement this method, I feel that the exception will get thrown more often than not

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Making Class Methods Instead Of Instance Methods In .NET?

Mar 29, 2010

I am not sure how clear my question is by the title, but I am trying to make Class methods instead of Instance methods in Visual Basic that way I don't have to waste memory and code creating temporary objects to execute methods that don't need instance variables.

I am not sure if you can do that in VB but I know you can in Objective-C by using either a "+" or "-" sign in front of the method declaration. And in C++ (at least I think, I can't remember) you put the static keyword or const keyword in front of the function.How would I do this in VB if it is possible? Or should I just make a separate set of functions that are not members of a class?

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Shared Methods In ASP.NET Sessions

Feb 25, 2011

As a followup to the previous question I have asked "ASP.Net Architecture Specific to Shared/Static functions" I am still struggling to understand the implications of using shared methods in ASP.NET.

So for example let us take the following code.[code...]

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Application Wide Shared Methods

Jul 26, 2011

I am developing an application that has multiple forms and I wanted to know the best method to have application wide methods and functions. Currently I am using a Module with all my methods that are needed to be used across the entire application in it. However, I read at one point that modules should not be used, as they are only there to preserve backwards compatibility with older VB code. Is there a better way to have methods able to be called anywhere?

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C# - Static (Shared In VB) Or Normal Methods

Oct 27, 2009

I Want to know which one is preferred while coding to use Static Methods or normal instances, I prefer to use static if they where few but if there was many of them I start to get some doubts

[code]...

if the EmployeeManager Has Many methods (selects deletes updates) is it ok to make them all static.and if it was Normal instance. wouldn't be a drawback if the object is initiated every time specially if GetAllEmployees() is heavily used.What is the better approach to use?

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Calling Private Shared Methods?

Aug 8, 2011

I have a form (frmMain) that contains a custom control (con class). frmMain contains a combo box control and when the user selects a value from it, I pass this value to a sub routine within con class (see red line below). This purpose of the sub routine is to populate a set of comboxes contained in con class according to the value that is passed in.

Private Sub cboGuidelines_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboGuidelines.SelectedIndexChanged
If bChanged = True Then

[code].....

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OOP - Shared Methods And Base Properties?

Feb 25, 2009

If you can't use Me. in a non-instance method, how would you use properties/functions from a base class in a Shared method?

For example, ClassB inherits from ClassA
ClassB has a Shared Method DoWork();
ClassA has a ReadOnly Property SecurityKey

How do I Public Sub DoWork() Dim test as String = Me.SecurityKey End Sub

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Subclassing Object With Shared Methods

Aug 3, 2009

I want to create a subclass of a class that has some shared methods. These shared methods all call one specific method. But I can't redefine that specific method in the subclass. If I try to make it overridable in the parent class, it says that shared and overridable can't both be used.

[Code]...

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Anything Wrong With Using Lots Of Shared Methods And Objects

Jul 9, 2009

I seem to find more and more that I declare a lot of objects or methods as Shared now but it feels like I am not doing things properly.I try to avoid doing this but then I just end up with situations where I have to create an instance of a class just to call one method that would act no differently if it was just a shared method.Basically I'm just wanting to know if there is any good reason to avoid using Shared objects/methods. Obviously I dont declare EVERYTHING as shared, but it just seems to make things a lot simpler most of the time.For example in my current project (a chat application using WCF) I have a class just called Core which houses a lot of the main functions of the client program, so it has methods such as: SignUserIn, SignUserOut, SendMessage, MessageReceived etc and it also holds properties such as a list that contains all of the currently online users. These things are all declared Shared in my program because as far as I can see there is no reason for having to do this:[code]

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Dynamic Assembly Loading And Using 'Shared' Methods?

Dec 20, 2011

I now have a need to dynamically load a dll into my application and I've found the reflection/assembly information and it's fairly easy to implement so I thought I was on my way. However, I quickly found out that I'm only able to use 'shared' methods. What I was originally thinking was I could have one shared method 'library.beginprocess' and then that would make all the necessary calls to the other methods, but this doesn't work unless all the other methods and class level objects are also shared.

I feel like I'm missing something or somethings just going right over my head. I've looked at many, many sites and examples, but I've only run across examples that expose 1 method,[URL]..which explain how to implement a plugin architechture, which I have not tried yet, but maybe would allow me to keep my class structure the same without having to make everything shared?

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Overload Shared Methods On Non-instance Types Using Extensions?

May 14, 2012

I want to extend the BitConverter class with an overload of ToString() that takes a parameter of type Char, representing a value delimiter.Why? By default, the ToString() call returns a string representation of a byte array, delimited by dash symbols. The signature does not allow you to specify a different delimiter, which I find very unfortunate.Now because this is not an instance type, or maybe because I'm overloading a shared method, I'm having a hard time finding the proper syntax to define my extension method.What am I doing wrong here, causing the overloads to not show up in IntelliSense:

Imports System.Runtime.CompilerServices
Module BitConverterExtensions
<Extension()>

[code].....

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Passing Parameters By Reference Into Public Shared Methods

Oct 21, 2009

I have a List(Of AddlInfo) with AddlInfo being an object. I'm trying to pass addlInfoList by reference into a function of another class:

[Code]...

This works if I'm not passing the reference into another class, but when I try to do this, I get the following error: Overload resolution failed because no accessible 'Sort' can be called with these arguments:

[Code]...

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Have Generics In A Class Property?

Jul 28, 2010

I have a Class that is defined as

Public MustInherit Class Entity(Of T As Entity(Of T))

And various classes derived from it. I would like to have another class accept all of the derived objects as a property, but I cannot seeem to find a workable syntax. If it were a parameter of a sub, I could say

Public Sub Foo(T As Entity(Of T))(TheEntity As T)

I can't seem to get that to work for a property:

Public Property E(Of Entity(Of T))() As Entity(Of T)

Gives me "Type parameters cannot be specified on this declaration"

Public Property E() As Entity2008(Of T)

Gives me "Type Parameter T does not inherit from or implement the constraint type ..."Is there an acceptable way to do this or am I stuck with using a Set Sub and a Get Function?

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Generics - Create A Common Database Class In .NET?

Jun 12, 2009

We have 3 databases providers we use to connect to our databases: DB2, MS SQL, and Interbase. I would like to create a single generic database wrapper class that can be used to talk to all three just by passing in the correct connection string, username, password, and the provider desired.

I don't want to have to add references and import all three providers in the database class. Is this possible?I have done this before in Java using the Class.forName() function.

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Interface Class (IUser) Which Is The Interface Of Class User?

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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Implement An Interface In .Net When Two Methods Have The Same Name But Different Parameters?

Mar 3, 2010

I am a C# programmer but I have to work with some VB.Net code and I came across a situation where I have two methods on an interface with the same name but different method parameters. When I attempt to implement this interface in a class, VB.Net requires explicitly declaring "Implements MethodName" after the method signature. Since both method names are identical, this is confusing the compiler. Is there a way to get around this sort of problem? I suspect this must be a common occurrence. Any thoughts?

N.B. This was more a case of the programmer not verifying that the interface in question had not changed from underneath him.

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Create A "shared" Variable That Is Shared With All Instances Of A Class?

Jan 14, 2011

I seem to be drawing a blank. I'd like to create a "shared" variable that is shared with all instances of a class but not classes that inherit from it. For example.Class A: Shared list As New List(Of String): list.Add("A")

Class B Inherits A: list.Add("B")Class C Inherits B: list.Add("C")The end result I'd like is that any instance of A has just A in the list. Any instance of B has A and B in the list. Any instance of C has A, B, and C in the list. I can accomplish it by creating Instance variables, but I have to construct the list for each instance of a class. I'd like to construct it once for a specific point in the Hierarchy and then share it accross other instances of that class.

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Shared Interface And ReaderWriterLockSlim?

Aug 27, 2009

I am using the suggested method from the log4net examples so at the top of said class I have: Private Shared ReadOnly log As log4net.ILog = og4net.LogManager.GetLogger(decType)And since the class involves multiple threads interacting with it, I have a ReaderWriterLockSlim instance that I use to make sure I don't get into any race conditions with my variables. So to recap,if I want to make sure I'm practicing safe threading do I need to do something like this:

If Me.ReaderWriterLockSlim.TryEnterUpgradableReadLock(-1) Then
If log.IsWarnEnabled Then
If Me.ReaderWriterLockSlim.TryEnterWriteLock(-1) Then

[code].....

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Can't Inherit Shared Properties From A Base Class In A Child Class?

Dec 29, 2010

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".

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Interface Methods With Handles - Display The Current Count

Sep 26, 2011

I have a small application that consists of multiple forms that each need to have the ability to be updated (not repainted, the data/components values redefined) when called to. So for instance, if I had a form that contained a count of some sort and another form modified that count I would need to update the form that displays the current count. With that being said it needs to implement an interface with these methods (see below). My issue comes when I want to add events to these methods so if I call the UpdateData event it would trigger the OnDataUpdate method, but because of the syntax of implementing methods and handling events you cannot do so.

[Code]....

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