How many instances of a shared variable will be created in a class? just one? correct
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So, in other words, the DocumentDelivery class will only have one instance of RenderList, correct? can somebody confirm?
Here's an example of what I'm talking about...
Public Class Sample1
Public Shared Function MyValue() As Integer
Return 0
End Function
Public Sub Code()
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Me.MyValue gives a warning in VB.NET and (the equivalent code gives) an error in C#. Is there a particular reason for this? I find it more intuitive/natural to access the shared function using 'Me.MyValue' - but I avoid it to keep my warnings at 0. Did someone else just decide 'Nah, it makes more sense to do it the other way' or is there some technical reason I don't understand?
EDIT: I was thinking of it wrong, more like a 'sub class' in OOP. Even if something is declared in the base class, you access it through the instance you have. But that relationship is not the same with shared or static.
I've taken over the maintenance of the website (ASP.NET VB) and on one particular page I noticed the below code
Inherits System.Web.UI.Page
Public Shared UserNumber As String
Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
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My question is whether the variable UserNumber can be accessed or changed by any other user than the current one?
creating single instance form in MDI Application. How to check whether form's instance created or not?
View 6 RepliesIf you want a instance of an object to be created when a form loads or another class is created, you have two options:
Public class example
private IAmAObject As IAmAObject
public sub new()
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Or like this:
public class example
private IAmAObject as new IAmAObject
public sub new()
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I always use the first one. It's more type work but I think it's neater. How about you people and is there any real difference between the two?
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.
As I stated before in my Sorting questions.When is it advisable to use Shared Functions vs Instance Functions References.The problem I posed was that in a threaded application if I was sorting an array of 999999999 elements I typically want to call a shared function that handles this; however in .NET the way to sort is through a .Sort method which you pass an array to be sorted and a function handler; or Comparisson(t of).
My impression is that if in order to do a ClosestToN Sort I would have to calculate the value of N in the array first; then sort and then subtract the value of N from the sorted array.JohnH suggested passing the value of N as a Property in a Class that contained a reference to a sort Algorithm.The benchmark suggested in a 1 thread model it would work faster (which I knew that it would through math, but the accessors I was speculative on; I turned out to be wrong it worked fine either way).
My issue is in a Multi-Thread application creating instances for an accessor may cause memory to fill quickly if I am dealing with 1000's of threads.Is it better in this case to use a slower Shared function, then a faster Instance Function?
After I formatted my laptop and reinstalled Visual Studio 2005, I receive a lot of same error as below message.
"Access of shared member through an instance; qualifying expression will not be evaluated"
If I click the error, it direct me to the line and all 102 error suggest me to add "Windows.Forms." before "DialogResult.OK". Should I add something on "Reference"?
I would like to create a global instance of a User Class that can be referenced by all the forms in my MDI application.This object may be set during the login procedure by the Login form but the user attributes are to be available for other forms. For example, MyUser.ID will be required for meeting the audit requirements whenever data is changed.
View 14 RepliesI have been thrown in at the deep end with an existing VB.NET project at work. I have never used VB.NET before so I am struggling a little. Does anyone know how to solve the following.I need to pass an instance to client side and then pass it to a shared method in order to access instance methods from when the shared method.The starting point is a fileupload control within the HTML of my Contacts.aspx file:
<asp:FileUpload ID="DocUpload1" runat="server" onchange="CallMe();" />
The onchange event calls a javascript method, see below, this uses AJAX PageMethods to called a Shared method in my code behind This is the script code which is in my Contact.aspx file
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If anyone knows the solution please could they update the code as I probably won't be able to understand if you just give a description. I just hope I am along the right tracks.
Suppose I have a class of objects called Porky with a property called IsHuge:
Public Class Porky
Public Property IsHuge As Boolean
End Class
Now I want to make a special kind of Porky -- let's call it UberPorky -- for which I want to change ALL instances to either IsHuge or not IsHuge. What I'd like to do is this:
Public Class UberPorky
Inherits Porky
Public Overrides Shared Property IsHuge As Boolean
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The trouble is, I can't do that. I'm not allowed to reference MyBase or Me in a Shared property.
Is it possible to prohibit an instance of a class from calling a shared/static method?
For example:
I want to allow this:
ClassName.MethodOne()
But I want to disallow this:
Dim A As New ClassName
A.MethodOne()
The reason this is desirable is that in this case it is semantically confusing if an instance can call the method.
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()>
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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?
The context of this question is that I am trying to debug performance issues (apart from the obvious ones I already know about and can find).I inherited a code base (VB.NET) for an ASP.NET app. This is an app that was developed way back in .NET 1.1 days, and was the first .NET app for a lot of the developers who worked on it.
In this code base is a class called DatabaseUtility that contains several Shared Public methods as well as non-Shared Public Functions and Subs for CRUD operations to the database (SQL Server).
It is common in my "BL" that a method creates an instance of the DatabaseUtility which essentially figures out what the connection string should be and opens a connection, as well as giving the developer a handle to the other methods contained within it.Dim utility as New DatabaseUtility()
Once I have that, I start to create parameters that I am going to pass to one of the methods in DatabaseUtility (like GetDataSet). There is a Shared method in my DatabaseUtility called CreateParameter which does essentially that. It creates a SqlParameter object so I can add it to a Parameters collection.
Now, the code base is littered with a lot of this:
utility.CreateParameter(...)However, because CreateParameter is a Shared method, I am not sure what is going on behind the scenes. I know because it is a Shared member that an instance of the DatabaseUtility is not created when I call it like this:DatabaseUtility.CreateParameter(...)
However, because I am calling it from an instance (utility), does that change the behavior at all?
If I have a very large function/sub in a class that is an instance method (i.e., not Shared), do I gain or lose anything by moving that to a shared method and then declaring a small stub method for the instance use?
I.e., I go from this:
Public Sub MyBigMethod(ByVal Foobar As String)
If String.IsNullOrWhitespace(Foobar) Then
Throw New ArgumentNullException("Foobar")
End If
[Code] .....
My thinking is I save on memory size per each instance of the object. Because each instance only has to lug around the stub method which handles calling the shared version and passing an instance of itself to the shared method so that it can do whatever it needs to do. But I'll wager that I sacrifice a very teensy amount of speed because of the added function call overhead.
why don't we declare a variable for instance variable with dim not private?
View 3 RepliesI use word automation and open a new word instance which opens a given document. Like that:Dim oDoc As Word.DocumentDim oWord As New Word.ApplicationoWord.Visible = FalseoDoc = oWord.Documents.Open(srcName)I need to identify the PID (process ID) of the newly created word instance. It seems that it isn't a son process of the process which called it.How can I find its PID?
View 7 RepliesI need my program to open just one instance of each form, and if the person clicks again on the button that opens a form that is already showing, the form should only be brought to front (probably with the "bringtofront" method). How do I do this?I tried checking if the form "is nothing" before showing it, but if I close it and then try to open it again it doesn't work.
View 4 RepliesWhat is the use of shared variable in vb.net?
View 3 RepliesNot sure exactly what I need to do to make this work, so my description may be lacking at first.Essentially I am writing a program launcher that recreates itself each time on load. It pulls the data regarding the tabs and buttons from an SQLite database and builds itself dynamically at run time. I get my problem when I pass the tab name through to the function that creates the buttons. I need the name to pull the right set of buttons from the database and I then tried to use the name to place the buttons on the right tab when I create them, but the debugger calls it a null reference because it doesn't point correctly to the tabpage that I'm trying to make it point to (at least that is what I'm guessing). Any ideas on how to make this work right?
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I have the following code:
Public Class TestClass
Public Sub Main()
If theGlobal IsNot Nothing Then Throw New Exception("What gives!")
End Sub
Private Shared theGlobal As Object = Nothing
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Why is theGlobal object NOT Nothing?
How to dispose the shared variable in vb.net.i am using shared object of Asterisk.NET Manager Variable, i assigned it in form load and i dispose it in main form closing, My problem is after closing the application, application.exe keeps live in task manager, if i not initializing the shared object in form load there is no problem,[code]
View 3 RepliesI have an arraylist in a user form (Mainform) that I would like to be able to share among multiple forms and edit the contents. Using the Public Shared method I have been able to view and even edit the arraylist, but it does not seem to be changing it back on the main form. I can give more detail if needed.
View 9 RepliesI am planning to use a shared variable to implement a logging facility. Have a look at the code below:
Imports System.IO
Public Class TestClass
Public Shared objError As New StreamWriter("C:Test.txt")
End Class
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I think I have found my answer here: [URL] "A static variable continues to exist and retains its most recent value. The next time your code calls the procedure, the variable is not reinitialized, and it still holds the latest value that you assigned to it. A static variable continues to exist for the lifetime of the class or module that it is defined in."
I am not convinced that this is the best way to create a logging facility.
Does session variable shared accross different browser? If not is there away that I can share information accross browser similar to the functionality of caching but the scope is wider.
View 3 RepliesI need some tips for shared variable to share the information for multiple running application. For example, the value of variable become 1 when a user run the first instance(execution), and become 2 when the user executes the second(in sames OS or through network).
View 3 RepliesI currently have two forms, and I need to share the value of a variable in one of them.
I declared the variable to be 'Public Shared', and assigned a value to it. However,
when I inspect the value it appears as 'Nothing'. Here is the snippet:
Public Class A
Public Shared sVar As String = Nothing
Private Sub A_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
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I've been looking at using PROPERTIES [URL] but frankly I don't understand it that well. Before I invest the time to read, understand, and truly comprehend this, I want to make sure it's the best way. My intended goal is to create my database connection string in a function/sub somewhere, then assign it to this project wide string variable, then I can use it in any form, project wide without having to recreate it.
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I have declared a class in VB.NET using VS2K5 with some shared variables and made that class a dllI made use of that dll in another project and tried to make use of those variables. Even though I can able to make use of them, Im unable to view the values of those variables like the values of normal variables when Im debugging. Is there any way that I can watch the values of those shared variables during debugging.
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