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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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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Mar 30, 2012
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
[Code]....
My question is whether the variable UserNumber can be accessed or changed by any other user than the current one?
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Jan 10, 2012
I 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
[Code]....
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Jun 20, 2012
Inside my .aspx I have some JSON code that looks like this:
[Code]....
Basically what I'm doing is pulling text from two labels on one page, and sending them to another page by calling the "doIt" function which looks like this:
[Code]....
Just so I'm clear, the "doIt" function and the JSON call are on two separate web forms. My problem is that with the "doIt" function being Shared, I can't access any global variables of the class. And if I remove the Shared, my JSON doesn't execute.
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Aug 3, 2010
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.
[Code]...
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Jul 13, 2009
I have created a synchronized queue and am using SyncLock on the SyncRoot property of that queue when I invoke the Enqueue/Dequeue methods. The methods are invoked from instances of standard producer/consumer classes.Is that a proper use of the SyncRoot property?
Would it be better practice to create a private shared object in each class and lock on that instead?
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Jan 27, 2010
I have an interface that i have declared some of the basic internal functions, subs, properties, etc. This interface is then implemented into 3 pre-defined classes. These classes are end-use classes so they dont get derived or inherited elsewhere. I am trying to create a generic shared class that can operate on each of these 3 predefined classes and potentially more as long as they implement the interface.
[Code]...
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Jan 24, 2011
VB.NET 2010, .NET 4. I am working on an application for controlling an industrial machine composed of many devices attached to the computer. Most if it is reasonable straight forward, but I'm having trouble thinking about the RS-232 devices. One of the RS-232 devices is a fancy power supply with many functions. The ones that are relevant right now are voltage read, voltage write, current read, and current write. The design pattern I'm trying to implement is one in which each attached device is represented by an object that has methods for reading/writing etc and properties for things like COM port etc.
For this power supply, clearly the Port reference should be shared among the instances, so I have a base class (say, PowerSupply) with a Protected Shared Property Port As IO.Ports.SerialPort. Then I have a couple classes that inherit from this class, PowerSupplyVoltage and PowerSupplyCurrent that each define read/write methods and properties for holding the last read/written values. My issue is in parsing the response from the power supply using the Port.DataRecieved event on the shared SerialPort object. The protocol the power supply uses specifies what data it's sending in each response packet.
So, basically, it might say something equivalent to "The voltage is 100V" or "The current is 1A" or "The voltage has been set to 150V" etc. I'm trying to parse this in a shared function. Only during the parsing process would I determine which instance's read/written value to update. I can't access the read/written value properties of the instances from within the shared function. The best I could think of is creating some kind of PowerSupplyCommunicator object that would maintain references to PowerSupplyVoltage and PowerSupplyCurrent instances along with the shared Port and DataRecievedHandler functions.
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Mar 17, 2010
i have an multi-threading applicaton. so I am using system.threading.thread class to create thread. each threads call its own class and inside each class i am accessing webservices. I need to have status returned from each webservice. thats why I defined a shared property as list of generic object which will be updated within each class called its thread. but I have an hesitation that when I run application on the server. this shared object will be used by all instances of web application. Is it true or shared properties is used only for its own instance?
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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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Aug 12, 2009
Given in the following language specification, for me at least, calling Db.Foobar() [In the following code] does not indeed call off to the Shared Constructors of the base classes. I am curious as to a) is this my own fault for doing something wrong or b) is this an error in the language specification[code]...
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Mar 5, 2009
What is the use of shared variable in vb.net?
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Jan 6, 2011
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
[Code] .....
Why is theGlobal object NOT Nothing?
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Apr 12, 2011
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]
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Jun 29, 2011
I 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.
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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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May 28, 2012
I 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
[Code]....
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.
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May 24, 2012
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.
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Apr 7, 2010
How many instances of a shared variable will be created in a class? just one? correct
[code]...
So, in other words, the DocumentDelivery class will only have one instance of RenderList, correct? can somebody confirm?
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Jul 22, 2011
I 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).
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Feb 20, 2009
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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Jan 1, 2011
I've gone brain dead and can't remember how (where) to declare a variable to be shared by 2 forms (classes) in the same project.
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Mar 3, 2011
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()
[Code]...
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.
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Mar 4, 2010
shared variables of particular form in vb.net 2005
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Jul 23, 2009
I am making a small application in which i have added a class module and a window forms in vb.net. i want to acess the shared variables and mathods of class without making any object.
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Aug 23, 2011
I was looking on the interweb to see if there were any good examples on how to initialize shared members within a class while still initializing instance variables.[code]How do I initialize both instance and shared members without re-initializing the shared members every time an object is created from a class?
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May 4, 2009
I've got a shared class (static in C#) which mostly carries some settings data that any class in the application can read and sometimes write. Also there are some static properties which holds some internal states.
Now I want to revert this class to initial stage of it. With all default variables etc. Assume that the user want to reset the current state and start over without restarting the application.
In a singleton model I'd simply renew it with something like this :
Public Sub Reset()
_Instance = New MyClass()
End Sub
However this is not possible in a Shared class. Or should I switch back to Singleton?
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Mar 29, 2010
I have no idea what is going on here but it is strange to say the least.I created a new solution in VS2008Pro under windows 7 This solution has 2 projects one for the pc and one for a CE based device.There is one class module which is shared between the 2 projects.In VS2005 under xp this same basic project worked fine but here I am seeing error messages that appear out of no where.
Example the CE portion flags 3 lines initially 1 related to a file i.o function and 2 others related to socket methods. All three of these were supported in VS2005 using framework 2.0 which is the same framework I am using here. This is just the tip of the ice berg however.If I attempt to run the code it runs fine for the pc client and of course not for the CE device. If I make any kind of change, add a line, comment a line or just add a comment I get lots more errors with odd messages that are not even valid.
In one case after I saved it jumped from 3 errors to 30, in another case to 50 and yet another to 144 errors yet the only errors that were present were the original 3 that were flagged.The ide threw errors like Try Catch must end with matching End Try.Get no longer supported ' apparently referring to the binary file get but here it is used as the get portion of the property.Get must end with matching end get.It also started complaining about functions and data types.For example saying "an is not declared" pointing to the word Boolean Or telling me my functions are not declared point to only 1/2 of the function name.
I do not see any errors in the code and it reports no errors in VS2005 under XP.As a test I tryed adding a new property to the project after it was telling me there were 144 errors. I allowed the ide to do most of the work and when I hit enter the errors went back to 3. Then I saved the project and the errors went to 105 pointing first at the new property just created.
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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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