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?
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...
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].....
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?
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.
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.
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.
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?
View 3 RepliesSo 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]..
Do I have to instantiate description every time for different method? Or should I use static? Here's how I'm doing this now: What is the best way of handling this kind of situations. it seems that I repeat this line:Dim description As BLLDescription = New BLLDescription() without any good reasn.
Protected Sub Button8_Click(sender As Object, e As System.EventArgs) Handles Button8.Click
Dim description As BLLDescription = New BLLDescription()
[Cdoe].....
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.
I'm currently refactoring an old Visual Basic DLL (VB.Net), which stores all of its data in one module called Globaldefinitions as public fields. There are about 200 fields, referenced thousands of times all around the code:
Public Module Globaldefinitons
Public a As Short
...
Public zz10 As Double
[Code]...
I need to change the module into a class with non-shared fields. This means, each and every of these thousands of references needs to reference the instance of that class:
globalDefinitionsInstance.a = 5
How do I go about this efficiently?
Regular expressions operating on the source fall flat. Refactoring tools like Re-Sharper or CodeRush don't seem to offer this functionality. Visual Studio 2010 cannot do it automatically either.
What I am trying to do is have a class where the functions of the same name are both instance functions and shared functions.
Public Shared Function Get...(byval xx as xx)
and
Public Function Get...
The Public Function uses a Property xx created in the constructor, whereas the Shared Function has the parameters (byval xx as xx).
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...]
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?
View 1 RepliesI 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?
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].....
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
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]...
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]
View 15 RepliesI 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?
I was trying to fill 10 checkedlistboxes with items..So I made a sub with 2 arguments like this Private Sub fill_checkedlistboxes(ByVal items As String, ByVal checkedlistbox As CheckedListBox) End sub the first argument items is a long string whitch splits in the sub into many strings and added them all into the second arguments (thecheckedlistbox) I want to make for next statement to fill all the 10 checkedlistboxes in my form with an 10 long strings held in an array called strings, so i write something like this [code] What i have to write in the "?????" area to have the checkedlistbox that i want? the checkedlistboxes names are checkedlistbox 1, 2 , 3 ....10
View 12 RepliesI 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]...
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 RepliesHow 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?
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.
I 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
[Code]...
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
[code]....
The trouble is, I can't do that. I'm not allowed to reference MyBase or Me in a Shared property.