Class Member Variables Methods And Their State
May 27, 2010
How should class member variables be used in combination with class methods?Let's say I have a class 'C' with a member variable 'someData'.I call C.getData(), which does not return a value but instead puts data in C.someData. The class that instantiated 'C' first calls C.getData and then uses the data by accessing the member variable C.someData.I call C.getData() in the class that instantiated 'C' which is a function that returns data.I myself prefer the second way. But it also depends on the situation and it's a small difference. Is it 'bad' to have class methods that depend on the classes internal state? What are the best conventions?
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Nov 4, 2011
Whats the difference between these two initialization methods for obj? I've seen both of these, but know know if there is an appropriate time to use one vs the other. I found this post which covers C#, but not sure if the same applies to VB.Net.[code]
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Mar 24, 2010
I'm not sure I used the right lingo in the subject header. But, here's what I want to do. Let's say I have a class with some variables:
Class XYZ
Public InfoNo1 As Integer
Public InfoStr1 As String = " ".PadRight(200) 'Hahaha
Public InfoStr2 As String = " ".PadRight(100)
End Class
I've been looking around for examples of writing methods that act on variables defined within the class. What I want to do is make it so that doing something like this:
[Code]...
I don't need to know how to write the method, I think I can do that. I need to now how to make the method cause a ".Fixed" option to be added to the class string variables so that assigning a string using that method will cause the variable itself to be equal to the string plus the padding.
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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 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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Mar 23, 2009
This is in VB6 (may also apply to VB.net) CheckBoxes can have three states (Checked, Unchecked, Greyed).
But I'm using them to set boolean variables (MuteSound, etc.) This is definitely a value that has only two states. Unfortunately, the Checked and Unchecked don't correspond to a True/False value.
So, I can't have:
[Code]...
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Jan 20, 2009
In VB.Net is there any difference between the following three ways of initializing object variables
Method 1
Dim commandObject As SqlCommand
commandObject = New SqlCommand("MadeUpCommand")
Method 2
Dim commandObject As SqlCommand = New SqlCommand("MadeUpCommand")
Method 3
Dim commandObject As New SqlCommand("MadeUpCommand")
Is one more efficient than the others, or are they effectively all the same?
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Aug 20, 2010
I read somewhere that interfaces can have member variables.Static final constants only, can use them without qualification in classes that implement the interface. On the other paw, these unqualified names pollute the namespace. You can use them and it is not obvious where they are coming from since the qualification is optional.
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Mar 23, 2012
I define some global variables of a class as follows:
Private Class MyClass
Private var1 as Decimal
Private list1 as List(Of string)[code].....
But I found that after this form is closed, all above variables, var1, list1, list2 still exist in memory. I thought they should be collected by gc since the form is already disposed as I confirmed.
Add: I have monitored half an hour after the form is closed. But these variables are not collected by gc. I have an automatic update procedure on the form which uses above variables.Since the above variables still hold values, the automatic update procedure is always called which causes exception. (One quick fix is to check if form.isDisposed in update procedure. But I do not think this is elegeant. Besides, these variables occupy memory.)
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Jun 9, 2012
I'm new in .NET programming.I have a class Form1 that includes Button1_Click event.Button1_Click creates a multiple Text Boxies at run time)Here is the class:
Public Class Form1
Dim shiftDown As Integer
Dim counter As Integer
[code].....
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May 14, 2011
I'm building a litle console app that involves a control hierarchy -- there are screens, and inside of screens you can compose controls together.
You can add controls to a screen by declaring member variables (which all inherit from AresControl). The control constructor takes a simple coordinate pair. It looks like this:
Public Class IntroScreen : Inherits AresScreen
'Controls
Private LabelSelect As New LabelControl(72, 0)
[Code]....
This would result in cleaner, convention-based code. But try as I might, I can't get it to work - I can walk the member variables of a type, but I need to walk the member variables of a live object.
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Jun 9, 2010
I am generally not one to engage in subjective arguments over matters like variable naming, code formatting, etc. So I have no intention of starting an argument here.I just came across this (old) blog post which recommends not prefixing member variable names:
[Code]...
I get it: member variables can be lower camelCase, and public properties/methods can be PascalCase. But VB.NET is case-insensitive, so you can't really give a private member the same name as a public property except with a lower case first letter.I've generally prefixed member variables with an underscore, but I've been told that's not idiomatic.
So really I'm just curious: how do you name your member variables in VB.NET? And is there a "standard" way?
I'm not asking because I believe there's a "right" way or because I particularly want to change my style, and certainly not because I have any desire to tell others they're "wrong." Like I said, I'm just curious.
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Oct 12, 2010
How should I handle events in this situation I have "Class1" with a "PropertyHasChanged" event.In "Class2" I've declare a Public Member Variable WithEvents of Type Class1.As well, Class2 has the Event "OtherPropertyHasChange".In a Form Class I've declare a Public Member Variable WithEvents of Type Class2.The Form Member has access to the "OtherPropertyChange" Event but not the "PropertyHasChanged" Event.Question is,how do I accesss the Events of Class1 from the Form Class?
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Jun 12, 2010
I have created a class called 'MyAddress' and in the form load event i am adding few objects of that class to the combobox. I want to know how should i set and read the values of the member variables of that selected item of the combobox. I have tried this and is working, but i am not sure whether it is the way to do
vb
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[code].....
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Jun 6, 2011
I am currently making a server monitoring application that pings the server to check its uplink, so far it creates all the picture boxes and labels for each server, and then pings the server, although I have a picture that I want to change dependant on the result.
Below is the code I am currently using, the problem occurs with the objectname variable which allows dynamic coding, where i get a error, saying that "Public member 'image' on type 'String' not found".
Private Sub Ping()
Dim i As Integer
Dim objectName As System.Object
For i = 1 To count - 1
[code].....
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Jun 2, 2011
how do I overcome it? I have created a class and compiled into .dll This code
[Code]...
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Aug 13, 2009
In Visual Studio 2008, if I do this:
[Code]....
Does anyone here know how to get the above to work WITHOUT warnings being generated?
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May 31, 2010
In the following code i get a warning at line 59:Warning 1: Access of shared member, constant member, enum member or nested type through an instance; qualifying expression will not be evaluated.and.. At line 78 I get this Warning:
Warning 2 Property 'SelectedCustomer' doesn't return a value on all code paths. A null reference exception could occur at run time when the result is used.
The program compiles and runs well, but i cant' undesrtand the reason for these warnings. Any Idea ?
1: Public Class Form1
2:
3: 'Form level members
4: Private objCustomers As New ArrayList
[code]....
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Sep 14, 2011
my question is simple. How do i add methods to the standard DataGridView control of VB.NET
I want to add some methods of my own to the class, but i tried inheritance and i get errors. What are the techniques out there to extend native classes in vb net
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Dec 18, 2011
Example ^. I must be forgetting something or being really dumb.
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Jul 16, 2011
In this project I am making a grade calculator; I am modifying an existing code I have to have the following characteristics: I need to modify the DetermineGrade method so that it accepts the maximum number of points that can be earned on both tests (currently, the max number of points is 200: 100 points per test). For an A grade, the student must earn at least 90% of the total number of points. For a B, the student must earn at least 80%. For a C, at least 70%. For a D, at least 60%. If they earn less than 60% of the total points, then grade is F. Here is the exisint code I have for the DetermineGrade method specifically:
Public Sub DetermineGrade()
Dim intTotal As Integer
intTotal = _intScore1 + _intScore2
[code]......
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Apr 28, 2011
Cannot appear to be able to get this function to not have the above error.Private Function GetIncidentActions(ByVal FromAgentID As Integer, ByVal ToAgentID As Integer, ByVal incidentAction As Integer, ByVal ActionDate As Date) As String
[Code]...
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Aug 22, 2010
When we create an instance of a class we also provide its state so are these both same and if not same what's the difference? And also what's the difference when we use equals method for instance or for state?
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Aug 4, 2010
I have a class definition that I've seen other define properties that return collections of objects.
Public Property GetAllAdults() as Adults End Property I made the argument that this should be a method in the class, because it doesn't define an attribute of the class, and could not be extended with parameters. Is/Are there reasons why this should be defined as a property vs. a function?
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Apr 23, 2012
I have a Public Class called "ClientConnection". Inside that class, I have a Public ReadOnly Property called "FileTransfers(ByVal TransferID)". The property returns an object of the class "FileTransfer". All methods in FileTransfer are set to public.
VS is able to discover the methods inside the parent class "ClientConnection". How would I expose the methods inside the sub-class "FileTransfer" that is returned by the property "FileTransfers(ByVal TransferID)"?
Public Class ClientConnection
'irreverent code removed
Public ReadOnly Property FileTransfers(ByVal TransferID As Integer)
[Code].....
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Jan 24, 2009
I have a database table called Job. I have mapped this table using LINQ to SQL so that I have a class called Job.
What I want to do is add some methods to the Job class. The Job class is defined in the LINQ to SQL classes .dbml file. So, in order to add methods, or anything else to the Job class what should I do?
Should I create a partial class named Job and define the methods in there? Will that then get mixed in properly? Not sure how to proceed on this one.
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Aug 3, 2011
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].....
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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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Oct 29, 2009
Is it possible to iterate through the properties and methods of a custom class, getting the details about those properties and methods in the process.[code]....
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Mar 26, 2010
I have a database table called Job. I have mapped this table using LINQ to SQL so that I have a class called Job.What I want to do is add some methods to the Job class. The Job class is defined in the LINQ to SQL classes .dbml file. So, in order to add methods, or anything else to the Job class what should I do?Should I create a partial class named Job and define the methods in there? Will that then get mixed in properly? Not sure how to proceed on this one.
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