Private Variable Instantiation: When Defined Or Within Constructor?
Jun 24, 2010
I don't know if this has been asked before, but we're having a discussion about it today at my job. Should private variables (that are shared/static) be instantiated when they are dimensioned/defined, or is it a better practice to do this inside of a constructor?
Public Class IpCam
Private Const HOST As String = "http://test.com/url/example"
Private Shared _Example As New OurClass(HOST)which one to use?
[code].....
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Mar 7, 2011
What I want to do is pass a Type to another object's constructor, where the other object creates a new instance of Type. I can create a constructor with a parameter declared as System.Type without problem, but when I try to instantiate it tells me there is no such type.
Public Sub New(targettype As System.Type)
Dim Test As System.Windows.Forms.Form = New targettype
End Sub
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Jul 23, 2010
if for example i have two private sub I declared a local variable on private sub a... is there a way that private sub b could use the variable created on private sub a? Im asking because im in a problem in my app were using global variable is not an option to make the long story short
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Nov 22, 2011
I have several similar classes but only want to instantiate one of these classes dependant on a selection from my main form.
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Mar 31, 2011
In C#, you can do this:
new MyClass().MyMethod();
The method is executed and the reference is (typically) discarded since no reference to the object is kept.Is this possible with VB.NET (.NET v4)?
Edit: I suppose this is a better example:
new Thread((x) => doSomething()).Start();
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Sep 9, 2011
I am trying to write some unit tests on a class that looks like this, using Moq [code] the parameterized constructor is private or internal one of the two methods relies on the result of the other.I want to check that when GetThisOrThat is called with a value, it actually calls GetThis. But I also want to mock GetThis so that it returns a specific well-known value.To me this is an example of Partial Mocking, where we create a Mock based on a class, passing the parameters for the constructor. The problem here is that there is no public constructor, and therefore, Moq can not call it..I tried using the Accessors generated by Visual Studio for MSTest, and use those accessors for the mocking, and this is what I came up with [code]
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Mar 3, 2011
comparing C# code and VB.NET and the results between the seemingly identical code were entirely different.(Why C# is always winning over VB.NET?)The explanation given is that C# will initialize the class fields, then call the base constructor, but VB.NET does the exact opposite. Is there a technical reason for the languages to be different? At first glance, it seems that either approach is equally valid, but I can't fathom why they wouldn't have selected the SAME approach.
EDIT: As 'Jeffrey L Whitledge' has pointed out, VB6 did not have inheritance, so I don't think we can say 'to keep VB.NET and VB6 more closely related'.
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Jul 19, 2010
If you have a class with a PRIVATE constructor.>>
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim example1 As New ExampleClass[code]......
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Jun 8, 2012
I have a class that looks like the following:
Public Class Utilities
Public Shared Function blah(userCode As String) As String
'doing some stuff
End Function
End Class
I'm running FxCop 10 on it and it says:"Because type 'Utilities' contains only 'static' Shared' in Visual Basic) members, add a default private constructor to prevent the compiler from adding a default public constructor."
[Code]...
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Mar 25, 2010
I am getting the error:"Range variable 'sender' hides a variable in an enclosing block or a range variable previously defined in the query expression."for this
Imports System.Data.SqlClient
Imports System.Linq
Public Class Form1
[code]....
I can select any other item from the table without the error. "sender" has the same properties as "receiver" in the SQL table.
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Feb 6, 2011
why don't we declare a variable for instance variable with dim not private?
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Jan 25, 2012
I have a class (let's call it foo) that has several public properties.
private _fee as object
private _fie as object
private _fo as object
[Code]....
So far this seems to work... I'm just worried that something might get screwed up scope wise.
What is the normal way someone would name the constructor variables in a class like this?
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Mar 13, 2010
I've been trying implement Constructor method in passing variable between two forms.Just a rough user interface guide - issue Invoice. User would type in all the Customer Name, Document Number. Once he reached Item Details, a Child Form would pop-up for the User to select/search the Invoice's Item; Once selected, the selected item would showed in the primary Form.
What I had tried is, the Constructor method worked perfectly when it is self-contain in a new project, yet to be implement in my application.But when I implemented, there is an error: Reference to a non-shared member requires an object reference.
[Code]...
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May 10, 2012
I'm working in VB.net and I want to create a generic ToString. is there a way to do a "For Each" in "Me".
[Code]...
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Aug 23, 2009
I have a public variable which seems to be going out of scope. I am confused as it has been dimensioned as a public variable: Public xlCell as As Microsoft.Office.Interop.Excel.Range
I originally had all my code in the same module in the same project and it was wrapped within a For/Next Loop (Example 1). I decided to clean up my code and make it more modular (Example 2). All the code is still in the same module in the same project.
Upon doing so, my public variable is not recognized in any of the private subs that I have created. I keep getting the following error: Message="Object reference not set to an instance of an object." When I test the variable using ?IsNothing(xlCell) in the Main Sub I get False in the main sub. this tells me te variable is recognized. However as soon as the Call SelectCaseSub() is triggered, I get a True value for ?IsNothing(xlCell). Why is this? Shouldn't this variable be in scope regardless?
[Code]...
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Jan 9, 2009
Trying to understand the best way to do this and I'm can't get it figured. Here's basically what I have:
Public Class CardParsingClass
Private iAcctIDStart as integer
Private iAcctIDLength as integer
[code]....
I've only included 2 of the class level fields here but there are actually 30, so that's why I was hoping to be able to send the name of the field to set and the value to set it at in the SetValue function. So in some other routine in the program I'd like to be able to issue the following call:
SetValue("iAcctIDStart", "3")
But then when I get into the SetValue routine, I'm not sure how to proceed. I thought about a case statement that would basically be this:
select Case strFieldToSet
case "iAcctIDStart"
iAcctIDStart = cint(strValue)
[code]....
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Sep 28, 2009
I come from C# (use VS 2005, .NET 2) and I know that when I declare a private variable I can "extract" from it the corresponding "property". In VB.NET I've declared a lot of properties (in the diagram class designer). Now am I forced manually adding the corresponding private fields?
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Jul 25, 2009
How to access a variable that is located in a private sub and then display that variable in another private sub located on the same form.
My actual code is:
Public Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
Dim strFileName As String
strFileName = OpenFD.FileName
OpenFD.InitialDirectory = _
[Code] .....
Obviously, the sub in blue has nothing in it currently and so this is the one I would like to access the variable in. The variable I want to use again is 'FILE_NAME'.
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Dec 30, 2009
When referencing class properties from a function within the class do you use the value from the actual property or the private variable value?
public class
private m_Foo as double
public property Foo() as double
[Code].....
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Apr 22, 2010
On one side, in Vb.Net when you add an event handler to an object the created method is named: <NameOfTheObject>_<NameOfTheMethod>.As I like to have consistent syntax I always follow this rule when creating event handlers by hand.On the other side when I create private variables I prefix them with m_ as this is a common thing used by the community, in C# people use to put _ at the beginning of a variable but this is no CLS compliant.
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Jul 16, 2009
I'd like to know if my textBox1 variable has the ABCAttribute. How can I check this?
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Jun 29, 2010
I can make the compiler give me an error (Use of variable prior to assignment) with:
private sub Test()
Dim ord As Order
Dim ord2 As Order
[code].....
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Feb 15, 2010
I have an abstract class which requires a delegate to function. I pass the delegate into the constructor. Now that I have a non default constructor I need to call the abstract class's constructors from the concrete class which means that I need to use MyBase.New(...). I have included a quick example below.
Public MustInherit Class BaseClass
Public Delegate Sub WorkMethod()
Private _Work As WorkMethod
[code]....
I have tried to do this but I keep getting the following error: "Implicit reference to object under construction is not valid when calling another constructor".Can I not do what I am trying to do above? I initially had the delegate setup in its own setter method. But then I am creating a deceptive API because it does require a point to a method to work properly.
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Nov 2, 2009
what's the rationale behind this limitation: Constructor call is valid only as the first statement in an instance constructor i want to pass an argument to my constructor which validates this argument and calls mybase.new according to this argument but it doesn't let me
example:
Public Class prob
Inherits System.ApplicationException
Public Sub New(ByVal problem As String, ByRef inner_exception As Exception)
[code]....
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Dec 25, 2010
I have a small problem, classes and threading with classes. The problem I have is a dynamic array variable defined in class. In the code below, when error pauses the code, I can see the data in the correct form but I can't write rigth code that writes the data to richtextbox.
Public Class Form1
Public k() As Integer
Private Class zaratma
[CODE]....
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May 5, 2011
Okay, I am TOTALLY confused here. I have a class... say MyClass. It has several properties of another class of my type, say MyHelperClass (along with other properties).
I am doing the following:
Dim inst As MyClass = New MyClass() With {
.p1 = sv1,
[code].....
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Feb 23, 2010
I've just opened a project I was working on yesterday perfectly well only to find it's gone nuts. I'm getting this error ..."Handles clause requires a WithEvents variable defined in the containing type or one of its base types."... on each one of my Sub declarations!
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Jun 11, 2012
I'm working with legacy data, which often brings me one information splited in multiple columns. I'm trying to reproduce the following SQL query.[code]This own statement will run into the following exception:Variable 'line' of type 'SomeTable' referenced from scope '', but it is not defined. Any directions? I'm trying to avoid magic strings, but I'm always giving up to it (as using HQL the concatenation expression + like function works like a charm).
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May 16, 2012
Solution at the bottom. I receive the following error when trying to update records: Must declare Scalar Variable @PaymentTermID Problem is, @PaymentTermID should be defined already in the Update parameters. The 2 functions for onrowdatabound and onrowupdate are tweaked versions of the ones found here for the DropDownList: GridViewRow.DataItem Property. Delete works fine. No new lines are added, just names changed around. I am not exactly used to working with asp objects.
[Code]...
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Nov 10, 2010
I am trying to write a module that will select cells from multiple, non-contiguous columns within a row that is defined by a variable. The column numbers are known and are unchanging. For example, my worksheet might look like this:
A B C D
Row 1 X X X X
I want to select cells A1, B1, and D1; however, I don't want to use the row number (1 in this case) in my code. Rather, I want the row number to be specified as a variable. The code I am writing is inside a For/Next loop, so I would like to use the iterative variable (i in this case) to define the row number. That way, every iteration of the For loop will select cells from a different row.
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