Static Constructor In .Net?
Feb 9, 2010
I am rewriting a C# class in VB. The C# class has a static constructor in it:
static Class()
{
...
}
which, through the Call Stack, I found is called by the main window's InitializeComponent() method.Everywhere I've looked has told me that the corresponding static constructor in VB is just:Shared Sub New()
but this method is never invoked. Am I creating my VB static constructor right? Is it likely something else that has nothing to do with my static constructor?
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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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Jul 22, 2009
When is it run? Does it run for each object to which I apply it, or just once? Can it do anything, or its actions are restricted?
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Apr 1, 2010
A project has a class (CAR Class) with the folloiwng details and the CARADMIN cLASS with the following details: The cardAdmin class has 2 constructor Public Sub New() & Public Sub New(ByVal rec As Rectangle) I dont know how to code the latter constructor..
cAR Class has this method/properties:
Public Class Car
Inherits HVSprite
Private fSoundFile As String
[code].....
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Jun 27, 2009
I have a defualt constructor that has a object of a Database connectivity class:[code]therefore in theory i have to call the defualt constructor of Question from overloaded constructor. [code]How every in realitty is it possible to call the defautl constructor from the overloaded constructor
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Aug 17, 2010
Do not know how to convert Me.Base to C#Imports Microsoft.VisualBasic
Public Class ReplaceHTML
Inherits System.IO.Stream
Private Base As System.IO.Stream
[code].....
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Jan 23, 2009
how to pass value other than from constructor.
In my code....value are usually passed through constructor.
ie everything is declared in constructor and while executing, these values are defined in new object.
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Dec 15, 2011
I am writing a code for a webapplication in vb.net. I am using a shared variable in the vb code.
Consider the static variable value is 3 for a user who hits the web application. Again when another user hits the same web application, whether the static variable will be 3 again or whether he will have a separate value for static variable for his session?
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Nov 10, 2010
A former co-worker wrote a class in C# that was to be used as an attribute. I'm having to convert his work to VB (yeah, it's pointless and way more work than necessary, but management thinks it's a good idea). Unfortunately I'm having an issue because one of the main properties of the class is an ArrayList which is set with a ParamArray in the constructor. The class looks like this (note I've tried to abstract out the problem, so this is a simplified version of the class only)
<AttributeUsage(AttributeTargets.Field Or AttributeTargets.[Property])> _
Public Class LabelAttribute
Inherits Attribute
Public Sub New()
[CODE]........
In the first one, there is just the single label being added. No Problem. In the second one there are 2 different labels being added. Again, no problem. The third one, however, is a problem because it's assuming that the "Description", which is supposed to be the description is instead being interpreted as another label.
This wasn't a problem in C# because it could be set as follows:
[CODE].................
Of course this doesn't work in VB because optional parameters aren't referred to by name as they are in C#. As a stopgap I've changed the constructor to allow only a single label like this
CODE]..................
But that undermines some of what this class is meant to do. Does anyone know how, or even if I can get the same basic functionality to work in VB?
Think there must be a way to make the existing design work. Imagine this class was built into a library that I could not modify. Would I be forever forbidden from setting Description because of this design?
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Jun 29, 2010
Why VB.NET (vs C#) does not "inherit" the constructors with parameters?
Public Class StopLine
Inherits Microsoft.VisualBasic.PowerPacks.LineShape
Public Sub New()
MyBase.New()
[code]....
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Oct 31, 2011
I've been searching for a while now and can't find a way to add a constructor to the Rectangle Structure.
Is this even possible without inheriting from the class?
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Oct 15, 2010
Im having trouble with assigning a Rectangle to this constructor
fTrainAdmin = New TrainAdmin( )
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Feb 16, 2012
I need to put following code in the Constructor of my startup form.
JohnKenedy.BusinessSQLEXPRInstaller _ins = new JohnKenedy.BusinessSQLEXPRInstaller(" _ <Installation Display Name>", "localhost", "<New database instance name>", _
"<new database name>", "<database password>", "<database backup filename>");
if (_ins.IsDone == false) _ins.ShowDialog();
if (_ins.IsRestart == true) {
Application.Exit();
this.Close();
return;
}
But I really do not know what the Constructor is and how to access it?
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Mar 27, 2009
I know that you cannot specify a constructor in an interface in .Net, but why can we not?
It would be really useful for my current project to be able to specify that an 'engine' must be passed in with the constructor, but as I cant, I have to suffice with an XML comment on the class.
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Mar 9, 2011
I'm not sure if this is possible or not. I have a number of different classes that implement interface IBar, and have constructors that take a couple of values. Rather than create a bunch of almost identical method, is it possible to have a generic method that will create the appropriate constructor?
private function GetFoo(Of T)(byval p1, byval p2) as List(Of IBar)
dim list as new List(Of IBar)
dim foo as T
' a loop here for different values of x
foo = new T(x,p1)
list.Add(foo)
' end of loop
return list
end function
I get:
'New' cannot be used on a type parameter that does not have a 'New' constraint.
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Jun 23, 2011
I searched quickly and not find an explicit answer at the following question:Why VB.NET (vs C#) does not "inherit" the constructors with parameters?
Public Class StopLine
Inherits Microsoft.VisualBasic.PowerPacks.LineShape
Public Sub New()
[code].....
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Feb 7, 2012
I trying create Application for the BMP Constructor, I already write the code in C# but I can't translate it into VB.NET, because its require pointer, and as far as i know, there are no pointer function in vb.net @@ so how I can translate this:
FileStream fs = new FileStream(OJSPathBox.Text, FileMode.Open);
BinaryReader rdr = new BinaryReader(fs);
int width = 555; // its just for example
int height = 555; //its just for example
[code]....
ptr declaration is using Pointer and I throught, there are no unsafe in vb.net, how I can translate to vb.net language?
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Feb 28, 2012
How come when I create new instances of a form and show it, it loads the form twice?[code]...
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Mar 4, 2011
One would think I'd already know this, but I never really gave it much thought before now. When declaring a member variable for a class, is it better to set the default value at the declaration
Private m_strMyVariable As String = ""
Or is it better to do it in the constructor
Private m_strMyVariable As String
[Code]....
Should I maybe always specify a value at declaration, even if it's Nothing, and just override that value in the constructor(s) as needed? Or is it situation specific? If so, a really quick rundown of which situations might warrant which treatment would be nice.
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Jun 1, 2010
I am stuck with a problem about generic classes. I am confused how I call the constructor with parameters. [Code] I get error in the starred area of the DBLayer Object. What might be the possible reason? what can I do to fix it? I even want to add New(byval someval as datatype) in IDBObject interface for overloading construction. but it also gives an error? how can i do it? [Code]
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Oct 2, 2009
I am trying to start a new window with a report generated by another aspx.vb member than the form I am in, and leave the current one open. The code below gives me an intellisense message (on the variable newreport):Type System.Windows.Forms.HtmlWindow has no constructors. What do I do?
Dim newreport As New Windows.Forms.HtmlWindow
Dim urlString As String = "report_new.aspx"
[code]....
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Jul 19, 2010
I just would like to know how to implement class constructor in this language.
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Apr 25, 2009
In the code below I recieve the compile error "Error Too many arguments to 'Public Sub New()'" on the "Dim TestChild As ChildClass = New ChildClass("c")". I do not recieve it on "TestChild.Method1()" even though they are both on the base class I am inheriting from.
Public Class BaseClass
Public ReadOnly Text As String
Public Sub New(ByVal SetText As String)[code].....
As suggested below but I do not have to do that for Method 1 or other inherited methods and I am looking for the cleanest code possible. This may be a limitation in the system with inheriting parameterized New statements but I can not find it documented anywhere. If it is required then I would like to see the documentation.
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Jul 24, 2009
Is it possible to make a Delegate to a Constructor? For example:
Class Bar
...
End Class[code]......
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Aug 31, 2011
While creating instance of a Delegetae there comes a intellicence AddressOf , Sub and Function .
AddressOf signifies the address of the function or Sub , what does Sub or Function signifies ?
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Mar 1, 2010
I am trying to make the properties of class which can only be set through the constructor of the same class
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Jan 2, 2012
I trying to create application that can read loss bmp with bmp constructor, what I mean loss is bmp without header, here the sample of loss bmp (zip is including with original bmp):
Download(you can see the different by comparing the original bmp and loss bmp with hex editor, the different is loss bmp don't have 54 bytes header bmp) Height of image is 126 px and width image is 45 px
my question is how I can preview that loss bmp in picture box? someone of my friend say, its need BMP Constructor to preview bmp properly but he doesn't know the code, please give me the code..
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Aug 22, 2011
I want to add a handler to an event in vb.net through a constructor .... i thought i would be able to do something like:
vb
Public Sub New(Optional ByVal PreDraw As [Delegate] = Nothing)
If PreDraw isnot Nothing then AddHandler Me.PreDraw, PreDraw
[code].....
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Dec 17, 2009
I have a webservice that connects to a sql express 2005 database. I use tableadapters to fill my dataset in the constructor of my webservice.My question is, when is this happening? Only when the webservice is started, or everytime a new user connects?
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