VS 2010 - Form Constructor Recursion Exception
Aug 15, 2010
I developed an app, tested on few computers and all seemed fine. But now, some people suddenly get an error, which I can't repeat on my computers. Part of the exception:
** Exception Text **
System.TypeInitializationException: The type initializer for 'NumoABC.functionsBurtuSummas' threw an exception. ---> System.InvalidOperationException:
The form referred to itself during construction from a default instance, which led to infinite recursion. Within the Form's constructor refer to the form using 'Me.'
at NumoABC.My.MyProject.MyForms.Create__Instance__[T](T Instance) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 180
at NumoABC.My.MyProject.MyForms.get_MainForm()
[Code] .....
The If Me.Created = False Then is because while the form is loading, some events fire the updatePersonDataHandlers() sub, but I don't want it to happen until form is fully loaded. In the module functionsBurtuSummas line 2
Module functionsBurtuSummas
Private f As MainForm = MainForm
I have many modules who work with the MainForms' controls, so I use a private variable f to refer to the MainForm.
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May 10, 2010
Is it possible to make this function iterative or must it be recursive?
The Function traverses a grid of x length and y height. At each point in the grid, it checks all of it's neighbors to see if they are valid, meaning they exist in the grid and haven't been used yet.
The function works in it's current form but I was wondering if an iterative version would be more efficient.
PathManip is a Stringbuilder, stores the path currently being manipulated. PathQueue is a List(Of String), stores all paths yet to be traversed.
IsPathAlreadyUsed is a boolean function that checks whether or not a specified point has been used in the current path.
Sub FindNeighbors(ByVal coords As String)
Dim x As Integer = CInt(coords(coords.Length - 2).ToString)
Dim y As Integer = CInt(coords(coords.Length - 1).ToString)
[Code]....
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Feb 13, 2012
I've got a menu with checkable items that appears on two different forms, and I'm making sure the two forms always have the same check states, so Form1 would have something like this:
Private Sub mnuWarnings_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles mnuWarnings.CheckedChanged
'when one of these is checked, the other should also be
[code].....
But that yields this error:
An error occurred creating the form. See Exception.InnerException for details. The error is: An error occurred creating the form. See Exception.InnerException for details. The error is: The form referred to itself during construction from a default instance, which led to infinite recursion. Within the Form's constructor refer to the form using 'Me.'
There definitely aren't any references to Form1 within Form1.It only occurs when I use CheckedChanged--if I use mnuWarnings.Click, it works fine. And it only occurs in Form1 (the main form); CheckedChanged works fine on Form2.
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Apr 14, 2010
I have two forms. A main form and then another form that you can change settings in. Now when I click on the menu item to get to the settings form I get this error. "An error occurred creating the form. See Exception.InnerException for details. The error is: The form referred to itself during construction from a default instance, which led to infinite recursion. Within the Form's constructor refer to the form using 'Me.'"I've tried these codes.
frmSettings.Show()
Application.Run(frmSettings)
those didn't work so i tried these
dim settings as new form = frmSettings
settings.show()
dim settings as form
[code]....
and those didn't work. I'm using visual studio 2010 Pro.
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Apr 10, 2012
I have a simple form that when filled out with a case # will return the name of the person that is handling the case. I am getting an error on any machine that does not have VS 2010 installed on it. The error is when ever the user uses the close button (the red X) at the top right of the form the following error is generated:
System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
[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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Mar 13, 2012
My code comes up with this error when i click save "Form exception was unhanded" , " Input string was not in a correct format."
[Code]...
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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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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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Jan 3, 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,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?
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Jan 19, 2011
I have written a number of classes in my time in VB.NET which set the basic elements in a custom New constructor through parameters. This makes things easier and enforces discipline. However, using Public Sub New() becomes pointless. If someone else tried to use this class, he or she could make a mess of it all by using Sub New without the arguments. I'd like to remove this method but I haven't found out how. I could make it raise an exception, but that somehow seems unseemly. I'd like a neater way. Does anyone know how?
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Jan 25, 2012
I was reading a old post, and came along this post in particular by jmcilhinney... [URL]He states Quote: Originally Posted by jmcilhinney The other alternative is to do your initialisation from the constructor instead of the Laod event handler. My question is...how/where is the constructor? I can't seem to do the right internet search to find out how to do this.
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Nov 12, 2010
I am suppose to call a method and define it from the constructor of a form.
MSDN says this in regards to something im doing.
Whatever, does it mean?
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Jun 7, 2010
I have a MDI app that I am creating. It, of course, will have multiple MDI child forms. In each child form, I have an options button so that each child form can have it's own set of options. When I click the options button it opens an Options form. This options form is not an MDIChild.
I have a class that contains the child forms options. I pass this class to the options form using a constructor. This is how I call the options form:
Dim dlgPatternOptions As dlgOptions = New dlgOptions(thisPatternOptions)
thisPatternOptions is the class that I am passing to the Options Form.
This works fine and the options form does populate the options correctly. The Options form constructor is this:
Public Sub New(ByRef thePatternOptions As CanvasOptions)
Me.InitializeComponent()
Me.txtCanvasWidth.Text = thePatternOptions.CanvasWidth.ToString
Me.txtCanvasHeight.Text = thePatternOptions.CanvasWidth.ToString
End Sub
I change the options in the options form. How can I get those changes back to the calling form? Do I need to somehow pass a handle of the calling form to the constructor to get the changed values back to the calling form? Is there some way to pass a handle to the options form so that changes made to options will be pushed back to the calling form?
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Jun 20, 2011
CODE:
This tells me "End of Statement" is expected. I'm trying to instantiate a new form, and I'm trying to pass information into the form that I will use to populate other data fields on the form.
I've tried looking up constructors, but I can't find where my is different than other examples.
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Jan 1, 2011
where can I find the default constructor of a windows form? I mean:
Public Sub New()
End Sub
I should say that I Use Visual Studio 2008 as my editor.
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Dec 27, 2010
I have a base class which must be overriden. This base class sits in one dll shared by all. The derived classes will each be in their own dll such that the addition of a new derived class can be done by distributing a new dll. The set of dlls, and therefore the set of derived classes, will be discovered by the main program on startup. That's all pretty straightforward. The problem is that the main program needs to be able to query a database to figure out which type of derived class it needs, then create a class of that type. Naturally, it can't know which types will be available ahead of time because even I don't know that. The program has to be dynamically extensible.The obvious way to do this is to have an interface in the dll that is implemented by a class with a default constructor. The sole purpose of that class would be to return an object of the type (one of the derived types) defined in that dll. The derived types can't really be this class, because they can't have a default constructor since the base class doesn't have a default constructor, and the derived class can't make up the arguments that the base class constructor needs.
So basically, each dll that houses a derived class would also house a simple class that implemented an interface for the sole purpose of creating that particular derived class. The main program would examine the dll to find a class that implemented the interface, and once it found one, it could ask it what type of class it created, or it could ask it to create an instance of that class. It seems like there ought to be an easier way to dynamically add new classes to the project. It seems like the derived class ought to be able to tell the main project what type it was. This could be done, except that the derived class would have to exist before any of its methods could be called unless the methods were shared. Since you can't have a shared method in an interface, the interface itself would make no sense at that point, in which case I would need to discover whether the class in the dll derived from the base class in the second dll, just to figure out whether or not I wanted to create it. That's getting convoluted by now, so I guess I'll leave it there. The basic point is that the base class is known to the main program from a common dll. The number and types of derived classes can't be known at this time, so the program has to be able to discover them dynamically. Each derived class will sit in its own dll (or there could be more than one in a dll), and has to be discovered, and instances created, as needed, by the main program.
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Feb 11, 2012
Implementing a simple MVC in vb. The controller instance creates and holds instances of the model and view:
Public Class Controller
Public Property myModel As Model
Public Property myView As View
[code].....
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Jan 27, 2012
I created an even on a form called Sub New so I can handle some events and close the window down if there is an error.Upon doing that, I came across 3 errors that I don't know how to fix.[code] ShowDialog really isn't necessary I could just use .Show. I want to use ShowDialog because the line under those 3 shows the current form.How do I pass the date to the form?In case it's relavent, my code for sub new on frmEmail.[code]
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Oct 23, 2010
I've constructed a custom System.Windows.Forms.Form that requires arguments to New. I want to use one of these as the MainForm in a Windows Forms Application. How do I get the Application Framework to pass those arguments as needed?
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Jul 19, 2011
I'm trying to create an array to be handled during my code. I want to create it as soon as I open the program so I've placed it in my bit of constructor code. This code was working fine before I tried to initialize a new array in there but when I place that in I get the above error message. This occurs whether I put the new array bit of code first in my constructor class or not.
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Jul 28, 2009
I have a class called Profile that has some simple properties and then it can have a collection of ProfileItem that again has some simple properties and then it can have a collection of ProfileItem (RECURSION). Now I am trying to generated a very simple save function using XML Literals that come with VB.NET (3.5).
[Code]....
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Oct 16, 2010
The code is from a text book.[code]SetProgress is referenced within SetProgress, I don't understand it.Is it a recursion call?
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Jun 21, 2012
I've tracked a recursion error down to one subroutine, So when my form loads, it populates some listboxes from a database; any one of these causes the error:
ListboxQuery("select sculptname, sculptid from sculptures;", CloseSculptList, "sculptname", "sculptid")
ListboxQuery("select distinct eventtype from events;", EventTypeList, "eventtype", "eventtype")
'etc, etc
And here's the subroutine (it's querying a MySQL database):
Public Sub ListboxQuery(ByVal queryText As String, ByVal resultObject As Object, ByVal resultDisplay As String, ByVal resultValue As String)
'queries the database for a 1- or 2-column list of values to display in a listbox
Dim myCommand As New MySqlCommand
Dim myAdapter As New MySqlDataAdapter
[Code] .....
The error is the standard recursion error:
An error occurred creating the form. See Exception.InnerException for details. The error is: The form referred to itself during construction from a default instance, which led to infinite recursion. Within the Form's constructor refer to the form using 'Me.'
This is weird for two reasons: One, as you can see, the subroutine doesn't refer to the form at all, so I don't see how it could cause a recursion error, and two, I wrote this subroutine almost a year ago and it only caused this error last week.
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Oct 20, 2010
I am trying to implement Selection Sort in vb.net using recursion. Problem is that I keep getting stackoverflow if the array I want to sort is 1000 elements. I can't find the problem. I don't know much about stack overflow or how to check it. From my research the problem could be infinite recursion but I check for that and exit the sub.Here is the main code:
Public Class SelectionSort
Inherits DefaultSort
Public Sub New(ByVal num As Integer)
[code]...
Everything should work as far as I know. It works on an array of 10 elements and an array of 100 elements.
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Mar 29, 2010
calculate the factorial of given number using recursion.input the number in textbox and show the
result in another textboxrajeev ranjan, on 29 March 2010 - 12:38 PM, said:calculate the factorial of
given number using recursion.input the number in textbox and show the result in another textbox.
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Aug 13, 2009
In my application I am selecting a folder path and then asking the user if he/she wants to display full path or file names only.
My problem arises when I want to insert the results in a datagridview. The datagridview has 2 columns:
column1 ----> shows file name
column2 ----> shows file size in MB.
with the below code I get the file name and then the file size on the same column one after the other
I want to show as follows:
File Name Size (MB)
sample.txt 1.2
myspreadsheet.xls 0.6
Seanie.bmp 0.8
What do I need to modify in order to achieve this?
Code:
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Dec 3, 2010
I have a situation where I have a hierarchy. I'm trying to use LINQ to get all of the items throughout the hierarchy as opposed to For Each loops. I spent some time looking for examples, but most where C# using lambdas, and I'm not quite sure I understand it. I'd like to try to get all of the Items for a specific system, the levels of items could be n-levels deep.
Code:
System
SubSystem1
Item1
Item99
Item100
Item2
Item121
Item3
SubSystem2
Itemx
Itemy
Itemz
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Dec 29, 2009
I got that little function(I changed the name of variables)
Private Function everythingLinked(ByRef myClass As cls, ByVal found As Boolean) As Boolean
If Not found AndAlso myClass.checked = False Then
myClass.checked = True
[code]....
I want to rewrite it so it would only be loop and no recursion and I'm currently lost?I'm passing a class to this function(with a starting value for found as false) to know if it is linked to the middle of the tree. The class got an array with a maximum of 4 link to other class and it can be circular(this is why I have a checked_link boolean).It does the recursion until there is no more link(return false) to check or until it find the middle link(return true).
edit?for an example, this
in pos 0 got link with 1
in pos 0 got link with 6
in pos 1 got link with 0
[code]....
middlepoint would be pos 15 the code above can prove that every position can be linked with the middlepoint so initial arg would be
everythingLinked(random pos, false)
and in this case it would be always true
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