When Calling New On An Object - Can The Object Being Created Refer Back To Its Caller
Nov 11, 2010
I hope the question makes sense, anyways. I'm looking to know if in VB.NET, when we call an object's constructor, is there some kind of a reference that points back to the caller? I'm interested because of a corner case where I want the object being created to first be able to validate the existence of some data in the caller before it allows itself to be created. If this validation fails, I plan on throwing an exception. This corner case will never happen at runtime unless the object being created is used improperly by a programmer. The object being created is not inheriting the object I want it to validate, so I can't do anything with the MyBase qualifier.
It's bit of a "future-proofing" issue that I have a (bad) habit of doing. Not critical -- I can always leave stern comments behind as a last resort. Wanted to know if this was possible.
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Oct 5, 2009
If you want a instance of an object to be created when a form loads or another class is created, you have two options:
Public class example
private IAmAObject As IAmAObject
public sub new()
[CODE]...
Or like this:
public class example
private IAmAObject as new IAmAObject
public sub new()
[CODE]...
I always use the first one. It's more type work but I think it's neater. How about you people and is there any real difference between the two?
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Mar 21, 2012
how I could have an object bounce back when it collides with an rectangle shape. There are multiple rectangle shapes and I don't want to do it all seperately for each one.
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Jun 13, 2012
I call the function GetDataTable and when it gets to the return line, I get the error message: Object reference not set to an instance of an object.
Dim DB As New DBConn
Dim gd As New DataAccess.GetData
Dim DT As New DataTable
[Code].....
Updated. I'll see if I can update with the DataAccess.GetData code. I didn't originally put it in there because our shop use it all the time and have no issues with it.
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Dec 1, 2011
I'm having trouble creating a sub that can create objects of a variable type on the fly. Here's an example of what I'm trying to achieve:
[Code]...
I can't get it to work. I've done a fair bit of research, and looked at generic types, reflection, and other tools, but I'm having trouble determining how best to tackle this problem.
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Jun 18, 2012
Is there a possible way to refer an object through it's name in Vb.Net?The case is, I have menu items created in my designer with names such as MenuA, MenuB and MenuC.On the database, I created a table consisting the list of all available menus in string format : MenuA, MenuB all the way to MenuZ.
Also I created a dynamic table consisting the user permission, what menu is accessible by a certain user.So when I started the app, it will get the name of menu assigned to the logged user, and start to turn the Visible property to TRUE.If it was a Control, I would just loop through it by Parent.Controls.Find(FoundMenu, True).My problem is most of it is not a control, it is an Item added to the Control, or even another SubItem added to the Item.So how can I found an object in my UI only by it's name?
SearchQuery = "SELECT menu_name FROM tbl_menulist menu, tbl_user user WHERE menu.id_menu = user.id_menu"
QueryReader = ExecuteQueryReader(SearchQuery)
QueryReader.Read()
[code]....
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Dec 22, 2009
I am doing a calculator project.In the given code below I want to modify the line txtDigitPanel.Text = Trim(txtDigitPanel.Text) + "0" as txtDigitPanel.Text = Trim(txtDigitPanel.Text) + this.text (the word 'this' is taken as a reference to the object that has invoked the event ) to avoid hardcoding. Because when I copy the BtnZero, the same code will work for other digits also. Is it possible?
Private Sub BtnZero_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If Len(Trim(txtDigitPanel.Text)) < 15 Then
txtDigitPanel.Text = Trim(txtDigitPanel.Text) + "0"[code]....
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Nov 12, 2010
Is there a way to reference an object by using the value of a string read from a text file? Here's an example of what I mean: I have a user control called 'Fish', one called 'Cats', and one called 'Dogs' and so on.... I have a text file containing this line, amongst many others in a long script written after compile time by the user:
[Code]...
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Apr 15, 2012
after searching on the web, i know that Me keyword is use to Refer to the Current Instance of an Object, but if i want to Refer to the others Instance of an Object, what is the keyword that i need to use?
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Apr 21, 2010
I have a label testlabel. is there some way I can refer to it as:
dim t as string = "testlabel"
(something here referring to the OBJECT with the same name as the string).text = "mytext"
? I have 50 labels with text to change and would love to be able to:
for i = 1 to 50
dim t as string = "testlabel" & i
convertsomehow(t, label).text = "mytext"
next
so that this would change testlabel1, testlabel2, testlabel3, ... , testlabel50.
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Jun 22, 2009
I know the name of a textbox in string format: txtbox & i. Through the loop, the txtbox name will be txtbox1, txtbox2,.... And I want to change the txtbox & 1 's text dynamically in the code. How can i refer to the textbox obj from the string?
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Sep 9, 2010
I'm using win7 64bit + express 2010. in the program, I need refer to Microsoft HTML Object Library. So, I added it, then I found, it can not be "copy local". I remeber it could before when I use oit on vista + 2008.
Now, the question is: how can I include it in the setup? since some users may not have this dll on their pc.
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Jul 10, 2010
I am somewhat new to object oriented programming and am attempting to flatten a Linq object hierarchy by using a shim class.how to initalize a derived class with property values from a base class?I have two objects, a base object with about 100 properties, and a derived object which inherits from the base object and adds a few additional properties beyond those of the base object. My simple constructor creates the derived object, but I am looking for a way to initialize the derived object properties with values from the base object.Right now I am using reflection to iterate over the properties individually and I suspect there may be a better way. The following example shows my shim class constructor for the derived class, and two properties:
newProperty1 - a new string property of the derived class
flattenedProperty2 - a new string property of the derived class, copied from a 2nd-level object of the base class
Code example:
Public Class derivedObj
Inherits baseObj
Private _newProperty1 As String[code].......
Is this the correct constructor approach to flatten the object hierarchy using a shim class? My second question relates to initialization of properties in the derived class. The constructor above creates the derived object, but what is the best way to initialize the derived object properties with values from the base object? The following code uses reflection to iterate over the properties individually, but I suspect there may be a better way.
Code example:
' property names are in the string array fieldNames
'baseObjQuery is an ienumerable of baseObj
'derivedObjList is a list of derivedObj[code].....
Is there a simple way to initialize values for the properties in the derived object based upon the values of the common properties in the base object?
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Mar 18, 2009
I'm building a DLL with several "master" objects that need access to the app LINDataContext.The DLL will serve several projects with different dataContexts, so I need the DLL can call the object that it's inside the EXE.What is the best or elegant way to do it?Edit: ClarificationCode example of what I'm trying to do:
'DLL
'---
Public MustInherit Class MasterObject(Of T As Class)
[code].....
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Mar 1, 2010
how to convert a linq query directly back to the same object type. But I have failed!
Dim test(2) As myStructures.ReturnData
test(0).Partnumber = "2055"
Dim result = From n In test _
Where n.Partnumber = "2055"
'now convert result to a myStrucutres.ReturnData() how?
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Jun 26, 2011
Version: visual basics 2008
Problem:
Form 1 contains a SWF object, which is called FlashGame (it has a movie set, which is a game)
Form 2 contains a button to set a variable on the FLashGame.
Example
Call FlashGame.SetVariable("variable will be here", 1)
That simple coding works when the button to call that SetVariable command is on the same form as the FlashGame, but I need them to be on different forms.
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Oct 11, 2010
I created an Access Object in vb.net:Dim acApp As Object = CreateObject("Access.Application.11")en I open Access I need to pass a parameter to it though "/cmd".I read that the only way to accomplish this is through a shell - that it is not possible directly using an Access object.
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Aug 12, 2011
I need to call this function saveBase from more than one place so i decided to send a number in variable x to know of what type to create the object named Model. however when it's within the if statemet i keep getting the error that model is not declared ![code]...
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Apr 12, 2011
I have a dll that create container object. How can dll inform a form that the container (me) has been created. Is it possible in new sub of that class?
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Oct 24, 2011
I am currently trying to maintain a VB6 module that it is being called from a vbscript. The module needs to have a reference to the MSScriptControl.ScriptControl COM object. However, I obtain a 80040154 error. I went ahead and registered the component using the C;WindowsSysWOW64Regsvr32.exe but then I get that the entry-point DllRegister was not found.
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Jul 6, 2009
I have a statement that will call a Sub.
Charts(CurChartNo) = Server.CreateObject("ChartFX.WebServer")
Call InitChart()
Inside this sub, I will assign values to the properties of the Charts object that is
Public Sub InitChart()
Charts(CurChartNo).RGB2Dbk = &HC0FFFF&
Charts(CurChartNo).Chart3D = False
[code]....
But the Charts is not recognized in the Sub. This is current program under ASP, I am converting to ASP.Net.
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Sep 15, 2011
Calling method in anonymous object?This works:
Call (New MyForm).Show
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Jun 2, 2010
Structure MainStruct
Dim Ans1 As String
Dim Ans2 As String
End Structure
[code]....
The question is how can i read back the contents of the list, stored in the Session?I mean something like...
Build = Session("MyData")
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Feb 22, 2012
I'm adding some functionality to an app that was made a few years ago and I need to raise an event when the tabcontrol is clicked. However it would seem because the control was created publicy I can't add a handler to it? I never ran across this before. I stripped the code down to the bare essentials. As you can see in the image, if I Dim the control within the sub I can add the handler. But any handler created for the publicly created control fails.
Is there another way to create the hander in this case?
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Dec 10, 2010
My
Public Class Form1
Dim x As Integer = 0
[Code]....
As you can see, i can retrieve the tag of the button (which is created at runtime) without any problems, i've made a temporary msgbox to show me the value of the tag, just for testing purposes. What i do have a problem with, is retrieving the tag of the individual web browsers, how should i do this?
Next issue, how would i code for my buttons to show the web browser with the same tag as the button that's just been clicked?
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Apr 3, 2010
I need to save a object that i programing to be drawed onto apictureboxPictureBox1.CreateGraphics().FillEllipse(Brushes.Blue, ci)how do i save the object as a image or the picturebox? And then be able to open it again?
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Jul 5, 2009
in vb I can do that
sub SetFocusControl(byref ctl as object)
ctl.Focus
end sub
in c# the compiler complaint that object doesn't have a Focus method
void SetFocusControl(ref object ctl)
{
ctl.Focus();
}
how can I do the same in c#?
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Aug 29, 2011
How can I access the values stored in a session object with a class in asp.net?
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May 4, 2012
I want to see if there is a way to do this... I'm Using vs2010 with the WP7 SDK. (VB.NET)
I am declaring this in the global scope.
public objGame as object then say i have classes: Game1 and Game2 for the sake of the example we'll just say both classes have an Update() function
I want to set objGame = Game1 (or Game2) and then be able to call objGame.Update()
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Jun 3, 2011
I'm developing this procedure using a timer object. The thing is the procedure is not in the timer's event procedure but I want it to depend on the timer's interval when executing, it's just not calling the timer procedure. How can u declare objects and use their event procedures in code.
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