Given this example:
Public Class Car
End Class
Public Class Vovlo
Inherits Car
End Class
[Code]...
where Car.CubClass is either a Volvo or BMW if the car object has a subclass, or a car if it do not have a sub class. The problem is how to get the Car.SubClass.
Sorry if the title isn't very clear. This is a VB.NET (2010) question I have a superclass called "Device" which has a number of subclasses that inherit it. Some of those subclasses also have subclasses. In particular, I have a class called "TwinCatIntegerDevice" which inherits "TwinCatDevice" which inherits "Device."The relevant parts of Device look like this:
[Code]...
I am working on a parser for a serial data protocol. I have an overarching Packet class, a couple sub-classes such as CommandPacket and StatusPacket, and then a few sub-classes of each of those:
[Code]..
While I don't think it is entirely relelvant to the discussion, I am doing this in VB.NET. There is also a similar (but not quite the same) question posted here: Java - subclass validation design pattern
I have subclassed the ASP.NET Panel control to customise the rendering of the GroupingText. However, while it appears fine in the final output, it is not appearing correctly in the designer. A sample of what I am doing follows: Is there anything else I need to do to make it appear correctly in the designer?
Imports System.Web.UI
Public Class CustomPanel
Inherits Panel
Public Overrides Sub RenderBeginTag(ByVal writer As System.Web.UI.HtmlTextWriter)
Me.AddAttributesToRender(writer)
[Code] .....
switching back to the code causes an error dialog to pop up with the message:"An error was encountered during code generation.The changes you have made in the designer have not been committed to the source code.it is recommended that you close and reopen the source file.The error message follows: Error HRESULT E_FAIL has been returned from a call to a COM component."The source code the Designer
View 2 RepliesI am trying to override a property of a subclass of an inherited base class. I've tried to simplify this code as much as possible but am not comfortable enough with my own abilities to simplify anything else without loosing the ability to understand an answer.The property propertyName in the otherClass is currently incorrect. I want to be able to override propertyName in baseClass with the propertyName in otherClass. Is this possible to accomplish?
Public Interface interfaceName
Interface iInterfacePropertyName
Enum enumName
[code].....
I'm developing this Usercontrol and I want it to capture theParentForm 's WM-Messages.I know how to just Subclass a Form, from the Forms code. Like:[code]But how do I do this from the Usercontrol? In VB6 I would have used code like:[code]All I want is to capture messages from the ParentForm's Window.
View 5 RepliesIn VS2010, targeting Framework 4.0, I have a UserControl which contains a TableLayoutPanel with an empty second row.Is it possible to add items to this second row using the Windows Forms Designer, or do I have to do it all via code?
EDIT: In reply to Hans Passant's comment, the linked question references a UserControl being used inside another control.I am asking a question about inherited controls.I have created the following test code, where TestControl is a UserControl containing a TableLayoutPanel named "TableLayoutPanel1":
Imports System.ComponentModel
Imports System.Windows.Forms.Design
<Designer(GetType(testDesigner))>[code]....
creates a control which, when viewed in the designer, contained a TableLayoutPanel named "TableLayoutPanel1" which is not designer-editable.Creating a new UserControl, not inheriting from either of the previous UserControls, and then placing a TestControl into it creates an instance of TestControl with a Designer-editable TableLayoutPanel named "TestControl1.TableLayoutPanelX".Is there any way to make the TestInheritedControl class, shown above, Designer-editable?
we changed the mapping from the table per concrete class to the subclass strategy and now the UnitTests fail, but I cannot recognize why.There's one base class Article and a child one SemifinishedArticle with no specific properties.
Article.hbm.xml:
<?xml version="1.0" encoding="utf-8" ?>
<ibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
[code].....
I'm trying to capture the initial value of a listbox immediately after it's clicked on, and before the SelectedIndex is changed. The following was taken from: MouseDown in WinForm ListBox Kills SelectedIndexChanged, converted to VB. The ListBoxComponent Class is in a Component that shows at the top of the Toolbox.
Public Class ListBoxComponent
Inherits ListBox
Public Const WM_LBUTTONDOWN As Integer = &H201
Public Event PreSelect As EventHandler
[code]....
I have a base class, "B", which has two constructors, one with no paremeters and the other that accepts one param, an integer. I have a subclass, "S", which inherits from "B" and does not define any constructors in it. I create an instance of S, attempting to pass to the constructor an integer.
I get the error: Error 1 Too many arguments to 'Public Sub New()"
This surprises me because I thought that if a constructor is not defined in the subclass, S, that the base class constructor method, specifically, the one with the single integer param would be invoked w/o an error. why I am getting this error? Are constructors a special case?
In re-engineering a windows forms application, I find that a lot of code-behind in the various form classes is duplicative and I'm trying to centralize as many procedures as possible into a base class which can be inherited and used by the subclassed forms.
This process seems to be going well and is making the code in my subclasses much simpler and hopefully easier to maintain, but I'm not sure where to draw the line between leaving code in the subclasses and engineering for generic resusability and moving it to the base class.
Specifically, in some subclasses I have code which manipulates variables and objects specific to the subclass, and although I could move the code-behind into the base class, the base class code references specific objects which are needed to compile. For example, each subclass manipulates a databound datagridview and form detail controls which allows the user to select between multi-record and detailed single-record views of a datatable.
In Visual Basic 2008 do I need to declare dummy data objects in the base class so that the base class will compile? Or is there a way to indicate that the data objects will be provided by the subclass?
take a look at the following code:
[Code]...
I have a copy function that I'd like to override in subclasses to return the type of the subclass. Here are my interfaces:
Public Interface IBase(Of T)
Function Copy() As T
End Interface
[Code]....
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?
I am getting following error whenever I want to use IIf function inside entity framework query.
LINQ to Entities does not recognize the method 'System.Object IIf(Boolean, System.Object, System.Object)' method, and this method cannot be translated into a store expression.
What do I need to convert?
Dim CEESearchByAppNo = From CEEsearch In dbCEE.tblScanneds _
Where CEEsearch.AppNo = iAppNo
[code].....
How do I calculate the direction an object is facing in degrees, if object A is at x1, y1 and facing object B which is at x2, y2?
View 2 RepliesOccasionally I encountered this exception message while trying to download file from a server using System.Net.FtpWebRequest and System.Net.FtpWebResponse Object.
Download a file.ftpRequest_DL.Method = WebRequestMethods.Ftp.DownloadFile get the response object
Dim ftpResponse_DL As FtpWebResponse = CType(ftpRequest_DL.GetResponse, FtpWebResponse)
[Code]...
If I declare my object at the beggining of my page class, and instantiate it in a dropdownlist selected_index change event. Shouldn't this object be available thru out the entire page and also persist thru a postback? I lose the object in my selected date change event in my calendar.
[Code]...
I have an ssis package that takes a flat file and dumps it to SQL. During that process, 150 columns need to have '-' and '.' removed from them. I have done this using a Script Transformation.
Public Overrides Sub Input0_ProcessInputRow(ByVal Row As Input0Buffer)
Dim column As IDTSInputColumn90
Dim rowType As Type = Row.GetType()
[code]....
Edit I've discovered that this line is the problem
Dim strCol As String = columnValue.GetValue(Row, Nothing).ToString()
I am trying to start the process with the following parameters When I try to start it though I get an System.nullreferenceexception: Object reference not set to an instance of an object
Dim exepath As String = Application.StartupPath + "inffmpeg.exe"
Dim sr As StreamReader
Dim cmd As String = " -i """ + input + """ -ar 22050 -y """ + output + """"
Dim ffmpegOutput As String
[code]....
In the Session_Start of the Global.asax i have
Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs)
Session("login") = False
[code]....
Why i am getting error the error Object reference not set to an instance of an object. at line
If Current.Session("login") Is Nothing Then
while checking for the login state as follows?
If GetLogin = False Then
'Do something
End if
I mean i have already created the instance on the Session_Start... Haven't i?
I have an object that is defined as a global variable based on custom class. Within that class I have an event that gets fired a certain intervals. These events are fired on the same thread as where the object is declared. How do I create a global object, but have the events within that object fire on a separate thread?
View 2 Repliesi am using VB.net 2003 and i am trying to get the number of rows of a dataset from form1 into form2 in order to use it for something else and i am getting the error"System.NullReferenceException occured...Additional information: object reference not set to an instance of an object"...my code is like this:in form1:Public x as integer= me.dataset.table.rows.count here it gives me the error
in form2:
dim frm as new form1
msgbox(frm.x)
I am getting this error when I try to print my report. Here is my print code.
Private Sub PrintToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PrintToolStripMenuItem.Click
Dim Print_Dialog As New PrintDialog
[code].....
Here is my error: System.NullReference Exception: Object reference not set to an instance of an object.
I'm trying to set the format of a column in a datagridview.When I put the format statement in the on load event for the form, it has no effect. When I put it in the cellformatting event I get the "Object reference not set to an instance of an object" error. I checked the column name. What I am doing wrong?
This is the code:Private Sub MeetingTblDataGridView_CellFormatting(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellFormattingEventArgs) Handles MeetingTblDataGridView.CellFormatting
Me.MeetingTblDataGridView.Columns("Starttime").DefaultCellStyle.Format = "HH:mm:ss"
End Sub What I'm trying to do is get rid of the date part of a Date/Time field (stored in an Access database) in a datagridview column.
dp.SyntaxHighlighter.ClipboardSwf = '/dp.SyntaxHighlighter/Scripts/clipboard.swf'
dp.SyntaxHighlighter.HighlightAll('09dde30f062e451a854266e66205b1cf')
I know how to handle a single objects property changed event very easily. I want to handle a objects property changed event that is part of another object.
Given Object:
[ObjectY = Y]
+ Public WithEvents X As ObjectX
I would like to do something like:
Private Sub XPropertyChanged() Handles Y.X.PropertyChanged
Right now I need to create a object that equals the object inside that object and then handle this variable pointers property changed, but that is just annoying.
with datagridview1
while looping through all the cells
i am trying to allot a cell value to another cell value basing on some conditions
& finally delete one column.my code is as fallows
Dim i, x As Integer
i = 0
x = Me.DataGridView1.Rows.Count[code]....
error i am getting is : Object reference not set to an instance of an object.it is extremely surprising for me the same code has worked nice for me but why & how the same line of code is generating this error.
I am trying to write an VBA application in Excel 2010 using "Microsoft Soap Toolkit 3.0" on 64 bit Windows 7 to consume an web service. But i got an error while initializing an object of SoapClient30.
Error message is :: Runtime error '429' :ActiveX component can't create object.