i wanted to do something simple that sort of replicate an object:
public function clone(byval realcopy as object) as object return new Control ' something like this works, however i want to return the type of realcopy, which may not be a control end function so i tried this:
public function clone(byval realcopy as object) as object
return new gettype(realcopy.gettype)
end function
I have a requirement where I need to have a "type safe" way of accessing property names, without actually instantiating an object to get to the property. To give an example, consider a method that takes as arguments a list of IMyObject and a string that represents a property name (a property that exists in IMyObject).
The methods implementation will take the list and access all the objects in the list using the property name passed... for some reason or another, we won't dwell on that!!
Now, I know that you can do this using an instantiated object, something like ...
Dim x as MyObject = nothing
Dim prop As PropertyInfo = PropHelper.GetProperty(Of MyObject)(Function() x.MyProperty)
Where my helper method uses reflection to get the name of the property as a string - there are numerous examples of this flying around on the web!
But I don't want to have to create this pointless object, I just want to do something like MyObject.MyProperty! Reflection allows you to iterate through a types properties and methods without declaring an object of that type... but I want to access a specific property and retrieve the string version of its name without iteration and without declaring an object of that type!
The main point here is that although I am trying to get the property name as a string... this is done at run time... at compile time, I want this to be type safe so if someone changes the property name, the compilation will break.
dim myCollection as new Specialized.StringCollection
dim myFoundThings as new ArrayList
dim index as Integer
dim newResultMemberName as String
[code]....
This is part of some code that will run without user interaction once it's spinning away, and I need to create a unique object from some items found in a StringCollection, naming the objects using information found in the strings stored in that StringCollection.
If I have a console application containing the class
[Code]...
I'm not a VB.NET guy. Am I correct in assuming I need to instantiate my object first? Why does the VB.NET example differ?
I'm trying to decide whether to get a value, call it X, in my class through a read only property or through a function. Normally I'd code it as a property except in this case the GET involves doing a lookup to a sql table. So there's way more overhead than a simple RETURN X. So my question is, when I instantiate a new object from my class, are all the properties calculated at that point, so that the sql lookup will occur too? Or is the property only evaluated when I actually reference it in the calling code.
View 3 RepliesI am having some real issues with this one. I have a class which contains two other objects...but I cannot seem to instantiate those sub objects. Here is the code for my class:
Code:
Option Explicit On
Public Class Boot
[code]......
I have an application which I am trying out on machines without mysql. The app runs fine on my local host however when I try to use the application on another machine I am getting the following error:
Access denied for user 'root'@'localhost (using password: YES)
Then I get a .net framework error
System.NullReferenceException: Object reference not set to an instance of an object.
I thought I had exported the DB but I was left with a mysql file which I placed in the bin directory.
I have a WPF windows project with a base Window, and then a series of user controls which I want to add at runtime based on a string from a file. I'm reading a string say "controlA" and i want to create an instance of the user control with the class name "controlA" and then add it to a base window. I want to have a constructor, but for now I would just like to see it work without.I need to do this: read a string (which is the user control type), create an instance of a user control based on that string, and then add the instance to the current WPF window. I've been playing around with Reflection.Assembly, getType, System.Activator.createInstance, Invokemember, CreateObject, and a few others. I can't seem to get it to work.
View 5 Repliesi've got a generic class for xml serialization and deserialization.
Public Class clsXMLHandler(Of T)
Public Sub serializeFromObject(ByVal filePath As String, ByVal [object] As T)
Dim creater As New FileStream(filePath, FileMode.Create)
Dim xml As New XmlSerializer([object].GetType)
xml.Serialize(creater, [object])
[Code]...
I see a sample code that an object is instantiated within the class definition block. But when I test the folllowing, I got error "Process is terminated due to
[Code]...
System.String is a class type, but why we can use it without instantiate it with New keyword?
For example:
Dim CommandLineParameters As String = Microsoft.VisualBasic.Interaction.Command
No new keyword being used at all?
I am trying to run a backgroundworker to load data from my DAL (which is available in another class). I want to keep the UI available and not have the "locked up" feel while the object is loading.When I create a simple backgroundworker and Sleep the UI stays responsive and my controls can be updated after the sleep. As soon as I replace the sleep with a call to instantiate the object from my DAL, the UI locks up. Is there someway I can instantiate this object using the background worked and keep the UI responsive?
When the situation object is instantiated it could take several seconds for it to load completely, during this time is when the UI is locked up... It does eventually load just fine.
Private WithEvents backWork As New BackgroundWorker()
Dim sit As Situation
Private Sub btnLoad_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnLoad.Click
[code]....
How can I instantiate an anonymous object while passing the propertynames and values as string?
new With { .SomeProperty = "Value" }
new With { ".SomeProperty" = "Value" }
In C# .NET 3.5, is there a way to instantiate an object given its string name? For example, suppose I have a DLL (e.g., MyClass.DLL) which contains type MyClass. Is possible to write something like... Object myClass = SomeMethodToInstantiate("MyClass"); // ? Is it possible to do this in VB .NET 3.5?
View 2 RepliesThis error makes no sense to me[code]...
Unable to cast object of type 'DynamicTreeNode' to type 'DynamicTreeNode'.
I have an inherited TreeView with an inherited class called DynamicTreeNode inside it. I am trying to loop through the DynamicTreeNodes in the TreeView.Nodes property which is causing this error.
I have an Account Class that is able to create notes(Class), however i am able to create the note object by itself which is not the desired outcome, i want only the account class to be able to create the note object. Another Example would be, an order item should not be created without an order class. But how do you enforce this in vb.net.
View 8 RepliesI am trying to write a generic method, to avoid code duplication, which will create or activate a Form as an MDI children, based on its type. But I have to lines in error (see comments).
[Code]...
For I = 0 To 10
If Items.Count = 0 Then Exit For
Dim T As New Thread(AddressOf Thread)
T.Start(New Object() {"Test", "Test"})
[code]....
When I put same code in empty project it works.
I've got a piece of code in a project (MyProject) that contains early bound object from a referenced assembly (We'll call it CommonAssembly):
Dim myObject As CommonAssembly.MyEarlyBoundType
now I have another assembly that is dynamically loaded because it is not present in all projects:
Dim myLateBoundObject As Object = AppDomain.CurrentDomain.CreateInstanceAndUnwrap("Utils", "Utils.MyLateBoundType")
MyLateBoundType derives from CommonAssembly.MyEarlyBoundType, and I want to cast myObject to myLateBoundObject and then programmatically invoke the additional
[Code].....
i always get this error when i tried to update my table: Unable to cast object of type 'System.Object[]' to type 'System.String[]'.
i only want to update STATUS, ENDTIME, and PRICE
the data type of each field are:
STATUS = nvarchar
ENDTIME = smalldatetime
PRICE = money
[Code]....
when view in browser, i got this error: Unable to cast object of type 'ASP.webform1_aspx' to type 'System.Web.UI.WebControls.Button'.
how should i solve this problem?
Line 7: If Not Page.IsPostBack Then
Line 8: Dim rowIndex As Integer = 0
<b>Line 9: Dim btn As Button = DirectCast(sender, Button)</b>
[Code].....
I had write code (just for learning), the codes :
dim Temp as string
Temp = Recordset("
Table_Field")
but, when I start Debugging the error messages "Unable to cast object of type 'ADODB.InternalField' to type 'System.String"
I am implementing IMAPI2 into my vb.net project but ran into a wall. I am getting the message Unable to cast object of type 'IMAPI2FS.FsiStreamClass' to type 'IMAPI2.IStream' when trying to start the burn. I googled around and found this is something that microsoft hasn't fixed.. which basically renders IMAPI2 useless in vb.net.
I found a post on codeproject.com by eric hadden who combined the IMAPI2.dll and IMAPI2fs.dll into an c# interop file. I also see the IBURN interop in microsoft SDK samples. I'd like to use either, but it's in c# and I'm using vb express. Does anyone know a way to get the interop into visual basic or a way around "Unable to cast object of type 'IMAPI2FS.FsiStreamClass' to type 'IMAPI2.IStream'"?
I'm having a problem with converting from one source type to a destination type. I have a form with 2 buttons (button 2 uses the OpenFileDialog to have the user open an excel file set to NewFile),(button 1 takes the contents from specific cells in NewFile and arranges them how I need into oXLApp1).
The error I get is "Unable to cast object of type 'System.IO.FileStream' to type 'Excel.Application'." in line 14 of the code below.
Public Class Form1
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
[Code]....
I'm new to VB 2005, the code below is actualy coded from VB 6 and just converted it to VB 2005. I'm having trouble with line that's on bold letters.In VB 6 this works just ok. By the way the error message is "Unable to cast object of type 'System.String' to type 'ADODB.Connection'." [code]
View 5 RepliesI can't cast my objects. I get: "Unable to cast object of type 'ClassA' to type 'ClassB'".
The service Class:
Public Class svc_Insp
Implements Isvc_Insp
Public Function Test(ByVal pm_income As ClassC) As String Implements Isvc_Insp.Test
[code]....
Unable to cast COM object of type 'System.__ComObject' to class type 'rjsDocMan.Folder'.Instances of types that represent COM components cannot be cast to types that do not represent COM components; however they can be cast to interfaces as long as the underlying COM component supports QueryInterface calls for the IID of the interface.The code where it is flagging the error is:
<div style="color: Black; background-color: White;">
treeview += AddChildren(Session("DocMan").RootFolder)
</div>
[code].....
I saw this thread and I had simple answer in mind. To use custom enumerator class. So I was trying to make one for that guy, which would have one more property to check whether its has reached end or not. It would also provide current position.I'm getting an error "Unable to cast object of type 'SZArrayEnumerator' to type 'WindowsApplication1.myEnumerator'." at the line 6 [see below].However, return type of values.getEnumerator says its IEnumerator. [code]
View 14 RepliesI have a question about ASP.Net, visual basic I have 2 LINQ query's, the first one works, the second one doesnt, produces a
"Unable to cast object of type 'System.Data.Objects.ObjectQuery'1[SelmaV2.Products]' to type 'System.Collections.Generic.List'1[System.String]'.
[Code]....
Columns 0 & 1 are filled from a DataAdapter from Access Database and three are added. I had this working, but I changed it to check for the column "Feed" so I could add several Locations. At first this worked,but I did someething in perfecting it and it now fails after filling the first row of the datagridview (dgvFdMed).I ran a check and the table LotsTab has 8 rows filled. Column 1 & 2 are strings and the database appears they are fine. The added columns have just been created with no value. My plan is to enter the values and then use the data from the grid.
Private Sub sfillGrid(ByVal Loc As String)
Dim i As Integer
Dim column As DataGridViewColumn
[code]....