I'm doing binary serialization and want to know if its possible to assign the type of the serializable object in the serializer method at runtime by passing the type as a parmeter. Is it also possible to assign the return type?
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I have an object, o, and a type, T. I'd like to use reflection to change object o to type T at runtime without instantiating it.The equivalent at compile time would be:
Dim p as Point = Nothing I know how to use Activator.CreateInstance to create an instance at run time that is equivalent to: Dim p as New Point()
But i don't want to do this. I have no knowledge of the type's constructor parameters and some types don't have a parameterless constructor. eg. Font. So, to sum up, I'd like a way of performing the equivalent of: Dim o as T = Nothing
In case you're wondering why I'm doing this, it's because I'm using a PropertyGrid on a form to edit types. If this is the first time for editing, say, a Font, then passing an uninitialised Font to the PropertyGrid makes the grid display the default values.
I tried 'o = GetUninitializedObject(T)', but the PropertyGrid either wants a properly initialised object or an object, with a defined type, set to nothing.
I've actually solved my particular problem here: how-to-use-the-property-grid-in-a-form-to-edit-any-type
, but i'd still be interested to know how to assign a type at run-time without the use of a wrapper class (which I was lucky enough to be using).
I'm trying to assign a datasource to a ComboBox control during runtime. When I do so, I get the attached message. Here is my
cmbAddressDesc.DataSource = dbDataSet4.tblAddressCodes.addrDescColumn
dbDataSet4 is a typed dataset. I want to learn how to use an Interface. The error message is suggesting using an IList. How would I do this. I'm having trouble finding good documentation on this.
sir, i have no idea how the code will look, but i want it to assign a value after reading from a text file and then store it for further use even if the text file is not there, but without using any external storage like registry, disk, ram. It should store the value in itself and do like this:-
dim variable1, variable2 as string
if file.exists("text.txt")
read the text
[code].....
I want to Assign the Value to Multiple Variable of same type in .net and that to in one line of Code.
View 6 RepliesIs it possible to declare a variable and to choose it's appropriate type during runtime?
it should be something like this (of course, the last line does not work):
'Determine what type of variable is needed later
Dim myVariableType As System.Type = System.Type.GetType("System.String", True, True)
'Create variable with needed type
Dim myVariable As myVariableType ' Should be a string variable in this case
Is there a way to build a new class during Runtime? Or at least, add a new property to an existing class.
I mean creating a class that doesn't exist and not an instance of an existing class. I could later on use reflections to load and use this class.
I'm in the process of creating a function which reflects over the properties in a class and adds them to this data structure I have. Some of the properties are generic types.So say we have DataType(Of T) that has a .Value property of type T:
Dim properties = GetType(MyType).GetFields(Reflection.BindingFlags.Public Or _
Reflection.BindingFlags.Instance)
For Each prop As fieldinfo In properties
Collection.Add(prop.Name,prop.GetValue(poco))
Next
In the collection.Add for primitive types (Integer, String, etc....) I just want to add the type... but in the case of generic I want to add the DataType(Of T).Value. I hope there is some work-around but I don't think there is a way because the type of T can not be determined at compile time right? Ideally DirectCast(prop.getvalue(poco), DataType(Of T)).Value would be possible. This is when you hoped even more dynamics appear than whats in .NET 4.0.
I have a project in VB6, when I am executing this project locally it is working fine, when I am trying to execute it remotely it is giving the error like "RUN TIME ERROR 13, Type Mismatch"
View 9 RepliesI made this procedure re-use a select query:
[code..]
And I use it like this if I would want the selected value placed in a textbox and it works fine
[code...]
However if I want the value to be passed in a string like so:
[code...]
The string ends up having an empty string value. How do I assign the value I queried to that String?
I am using reflection to get an object's type, or for this issue an object that has instance properties type, at runtime and then I need to change an existing variable's type into that newly found type. Is this possible? For example, the following code does not work in the line indicated within:
Public Sub DoSomething(x As T, y As T, exp As String)
'This is a instance property on the object of a different type
'i.e. 'T.AnotherType' We need to reflect to find out what type of object
[code].....
I am trying to set to autonumber, the column called "enregistrement" , that exists into different dataTables that I have.
vb.net
For TabIndex = 0 To oData.Tables.Count - 1
oData.Tables(TabIndex).Columns("enregistrement").Au
[code].....
Is there a way for a property to access its own name and type at runtime using reflection? I want to access this info without hard coding the name or index of the property in the class.
Simple Example Code:
Private ReadOnly Property MyProperyName() As String
Get
Console.WriteLine((Get Current Property Info).Type.ToString)
Console.WriteLine((Get Current Property Info).Name)
[code]....
I'm trying to create an object Of a specific type. I've got the following code, but it fails because it can't cast the new table object to the one that is already defined. I need table to start of an IEnumerable type so I can't declare is an object.
Public sub getTable(ByVal t as Type)
Dim table As Table(Of Object)
Dim tableType As Type = GetType(Table(Of )).MakeGenericType(t)
[code]....
is there a way of changing a variable type at runtime?
I am using vb.net framework 3.5. I am developing an windows application in that i am displaying the Richtextbox data on Web browser. But in my rtf data contains the Math type functions which are not properly displayed in the web browser. For changing the font i used the method like put the data in the richtextbox change the size and font and again update it . But it's not working for math type.
View 2 RepliesI thought I saw how to do this but can't seem to find it now.Is there a way to set the properties of all controls on a Form by Control Type?Meaning, if I have 5 textboxes on a form can I write code like .If page.contol is TextBox then
textbox.forecolor = Blue
Then when the page loads is sets all the textboxes forecolor on the form to Blue.
I know about the existence of System.Nullable(Of T) Structure.I am trying to write a class to replace it: The Nullable(Of T) Class [VB code below]. But when I tested the Nullable(Of T) Class (See NullableOfTClassTest Class, Method Main) an exception occurs when using the CType operator to convert from System.Int32.Why does this happen at runtime, why isn't my Ctype operator method being called?
NOTE: code below reordered and reduced in order to hilite problem.
Namespace MyNamespace
Public NotInheritable Class NullableOfTClassTest
Private Sub New()
End Sub
[Code]...
How i can change data grid view column type runtime. like i want to make a coloumn checkbox but runtime.
View 8 RepliesNET 2008 to write a windows application. I try to connect to my ACCESS database and run the
program, the immediate window prompted me with this error message. May I know what went wrong in my
codings?[code...]
I'm using a 64 Bit Windows 7 system and trying to use PrintDialog. I know it doesn't work on Windows 7 unless you add this code: PrintDialog1.UseEXDialog = True. So I have added that code but then I get this error for the following code: Dim result As DialogResult = PrintDialog1.ShowDialog().
And the error: "An exception of type 'System.Runtime.InteropServices.SEHException' occurred in System. Windows.Forms.dll but was not handled in user code. Additional information: External component has thrown an exception."
An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in STUB_CREATOR.exe Additional information: Exception from HRESULT: 0x800A0036 (CTL_E_BADFILEMODE)
This is the line that creates the error
Dim f As New Scripting.FileSystemObject
starter = f.OpenTextFile(stub_path.Text + "" + cpp_file, Scripting.IOMode.ForWriting)
I have just previously opened the file for writing. but however i have closed the textstream with which i was writing into the file.
Admin assigns the authority and get a new form to the new assign in with vb.net & access. I am not sure about this,I need a way to do the new form assigned? How?Actually, this project is the admin will assign the authority to a manager, and the manager will get the password to log in. Then, the manager once log in and will get a form to set the rooms who is going to use and date, etc, this is multi-manager to handle the room setting jobs.But, I think, I got stuck, I am not sure how to do the new form, HOW DO YOU ASSIGN THIS NEW FORM FOR EACH NEW MANAGER?????? THIS IS VB.NET WITH ACCESS.
View 3 RepliesBelow is my entire code for trying to add some boolean values to a list box that are queried from a datatable called "Availability" and the value booRV which is my OleDbDatReader is "Nothing" at runtime. The error is: No value given for one or more required parameters. I assume this is all the items that are being queried, but i am not sure. Here is the code:
[code]...
I'm using a 64 Bit Windows 7 system and trying to use PrintDialog. I know it doesn't work on Windows 7 unless you add this
PrintDialog1.UseEXDialog = True
So I have added that code but then I get this error for the following
Dim result As DialogResult = PrintDialog1.ShowDialog()
And the error:
"An exception of type 'System.Runtime.InteropServices.SEHException' occurred in System.Windows.Forms.dll but was not handled in user code
Additional information: External component has thrown an exception."
I have a Journal that records entries for different types: Journal(Of ParentT)
[Code]....
I have created multiple dropdown list at runtime and populated with data. I also have added an eventhandler to determine the selected value of the drop down list.
The code is as follows :
Dim tbl As New Table()
tbl.EnableViewState = "true"
[code].....
I have a Visual Basic 2005 program which runs fine if I execute the built Executable. However if I start the application in VS2005 debugger it gives a weird error
[Code]...
Soemone recently downloaded my software and they got this error: microsoft common languages runtime version 4.0.30319.0 how do i fix this
View 1 RepliesI've come from a Assembler and C/C++ background, so I understand the concept behind reference types versus value types in vb.net. Also, I've read Jon Skeet's article regarding references and value types and I understand all of that. My question is: How can you tell if a given type is a reference type or a value type? Is it simply that all integral types (ints, floats, etc.) are value types and all classes are reference types? (If so, where do strings fall?)
[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].....
