I'm trying my best now to develop a way or a function which can automatically cast a variable from type : OBJECT to instance of my own class based on some parameter.
I tried the following but it's not working fine
it show an exception ("
Object reference not set to an instance of an object.") on line :
OT = obj.GetType
Imports System.Reflection
Public Class APP_USER
[Code]....
Dim a as Type=GetType(className) would gimme the type. But I have only the name of the class as string. I want something like GetType("class1") which would return the type.
View 2 RepliesUnable 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 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]....
In VB.NET, if I create a class it is a reference-type. But, if that class it chock full of value type properties, how is this handled? If the class is instantied but never filled, I suspect a pointed for to the heap is allocated. But is more space allocated on the stack for all of it's value type properties?
View 4 Repliesi was trying to inherit System.Type. this is what i have:
[Code]...
and anyway the real problem is that inheriting System.Type without declaring my derived class as 'MustInherit
1) VB Allows non-type template parameters2) VB supports explicit specialization 3) VB allows the type parameters to be used as the base class for the generic type4) VB allows a generic type parameter itself to to be a generic 5) VB enforces that all codes are valid for all types of parametrs
View 1 RepliesI suspect I am being very silly here but I have the following setup
Class MustInherit myBaseClass
'some stuff
End Class
Class myInheritedClassA
[code]....
Running this results in the following error
Unhandled Exception: System.InvalidOperationException:
There was an error generating the XML document. --->
System.InvalidOperationException:
[code]....
is there any way of 'Widening' the inherited class to the base class so this would work?
EDIT:regarding XmlInclude(typeof inheritedClass), currently this method could potentially return a number of types of inherited class (i.e myInheritedClassA and myInheritedClassB) is it case of simply having to add each of the inheritedTypes in this tag?
I have a class that hosts inside other classes that can host otherclases as well and so on.
I want to change the value of one property (PropertyA) in all classes down the tree.
How can i do that when i dont know the the type of class inside?
How can i iterate through the classes hostes as proeprty of the mother class?
I am trying to use reflection but i get just the properties of the first class
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 have the following two tables defined...
CREATE TABLE [LogLevel] (
[Id] int primary key
,[Name] nvarchar(50) not null
[code]....
After creating a fresh endity model, I add the two tables above. When I try to build I get the following errors...
Type argument 'Inxsol.CommandPlan.Data.Model.Log.LogLevel' does not satisfy the 'Class' constraint for type parameter 'TEntity'.
Value of type 'System.Data.Objects.DataClasses.EntityReference(Of Inxsol.CommandPlan.Data.Model.LogLevel)' cannot be converted to 'System.Data.Objects.DataClasses.EntityReference(Of Inxsol.CommandPlan.Data.Model.Log.LogLevel)'.
[code]....
Code: Dim dom As New DOMDocument30 dom.async = False
dom.Load(serverAddress & "/App/filelist.jsp?type=content")
For i = 0 To dom.childNodes.item(1).childNodes.length - 1 downloadfile(dom.childNodes.item(i), mcount, currentpath) Next
The above code is activated upon clicking of a button. i have the server address declared. and using the domdoc to load the jsp file to generate the xml data. and using for loop, i call the download file function which accepts the following parameters
Code:Public Sub downloadfile(ByVal domdoc As Xml.XmlNode, ByVal totalcount As Integer, ByVal currentpath As String)
The totalcount and currentpath work fine, but when i pass in the dom.childNodes.item(i) , error pops up.
--------------------error message------------------------------------------Unable to cast COM object of type 'System.__ComObject' to class type 'System.Xml.XmlNode'. 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.-------------------------------------------------------------------------------
[code]....
[Code]...
Take a look at the snippet above. On the third line, I'm trying to set a multidimensional array to the type that the current class is. How can I get the type of the class that I am currently in? I'm using VB.net so all .net examples are acceptable.
How can I get all the properties of a class that implement a specific base class or interface? I have a properties class that contains several other property classes. Some, not all, of these classes implement an interface. I would like to know if it's possible to iterate over all properties of parent class for child-classes that implement the target interface. It sounds like a job for reflection? I'm just not sure how. Can it be done via the "PropertyInfo" object?
View 1 RepliesI have the following sample code in a VB.NET console application. It compiles and works, but feels like a hack. Is there a way to define EmptyChild so that it inherits from Intermediate(Of T As Class) without using the dummy EmptyClass?
Module Module1
Sub Main()
Dim Child1 = New RealChild()[code].....
The other way to do this would be to move the generic code out of the Base class and then create 2 Intermediate classes like this [code]...
Then RealChild would inherit from the generic Intermediate and EmptyChild would inherit from the non-generic Intermediate. My problem with that solution is that the Base class is in a separate assembly and I need to keep the code that handles the generic type in that assembly. And there is functionality in the Intermediate class that does not belong in the assembly with the Base class.
Does this mean that the type is not set up correctly?If you're not living on the edge, you're taking up too much room
View 5 RepliesI am trying to check whether an object is of a particular class type, or if it derives from a particular class type. I've tried to do this muliple ways. But have not had much success. I am using VB.NET.
Here is the code that am using:
If Me.Page.GetType() Is GetType(AALASWebsite.ContentPage) Then
hlPrintPage.Visible = False
End If
I have a "generic" Tag class which holds an ItemValue, which at this time is declared as Object. The ItemValue could be one of several datatypes; String, Boolean, Integer, etc. Is there a way to create a class property to identify which data type the Tag is?
I've tried this but it's not working;
Public Property DataType As Type
Get
Return m_DataType
[code]....
The consturctor of System.Xml.Serialization.XmlSerial need the type of the class I want to serialize.[code]...
No problem. But how can I get the type of AnyClass without initiating?
I create a object type entity in the main function and would like to pass it to a separate class, do some calculation, and then pass the result back to the main function. But I keep getting errors, can someone point me where I did wrong? It's in windows application[code]...
View 2 Repliesim making a function that disables controls except for a type of control i want to specify. how would I make the header of this procedure is my procedure should capture a control and a object of any type If I would call modUtilities.DisableControls(Panel_OwnerInfo, CheckBox_HasCell) is should disable all the controls inside Panel_OwnerInfo except for the CheckBox_HasCell Now I've done the disabling thing, but how would I specify the procedure parameter to recieve a class type?
[Code]...
What I wanted to do was, given the table name (as string), use reflection to instantiate the get method for specific fields (defined as properties with Get and Set methods.
Public Property VC60() As String
Get
Return _VC60
[code].....
I have to implement a COM class with VB.NET. An object of this class has then to be created from a VB6 DLL. The code for the COM dll is very simple:
Code:
Public Class AdapterWrapper
Implements SchemaCompInterfaces.IEFAdapter
#Region "COM-GUIDs"
[code]....
Now when I'm running this code, I'm getting the Run-time error '13' Type mismatch in the CreateObject line. Late binding with
Code:
Dim adapter as Object
seems to work for my test code, but is not a solution for me, because I can't change the proprietary VB6 code where the COM object is created. So somehow the interface "SchemaCompInterfaces.IEFAdapter" is not known... :sigh: In the project properties I checked the flag for registration with COM-Interop. Perhaps something to do with the ClassInterface?
I have been having some trouble today with a User-Control of mine. Is what is happening is when I try to build an application with the control in it, the Form.Designer has an Error saying that Namespace.ControlClass is not defined. I have no idea what the problem might be and hope that one of you do.The weird thing is that the Control Builds just fine and I can drag it from toolbox to the form and THAT works. Also, it works just fine in Design-time. It didn't start erroring until either, I upgraded it to VS2010 or until I changed it a bit today. If necessary, I can post it here.
View 2 RepliesOne thing that always bugged me, is that I do not see the base type in Visual Studio.I just stumbled on this, because I tried to cast a System. Windows.Forms.MenuItem to a System.Windows.Forms.Control..In eclipse the "intellisense" (or whatever it is called) shows me while exploring the members of a class for each member from which base class it is inherited.In Visual Studio I cannot see the base class, even if I use the Object browser or the help.[code]Is there a way to query the base type tree of a class at Design Time?
View 8 RepliesI will preface this by saying Im previously an asp developer and am learning oop programming/Vb.Net
Im working on a 3 tier architecture and trying to abstract my code as much as possible since I have a very large intranet to convert. In my business layer I am defining my classes with management methods. Below is an example of one of my classes.
My question: Is there a way for me to genericaly refer to the class type and object type so that I dont have to continualy refer to the class name/type "ServiceRequest" throughout the class. For example something like:
[Code]...
I'm about to start translating my vb.net application, and I don't want to use the default methods provided by Visual Studio to do so. I need my application to be very light, and it nearly doubles it size to use the resources option.Therefore, I'm planning to use some thing like a class, of which I would have one instance per language. Since I don't want to distribute language files as separate files (I'd rather have them hard-coded), I would like to find an easy way to check if every field of the class is initialized. I was thinking of something like an Interface, where I would do something like this:
Public Interface Language
Dim HelloMsg As String
Dim GoodbyeMsg As String
End Interface
[code]....
It's obviously not the right way to do it (although I could use properties instead of vars), but I was wondering whether the was a way to have the compiler check that everything is translated and warn about it if not.
what's the main difference between a Class and a Type and a ValueType.and is a Delegate a Type? or an eventhandler/event (the actual event itself)is every object a type? or is it only true in VB
View 3 RepliesI'm a newbie to VB, and I am having difficulty understanding what the following (legacy code) class declaration actually means:
Public MustInherit Class ModelBase(Of T As {ModelBase(Of T, TIdType), New}, TIdType)
There is also a related ModelBaseCollection:
Public MustInherit Class ModelBaseCollection(Of TCollection As {ModelBaseCollection(Of TCollection, TModel, TIdType), New}, TModel As {ModelBase(Of TModel, TIdType), New}, TIdType)
Inherits Collection(Of TModel)
I have difficulty understanding the need for the ModelBaseCollection class as the ModelBase class is a generic type.
I have an .net app that I created using visual studio 2005 and it also incorporates an autocad .api; therefore, in the project properties, under the application type, I have it listed as a class library.
I'd like to see if I can incorporate a splash screen; however, all the material i read indicates that I need to set the application type as a windows app in order to set the splash screen as the startup form.
I was able to tell the form to load...with out the use of this setting; however, I don't know how to tell the screen to only display for x amount of time. The example code suggests that i create an OnInitializer method by loading the app events..which i'm unable to do.