Generic Error Handling Class?
Jan 10, 2012
We are developing an application for our shop floor. This program will be tracking material through the shop and we need to capture any errors the program generates, but we don't need to stop the program for all errors. I have some code to do a screen capture and put it in a database with exception.tostring data for debugging.
What we would like to do, is create an exception from the base class, but provide additional properties to allow us to set a severity and a user friendly error message. I would like to encapsulate this in a class that we would call in the catch of a try/catch, set the properties on the class, have the class record the data to the database, then raise the exception to the main program to display only the user friendly message and severity. The main program would then determine the severity and based on the severity stop the program or just display a discreet msg and continue to process.
Does anyone have an example of a custom exception class derived from exception that does something similar, or if I heading in the wrong direction, does anyone have a better solution?
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Jan 21, 2010
I can do this without problem.
Class A
End Class
Class B : Inherit A
End Class
Dim Obj1 As A = New B
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Apr 13, 2012
Consider:
Public MustInherit Class Column
Public ReadOnly Property ReturnSomethingUseful() As Object
Get
'return something useful
[code]....
But this gives the following error:
Public Overrides Function ParseValue(sValue As String) As Boolean'
cannot override 'Public Overridable Function ParseValue(sValue As String) As Object'
because they differ by their return types.
I accept that you can't do this, but I'd like to be able to preserve the semantics of what I'm. trying to do, which is to have an untyped version that deals with Object, but a typed version in derived classes that knows about the specific type T.
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Aug 14, 2010
I have a Journal that records entries for different types: Journal(Of ParentT)
[Code]....
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Nov 25, 2011
I am trying to construct a generic interface class with generic functions. My goal was to use this to implement multiple worker classes for database interaction that have the same basic functionality. Each class will deal with different object for example, category, product or supplier but unless the the functions in the interface are generic that this won't work.This is the interface code that I have but I don't know if I have done it correctly. [code]
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Feb 19, 2010
I am working on a general helper class to sort ListView SubItems. I wrote a base class that has much of the code I need. It includes a MustOverride for the Compare method so that the various inherited classes can implment their own comparisons based upon their type. For the value types, I end up with very similar code such as the following, where x and y are ListViewItems: Public Overloads Overrides Function Compare(ByVal x As Object, ByVal y As Object, ByVal sortColumnIndex As Integer, ByVal sortOrder As System.Windows.Forms.SortOrder) As Integer [code]
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Dec 1, 2011
I have an event defined and firing in class B
Public myEvent()
In class A:
Private WithEvents _b as B
Private Sub hander() Handles _b.myEvent
but, this handler does not get called.
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Jan 8, 2009
I haven't done any programming in a while, and I have pretty much 0 experience with databases, so I'm hoping I can get some guidance with what I'm trying to achieve.I have a class (or want to have) which represents a person, for each person there's multiple dates, and for each date there's multiple events which have properties like time, place, duty, etc. I want to be able to save and load this from a database using a form. I want it to be able to function where I can type in the person's name and it will load all the data into the form, which has a combo box for the different dates and events, and when I select a different date and/or event I want the data to change correspondingly.
If someone could just give me a push in the right direction as to where I should be looking for help in achieving that I would really appreciate it. I don't have the class made to do any of that, just an idea of how it will function. I haven't worked much with classes, so I'm not sure how to approach it. Meaning I need guidance with classes and databases alike.
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Sep 8, 2009
I have an object, say Order where if an error occurs, it raises the ErrorOccurred event. If I'm running some code in say, the codebehind for a .aspx page with an public Order registered as WithEvents and I want to check to see if an error has occurred before I run more code, how do I do this? I can't simply check theOrder.ErrorOccurred. Do I have to create a local boolean flag that switches over in the event handler (OnErrorOccurred)?
Example:
Public WithEvents theOrder As New Order
Public Sub DoStuff()
theOrder.DoSomething()
If theOrder.ErrorOccurred Then
[code]....
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Jul 6, 2010
Basically, I have a custom child form class which has events that will be passed to the parent. In the custom child form, I have a declaration of a "MustInherit" class that inherits the DevExpress User Control Class.
The reason for this, is I have many user controls that derive from this base class, and the child form can have an instance of any one of these controls, and doesnt care which. The only requirement is that the child form can handle the same events from each type of control the same way.
Some watered down code snippets(still pretty long unfortunately):
'''Inherited Class
Public Class ChildControlInheritedClass
[Code].....
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Aug 13, 2009
I already read a lot about exception handling and saw many different threads on the subject but still confused when creating class libraries like the following scenario.
Lets say i have a class library "MyClass.dll", inside the project i have two classes:
Skeleton.vb
Imports System.IO
Public Class Skeleton
Public Function Create(ByVal resourceName As String) As String
[Code].....
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Apr 22, 2009
I need to have a dynamic URL preferably from a Test Classformatting this design pattern to handle dynamic links from tests. instead of a constant HomePageURL.
Namespace TestDesign
Public Class HomePage
Inherits IE
[code].....
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Mar 19, 2010
How can I recognize (.NET 2) a generic class?
Class A(Of T)
End Class
' not work '
If TypeOf myObject Is A Then
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Jul 24, 2010
I have a custom class which basically manages the program settings.
In it's New() event, I'm performing a check to see whether a value stored in My.Settings is the same as the default value (I made sure the value wasn't!), if not then it will perform a RaiseEvent ValueChanged().
On my form, I have an instance of the class declared "Private Withevents ProgramSettings as New clsProgramSettings", I also have a handler "Private Sub DoSomething() Handles ProgramSettings.ValueChanged" declared.
When I run the program the form gets loaded, the instance is created, the RaiseEvent is called, but the handler is not receiving the event?
I tried "Private Withevents ProgramSettings as clsProgramSettings", then creating the instance in the Form.Load(), but still no success!?
Is there something I'm doing wrong, or is there a problem with the IDE? I'm using VS 2010.
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Apr 29, 2009
I 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.
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May 10, 2010
I created two classes. One class is StudentClass and the other is HomeroomClass. The HomeroomClass contains a readonly property as a generic list of the StudentClass. [code]...
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Apr 28, 2010
I am really trying to follow the DRY principle. I have a sub that looks like this?
Private Sub DoSupplyModel
OutputLine("ITEM SUMMARIES")
Dim ItemSumms As New SupplyModel.ItemSummaries(_currentSupplyModel, _excelRows)
ItemSumms.FillRows()
[Code]...
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Jan 1, 2011
Here are essential excerpts for the code creating the class and the page using it:
Imports System.Collections.ObjectModel
Public Class Test (Of T as xyz)
Inherits Collection (Of T)
[code].....
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Dec 30, 2009
i've got a Class like this public Class Cart(Of Item) Public Sub New(ByVal a As Integer, ByVal ParamArray items As Item())but i do not see how to create an instance of it: Dim block_names As New Cart(Of String, 5I)i get something like "type expected" o.O
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Jan 11, 2010
I'm having trouble with the definition of an inherited generic class. I have two base classes that are defined like this:[code]
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Jun 10, 2010
how Inheriting List(of T) should work.It seems like what I have below should work but at runtime I get the error:[code..]
If I want to cast a List(of x) to the class xlist, how should I do that?[code...]
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Jul 15, 2010
ok this is the thing I have right now which is working quite well beside its a bit slow:
Public Function GetList() As List(Of SalesOrder)
Try
Dim list As New List(Of SalesOrder)
Dim ds As DataSet
ds = cls.GetSalesOrderList 'CLS is the data access class
[Code]...
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Jun 17, 2012
I am trying to create a class implementing the generic IComparer of my own class "Stellungen" (which translates to positions, like on a chess or checkers board).
This is what I got:
Private Class comparer(Of Stellung)
Implements System.Collections.Generic.IComparer(Of Stellung)
Public Function Compare(x As Stellung, y As Stellung) As Integer Implements System.Collections.Generic.IComparer(Of Stellung).Compare
End Function
End Class
Problem is: inside the function I have no access to any fields of my class. If I start off with x. Intellisense will only give me .Equals, .GetHashCode - the methods you get on a type but not on an instance. Visual Studio 10 also highlights this, in the definition of the function the bits "x as Stellung" and "y as Stellung" are written in light blue, meaning it is a type and not an actual object. How do I access the things I want to compare inside my class?
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Jun 26, 2009
I am creating a generic class that is Implementing IList(Of T) which requires that I implement the GetEnumorator of both IEnumerable(Of T) and IEnumerable. When looking at the members of IList(Of T) I see only one GetEnumorator function, yet it implements IEnumerable(Of T) and IEnumerable. How can I use one function to implement both interfaces when the function definitions only vary by return type?
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Jul 20, 2010
Public Function GetList() As List(Of SalesOrder)
Try
Dim list As New List(Of SalesOrder)
Dim ds As DataSet
[code]....
Now once I start retrieving more than 10000 records from the table, the loop takes long time to load values into generic class. Is there any way that I can get rid of loop? Can I do something like the following with the generic class?
txtSearch.AutoCompleteCustomSource.AddRange(Array. ConvertAll(Of DataRow, String)(BusinessLogic.ToDataTable.ConvertTo(WorkOr derList).Select(), Function(row As DataRow) row("TradeContactName")))
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Oct 7, 2010
I am trying to serialize a class that contains a generic list, and I am finding it all works with the exception of the generic list property. That is to say the other properties are serialized fine and no error is produced.
I have in the past serialized an arraylist - but I thought it was possible to do a generic list in the same way.
Am I missing something or is it not possible to serialize/deserialize a generic list - I have read mixed comments on this..
The relevant parts of the class that gets serialized is defined as..
<XmlInclude(GetType(cConfigUser)), _
Serializable(), XmlRoot(ElementName:="Config")> _
Public Class cConfig
[Code].....
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Jan 28, 2010
I have created a Interface and a couple classes that implement this Interface. I am in the process of developing a Shared Class that utilizes the functions that each of the individual classes have, due to the interface implementation.What i need to know is how do i develop this Shared Class so that way each of the methods within it are restricted to a single data type. This single data type needs to be restricted to any class that has implemented the Interface.
Some examples:
Public Interface IVector(Of T)
Sub Add(ByVal v2 as T)
[code]....
As you can see it would allow me to develop one form, since i have standardized the required Subs/Functions for any class the implements the IVector interface. As i am still in developement, i was wondering if my current understanding of the method generics is correct in its current form or what i would have to do to make the Generic Shared Class work in the fashion that i am looking for in the example implementation.
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Feb 4, 2010
'I am trying to create a public class for handling stored procedures
'Class declarations
'1) Mode (delete, insert, edit)
'2) Stored procedure Name (sp_insert_MyTable, sp_delete_MyTable)
'3) Stored Procedure Parameter Count ( 10 or 5 depends) (need to avoid this)
'4) Stored Procedure Parameters (Here I need to declare as Structure, use dynamic array)
'5) How I can call this in Form
'My Study Code, Please correct it...
Public Class clsTest
Public Structure spParameters
Public varPara As String
Public varDataType As String
Public varDatatypeSize As Integer
[Code] .....
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Aug 26, 2010
I'm relatively new to VB.NET and am having a problem when Databinding a Class to a Forms Controls. Basically within the Class, when Setting certain String Properties I heck that they are not Null/Empty and if they are Throw an Exception. The problem occurs when I bind the properties to textboxes - when the textbox is empty I expect an error to occur (which I will handle). So does anyone have any insight or solutions into why the exceptions are not being thrown when a textbox changed to an empty string?
A condensed example follows:
Dim a As New SomeClass("Random", "Text")
Dim f As New SomeForm(a)
[code].....
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Jun 8, 2010
i created a Class library (.dll) and loaded it as reference into a main project. In the code for the class i've handled exceptions using try..catch subs, however when debugging the main project exceptions that are handled in the DLL still get thrown! (the class ".vb" file gets loaded into the debugger and the line of the exception shows up)
Up till now i've found it useful that when an unhandled error occurs in the imported reference, it shows up in the main project with tracing back to the referenced class. But i dont want the exceptions that are handled in the reference class to be thrown when debugging the main project!
As you can see the exception thrown was handled with try...catch this class exception.vb belongs to the project that created the class library (.DLL that i referenced). i didnt even load the project that built the reference so it amazes me that it could find the coding class to begin with.
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