VS 2008 Handling Exceptions In Referenced Class Libraries
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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Dec 6, 2009
I'm creating a class library that contains a series of functions with Try...Catch blocks to handle errors. When i run another application that uses the class library, and call a function in the library using parameters that i know should cause an error (i.e. divide by zero), i don't get an exception thrown.
Can you not use Try.. Catch blocks in external libraries? If not, how are you suppose to handle errors in these functions?
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Sep 28, 2011
I am writing a class library that envelopes an USB device driver. This device has its own class library, provided by the hardware vendor.
Very often, especially if you handle with old DLL or COM assemblies, there are methods (functions to be correct) that return TRUE if all was OK, or FALSE if any error happen. Often these methods return information about the error in one of their parameters or separately in a GetLastError method or even if in an OnError event.
Now, normally I handle all native .NET exceptions in my class libray handling locally or re-throwing to the client if the error is useful to know. But what to do with all other errors that are hidden in the vendor's methods? (in the true I have no exceptions, but only returned TRUE or FALSE values).
Let's make an example with the method "CONNECT" that connect the client to the USB device.
I envelope the method in this way:
Public Sub Connect()
oVendorDevice.connect()
End Sub
now if any connection error happen, the vendor's connect method return FALSE. But I do not know why the connection failed. To know why the connection failed I have to call (for example) the method GetLastError that gives me information about the error. (but do not forget that other vendors use other strategies like returning the error in a method's parameter or in a OnError events.
Now, in order to follow a good .NET exception handling strategy I could write something like this:
Public Sub Connect()
Dim res As Boolean = oVendorDevice.connect()
If res = False Then
[Code].....
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Oct 21, 2009
So I've made this control that inherits from the treeview control and basically loads objects from active directory into a treeview (url...).All working fine, but as this is the first custom control I have made that I have intended for other people to use, I'm not quite sure how I should approach error handling.I mean, obviously I shouldnt do something like show any exceptions in a messagebox because that might not be what the person that is using the control wants to happen. So do I just write out exception messages to the debug window? Do I swallow exceptions (guessing not)? Do I just totally ignore them so that they are thrown in the user's project?
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Oct 19, 2009
I'm looking to create a bunch of re-usable classes. I understand the strength of creating a DLL that is reusable, but I would rather keep them un-compilled. When adding an existing .vb file, visual studio makes a copy of that object instead of a simply reference.Is there any way to do this or creating a class library with .DLL the only way?
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Dec 17, 2010
I designed 7 class libraries for 1 project.The project references all 7 libraries.3 of the 7 libraries make references to the other 4 libraries.I thought of just duplicating the code that's referenced in the other 4 libraries, but thats a lot of code.
Example:
PrjctA makes reference to LibA, LibB, LibC, & LibD.If LibA references LibB & LibC also will this fail?
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Aug 13, 2010
writing code to read, write, parse, navigate XML files. Are there any good, simple XML developer libraries/SDKs for handling XML files? If you're familiar with the Kellerman FTP Library, that is the paradigm I have in mind -- i.e., add an import, declare an object and you have every FTP function you'd ever want, with simple syntax.
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Jun 2, 2009
All of us use the try catch blocks. But what is the best way of handling errors within custom functions?Display a messagebox to the user when the exception is thrown (if possible within the function), or return a value indicating that an error was found within the function?
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Apr 18, 2011
I have set up a process to create new tasks to handle file processing. A problem arised where I received and unhandled exception error and just clicking on the continue button, the main process continued to run. Now I also found that within the child task I was having a file conflict error and as the tasks run as separate .exe i was under the impression that everything would have been thread safe. So for the first issue here is the task creation in the main process..GProcess is a complete project on its own consisting of 6 classes. This is added as a class library reference to the main process class form1
Public Class Form1
..Private parser as GProcess.module = new GProcess.module()
dim factory as new taskfactory
[code].....
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Aug 29, 2011
How does one handle unhandled exceptions in a DLL? VS doesn't give me the option to add Application Events, I'm guessing because it's a DLL. Do I just have to do it in the main app?
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Sep 29, 2010
This was a difficult question to google. I have an Order class with a couple of dozen properties such as ClientReference, ShipMethod, etc. I use databinding to bind this class to an Order form. If a user enters an invalid shipping method, an exception is raised in the ShipMethod property and a validation error is displayed to the user. But I'm trying to use the same Order class within an OrderImport class whose job it is to take a flat file and create multiple orders. The problem occurs if I'm assigning to a dozen of the order fields consecutively, and say the first one causes a validation exception. If I have all dozen assignments occuring within a single try-catch block, the next 11 assignments will be skipped and I'll only be able to record one validation error. I could solve the problem by doing a dozen separate try-catch statements, but that doesn't seem very elegant.
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May 21, 2010
What are some of the most common mistakes you've seen made when handling exceptions?It seems like exception handling can be one of the hardest things to learn how to do "right" in .Net. Especially considering the currently #1 ranked answer to Common programming mistakes for .NET developers to avoid? is related to exception handling.
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Apr 28, 2012
When two computers are connected through TCP, and one of them closes and breaks the connection, it throws error 10054 "Remote host forcibly closed the connection".I want to handle this error because I know it will happen more often than not with the application I'm building. In System.Net.Sockets.SocketException, there is an on the error code. But when I run the program, the exception that is being thrown is System.IO.IOException, and the GetType for IOException is the socket exception. I don't know how to handle the socket exception if it's not the root cause of the exception.
Here is the code for my Try Catch block:
For infiniteCounter = 1 To 2
infiniteCounter = 1
[code].....
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May 18, 2010
If any directory within a set being searched by the [URL] or [URL] methods contains a junction point, the entire method fails and returns zero results on my tests under VB 2008. I would like to make the call more robust: to return the folders or files not blocked by access restrictions and to note the folders which were blocked. Do those methods offer a means to do this, or is a recursive folder-by-folder call necessary?
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Dec 3, 2009
I'm creating an application that will utilize a lot of functions for performing scientific calculations. There will also be a lot of 3D and 2D rendering in my application. Hence i will have a lot of common functions that will be utilized frequently.
I have noticed that class libraries (DLL's) are utilized in applications similar to mine, and am wondering if i should utilize them in my application. The trouble is, i can't really think of what use they will be to me. The functions in my application will only be called upon by my application, so i do not need to make my functions accessible to others. The only other benefit i can see from using DLL's is reduced memory usage and .exe size.
Whats the benefit of using DLL's instead of just creating a bunch of modules in my application to store my functions? I have read that another benefit of using DLL's is they are easier to maintain and update as you can update the DLL rather than your entire application. I dont quite understand this, as if you are going to utilize new and updated functions you have added to your DLL's, then you will need to update the code that calls them as well. So again i don't see the benefit in using DLL's in my application.
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Aug 31, 2009
I've just about finished my WPF app, but I just hit a hurdle: my app needs to be totally localized (I've achieved this using databinding/RESX files & multiple cultures), and the actual program does this My problem is that I have a window where you generate reports on your progress.It's designed so that programmers will be able to design their own 'report sections', using interfaces & class libraries.Just one problem though: when I use RESX files inside these class libraries, they won't actually change even if I set their culture to the relevant culture I want to test.
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Mar 22, 2012
im searching for .net class libraries that could help me in accounting and calculating payrolls and other financial processes is there any libraries like that?
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Jan 14, 2010
I want to create a library (.dll) of custom dialog forms. Which type of project do i make? Class Library, Windows Forms Control Library, other? Whats the difference between the two?
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Dec 7, 2009
why intellisense does not work for MessageBox.Show() in a class library? It works for MsgBox.
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Jan 14, 2011
I've wrote a class library in vb. it only has a class called MathEx. Now when i add a reference to a test project, i had to refer to the class as MathEx.MathEx is there anyway i could refer to the class as simply MathEx? (in other words i do not wish to have the default namespace added to my class libraries)
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Mar 13, 2009
I've got a bunch of DLL projects that I'm pulling into my application, each contains their own Settings.settings/app.config. When I compile the app and run for debugging, everything works just fine, but come deployment time I can't get my DLLs to read their own settings files.I've been doing some reading and it has become apparent that there's a couple of methods to getting each dll to read its own configuration - one is to dedicate a .dll.config to the library and the other is to embed the dll's configuration in the process.exe.config.I'm having significant issues trying to implement either and I wondered if anyone has any good docs on this - there appears to be a shortage on the Net.
I'd like a separate .dll.config for each of the libraries if possible, but in a pinch, getting each of my libraries to read their own section of the process.exe.config will he right direction because I'm so close to rolling this application out but this stumbling block is causing me a significant headache.Edit: When I merge the configuration files, I start getting TypeInitializer exceptions when I initialize objects withing my libraries. This is likely just me being retarded, but does someone have a working example of a merged config file and some basic demonstrative code for reading it from multiple assemblies?
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Dec 13, 2010
I am wanting to make a class that can be referenced in from other applications. In this class I simply want to do a showdialog to a form. That form has a ssrs pre-defined within it and a viewer all set to show the report. But when I try and define that action I get that my form is now declaired
Imports System
Imports System.Drawing
Imports System.Collections
[Code]......
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May 12, 2009
I am attempting to move a highly referenced class from one namespace to another. Simply moving the file into the new project which has a different root namespace results in over 1100 errors throughout my solution.Some references to the class involve fully qualified namescape referencing and others involve the importing of the namespace.
I have tried using a refactoring tool (Refactor Pro) to rename the namespace, in the hope all references to the class would change, but this resulted in the aforementioned problem.Anyone have ideas of how to tackle this challenge without needing to drill into every file manually and changing the fully qualified namespace or importing the new one if it doesn't exist already?
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Oct 11, 2009
how to word this, as it is it's complex to understand the concept of the idea. Basically, I'm trying to use an interpreter pattern, based off of the code I used in php. In php the code is:
abstract class Expression {
private static $keycount=0;
private $key;
[code]......
The problem I'm having is that the static variable is blank for each child using it. How can I have it where one child increases the keycount,and ALL of the children have the new keycount variable?
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Jun 6, 2011
I am trying to instantiate a c# class whose project is referenced within a vb.net project.By providing the following declaration/instantiation of the class, I hoped to be able to access the instantiated classes publicly declared byte array within a vb.net module.The compiler won't let me. I get the message Access of shared member, constant member, enum member or nested type through an instance; qualifying expression will not be evaluated. It wants me to replace the reference to the instantiated class and public member frameData() with the general Class definition name. Why can't I access frameData through the instantiated variable rxFrame?
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Oct 15, 2009
I've created a class library and built a dll (release build). I've then referenced the DLL in another project (I've tried several). I can see the namespace and classes in Object Browser and I can declare instances of the classes but I cannot use or see any of the methods or properties! there is no IntelliSense whatsoever and calling the methods manualy results in a 'Declaration expected' error.
Within the class library solution I have a unit test project referencing the class library project which works all works fine (and all the tests pass).
Can anyone provide any pointers to what might be going wrong here? I've built plenty of dlls in the past and have had no trouble referencing them at all.[code]...
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Mar 1, 2011
I am using VB .NET 2003. I have created a user defined Class Library and created a reference to it in my application. Is there a way I can compile the application so that the Class Library DLL is embedded into the application? I would really like to be able to distribute the application without having to distribute the DLL as a second a file.
In other words, I made a New Class Library lets say called TEST. I developed a new class within this library called MYCLASS. I built the Library TEST and created TEST.DLL. I then made a new visual basic project called APP1. I added a reference to TEST.DLL. I now can use TEST.MYCLASS within my APP1 project. The application APP1.EXE will run in the test environment, but if I move it to the runtime environment it will give me an error "File or assembly name TEST or one of its dependencies was not found". To correct this error I can place TEST.DLL in the directory where APP1.EXE resides. I would prefer not to have to put TEST.DLL in the directory. Can I easily compile it into APP1?
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Sep 29, 2009
How would I test the following code?
Public Sub SetSerialIdForDevice()
Try
Dim component As Object = container.getComponentRef("componentInterface")
[code].....
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Feb 26, 2012
I created a custom collection class with some methods: each of these has some parameters and throws an exception if a parameter is not valid.For example, the Add and Remove methods throw an NullReferenceException if one of their parameters is null.[code]...The Replace method replaces an item in the collection with another specified object: to reach the goal, it first calls the Remove method and after the Add method. Obviously the Replace method could throw exceptions if at least one of the specified parameters is null, because Remove and Add methods could throw exceptions.Is this the right way to go? Or should I also check the parameters in the Replace method as in the following code? [code]...In fact, in this second case, each check would be executed twice: first in the Replace method and after in the Remove and Addmethods, which are called by Replace, and in other cases the checks may be rather expensive.
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Sep 23, 2010
Part of my assignment is to check if input to Group Number and Number of Units are correct input by making error handling exceptions...
I have to check the following:
a) group number is neither 501 nor 062
b) number of units are NOT numbers
c) number of units is NOT a positive number
So my first question is, am I checking correctly? 2nd question is, How do I make sure my Exceptions will pertain to their correct respective things (a, b, and c.. above)?
[Code]...
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