I'm developping a winform application and I would like to make it as robust as possible.
In my code there are classes where I throw exceptions that I master very well and catch them whenever it's needed. However, there are some other classes/methods that throw exception that I may have forgotten and are not thrown in the current testing scenarios.
Let's say for example the class StreamReader The constructor may throw different exceptions that should be handeled (MSDN)
My question is there any tool for VB.Net (which works) that would check if am I instanciating the class StreamReader in a Try and Catch ?
I have been looking to the page : Wiki
I checked also the threads StackOverFlow and StackOverFlow
But none of them really helped me.
I read somewhere that every operation theoretically can throw an exception. Well, the idea is to reduce at least the "first level" exception and at least only for core .Net components that may have been forgotten without necessarily targetting 100% of the exceptions or targetting third parties classes.
If someone has an answer I would appreciate your help :)
Cheers in advance.
Related
I've been strugling with WCF to do REST the way I want it to work. And apparently so has quite a few others. I've heard about the WCF Web Api project, but wrongly dismissed it without looking too closely at it. Sadly, now that I'm looking at it I find that the documentation is rather outdated. Like, this blog post has some nice information, but classes have changed, parameters have changed, in short, design has changed.
So I've been using an old example of how to plug in Json.NET (newtonsoft) as my serializier, only to realize that after I had it working, it wouldn't work for my IErrorHandler. Further I had a problem with how to Deserialize a string from the uri template to an operation Type parameter.
It appears however that I should be able to solve these two problems (and presumably many others that I haven't stumbled over yet) by using the media formatter extension point and what's referred to as Processor<..>s in outdated documentation, which is now HttpOperationHandler<..>s unless I've missunderstood.
My problem is rather basic, I can't figure out how to correctly configure my IIS-hosted app to use my operation handler, assuming I've implemented it correctly. Since it feels rather dumb to ask for instructions on such a basic thing, I'll rather ask where I can find some documentation on how to do this sort of thing? (Explanations are welcome of course.)
I'm not after seing which classes exist, or what their methods are named with what parameters. I can see all that in my object browser. I need documentation for the overall design, and/or examples implicitly describing things like:
How do the different classes in the API fit together?
How can I configure from web.config?
Must I rather do a custom HttpServiceHostFactory?
What and how are you meant to use the framework?
How should I extend to reach what sort of goals?
How should I configure to place the extensions in effect?
From the lack of answers I assume the documentation quite simply isn't ready.
I was looking for it on the codeplex site under the Documentation tab, and found outdated stuff.
However, after familiarizing myself a bit with Codeplex I found out that the good stuff was in this Discussion section. Searching a bit in there helped a lot to be honest.
Concerning config-file configuration, I didn't find anything, so I'm assuming this will be added as the last thing before official release. Meaning I'll use the HttpConfiguration in a custom HttpServiceHostFactory for now.
The trick about the HttpOperationHandlers was twofold: Firstly I was throwing an exception in my operation and hadn't implemented a global HttpErrorHandler yet. (Doh!) Secondly I didn't know that the parameter name of HttpOperationHandler<..>.OnHandle had to match the name of the operation parameter.
Firstly, I've never used threads, but have found lots of examples on the internet about their use but nothing that obviously answers my question.
I have a class that loads and manipulates a file(s). It is fairly CPU intensive so I intend to put it in its own thread so that the GUI remains responsive. However, I would also like to use a progress bar to indicate the current status of the file operations.
The question is, what is the best way of approaching this, i.e. How do I get my file class to tell the app where it's up to? Do I have to add thread specific code to my class? Or is there an interface I can implement? Or, am I approaching this all wrong. Additionally (sorry, another stupid question) I assume I need an indicator in my file class to tell the thread when it's finished?
I'm using VS2010 and intend to build the app with WPF (if that's relevant)
Thanks for any advice,
Bob
Since you are intending to use WPF, use a Dispatcher:
Build More Responsive Apps With The Dispatcher
(Otherwise, for Winforms use a BackgroundWorker)
We have 3 developers all using the same version (VS 2008 SP1) and we all use large VB projects (windows forms). From time to time, the IDE will have all sorts of issues such as locking up, crashing, and even not being able to drag a form object around or it will just instantly disappear.
On the largest of our projects (which is actually 5 projects in one solution file), a couple people here can only rebuild the project for testing 2 - 3 times before they have to close the studio and reopen it.
Has anyone else experienced this? Does this happen with large C# projects?
Yes, I experience this all the time! It has gotten better in 2008, if you can believe it.
I usually find that the reason has to do with an exception in my own code. The UI might bring in a custom control that does not behave well in design mode, causing the problem.
Sometimes, I will bring up a second execution of VS2008 and attach the debugger to the first execution of VS. Then, I can debug my own code as it is being run in the designer of the first instance. Often, an exception is thrown and I can fix my code to play better in the designer.
In other circumstances, I have no idea why it happens.
I have heard of people having this issue, however, I have never had an issue at all myself.
I have heard that a number of people trace the issues back to the use of ReSharper as the primary cause.
The most common problem I've had that causes the designer to crash is when I create a form where the only constructors require parameters.
To alleviate that, when I need the form only to be instantiated with parameters, I create a private parameterless constructor that the designer can use but which the form's consumers won't see.
I have personally experienced all sorts of designer wickedness with VS2008 sp1. I uninstalled the service pack to return stability to my dev environment. This is an unfortunate answer, but give it a try.
Only thing I've had close to this is the design view crashing and bringing up an error, formerly causing me to have to recreate the form and copy and paste the code across until I learnt how to fix it.
My problem was occurring because of me using ctrl+f a lot though. If you are using big files, this might be what's happening.
I am working on a VB.NET WinForms app that was "upgraded" by Visual Studio (originally 1.0 or 1.1) from VB6 code (which was itself upgraded from VB5). Except for the few new forms I've created since taking over maintenance of this app, all of the forms in the application have a method called DefInstance which allows you to grab an in-memory copy of the form if there is one. What I can't figure out is why: when would I ever need to reference a form object in memory when it's not immediately in scope where I'm working. To my mind this violates all kinds of sound programming principles and seems like an invitation for memory leaks or worse.
The questions: (1) is this DefInstance thing an merely unfortunate remnant of the VB6 heritage of this app, and (2) should I make a point of removing DefInstance methods throughout the application?
I received this answer from a Microsoft employee:
http://msdn.microsoft.com/en-us/library/aa289529(VS.71,printer).aspx
In short, DefInstance is a "not best practices" compatibility method for older apps that haven't been made into true .NET WinForms apps. Being a web programmer until earlier this year I had never worked with VB6 "WinForms" applications nor had to deal with the compatibility compromises that the upgrade wizard makes in forcing them into .NET.
Yes, the default instance is a terrible byproduct of importing the application through the upgrade wizard. Using the default instance was a VB habit in pre dot net versions because forms were always resident in memmory as a default instance, although you could also g=create additional instances.
As Parvenu74 said, it is not a best practise. That being said, you should be very careful when removing it from an imported application because of side affects and references where it might be being used. Your best bet is to not use it in new code that you develop and slowly migrate yourself away from the "converted" code over time. As was mentioned above the default instance stuff was re-instroduced in VB 2005, but it's use is highly discouraged.
As you mention, it lets you get a reference to the form.
I've seen lots of VB written like this:
Private Sub Command_Click()
Call DoStuff
End Sub
Private Sub DoStuff()
Form1.myTextbox.Text = "Bad Idea"
End Sub
DefInstance allows DoStuff() to continue working without passing controls around.
See here: http://social.msdn.microsoft.com/Forums/en-US/vbgeneral/thread/6d7985b5-6db6-47a8-9e11-cbf114a48d37/ for more info.
Sadly, that toxic bit of syntactic sugar was added to VB8 (VS2005). Now fatally confusing VB.NET programmers when they can't comprehend that each thread has a separate instance of "Form1". The good news: now you definitely don't need DefInstance anymore.
Is there a method for handling errors from COM objects in RDML? For instance, when calling Word VBA methods like PasteSpecial, an error is returned and the LANSA application crashes. I cannot find anything in the documentation to allow handling of these errors.
Actually, error handling in general is a weak-point for LANSA and RDML, but that's another topic.
I know almost nothing about LANSA etc. A few minutes in Google convinced me that error handling is, as you say, not a strong point. Over on the lansa.us site there is this article about remote debugging which, at a stretch, might be going in the right direction.
One wonders if a DEF_BREAK would work. Here's a longish post about using DEF_BREAK. If DEF_BREAK hooks in with #COM_* functions, that might be a possibility. Please pardon my naivety in this regard.
I also found some code at the LANSA Tech Exchange. I had hoped that there'd be something obvious, but no. Being more LANSA-aware than me, you may find something.
At my company, we were able to handle Communication API's through the ActiveX part of LANSA. The supplier embedded his API's in an ActiveX component. We used this component in our LANSA application. This works fine and stable.
Maybe you could embed the Microsoft API's in an ActiveX component too? I don't know from the top of my head if Microsoft Word can be addressed as an ActiveX component.