I have taken over support of a VB.Net WinForms application. I am actually a c# developer and am more familiar with the setup of visual studio projects in c# projects. Now I am trying to determine why my application is crashing on a specific XP installation, and I read the suggestion here
http://social.msdn.microsoft.com/forums/en-US/winformssetup/thread/53c2de93-ab33-41d0-b5dd-7ca5fbfa5c24/
to add a try catch block in the main function. This is suggested in about the 5th post from the bottom. (I will quote it below) However, if I look in the VB.Net visual studio project, I do not find a Main() procedure. What I do find is a grey folder called "My project" with a "Application.myapp" file inside it. This file has an associated designer file, but if I click on it I see the following xml:
<?xml version="1.0" encoding="utf-8"?>
<MyApplicationData xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<MySubMain>true</MySubMain>
<MainForm>MDIMain</MainForm>
<SingleInstance>false</SingleInstance>
<ShutdownMode>0</ShutdownMode>
<EnableVisualStyles>true</EnableVisualStyles>
<AuthenticationMode>0</AuthenticationMode>
<SaveMySettingsOnExit>true</SaveMySettingsOnExit>
</MyApplicationData>
So can anyone enlighten me to where the actual main procedure call is for this VB.Net project so that I can try catch the exception that is occurring. If, as I suspect, there isn't actually a Main procedure in my VB.Net project, can someone maybe let me know how I can go about doing the following in my project:
[STAThread]
static void Main()
{
try
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
catch (System.IO.FileNotFoundException ex)
{
MessageBox.Show(ex.Message + " \n\n\n" + ex.StackTrace);
}
}
VB has a special mode called “Application Framework” (which can be found under the main options).
If this mode is enabled, the compiler auto-generates a Main method and some fluff around it. You can disable this option; however, this may cause problems in the project since the application framework functionality might actually be used by the project.
Alternatively, you can register an event handler for uncaught exceptions (UnhandledExceptions) using this same application framework.
The more VB way to do this is to open the Application properties and click on the ViewApplicationEvents button. This will open the Application.xaml.vb file where you can add custom event handlers for the application. Select Application Events from the left drop-down and you can easily access a bunch of events including DispatcherUnhandledException, Activated, Navigating, Startup, Exit, etc. You can also add the Main method here by selecting Applciation from the left drop-down and selecting Main from the right drop down.
In the case of WindowsForms applications, the process is similar. However when you select the Applciation Events button, the file that is shown is the ApplicationEvents.vb file. In here, to add a global error handler, select the left drop-down and select MyApplication Events. Then in the right drop-down, add the UnhandledException handler. You can also create your Main method here as well.
It is generated automatically by the compiler when it can't find one, but you can create one yourself.
http://msdn.microsoft.com/en-us/library/ms235406%28v=VS.100%29.aspx
http://msdn.microsoft.com/en-us/library/y4bwckbb.aspx
I came to this page today in search of answers, and I found some good ones, both here and in The Code Project.
By the time I satisfied myself that I knew what to do, I also had in hand a simplified approach that leaves the project properties virtually untouched. (You must turn off the Application Framework, or the VB runtime won't run your Main routine!) In a nutshell, if you define your Main routine in the class module that defines your startup form, the Visual Basic runtime engine will find and execute it.
As is stated above, your routine must be defined as Shared. You can see my example, along with a few other notes, at How to Run a Particular Form in VB.NET
Caveat
When you disable the Application Framework, you lose the Single Instance check box. I just finished updating the cited example to include the code that I developed and tested to enforce single instance.
You can create that method anywhere, as long as it's Shared. To wire it up, you have to go into the project settings and set the entry point to be your Main method.
Related
I have a visual studio windows forms application that has multiple projects, each having multiple forms. The project that loads on startup calls another project's form and closes its own. Referring to the startup program as "setup" and the other as "main". I have a scenario where I want to skip setup and be able to return to it later. Since setup is a dependency of main, and not the other way around, I cannot seem to create an instance of the setup form. Is this the case, or am I doing something wrong?
The call from setup to open main is as so
this.Hide();
frmDemo demo = new frmDemo();
demo.ShowDialog();
this.Close();
I want to do the same thing from main to setup form, but I am having trouble.
Essentially it should just be
frmSetup setup = new frmSetup();
setup.show();
But this isn't working because it cannot find the form.
Well if you want to reference Setup from Main then you need to add a reference in Main.
The problem then is that you will create a circular dependency, which is bad design (and I think you will also get compiler errors).
There are some ways to get around this, but the best approach it to make your Main program the first one that starts-up (not setup). Then during startup it launches the set-up form and waits until it is finished and then continues. And then when it needs to launch setup again, then it is no problem.
So you are effectively reversing the dependency.
I've been debugging a WPF application bequeathed to me by a gentleman who is fond of making interesting architectural decisions. As a result, I'm having trouble locating the code that runs when a user clicks an on-screen menu item. Following the binding from the view to the viewmodel got me to some collection of "control functions" that's initialized at startup (apparently, all manner of different controls with varying functions had to go into a single collection). I've managed to find some code that's triggered by the click, but it's too deep, too far removed from the click event to be of any use to me.
This got me thinking...
In Visual Studio, (I'm using VS2015) when the application isn't running, if you select Debug -> Step into, debug is triggered, and then the debugger breaks on the very first line of the code (in my case the constructor call of the class that inherits from System.Windows.Application)
Isn't there a way to do this while the application is already running? Let's say I've started a WPF (or WinForms) application, a window has been displayed, the UI thread is running and awaiting user input. The user clicks on a button, and some code is executed. But unless there's a breakpoint in the code, the debugger doesn't do anything about it. As I've explained, this can be a problem if I don't know which code is actually run. Is there a way to tell Visual Studio, "listen, if the user clicks on something, break on the first line of (user) code triggered by this action." Is that possible?
Visual Studio opens source code on top of the stack when I "break all" while debugging; I want to keep the cursor on the document I'm currently working on, without any other document or window (e.g.: no symbols loaded) being opened.
There is a way to stay on the current document, but that requires creating a Visual Studio add-in and a new UI command in the Debug toolbar. Credits for this answer should actually also go to openshac, who posted a similar SO question and also gave a workaround in his OP by using a macro.
The implementation is fairly simple (it took me a few minutes to have it working). First, in the add-in project, modify the Exec method in the Connect.cs file like this:
public void Exec(string commandName, vsCommandExecOption executeOption, ref object varIn, ref object varOut, ref bool handled)
{
handled = false;
if(executeOption == vsCommandExecOption.vsCommandExecOptionDoDefault)
{
if(commandName == "BreakInCurrentDocument.Connect.BreakInCurrentDocument")
{
// here's where the magic happens
// ******************************
var activeWindow = _applicationObject.ActiveWindow;
_applicationObject.Debugger.Break();
if (_applicationObject.ActiveWindow != activeWindow)
{
_applicationObject.ActiveWindow.Close(vsSaveChanges.vsSaveChangesNo);
}
// ******************************
handled = true;
return;
}
}
}
After creating and registering the add-in, just:
click TOOLS on the Visual Studio's menu
Customize
Commands
Choose the "Toolbar" radio button
Select "Debug"
Add Command...
From the "Addins" category, choose your custom add-in.
That's it.
Latest build of VSCommands extension (free version) available from http://visualstudiogallery.msdn.microsoft.com/a83505c6-77b3-44a6-b53b-73d77cba84c8 has just what you want.
It adds a Break In Current Document button to Debug Toolbar and Debug Menu:
http://vscommands.squaredinfinity.com/Media/VSCommands/BlogPost//blog/breakincurrentdocument.png
It's a feature.. when you do "break all" then it is assumed that your process has hung. The first thing you might be interested in such case is - WHERE. Hence, it's directing you right down to the 'current' place that is being executed. IIRC, this is defacto standard for all low-level debuggers. If you don't want the "no symbols loaded" just mark the 'show disasembly' and it will never pop up again:) (of course, instead, you will see the exact point of stop. And yes, this is also a feature that I myself used many times to debug unknown library code)
On the other hand, if you know where you want the code to stop, place the breakpoint there instead.
On yet another hand (as if we had three), if you want to actually stop the application - stop it, don't break, just stop.
I sense that your actual problem lies in the fact that you use one of the features in a wrong way, and therefore another feature bugs you. Please tell me, what do you use the "break all" for and how/why does it collide with your current text-editing. Why can't you stop or break-at-here instead? Or "detach"?
Anyways, I have to admit that as a feature, there should be some option for turning it off, just for the sake of configurability of the IDE.
EDIT
AAhh.. you're right. I've completely forgot about the glorious edit&continue. I'm not joking/teasing, E&C is a great feature that I wish all other platforms had. I've forgot about it, because... I extensively use lambdas, generics, foreachs and etc features that effectively block edit-and-continue.
Anyways, the point is, since that the edit-and-continue is the golden feature that you'd like to use - the application must be in 'break' mode. However, nevertheless how do 'break'/'pause' etc it, the IDE will assume it that the PAUSE was you goal, not editing, hence it will show you where did you pause the app.
There are a few options in MSVS like "show just my code" that may help you a little, but it will not solve the problem: edit-and-continue during debugging was designed for "small, local edits". Like, if(x>0)throw new uncaught() instead if(x<0)throw new uncaught(). Your app stopped on assertion or breakpoint and is about to crash, first-change exception handler fired off and here's your chance! You unwind the crash handler, correct the code, then run. Everything in the same one method which you had the stop occur in, as a way of just-in-time patches..
This is one of the main problems why can't you add methods, classes, modify generics, etc during E&C session: ie. editing your current lambda or current foreach might be OK, but the IDE would be not able to relocate the flows and execute the new code properly. This is a bit similar to why you sometimes see the "stale code" warning, but with those code constructs it is even harder to analyze, and therefore not implemented. And probably will never hit the top of MS's TO-DO list :/
The current boom in .Net/C# is not 'live development' but 'notaliveyet development' heavily supported by modularity and unit testing, where you put the effort to be able to test most of the features of the application off-line.. But that's a paradigm shift and for small projects or for local desktop development sometimes it is simply an overkill.
I have put some code inside of the public MainWindow() {} but I kept getting some obscure XAML parsing errors as soon as I did that (not on my computer but on 3 others I've tried it on - yep!)
Is there the preferred way to run code AS SOON as t he application starts?
The theory is I want it to call home and ask it it's ok to start. If it's not, I want the app to close out. Call it a makeshift copy-protection :)
Under normal circumstances, WPF creates the Main method (the entrypoint of the application) for you. Your options
Create a handler for the Application.Startup event and put your code there. Alternatively, you can override the OnStartup() method.
If that's too late for you, put your code in the App's parameterless constructor (it probably doesn't exist, but you can create it).
If even that's too late, you can create your own Main() method. There are several ways how to do that. Probably the easiest is to put it in another class and tell Visual Studio you want to use this method in the project's properties.
On the other hand, you said you're getting some obscure XAML parsing errors. Maybe you should figure out what exactly do they mean?
You have Window.Loaded event in WPF.
But if if you want to check for run permission before application loads ( due some resource consuption or some business strategy) use a bootstrapper a separate small executable that first launched by mainexe and after if everything ok a bootstrapper runs main exe
I am designing a basic app with multiple forms I seem to be coming across this problem and it will probably be something stupid.
When I make a change to my main form in design mode (like add a button), the button appears in design mode and I can code it but when I build the program it doesn't show up.
Any ideas?
Clean and Rebuild
Make sure you're you're starting a correct form in Application.Run in Program.cs
Most Important of all ..
Save your changes !
And make sure that the build compiles (it might not compile and not ask you if you want it to run the last successful build).
Check out what Microsoft themselves say:
http://vidmar.net/weblog/archive/2005/02/04/999.aspx
The problem was resolved. Just go to taskbar> build >clean rebuild.
Some questions:
If you change the code-behind, does the debugger stop on a breakpoint you put on that change? Also, declare a dummy variable and check if it is visible through the debugger windows such as "Locals", "Autos", "Watch" or "Immediate"?
Did you tamper with Form's default constructor (add parameters, change visibility, that sort of things)?
The form you are changing - are you positive that it is actually a main form (check the Program.Main)?
Does your form include user controls?
Did you try restarting the Visual Studio?
Did you try a full rebuild?
Did you try manually deleting all bin/obj folders then rebuilding?
Is your project actually selected for building under current configuration/platform (investigate the Build check-box under Configuration Manager)?
Did the project successfully build (check the error log)?
Are you running the same configuration/platform that you are building? Are you running the same project that you are building?
Ensure the right project is bold in the Solution Manager or check the start-up project in Solution Manager.
Do you happen to use "Start external program" under debugging options?
OK, this is not exactly an "answer", but answering these questions may produce some clues as to where is the actual problem...