[Ironruby-core] Handling runtime errors in embedded applications

[Jimmy Schementi]

Oh really? Is there any way to get a to the dynamic stack trace info  
without parsing it yourself?

~Jimmy

On Dec 29, 2009, at 12:51 AM, "Tomas Matousek" <Tomas.Matousek at microsoft.com 
 > wrote:

> ScriptingRuntimeHelpers.GetDynamicStackFrames does not work for  
> IronRuby frames though, only Python is using this technique of stack  
> tracing.
>
> Tomas
>
> -----Original Message-----
> From: ironruby-core-bounces at rubyforge.org [mailto:ironruby-core- 
> bounces at rubyforge.org] On Behalf Of Jimmy Schementi
> Sent: Tuesday, December 29, 2009 3:27 AM
> To: ironruby-core at rubyforge.org
> Subject: Re: [Ironruby-core] Handling runtime errors in embedded  
> applications
>
> James,
>
> To be up-front, your requirements are all possible with IronRuby.
>
> For syntax errors, you're doing the right thing by using  
> ScriptSource.Compile(ErrorListener).
>
> For runtime errors, this gets trickier since all IronRuby runtime  
> errors are also actual CLR exceptions, so you need to depend on the  
> CLR's exception catching mechanisms to detect runtime errors and  
> have your application react accordingly. While using try/catch is  
> one way to simply capture exceptions, as you say, it doesn't cover  
> all cases like catching exceptions from other threads. To solve  
> this, you can hook the CLR's ApplicationUnhandedException event to  
> catch all exceptions from code executing in an AppDomain:
>
>   public static void Main() {
>      AppDomain currentDomain = AppDomain.CurrentDomain;
>      currentDomain.UnhandledException += new  
> UnhandledExceptionEventHandler(MyHandler);
>      try {
>         throw new Exception("1");
>      } catch (Exception e) {
>         Console.WriteLine("Catch clause caught : " + e.Message);
>      }
>      throw new Exception("2");
>      // Output:
>      //   Catch clause caught : 1
>      //   MyHandler caught : 2
>   }
>   static void MyHandler(object sender, UnhandledExceptionEventArgs  
> args) {
>      Exception e = (Exception) args.ExceptionObject;
>      Console.WriteLine("MyHandler caught : " + e.Message);
>   }
>
> AppDomain.UnhandedException documentation: http://msdn.microsoft.com/en-us/library/system.appdomain.unhandledexception.aspx 
> .
>
> Now that you have a reliable way of capturing the actual exception  
> object, you need to do something useful with it. Rather than using  
> RubyExceptionData, it's preferred to use the DLR hosting API:  
> "ScriptEngine.GetService<ExceptionOperations>()". This gives you a  
> ExceptionOperations type, which you can use to format an exception  
> as the language defines.
>
> However, it sounds like you'd rather get a list of stack frames to  
> iterate through, and get information about the frame, rather than  
> just a stacktrace string. You can get the actual dynamic stack  
> frames with ScriptingRuntimeHelpers.GetDynamicStackFrames 
> (exception), which will give you a DynamicStackFrame[] to iterate  
> through, and pull out filenames, line numbers, and method names,  
> without resorting to a regex.
>
> Does that answer all your questions?
>
> ~Jimmy
> ________________________________________
> From: ironruby-core-bounces at rubyforge.org [ironruby-core- 
> bounces at rubyforge.org] on behalf of James Leskovar [lists at ruby- 
> forum.com]
> Sent: Saturday, December 26, 2009 3:12 AM
> To: ironruby-core at rubyforge.org
> Subject: [Ironruby-core] Handling runtime errors in embedded  
> applications
>
> Hi there,
>
> So my application is basically a lightweight IDE for IronRuby, built  
> in C#, with the idea that users should be able to quickly edit and  
> prototype ruby scripts. Part of the application's requirements is to  
> have the ability to handle compilation/syntax errors and runtime  
> exceptions, as well as the ability to 'jump to' the source of errors.
>
> At the moment, I'm wrapping CreateScriptSourceFromFile, Compile and  
> Execute within a try/catch. Syntax errors are easily handled with a  
> custom ErrorListener passed into ScriptSource.Compile. Handling  
> runtime errors though are a little bit more tricky; the easiest way  
> I've found so far involves RubyExceptionData.GetInstance and a linq  
> expression to parse the backtrace with regexes. Not the most elegant  
> solution, but it works.
>
> However, one area where this method falls flat is when the error  
> occurs in a thread created within the script itself; execution is  
> now outside the try/catch, so I'm not able to catch the Exception  
> object.
> Futhermore, nothing seems to happen when the error does occur;  
> nothing gets written to the errorstream, nor is there any indication  
> of any error. It seems like the only way to handle these thread  
> errors is to do it within the script using a begin-rescue block.
>
> My question is, is there an easier way to get runtime error  
> information other than RubyExceptionData? Additionally, what is the  
> best way to handle errors when they occur in a thread other than the  
> one which calls Execute()? It would be handy to be able to set some  
> sort of global 'ErrorListener', or perhaps have the ability to pass  
> in such an object to the call to Execute.
>
> Kind regards,
> James
> --
> Posted via http://www.ruby-forum.com/.
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