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  • Why doesn't list.get(0).equals(null) work?

    - by Jessy
    The first index is set to null (empty), but it doesn't print the right output, why? //set the first index as null and the rest as "High" String a []= {null,"High","High","High","High","High"}; //add array to arraylist ArrayList<Object> choice = new ArrayList<Object>(Arrays.asList(a)); for(int i=0; i<choice.size(); i++){ if(i==0){ if(choice.get(0).equals(null)) System.out.println("I am empty"); //it doesn't print this output } }

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  • A couple of questions on exceptions/flow control and the application of custom exceptions

    - by dotnetdev
    1) Custom exceptions can help make your intentions clear. How can this be? The intention is to handle or log the exception, regardless of whether the type is built-in or custom. The main reason I use custom exceptions is to not use one exception type to cover the same problem in different contexts (eg parameter is null in system code which may be effect by an external factor and an empty shopping basket). However, the partition between system and business-domain code and using different exception types seems very obvious and not making the most of custom exceptions. Related to this, if custom exceptions cover the business exceptions, I could also get all the places which are sources for exceptions at the business domain level using "Find all references". Is it worth adding exceptions if you check the arguments in a method for being null, use them a few times, and then add the catch? Is it a realistic risk that an external factor or some other freak cause could cause the argument to be null after being checked anyway? 2) What does it mean when exceptions should not be used to control the flow of programs and why not? I assume this is like: if (exceptionVariable != null) { } Is it generally good practise to fill every variable in an exception object? As a developer, do you expect every possible variable to be filled by another coder?

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  • C# - WinForms - Exception Handling for Events

    - by JustLooking
    Hi all, I apologize if this is a simple question (my Google-Fu may be bad today). Imagine this WinForms application, that has this type of design: Main application - shows one dialog - that 1st dialog can show another dialog. Both of the dialogs have OK/Cancel buttons (data entry). I'm trying to figure out some type of global exception handling, along the lines of Application.ThreadException. What I mean is: Each of the dialogs will have a few event handlers. The 2nd dialog may have: private void ComboBox_SelectedIndexChanged(object sender, EventArgs e) { try { AllSelectedIndexChangedCodeInThisFunction(); } catch(Exception ex) { btnOK.enabled = false; // Bad things, let's not let them save // log stuff, and other good things } } Really, all the event handlers in this dialog should be handled in this way. It's an exceptional-case, so I just want to log all the pertinent information, show a message, and disable the okay button for that dialog. But, I want to avoid a try/catch in each event handler (if I could). A draw-back of all these try/catch's is this: private void someFunction() { // If an exception occurs in SelectedIndexChanged, // it doesn't propagate to this function combobox.selectedIndex = 3; } I don't believe that Application.ThreadException is a solution, because I don't want the exception to fall all the way-back to the 1st dialog and then the main app. I don't want to close the app down, I just want to log it, display a message, and let them cancel out of the dialog. They can decide what to do from there (maybe go somewhere else in the app). Basically, a "global handler" in between the 1st dialog and the 2nd (and then, I suppose, another "global handler" in between the main app and the 1st dialog). Thanks.

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  • How to eliminate Unhandled Exception dialog produced by 3rd party application

    - by Tappen
    I'm working with a 3rd party executable that I can't recompile (vendor is no longer available). It was originally written under .Net 1.1 but seems to work fine under later versions as well. I launch it using Process.Start from my own application (I've tried p/invoke CreateProcess as well with the same results so that's not relevant) Unfortunately this 3rd party app now throws an unhandled exception as it exits. The Microsoft dialog box has a title like "Exception thrown from v2.0 ... Broadcast Window" with the version number relating to the version of .Net it's running under (I can use a .exe.config file to target different .Net versions, doesn't help). The unhandled exception dialog box on exit doesn't cause any real problems, but is troubling to my users who have to click OK to dismiss it every time. Is there any way (a config file option perhaps) to disable this dialog from showing for an app I don't have the source code to? I've considered loading it in a new AppDomain which would give me access to the UnhandledException event but there's no indication I could change the appearence of the dialog. Maybe someone knows what causes the exception and I can fix this some other way?

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  • How to refactor use of the general Exception?

    - by Colin
    Our code catches the general exception everywhere. Usually it writes the error to a log table in the database and shows a MessageBox to the user to say that the operation requested failed. If there is database interaction, the transaction is rolled back. I have introduced a business logic layer and a data access layer to unravel some of the logic. In the data access layer, I have chosen not to catch anything and I also throw ArgumentNullExceptions and ArgumentOutOfRangeExceptions so that the message passed up the stack does not come straight from the database. In the business logic layer I put a try catch. In the catch I rollback the transaction, do the logging and rethrow. In the presentation layer there is another try catch that displays a MessageBox. I am now thinking about catching a DataException and an ArgumentException instead of an Exception where I know the code only accesses a database. Where the code accesses a web service, then I thought I would create my own "WebServiceException", which would be created in the data access layer whenever an HttpException, WebException or SoapException is thrown. So now, generally I will be catching 2 or 3 exceptions where currently I catch just the general Exception, and I think that seems OK to me. Does anyone wrap exceptions up again to carry the message up to the presentation layer? I think I should probably add a try catch to Main() that catches Exception, attempts to log it, displays an "Application has encountered an error" message and exits the application. So, my question is, does anyone see any holes in my plan? Are there any obvious exceptions that I should be catching or do these ones pretty much cover it (other than file access - I think there is only 1 place where we read-write to a config file).

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  • vb.net documentation and exception question

    - by dcp
    Let's say I have this sub in vb.net: ''' <summary> ''' Validates that <paramref name="value"/> is not <c>null</c>. ''' </summary> ''' ''' <param name="value">The object to validate.</param> ''' ''' <param name="name">The variable name of the object.</param> ''' ''' <exception cref="ArgumentNullException">If <paramref name="value"/> is <c>null</c>.</exception> Sub ValidateNotNull(ByVal value As Object, ByVal name As String) If value Is Nothing Then Throw New ArgumentNullException(name, String.Format("{0} cannot be null.", name)) End If End Sub My question is, is it proper to call this ValidateNotNull (which is what I would call it in C#) or should I stick with VB terminology and call it ValidateNotNothing instead? Also, in my exception, is it proper to say "cannot be null", or would it be better to say "cannot be Nothing"? I sort of like the way I have it, but since this is VB, maybe I should use Nothing. But since the exception itself is called ArgumentNullException, it feels weird to make the message say "cannot be Nothing". Anyway, I guess it's pretty nitkpicky, just wondered what you folks thought.

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  • Keep Hibernate Initializer from Crashing Program

    - by manyxcxi
    I have a Java program using a basic Hibernate session factory. I had an issue with a hibernate hbm.xml mapping file and it crashed my program even though I had the getSessionFactory() call in a try catch try { session = SessionFactoryUtil.getSessionFactory().openStatelessSession(); session.beginTransaction(); rh = getRunHistoryEntry(session); if(rh == null) { throw new Exception("No run history information found in the database for run id " + runId_ + "!"); } } catch(Exception ex) { logger.error("Error initializing hibernate"); } It still manages to break out of this try/catch and crash the main thread. How do I keep it from doing this? The main issue is I have a bunch of cleanup commands that NEED to be run before the main thread shuts down and need to be able to guarantee that even after a failure it still cleans up and goes down somewhat gracefully. The session factory looks like this: public class SessionFactoryUtil { private static final SessionFactory sessionFactory; static { try { // Create the SessionFactory from hibernate.cfg.xml sessionFactory = new Configuration().configure().buildSessionFactory(); } catch (Throwable ex) { // Make sure you log the exception, as it might be swallowed System.err.println("Initial SessionFactory creation failed." + ex); throw new ExceptionInInitializerError(ex); } } public static SessionFactory getSessionFactory() { try { return sessionFactory; } catch(Exception ex) { return null; } } }

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  • PHP: Exception not caught by try ... catch

    - by Christian Brenner
    I currently am working on an autoloader class for one of my projects. Below is the code for the controller library: public static function includeFileContainingClass($classname) { $classname_rectified = str_replace(__NAMESPACE__.'\\', '', $classname); $controller_path = ENVIRONMENT_DIRECTROY_CONTROLLERS.strtolower($classname_rectified).'.controller.php'; if (file_exists($controller_path)) { include $controller_path; return true; } else { // TODO: Implement gettext('MSG_FILE_CONTROLLER_NOTFOUND') throw new Exception('File '.strtolower($classname_rectified).'.controller.php not found.'); return false; } } And here's the code of the file I try to invoke the autoloader on: try { spl_autoload_register(__NAMESPACE__.'\\Controller::includeFileContainingClass'); } catch (Exception $malfunction) { die($malfunction->getMessage()); } // TESTING ONLY $test = new Testing(); When I try to force a malfunction, I get the following message: Fatal error: Uncaught exception 'Exception' with message 'File testing.controller.php not found.' in D:\cerophine-0.0.1-alpha1\application\libraries\controller.library.php:51 Stack trace: #0 [internal function]: application\Controller::includeFileContainingClass('application\Tes...') #1 D:\cerophine-0.0.1-alpha1\index.php(58): spl_autoload_call('application\Tes...') #2 {main} thrown in D:\cerophine-0.0.1-alpha1\application\libraries\controller.library.php on line 51 What seems to be wrong?

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  • Catch a thread's exception in the caller thread in Python

    - by Mikee
    Hi Everyone, I'm very new to Python and multithreaded programming in general. Basically, I have a script that will copy files to another location. I would like this to be placed in another thread so I can output "...." to indicate that the script is still running. The problem that I am having is that if the files cannot be copied it will throw an exception. This is ok if running in the main thread; however, having the following code does not work: try: threadClass = TheThread(param1, param2, etc.) threadClass.start() ##### **Exception takes place here** except: print "Caught an exception" In the thread class itself, I tried to re-throw the exception, but it does not work. I have seen people on here ask similar questions, but they all seem to be doing something more specific than what I am trying to do (and I don't quite understand the solutions offered). I have seen people mention the usage of sys.exc_info(), however I do not know where or how to use it. All help is greatly appreciated! EDIT: The code for the thread class is below: class TheThread(threading.Thread): def __init__(self, sourceFolder, destFolder): threading.Thread.__init__(self) self.sourceFolder = sourceFolder self.destFolder = destFolder def run(self): try: shul.copytree(self.sourceFolder, self.destFolder) except: raise

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  • java.lang.ExceptionInInitializerError Exception when creating Application Context in Spring

    - by cyotee
    I am practicing with Spring, and am getting a java.lang.ExceptionInInitializerError exception when I try to instantiate the context. The Exception appears below, with my code following it. I have simplified my experiment from before. The Exception Oct 17, 2012 5:54:22 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@570c16b7: startup date [Wed Oct 17 17:54:22 CDT 2012]; root of context hierarchy Exception in thread "main" java.lang.ExceptionInInitializerError at org.springframework.context.support.AbstractRefreshableApplicationContext.createBeanFactory(AbstractRefreshableApplicationContext.java:195) at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:128) at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:535) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:449) at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139) at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83) at helloworld.HelloWorldTest.main(HelloWorldTest.java:13) Caused by: java.lang.NullPointerException at org.springframework.beans.factory.support.DefaultListableBeanFactory.<clinit>(DefaultListableBeanFactory.java:105) ... 7 more My configuration XML <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:c="http://www.springframework.org/schema/c" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd"> <bean id="messageContainer" class="helloworld.MessageContainer"> <property name="message" value="Hello World"> </property> </bean> <bean id="messageOutputService" class="helloworld.MessageOutputService"> </bean> My test class. package helloworld; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class HelloWorldTest { /** * @param args */ public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("HelloWorldTest-context.xml"); MessageContainer message = context.getBean(MessageContainer.class); MessageOutputService service = context.getBean(MessageOutputService.class); service.outputMessageToConsole(message); } }

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  • php: autoload exception handling.

    - by YuriKolovsky
    Hello again, I'm extending my previous question (Handling exceptions within exception handle) to address my bad coding practice. I'm trying to delegate autoload errors to a exception handler. <?php function __autoload($class_name) { $file = $class_name.'.php'; try { if (file_exists($file)) { include $file; }else{ throw new loadException("File $file is missing"); } if(!class_exists($class_name,false)){ throw new loadException("Class $class_name missing in $file"); } }catch(loadException $e){ header("HTTP/1.0 500 Internal Server Error"); $e->loadErrorPage('500'); exit; } return true; } class loadException extends Exception { public function __toString() { return get_class($this) . " in {$this->file}({$this->line})".PHP_EOL ."'{$this->message}'".PHP_EOL . "{$this->getTraceAsString()}"; } public function loadErrorPage($code){ try { $page = new pageClass(); echo $page->showPage($code); }catch(Exception $e){ echo 'fatal error: ', $code; } } } $test = new testClass(); ?> the above script is supposed to load a 404 page if the testClass.php file is missing, and it works fine, UNLESS the pageClass.php file is missing as well, in which case I see a "Fatal error: Class 'pageClass' not found in D:\xampp\htdocs\Test\PHP\errorhandle\index.php on line 29" instead of the "fatal error: 500" message I do not want to add a try/catch block to each and every class autoload (object creation), so i tried this. What is the proper way of handling this?

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  • Is catching general exceptions really a bad thing?

    - by Bob Horn
    I typically agree with most code analysis warnings, and I try to adhere to them. However, I'm having a harder time with this one: CA1031: Do not catch general exception types I understand the rationale for this rule. But, in practice, if I want to take the same action regardless of the exception thrown, why would I handle each one specifically? Furthermore, if I handle specific exceptions, what if the code I'm calling changes to throw a new exception in the future? Now I have to change my code to handle that new exception. Whereas if I simply caught Exception my code doesn't have to change. For example, if Foo calls Bar, and Foo needs to stop processing regardless of the type of exception thrown by Bar, is there any advantage in being specific about the type of exception I'm catching?

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  • Exception Logging for WCF Services using ELMAH

    - by Ismail
    I tried this solution but I'm getting following exception System.ArgumentNullException was unhandled by user code Message="Value cannot be null.\r\nParameter name: context" Source="Elmah" ParamName="context" StackTrace: at Elmah.ErrorSignal.FromContext(HttpContext context) in c:\builds\ELMAH\src\Elmah\ErrorSignal.cs:line 67 at Elmah.ErrorSignal.FromCurrentContext() in c:\builds\ELMAH\src\Elmah\ErrorSignal.cs:line 61 at ElmahHttpErrorHandler.ProvideFault(Exception error, MessageVersion version, Message& fault) in c:\Myapplication\App_Code\Util\ElmahHttpErrorHandler.cs:line 19 at System.ServiceModel.Dispatcher.ErrorBehavior.ProvideFault(Exception e, FaultConverter faultConverter, ErrorHandlerFaultInfo& faultInfo) at System.ServiceModel.Dispatcher.ErrorBehavior.ProvideMessageFaultCore(MessageRpc& rpc) at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessageCleanup(MessageRpc& rpc) InnerException:

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  • java.lang.IllegalStateException: Parent was not null, but this component not related

    - by Muneeswaran Balasubramanian
    Hi to all, I have the following exception at the time of running jsf program. org.apache.jasper.JasperException: An exception occurred processing JSP page /pages/general/internalServerErrorPage.jsp at line 44 41: <link rel="shortcut icon" href="<%=request.getContextPath()%>/resources/images/infomindzicon.ico" type="image/x-icon" /> 42: </head> 43: <body id="sscmsMainBody"> 44: <h:form id="internalServerErrorPageForm" binding="#{ServerErrorBean.initForm}"> 45: <rich:page id="richPage" theme="#{LayoutSkinBean.layoutTheme}" 46: width="#{LayoutSkinBean.layoutScreenWidth}" 47: sidebarWidth="0"> Caused by: javax.servlet.ServletException: javax.servlet.jsp.JspException: java.lang.IllegalStateException: Parent was not null, but this component not related at org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:858) at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:791) at org.apache.jsp.pages.general.internalServerErrorPage_jsp._jspService(internalServerErrorPage_jsp.java:207) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377) What is the meaning of this exception and how can i resolve this?Please help me.Thanks in advance.

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  • How can I set up .NET UnhandledException handling in a Windows service?

    - by Mike Pateras
    protected override void OnStart(string[] args) { AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException); Thread.Sleep(10000); throw new Exception(); } void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e) { } I attached a debugger to the above code in my windows service, setting a breakpoint in CurrentDomain_UnhandledException, but it was never hit. The exception pops up saying that it is unhandled, and then the service stops. I even tried putting some code in the event handler, in case it was getting optimized away. Is this not the proper way to set up unhandled exception handling in a windows service?

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  • LINQ error when deployed - Security Exception - cannot create DataContext

    - by aximili
    The code below works locally, but when I deploy it to the server it gives the following error. Security Exception Description: The application attempted to perform an operation not allowed by the security policy. To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file. Exception Details: System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. The code is protected void Page_Load(object sender, EventArgs e) { DataContext context = new DataContext(Global.ConnectionString); // <-- throws the exception //Table<Group> _kindergartensTable = context.GetTable<Group>(); Response.Write("ok"); } I have set full write permissons on all files and folders on the server. Any suggestions how to solve this problem? Thanks in advance.

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  • C# File Exception: cannot access the file because it is being used by another process

    - by Lirik
    I'm trying to download a file from the web and save it locally, but I get an exception: C# The process cannot access the file 'blah' because it is being used by another process. This is my code: File.Create("data.csv"); // create the file request = (HttpWebRequest)WebRequest.CreateDefault(new Uri(url)); request.Timeout = 30000; response = (HttpWebResponse)request.GetResponse(); using (Stream file = File.OpenWrite("data.csv"), // <-- Exception here input = response.GetResponseStream()) { // Save the file using Jon Skeet's CopyStream method CopyStream(input, file); } I've seen numerous other questions with the same exception, but none of them seem to apply here. Any help?

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  • When to log exception?

    - by Rune
    try { // Code } catch (Exception ex) { Logger.Log("Message", ex); throw; } In the case of a library, should I even log the exception? Should I just throw it and allow the application to log it? My concern is that if I log the exception in the library, there will be many duplicates (because the library layer will log it, the application layer will log it, and anything in between), but if I don't log it in the library, it'll be hard to track down bugs. Is there a best practices for this?

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  • Undefined reference to cmph functions even after installing cpmh library

    - by user1242145
    I am using gcc 4.4.3 on ubuntu. I installed cmph library tools 0.9-1 using command sudo apt-get install libcmph-tools Now, when I tried to compile example program vector_adapter_ex1.c , gcc is able to detect cmph.h library in its include file but is showing multiple errors like vector_adapter_ex1.c:(.text+0x93): undefined reference to cmph_io_vector_adapter' vector_adapter_ex1.c:(.text+0xa3): undefined reference tocmph_config_new' vector_adapter_ex1.c:(.text+0xbb): undefined reference to cmph_config_set_algo' vector_adapter_ex1.c:(.text+0xcf): undefined reference tocmph_config_set_mphf_fd' even though, these are all defined in the source code of the cmph library. Could anyone tell the error that might have occurred or suggest an alternate method to go about building minimal perfect hash functions.

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  • Tomcat Exception-Type Ignoring Specific Exception for More General

    - by David Marks
    For one type of exception, IOException, I want to display one page. For all other exceptions I have a default error page. In my web.xml I have things setup like this: java.io.IOException /queryException.jsp java.lang.Exception /error.jsp The problem is the error.jsp is the only page that ever shows, even if an IOException is thrown. The order the tags appear in doesn't matter; if I remove the java.lang.Exception tag though, I can get queryException to show for IOExceptions. What is the solution here? How can I keep a general error page for all exceptions EXCEPT for those with specific pages?

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  • Exception declared on ANTLR grammar rule ignored

    - by Kaleb Pederson
    I have a tree parser that's doing semantic analysis on the AST generated by my parser. It has a rule declared as follows: transitionDefinition throws WorkflowStateNotFoundException: /* ... */ This compiles just fine and matches the rule syntax at the ANTLR Wiki but my exception is never declared so the Java compiler complains about undeclared exceptions. ./tool/src/main/antlr3/org/antlr/grammar/v3/ANTLRv3.g shows that it's building a tree (but I'm not actually positive if it's the v2 or v3 grammar that ANTLR 3.2 is using): throwsSpec : 'throws' id ( ',' id )* -> ^('throws' id+) ; I know I can make it a runtime exception, but I'd like to use my exception hierarchy. Am I doing something wrong or should that syntax work?

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  • How to log python exception ?

    - by Maxim Veksler
    Hi, Coming from java, being familiar with logback I used to do try { ... catch (Exception e) { log("Error at X", e); } I would like the same functionality of being able to log the exception and the stacktrace into a file. How would you recommend me implementing this? Currently using boto logging infrastructre, boto.log.info(...) I've looked at some options and found out I can access the actual exception details using this code: import sys try: 1/0 except: exc_type, exc_value, exc_traceback = sys.exc_info() traceback.print_exception(exc_type, exc_value, exc_traceback) I would like to somehow get the string print_exception() throws to stdout so that I can log it. Thank you, Maxim.

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  • PHP: variable-length argument list by reference?

    - by GetFree
    Is it possible to create a PHP function that takes a variable number of parameters all of them by reference? It doesn't help me a function that receives by reference an array of values nor a function that takes its arguments wrapped in an object because I'm working on function composition and argument binding. Don't think about call-time pass-by-reference either. That thing shouldn't even exist.

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  • JNI_CreateJavaVM: Buffer overrun if I throw an exception in case of failure

    - by Dominik Fretz
    Hi, In a C++ project, I use the JNI invocation API to launch a JVM. I've done a little wrapper arount the JVM so I can use all the needed parts in a OO fashion. So far that works great. Now, if the JVM does not start (JNI_CreateJavaVM returns a value < 0) I'd like to raise an exception within my C++ code.But if I throw an exception after JNI_CreateJavaVM, I get a buffer overrun. If I raise the exception without the JNI_CreateJavaVM call, it works as expected. Does anyone have a clue on what the issue could be here? Or how to debug this? Environment: Windows, Visual Studio 2008 JDK: jrockit27.6jdk16005, but happens with SUN stock one as well Cheers Dominik

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