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  • Catching errors in ANTLR and finding parent

    - by Andreas
    I have found out that I can catch errors during parsing by overwriting displayRecognitionError, but how do I find the parent "node" of this error? ex. if I have the grammar: prog: stat expr; stat: STRING; expr: INTEGER; And give it the input "abc def". Then I will get an error at "def" which should be an integer. At this point I then want to get the parent which is "expr" (since it fails inside the INTEGER part) and it's parent "prog". Kind of like printing stack trace in java. I tried to look at the node from RecognitionException parsed to displayRecognitionError, but it is null, and using CommonErrorNode the parent is null. Should I maybe take a completely different approach?

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  • How to make Net::Msmgr run?

    - by codeholic
    There's Net::Msmgr module on CPAN. It's written clean and the code looks trustworthy at the first glance. However this module seems to be beta and there is little documentation and no tests :-/ Has anyone used this module in production? I haven't managed to make it run by now, because it requires all event loop processing to be done in the application and as I've already said there is little documentation and no working examples to study. That's where I've gone so far: #!/usr/bin/perl use strict; use warnings; use Event; use Net::Msmgr::Object; use Net::Msmgr::Session; use Net::Msmgr::User; use constant DEBUG => 511; use constant EVENT_TIMEOUT => 5; # seconds my ($username, $password) = qw/[email protected] my.password/; my $buddy = '[email protected]'; my $user = Net::Msmgr::User->new(user => $username, password => $password); my $session = Net::Msmgr::Session->new; $session->debug(DEBUG); $session->login_handler(\&login_handler); $session->user($user); my $conv; sub login_handler { my $self = shift; print "LOGIN\n"; $self->ui_state_nln; $conv = $session->ui_new_conversation; $conv->invite($buddy); } our %watcher; sub ConnectHandler { my ($connection) = @_; warn "CONNECT\n"; my $socket = $connection->socket; $watcher{$connection} = Event->io(fd => $socket, cb => [ $connection, '_recv_message' ], poll => 're', desc => 'recv_watcher', repeat => 1); } sub DisconnectHandler { my $connection = shift; print "DISCONNECT\n"; $watcher{$connection}->cancel; } $session->connect_handler(\&ConnectHandler); $session->disconnect_handler(\&DisconnectHandler); $session->Login; Event::loop(); That's what it outputs: Dispatch Server connecting to: messenger.hotmail.com:1863 Dispatch Server connected CONNECT Dispatch Server >>>VER 1 MSNP2 CVR0 --> VER 1 MSNP2 CVR0 Dispatch Server >>>USR 2 MD5 I [email protected] --> USR 2 MD5 I [email protected] Dispatch Server <<<VER 1 CVR0 <-- VER 1 CVR0 And that's all, here it hangs. The handler on login is not being triggered. What am I doing wrong?

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  • How to handle different roles with different previliges in PHP?

    - by user261002
    I would like to know how we can create different "user Roles" for different users in PHP. example: Administrator can create all types of users, add, view, manipulate data, delete managers, viewers, and workers, etc managers can only create, workers and viewers, can add and view data, workers can't create new users, but can only add data and view data, viewers can only view data that has been added to the DB by workers, managers and administrators. I though its better to use different sessions like : $_SESSION['admin'] $_SESSION['manager'] $_SESSION['worker'] $_SESSION['viewvers'] and for every page check which of them have a true or yes value, but I want to know how do they do it in real and big projects??? is there any other way???

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  • Several client waiting for the same event

    - by ff8mania
    I'm developing a communication API to be used by a lot of generic clients to communicate with a proprietary system. This proprietary system exposes an API, and I use a particular classes to send and wait messages from this system: obviously the system alert me that a message is ready using an event. The event is named OnMessageArrived. My idea is to expose a simple SendSyncMessage(message) method that helps the user/client to simply send a message and the method returns the response. The client: using ( Communicator c = new Communicator() ) { response = c.SendSync(message); } The communicator class is done in this way: public class Communicator : IDisposable { // Proprietary system object ExternalSystem c; String currentRespone; Guid currentGUID; private readonly ManualResetEvent _manualResetEvent; private ManualResetEvent _manualResetEvent2; String systemName = "system"; String ServerName = "server"; public Communicator() { _manualResetEvent = new ManualResetEvent(false); //This methods are from the proprietary system API c = SystemInstance.CreateInstance(); c.Connect(systemName , ServerName); } private void ConnectionStarter( object data ) { c.OnMessageArrivedEvent += c_OnMessageArrivedEvent; _manualResetEvent.WaitOne(); c.OnMessageArrivedEvent-= c_OnMessageArrivedEvent; } public String SendSync( String Message ) { Thread _internalThread = new Thread(ConnectionStarter); _internalThread.Start(c); _manualResetEvent2 = new ManualResetEvent(false); String toRet; int messageID; currentGUID = Guid.NewGuid(); c.SendMessage(Message, "Request", currentGUID.ToString()); _manualResetEvent2.WaitOne(); toRet = currentRespone; return toRet; } void c_OnMessageArrivedEvent( int Id, string root, string guid, int TimeOut, out int ReturnCode ) { if ( !guid.Equals(currentGUID.ToString()) ) { _manualResetEvent2.Set(); ReturnCode = 0; return; } object newMessage; c.FetchMessage(Id, 7, out newMessage); currentRespone = newMessage.ToString(); ReturnCode = 0; _manualResetEvent2.Set(); } } I'm really noob in using waithandle, but my idea was to create an instance that sends the message and waits for an event. As soon as the event arrived, checks if the message is the one I expect (checking the unique guid), otherwise continues to wait for the next event. This because could be (and usually is in this way) a lot of clients working concurrently, and I want them to work parallel. As I implemented my stuff, at the moment if I run client 1, client 2 and client 3, client 2 starts sending message as soon as client 1 has finished, and client 3 as client 2 has finished: not what I'm trying to do. Can you help me to fix my code and get my target? Thanks!

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  • iPhone: Error and error handling confusion in comparison.

    - by Mr. McPepperNuts
    NSArray *results = [managedObjectContext executeFetchRequest:request error:&error]; if(results == nil){ NSLog(@"No results found"); searchObj = nil; }else{ if ([[[results objectAtIndex:0] name] caseInsensitiveCompare:passdTextToSearchFor] == 0) { NSLog(@"results %@", [[results objectAtIndex:0] name]); searchObj = [results objectAtIndex:0]; }else { NSLog(@"No results found"); searchObj = nil; } } The code above compares data a user enters to data pulled from a database. If I enter data which is in the database; it works. But if I enter complete gibberish it returns the error below instead of "No results found." *** WebKit discarded an uncaught exception in the webView:shouldInsertText:replacingDOMRange:givenAction: delegate: <NSRangeException> *** -[NSCFArray objectAtIndex:]: index (0) beyond bounds (0) The results array being null should be accounted for during the checks in the above code, no?

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  • Asp.net error object not set to a reference

    - by Frank
    Hi all, Because I rush in development (a lot of whip cracking here) and declare my objects at the top of the function and instantiate inside my try-catch block, I get a lot of the good old "object not set to an instance of an object" errors while doing TDD, and later if I do miss a branch that object was used in (doing VB now, would prefer C#) or just in every day coding, object not set to an instance of an object is a bit vague. Sure the stack trace sends me to the line the error occured at, but it would be nice if I could modify my logging to either name the object or its type because sometimes I have multiple objects on the same line. It's not the end of the world, but in the end it would save me a few minutes each day. Any ideas on how I can pass the info on which object wasn't set? Thanks

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  • How to catch this type of exceptions ?

    - by Lukas Šalkauskas
    I'm starting getting tired of this exception. Can't handle it, even so I'm using this: AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException); Still no success, Can anyone explain me, how I should handle it in a nice way. Or how to detect that it have fired this message and close the application, because I'm starting it automatically everytime it closes.

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  • I have an Errno 13 Permission denied with subprocess in python

    - by wDroter
    The line with the issue is ret=subprocess.call(shlex.split(cmd)) cmd = /usr/share/java -cp pig-hadoop-conf-Simpsons:lib/pig-0.8.1-cdh3u1-core.jar:lib/hadoop-core-0.20.2-cdh3u1.jar org.apache.pig.Main -param func=cat -param from =foo.txt -x mapreduce fsFunc.pig The error is. File "./run_pig.py", line 157, in process ret=subprocess.call(shlex.split(cmd)) File "/usr/lib/python2.7/subprocess.py", line 493, in call return Popen(*popenargs, **kwargs).wait() File "/usr/lib/python2.7/subprocess.py", line 679, in __init__ errread, errwrite) File "/usr/lib/python2.7/subprocess.py", line 1249, in _execute_child raise child_exception OSError: [Errno 13] Permission denied Let me know if any more info is needed. Any help is appreciated. Thanks.

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  • How can I make properties files mandatory in Spring?

    - by Paulo Guedes
    I have an ApplicationContext.xml file with the following node: <context:property-placeholder location="classpath:hibernate.properties, classpath:pathConfiguration.properties" /> It specifies that both properties files will be used by my application. But if one of these files does not exist, no error ir thrown. How can I throw an exception for any of these files? They should me mandatory.

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  • How do I indicate that a class doesn't support certain operators?

    - by romeovs
    I'm writing a class that represents an ordinal scale, but has no logical zero-point (eg time). This scale should permit addition and substraction (operator+, operator+=, ...) but not multiplication. Yet, I always felt it to be a good practice that when one overloads one operator of a certain group (in this case the math operators), one should also overload all the others that belong to that group. In this case that would mean I should need to overload the multiplication and division operators also, because if a user can use A+B he would probable expect to be able the other operators. Is there a method that I can use to throw an error for this at compiler time? The easiest method would be just no to overload the operators operator*, ... yet it would seem appropriate to add a bit more explaination than operator* is not know for class "time". Or is this something that I really should not care about (RTFM user)?

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  • how to remove ConcurrentModificationException

    - by maverick
    what is this exception and how to remove this in my problem i am creating an arraylist of objects, and after checking some condition,i want to remove some objects. but the program is giving this exception ConcurrentModificationException. how to remove this thanks in advance

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  • How to roll back changes in gridview in case of incorrect input

    - by Mustafa A. Jabbar
    Hi, I have a DataGridView that is bound to a list of object. It has some columns that the user can edit. There are certain inputs that are not allowed for a row as a whole. How can I roll back if the user enters invalid inputs in some cell. I tried using the RowValidating event handler but it was not called after cell value has been changed. Even when I implemet CellValueChanged, I still cannot roll back the changes. Any idea how to accomplish this

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  • ASP.NET: How can I properly redirect requests with 404 errors?

    - by Adrian Grigore
    Hi, I'd like my ASP.NET MVC application to redirect failed requests to matching action methods of a certain controller. This works fine on my development machine running Windows 7, but not on my production machine running Windows 2008 R2. I set up my web.config as follows: <customErrors mode="On" defaultRedirect="/Error/ServerError/500"> <error statusCode="403" redirect="/Error/AccessDenied" /> <error statusCode="404" redirect="/Error/FileNotFound" /> </customErrors> This customErrors section works fine on both of my machines (production and development) for 500 Internal Server errors. It also works fine for 404 errors on my development machine. However, it does not properly redirect 404 errors on the production machine. Instead of /Error/FileNotFound, I get the standard 404 page that comes with IIS 7. What could be the problem here?

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  • Detecting GWT RichTextArea 'dirty' state

    - by David
    I want to detect when the contents of my GWT RichTextArea become 'dirty' (have been changed by the user) in order to enable a 'save' button accordingly. I suppose I could listen for key presses that are likely to have changed the contents; but browser support for key presses is notoriously quirky. I suppose I could, before editing begins, save the original contents in a variable, and upon key press, compare the current contents against that variable, but doing that on each key press is going to be really slow. Is there some neat way to achieve RichTextArea dirty-detection?

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  • What should I do if a IOException is thrown?

    - by Roman
    I have the following 3 lines of the code: ServerSocket listeningSocket = new ServerSocket(earPort); Socket serverSideSocket = listeningSocket.accept(); BufferedReader in = new BufferedReader(new InputStreamReader(serverSideSocket.getInputStream())); The compiler complains about all of these 3 lines and its complain is the same for all 3 lines: unreported exception java.io.IOException; In more details, these exception are thrown by new ServerSocket, accept() and getInputStream(). I know I need to use try ... catch .... But for that I need to know what this exceptions mean in every particular case (how should I interpret them). When they happen? I mean, not in general, but in these 3 particular cases.

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  • Are event handlers in JavaScript called in order?

    - by musicfreak
    I know this is a simple question, but I haven't had the chance to test it in any browser other than Firefox. If I attach multiple event handlers to a single event on a single DOM element, are the event handlers guaranteed to be called in the order they were added? Or should I not rely on this behavior?

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  • How should I handle the case in which a username is already in use?

    - by idealmachine
    I'm a JavaScript programmer and new to PHP and MySQL (want to get into server-side coding). Because I'm trying to learn PHP by building a simple online game (more specifically, correspondence chess), I'm starting by implementing a simple user accounts system. Of course, user registration comes first. What are the best practices for: How I should handle the (likely) possibility that when a user tries to register, the username he has chosen is already in use, particularly when it comes to function return values?($result === true is rather ugly, and I'm not sure whether checking the MySQL error code is the best way to do it either) How to cleanly handle varying page titles?($gPageTitle = '...'; require_once 'bgsheader.php'; is also rather ugly) Anything else I'm doing wrong? In some ways, PHP is rather different from JavaScript... Here is a (rather large) excerpt of the code I have written so far. Note that this is a work in progress and is missing security checks that I will add as my next step. function addUser( $username, $password ) { global $gDB, $gPasswordSalt; $stmt = $gDB->prepare( 'INSERT INTO user(user_name, user_password, user_registration) VALUES(?, ?, NOW())' ); $stmt || trigger_error( 'Failed to prepare statement: ' . htmlspecialchars( $gDB->error ) ); $hashedPassword = hash_hmac( 'sha256', $password, $gPasswordSalt, true ); $stmt->bind_param( 'ss', $username, $hashedPassword ); if( $stmt->execute() ) { return true; } elseif( $stmt->errno == 1062) { return 'exists'; } else { trigger_error( 'Failed to execute statement: ' . htmlspecialchars( $stmt->error ) ); } } $username = $_REQUEST['username']; $password = $_REQUEST['password']; $result = addUser( $username, $password ); if( $result === true ) { $gPageTitle = 'Registration successful'; require_once 'bgsheader.php'; echo '<p>You have successfully registered as ' . htmlspecialchars( $username ) . ' on this site.</p>'; } elseif( $result == 'exists' ) { $gPageTitle = 'Username already taken'; require_once 'bgsheader.php'; echo '<p>Someone is already using the username you have chosen. Please try using another one instead.'; } else { trigger_error('This should never happen'); } require_once 'bgsfooter.php';

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  • Error debugging - Conversion from String to Double

    - by Jamie Taylor
    I'm doing some error debugging trying to get the errors on our website down to a minimum and there seems to be an error that is popping up quite a lot Conversion from string "" to type 'Double' is not valid. I'm unable to replicate this problem but I can see that it is happening. I've been looking through the code in one of the pages and strolled across this Dim varWeek As String If varWeek < 10 Then 'Do something' End If Could this be causing the problem as it is trying to see if a String is less than 10 which is an Integer? As I said before as I am unable to see this error in the first place so changing this to an Integer doesn't change anything on my system. Thanks.

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  • Iterating through Event Log Entry Collection, IndexOutOutOfBoundsException

    - by fjdumont
    Hello, in a service application I am iterating through the Windows application event log to parse Events in order react depanding on the entry message. In the case that the event log is full (Windows usually makes sure there is enough space by deleting old entries - this is configurable in the eventvwr.exe settings), the service always runs into an IndexOutOfBoundsException while iterating through the EventLog.Entries collection. No matter how I iterate (for-loop, using the collections enumerator, copying the collection into an array, ...), I can't seem to get rid of this ´bug´. Currently, I ensure that the log is not full in order to keep the service running by regularly deleting the last few item by parsing the event log file and deleting the last few nodes (Don't beat me up, I couldn't find a better alternative...). How can I iterate through the collection without trying to access already deleted entries? Is there probably a more elegant method? I am only trying to acces the logs written during the last x seconds (even LINQ failed to select those when the log is full - same exception), could this help? Thanks for any advice and hints Frank Edit: I forgot to mention that my assumption is the loops are accessing entries which are being deleted during iteration by Windows. Basically that is why I tried to clone the collection. Is there perhaps a way to lock the collection for a small amount of time for just my application?

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  • C++ visitor pattern handling templated string types?

    - by Steve the Plant
    I'm trying to use the visitor pattern to serialize the contents of objects. However one snag I'm hitting is when I'm visiting strings. My strings are of a templated type, similar to STL's basic_string. So something like: basic_string<char_type, memory_allocator, other_possible_stuff> \\ many variations possible! Since I can have very many different templated string types, I can't go and add them to my visitor interface. It would be ridiculous. But I can't add templates to my VisitString method because C++ prevents using templates parameters in virtual methods. So what are my options to work around this?

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  • Communication between layers in an application

    - by Petar Minchev
    Hi guys! Let's assume we have the following method in the business layer. What's the best practice to tell the UI layer that something went wrong and give also the error message? Should the method return an empty String when it was OK, otherwise the error message, or should it throw another exception in the catch code wrapping the caught exception? If we choose the second variant then the UI should have another try,catch which is too much try,catch maybe. Here is a pseudocode for the first variant. public String updateSomething() { try { //Begin transaction here dataLayer.do1(); dataLayer.do2(); dataLayer.doN(); } catch(Exception exc) { //Rollback transaction code here return exc.message; } return ""; } Is this a good practice or should I throw another exception in the catch(then the method will be void)?

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