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  • When is it appropriate to use error codes?

    - by Jim Hurne
    In languages that support exception objects (Java, C#), when is it appropriate to use error codes? Is the use of error codes ever appropriate in typical enterprise applications? Many well-known software systems employ error codes (and a corresponding error code reference). Some examples include operating systems (Windows), databases (Oracle, DB2), and middle-ware products (WebLogic, WebSphere). What benefits do error codes provide? What are the disadvantages to using error codes?

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  • jQuery event handling with .live() problem with setInterval and clearInterval

    - by Kyle Lafkoff
    jQuery 1.4.2: I have an image. When the mouseover event is triggered, a function is executed that runs a loop to load several images. On the contrary, the mouseout event needs to set the image back to a predetermined image and no longer have the loop executing. These are only for the images with class "thumb": $("img.thumb").live("mouseover mouseout", function(event) { var foo = $(this).attr('id'); var wait; var i=0; var image = document.getElementById(foo); if (event.type == 'mouseover') { function incrementimage() { i++; image.src = 'http://example.com/images/file_'+i+'.jpg'; if(i==30) {i=0;} } wait = setInterval(incrementimage,500); } else if (event.type == 'mouseout') { clearInterval (wait); image.src = 'http://example.com/images/default.jpg'; } return false; }); When I mouseout, the image is set to the default.jpg but the browser continues to loop though the images. It will never stop. Can someone hit me with some knowledge? Thanks.

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  • Error handling in PHP

    - by Industrial
    Hi guys, We're building a PHP app based on Good old MVC (codeigniter framework) and have run into trouble with a massive chained action that consists of multiple model calls, that together is a part of a big transaction to the database. We want to be able to do a list of actions and get a status report of each one back from the function, whatever the outcome is. Our first initial idea was to utilize the exceptions of PHP5, but since we want to also need status messages that doesnt break the execution of the script, this was our solution that we came up with. It goes a little something like this: $sku = $this->addSku( $name ); if ($sku === false) { $status[] = 'Something gone terrible wrong'; $this->db->trans_rollback(); return $status; } $image= $this->addImage( $filename); if ($image=== false) { $error[] = 'Image could not be uploaded, check filesize'; $this->db->trans_rollback(); return $status; } Our controller looks like this: $var = $this->products->addProductGroup($array); if (is_array($var)) { foreach ($var as $error) { echo $error . '<br />'; } } It appears to be a very fragile solution to do what we need, but it's neither scalable, neither effective when compared to pure PHP exceptions for instance. Is this really the way that this kind of stuff generally is handled in MVC based apps? Thanks!

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  • Best practice for handling ConnectionDroppedHandler in OCS Server Application

    - by Paul Nearney
    Hi all, In general, it seems that the majority of times that ConnectionDroppedHandler would get called in an OCS server application is for expected reasons e.g. server application has been unregistered, server is shutting down, etc. Are there any unexpected situations in which ConnectionDroppedHandler can be called? Basically, i'm wondering whether it will ever be necessary to log an error to the event log from this event handler. Many thanks, Paul

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  • C++ wxWidgets Event Handling

    - by Wallter
    Q1:I am using wxWidgets (C++) and have come accost a problem that i can not locate any help. I have created several wxTextCtrl boxes and would like the program to update the simple calculations in them when the user 'kills the focus.' I could not find any documentation on this subject on the wxWidgets webpage and Googling it only brought up wxPython. The two events i have found are: EVT_COMMAND_KILL_FOCUS - EVT_KILL_FOCUS for neither of which I could find any snippet for. Could anyone give me a short example or lead me to a page that would be helpful? Q2:Would i have to create an event to handle the focus being killed for each of my 8 wxTextCtrl boxes? In the case that i have to create a different event: How would i get each event to differentiate from each other? I know i will have to create new wxID's for each of the wxTextCtrl boxes but how do I get the correct one to be triggered? class BasicPanel : public wxPanel { ... wxTextCtrl* one; wxTextCtrl* two; wxTextCtrl* three; wxTextCtrl* four; ... }

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  • Strategies for Error Handling in .NET Web Services

    - by Jarrod
    I have a fairly substantial library of web services built in .NET that I use as a data model for our company web sites. In most .NET applications I use the Global ASAX file for profiling, logging, and creating bug reports for all exceptions thrown by the application. Global ASAX isn't available for web services so I'm curious as to what other strategies people have come up with to work around this limitation. Currently I just do something along these lines: <WebMethod()> _ Public Function MyServiceMethod(ByVal code As Integer) As String Try Return processCode(code) Catch ex As Exception CustomExHandler(ex) 'call a custom function every time to log exceptions Return errorObject End Try End Function Anybody have a better way of doing things besides calling a function inside the Catch?

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  • SSIS Handling Extenal Issues

    - by durilai
    I have an SSIS package that works fine. The package runs every night and takes about 4 hours to complete. I have am a newb to SSIS, so I want to see what my options are. I am not finding anything on the web about these two issues, so any advice is greatly appreciated. What to do when I have an external issue such as a power failure/accidental restart. Is there a way to alert someone or have the package begin again on restart. A couple weeks ago there was a process that got hung and locked table, making the process not execute. How is the best way to handle ensuring I have the proper access before starting and if not, get the access. I am ok with killing the processes etc. Looking for best practice info. Thanks

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  • PHP DOMDocument Error Handling Problem

    - by Jon
    I'm having trouble trying to write an if statement for DOM that will check if $html is blank. However whenever the html page does end up blank, it just removes everything that would be below DOM (including what I had to check if it was blank). $html = file_get_contents("http://example.com/"); $dom = new DOMDocument; @$dom->loadHTML($html); $links = $dom->getElementById('dividhere')->getElementsByTagName('img'); foreach ($links as $link) { echo $link->getAttribute('src'); } All this does is grab an image url in the specified div, which works perfectly until the page is a blank html page. I've tried using SimpleHTMLDOM, which didn't work either (it didn't even fetch the image on working pages). Did I happen to miss something with this one or am I just missing something in both? include_once('simple_html_dom.php') $html = file_get_html("http://example.com/"); foreach($html->find('div[id="dividhere"]') as $div) { if(empty($div->src)) { continue; } echo $div->src; }

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  • Handling PHP exceptions with JQuery

    - by Itamar Bar-Lev
    Hello, I'm using JQuery to call a PHP function that returns a JSON string upon success or throws some exceptions. Currently I'm calling jQuery.parseJSON() on the response and if it fails I assume the response contains an exception string. $.ajax({ type: "POST", url: "something.php", success: function(response){ try { var json = jQuery.parseJSON(response); } catch (e) { alert(response); return -1; } // ... do stuff with json } Can anyone suggest a more elegant way to catch the exception? Many thanks, Itamar

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  • Programming Concepts: What should be done when an exception is thrown?

    - by Dooms101
    This does not really apply to any language specifically, but if it matters I am using VB.NET in Visual Studio 2008. I can't seem to find anything really that useful using Google about this topic, but I was wondering what is common practice when an exception is thrown and caught but since it has been thrown the application cannot continue operating. For example I have exceptions that are thrown by my FileLoader class when a file cannot be found or when a file is deemed corrupt. The exception is only thrown within the class and is not handled really. If the error is detected, then the exception is thrown and whatever function is was thrown is basically quits. So in the code trying to create that object or call one of its members I use a Try...Catch statement. However, I was wondering, what should even do when this exception is caught? My application needs these files to be intact, and if they are not, the application is almost useless. So far I just pop up a message box telling the user their is an error and to reinstall. What else can I do, or better, what's common practice in these situations?

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  • Pylons error handling

    - by TJ Huffington
    Hello, I am just getting started with Pylons and am confused as to how to account for exceptions. What is the proper way to error check user input (ensure a correct email address, check that it doesn't yet exist in the database, etc ...)? Should these checks go inside the model classes or somewhere else? Sample code would be great.

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  • Error Handling for Application in PHP

    - by Zubair1
    I was wondering if someone can show me a good way to handle errors in my PHP app, that i am also easily able to reuse in my codes. So far i have been using the following functions: Inline Errors function display_errors_for($fieldname) { global $errors; if (isset($errors[$fieldname])) { return '<label for="' .$fieldname. '" class="error">' . ucfirst($errors[$fieldname]). '</label>'; } else { return false; } } All Errrors function display_all_errors($showCounter = true) { global $errors; $counter = 0; foreach ($errors as $errorFieldName => $errorText) { if ($showCounter == true) { $counter++; echo '<li>' . $counter . ' - <label for="' .$errorFieldName. '">' .$errorText. '</label></li>'; } else { echo '<li><label for="' .$errorFieldName. '">' .$errorText. '</label></li>'; } } } I have a $errors = array(); defined on the top of my global file, so it is appended to all files. The way i use it is that if i encounter an error, i push a new error key/value to the $errors array holder, something like the following: if (strlen($username) < 3) { $errors['username'] = "usernames cannot be less then 3 characters."; } This all works great and all, But i wondering if some one has a better approach for this? with classes? i don't think i want to use Exceptions with try/catch seems like an overkill to me. I'm planning to make a new app, and i'll be getting my hands wet with OOP alot, though i have already made apps using OOP but this time i'm planning to go even deeper and use OOP approach more extensively. What i have in mind is something like this, though its just a basic class i will add further detail to it as i go deeper and deeper in my app to see what it needs. class Errors { public $errors = array(); public function __construct() { // Initialize Default Values // Initialize Methods } public function __destruct() { //nothing here too... } public function add($errorField, $errorDesc) { if (!is_string($errorField)) return false; if (!is_string($errorDesc)) return false; $this->errors[$errorField] = $errorDesc; } public function display($errorsArray) { // code to iterate through the array and display all errors. } } Please share your thoughts, if this is a good way to make a reusable class to store and display errors for an entire app, or is getting more familiar with exceptions and try/catch my only choice?

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  • ASP.NET Exception Handling in background threads

    - by Xodarap
    When I do ThreadPool.QueueUserWorkItem, I don't want unhandled exceptions to kill my entire process. So I do something like: ThreadPool.QueueUserWorkItem(delegate() { try { FunctionIActuallyWantToCall(); } catch { HandleException(); } }); Is this the recommended pattern? It seems like there should be a simpler way to do this. It's in an asp.net-mvc app, if that's relevant.

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  • Websphere exception handling

    - by Benjamin
    Hi all, From a security standpoint, what is the best solution to handle application errors with Websphere? I've been thinking of creating a class that is called every time an application error is generated, log the error and display a generic error message to the users. In PHP this can be achieved using the set_exception_handler() function. Is there something similar for websphere that could be configured in the web.xml? I've found codes like this on the internet: <error-page> <error-code>500</error-code> <location>/servlet/ExceptionHandlerServlet</location> </error-page> But that would only work with "500" HTTP error codes. I really want something generic that catches everything. Something like a class that implements a certain interface which can have access to all information about the error. Thanks for your time.

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  • Graceful DOS Command Error-Handling w/PHP popen()

    - by Captain Obvious
    PHP 5.2.13 on Windows 2003 I am using the DOS Start /B command to launch a background application using the PHP popen() function: popen("start /B {$_SERVER['HOMEPATH']}/{$app}.exe > {$_SERVER['HOMEPATH']}/bg_output.log 2>&1 & echo $!", 'r'); The popen() function launches a cmd.exe process that runs the specified command; however, if the command fails (e.g. the {$app}.exe doesn't exist or is locked in the above example), the cmd.exe process never returns, and PHP hangs indefinitely as a result. Calling the failing DOS command directly using the Command Prompt results in an Error prompt that requires clicking the OK button. I assume this error confirmation requirement is what's preventing the cmd.exe process from returning to PHP both from the Command Prompt (using both CGI and CLI) and the web (using Apache 2.0 handler w/Apache 2.2). Is there a way to configure PHP, Apache, and/or Win 2003 to return the DOS error to the originating call rather than waiting for confirmation?

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  • best practice on precedence of variable declaration and error handling in C

    - by guest
    is there an advantage in one of the following two approaches over the other? here it is first tested, whether fopen succeeds at all and then all the variable declarations take place, to ensure they are not carried out, since they mustn't have had to void func(void) { FILE *fd; if ((fd = fopen("blafoo", "+r")) == NULL ) { fprintf(stderr, "fopen() failed\n"); exit(EXIT_FAILURE); } int a, b, c; float d, e, f; /* variable declarations */ /* remaining code */ } this is just the opposite. all variable declarations take place, even if fopen fails void func(void) { FILE *fd; int a, b, c; float d, e, f; /* variable declarations */ if ((fd = fopen("blafoo", "+r")) == NULL ) { fprintf(stderr, "fopen() failed\n"); exit(EXIT_FAILURE); } /* remaining code */ } does the second approach produce any additional cost, when fopen fails? would love to hear your thoughts!

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  • Best practice for error handling in an Android Service

    - by Omar Kohl
    I have an Android Service that does some background processing on an image using a separate Thread. If an error occurs in this Service or even worse in the thread, what is the best practice to inform the launching Activity of the problem and allow the application to recover to a stable state (i.e. the state it was in before launching the service). From within the Service I could post a Toast or a Notification, but that doesn't help me. I would like to inform the user about the problem but at the same time recover the application to a stable state.

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  • Ruby on Rails bizarre behavior with ActiveRecord error handling

    - by randombits
    Can anyone explain why this happens? mybox:$ ruby script/console Loading development environment (Rails 2.3.5) >> foo = Foo.new => #<Foo id: nil, customer_id: nil, created_at: nil, updated_at: nil> >> bar = Bar.new => #<Bar id: nil, bundle_id: nil, alias: nil, real: nil, active: true, list_type: 0, body_record_active: false, created_at: nil, updated_at: nil> >> bar.save => false >> bar.errors.each_full { |msg| puts msg } Real can't be blank Real You must supply a valid email => ["Real can't be blank", "Real You must supply a valid email"] So far that is perfect, that is what i want the error message to read. Now for more: >> foo.bars << bar => [#<Bar id: nil, bundle_id: nil, alias: nil, real: nil, active: true, list_type: 0, body_record_active: false, created_at: nil, updated_at: nil>] >> foo.save => false >> foo.errors.to_xml => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<errors>\n <error>Bars is invalid</error>\n</errors>\n" That is what I can't figure out. Why am I getting Bars is invalid versus the error messages displayed above, ["Real can't be blank", "Real you must supply a valid email"] etc. My controller simply has a respond_to method with the following in it: format.xml { render :xml => @foo.errors, :status => :unprocessable_entity } How do I have this output the real error messages so the user has some insight into what they did wrong?

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  • Graceful DOS Command Error-Handling

    - by Captain Obvious
    PHP 5.2.13 on Windows 2003 I am using the DOS Start /B command to launch a background application using the PHP popen() function: popen("start /B {$_SERVER['HOMEPATH']}/{$app}.exe > {$_SERVER['HOMEPATH']}/bg_output.log 2>&1 & echo $!", 'r'); The popen() function launches a cmd.exe process that runs the specified command; however, if the command fails (e.g. the {$app}.exe doesn't exist or is locked in the above example), the cmd.exe process never returns, and PHP hangs indefinitely as a result. Calling the failing DOS command directly using the Command Prompt results in an Error prompt that requires clicking the OK button. I assume this error confirmation requirement is what's preventing the cmd.exe process from returning to PHP both from the Command Prompt (using both CGI and CLI) and the web (using Apache 2.0 handler w/Apache 2.2). Is there a way to write the DOS command or configure the server or cmd.exe app itself to return the DOS error to the originating call rather than waiting for confirmation?

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  • What is the suggested way to show exception messages on UI which were produced in Business Layer?

    - by burak ozdogan
    Hi, Is there a pattern OR 'a best practice' on creating user's friendly messages in the presentation layer by using exceptions which were thrown from the Business Layer? Actually in many cases I prefer to throw Application Exceptions and this is forcing me to catch them on UI (aspx.cs pages). And if the process is complex which may produce many different types of exceptions I have to have many catch blocks to produce specific error messages. Is there a better way coming to your mind? A pattern maybe for similar cases? thanks

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  • Handling multiple exceptions

    - by the-banana-king
    Hi there, I have written a class which loads configuration objects of my application and keeps track of them so that I can easily write out changes or reload the whole configuration at once with a single method call. However, each configuration object might potentially throw an exception when doing IO, yet I do not want those errors to cancel the overall process so that the other objects are still given a chance to reload/write. Therefore I collect all exceptions which are thrown while iterating over the objects and store them in a super-exception, which is thrown after the loop, since each exception must still be handled and someone has to be notified of what exactly went wrong. However, that approach looks a bit odd to me. Someone out there with a cleaner solution? Here is some code of the mentioned class: public synchronized void store() throws MultipleCauseException { MultipleCauseException me = new MultipleCauseException("unable to store some resources"); for(Resource resource : this.resources.values()) { try { resource.store(); } catch(StoreException e) { me.addCause(e); } } if(me.hasCauses()) throw me; }

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  • ASP.NET AJAX WebForms custom error handling question

    - by Vilx-
    I've made a web application that has the following architecture: Every form is a UserControl, there is just one actual page (Default.aspx), and a parameter in the URL specifies which UserControl to load. The UserControl is loaded in an UpdatePanel so that it can enjoy full AJAX-iness. There is also an elaborate message displaying mechanism that I use. Eventually messages end up in one designated area on top of the Default.ASPX with some nice formatting 'n stuff. Now, I would also like to capture any unhandled exceptions that originate in the UserControl and display it in this area with all the bells-and-whistles that I've made for messages. How can I do this? The Page.Error and ScriptManager.AsyncPostBackError somehow don't work for me...

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  • wxWidgets exception handling

    - by Alex Farber
    When unhandled exception is handled in wxWidgets application in Windows, program shows Abort-Retry-Ignore message produced by Widgets exception handler. I want to get normal unhandled exception behavior: program should terminate with standard Windows unhandled exception dialog. Can I prevent Widgets to catch unhahnled exceptions?

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