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  • Basic Python: Exception raising and local variable scope / binding

    - by SuperJdynamite
    I have a basic "best practices" Python question. I see that there are already StackOverflow answers tangentially related to this question but they're mired in complicated examples or involve multiple factors. Given this code: #!/usr/bin/python def test_function(): try: a = str(5) raise b = str(6) except: print b test_function() what is the best way to avoid the inevitable "UnboundLocalError: local variable 'b' referenced before assignment" that I'm going to get in the exception handler? Does python have an elegant way to handle this? If not, what about an inelegant way? In a complicated function I'd prefer to avoid testing the existence of every local variable before I, for example, printed debug information about them.

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  • Ruby xml rpc error handling

    - by stel
    I have a model class Car @@RPCServer = XMLRPC::Client.new("localhost", "/", 8080) def self.count @@RPCServer.call("cars.count") end end If server is not running on localhost:8080 I've got a Errno::ECONNREFUSED error. I want to display an error message to user, how can a handle this error?

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  • Exceptions over remote methods

    - by Andrei Vajna II
    What are the best practices for exceptions over remote methods? I'm sure that you need to handle all exceptions at the level of a remote method implementation, because you need to log it on the server side. But what should you do afterwards? Should you wrap the exception in a RemoteException (java) and throw it to the client? This would mean that the client would have to import all exceptions that could be thrown. Would it be better to throw a new custom exception with fewer details? Because the client won't need to know all the details of what went wrong. What should you log on the client? I've even heard of using return codes(for efficiency maybe?) to tell the caller about what happened. The important thing to keep in mind, is that the client must be informed of what went wrong. A generic answer of "Something failed" or no notification at all is unacceptable. And what about runtime (unchecked) exceptions?

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  • Does rails do a rollback if I use begin...rescue?

    - by codeman73
    I'd like to add a begin...rescue block to one of my controllers create method, in order to log better info and construct the correct error message to return to the client. Does the rescue in any way 'interrupt' the rollback process? I'm assuming rails automatically does a rollback. When does it happen? Has it already happened by the time I get in the rescue clause? I'm using mySQL on Dreamhost and I think they use innoDB.

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  • Handling RSS Tags with NSXMLParser for iPhone

    - by MartinW
    I've found the following code for parsing through RSS but it does not seem to allow for nested elements: - (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{ NSLog(@"ended element: %@", elementName); if ([elementName isEqualToString:@"item"]) { // save values to an item, then store that item into the array... [item setObject:currentTitle forKey:@"title"]; [item setObject:currentLink forKey:@"link"]; [item setObject:currentSummary forKey:@"summary"]; [item setObject:currentDate forKey:@"date"]; [item setObject:currentImage forKey:@"media:thumbnail"]; The RSS to used is: <item><title>Knife robberies and burglaries up</title> <description>The number of robberies carried out at knife-point has increased sharply and burglaries are also up, latest crime figures indicate</description> <link>http://news.bbc.co.uk/go/rss/-/1/hi/uk/7844455.stm</link> <guid isPermaLink="false">http://news.bbc.co.uk/1/hi/uk/7844455.stm</guid> <pubDate>Thu, 22 Jan 2009 13:02:03 GMT</pubDate><category>UK</category> <media:thumbnail width="66" height="49" url="http://newsimg.bbc.co.uk/media/images/45400000/jpg/_45400861_policegeneric_pa.jpg"/> </item> I need to extract the "url" element from the "media" tag. Thanks Martin

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  • 'Advanced' Console Application

    - by keynesiancross
    Hi all, I'm not sure if this question has been answered elsewhere and I can't seem to find anything through google that isn't a "Hello World" example... I'm coding in C# .NET 4.0. I'm trying to develop a console application that will open, display text, and then wait for the user to input commands, where the commands will run particular business logic. For example: If the user opens the application and types "help", I want to display a number of statements etc etc. I'm not sure how to code the 'event handler' for user input though. Hopefully this makes sense. Any help would be much appreciated! Cheers.

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  • How to implement event notification mechanism in AIR

    - by nxhoaf
    Do you know how to implement event notification mechanism in AIR ? For simplicity, consider an example: I want to build two applications: "television" and "remote". Among them, television is implemented using AIR. For the "television" I want to use my remote to send message to the television. How must I do to implement "television" in such way that, it runs in waiting mode and whenever it receives a message from "remote", it will process the message and make a suitable action (i.e. change channel, increase volume...). Thank you in advance.

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  • Handling very large lists of objects without paging?

    - by user246114
    Hi, I have a class which can contain many small elements in a list. Looks like: public class Farm { private ArrayList<Horse> mHorses; } just wondering what will happen if the mHorses array grew to something crazy like 15,000 elements. I'm assuming that trying to write and read this from the datastore would be crazy, because I'd get killed on the serialization process. It's important that I can get the entire array in one shot without paging, and each Horse element may only have two string properties in it, so they are pretty lightweight: public class Horse { private String mId; private String mName; } I don't need these horses indexed at all. Does it sound reasonable to just store the mHorse array as a raw Text field, and force my clients to do the deserialization? Something like: public class Farm { private Text mHorsesSerialized; } then whenever the client receives a Farm instance, it has to take the raw string of horses, and split it in order to reinstantiate the list, something like: // GWT client perhaps Farm farm = rpcCall.getMyFarm(); String horsesSerialized = farm.getHorses(); String[] horseBlocks = horsesSerialized.split(","); for (int i = 0; i < horseBlocks.length; i++) { // .. continue deserializing the individual objects ... } yeah... so hopefully it would be quick to read a Farm instance from the datastore, and the serialization penalty is paid by the client, Thanks

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  • Java File Handling, what did I do wrong?

    - by Urda
    Wrote up a basic file handler for a Java Homework assignment, and when I got the assignment back I had some notes about failing to catch a few instances: Buffer from file could have been null. File was not found File stream wasn't closed Here is the block of code that is used for opening a file: /** * Create a Filestream, Buffer, and a String to store the Buffer. */ FileInputStream fin = null; BufferedReader buffRead = null; String loadedString = null; /** Try to open the file from user input */ try { fin = new FileInputStream(programPath + fileToParse); buffRead = new BufferedReader(new InputStreamReader(fin)); loadedString = buffRead.readLine(); fin.close(); } /** Catch the error if we can't open the file */ catch(IOException e) { System.err.println("CRITICAL: Unable to open text file!"); System.err.println("Exiting!"); System.exit(-1); } The one comment I had from him was that fin.close(); needed to be in a finally block, which I did not have at all. But I thought that the way I have created the try/catch it would have prevented an issue with the file not opening. Let me be clear on a few things: This is not for a current assignment (not trying to get someone to do my own work), I have already created my project and have been graded on it. I did not fully understand my Professor's reasoning myself. Finally, I do not have a lot of Java experience, so I was a little confused why my catch wasn't good enough.

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  • Proper exceptions to use for nulls

    - by user200295
    In the following example we have two different exceptions we want to communicate. //constructor public Main(string arg){ if(arg==null) throw new ArgumentNullException("arg"); Thing foo=GetFoo(arg); if(foo==null) throw new NullReferenceException("foo is null"); } Is this the proper approach for both exception types?

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  • Browser not handling exception from AJAX panel, ASP.NET c#

    - by Grant
    Hi, i am having trouble catching errors in an AJAX panel. Even when i throw an exception in the c# code behind the front end completely ignores it. Here is the code i have setup, can anyone see why? I ideally want to show a js alert window on error. Code Behind: protected void btnX_Click(object sender, EventArgs e) { throw new ApplicationException("test"); } protected void ScriptManager_AsyncPostBackError(object sender, AsyncPostBackErrorEventArgs e) { ScriptManager.AsyncPostBackErrorMessage = e.Exception.Message; } Markup: <script type="text/javascript" language="javascript"> Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler); function EndRequestHandler(sender, e) { window.alert(e.get_error().name); } </script> <asp:ScriptManager ID="ScriptManager" runat="server" AllowCustomErrorsRedirect="true" OnAsyncPostBackError="ScriptManager_AsyncPostBackError" />

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  • Excel VBA: Error Handling with Case Statement

    - by AME
    I am trying to validate a file that is uploaded by the user using the code below. The error handler checks the top row of the uploaded file for three specific column names. If one or more of the column names is not present, the program should return a prompt to the user notifying them which column(s) are missing from the file that they uploaded and then close the file. There are a couple issues with my current VBA code that I am seeking help with: The prompt doesn't specify which column(s) are missing to the user. The error handler is triggered even when all required columns are present in the uploaded file. Code: Sub getworkbook() ' Get workbook... Dim ws As Worksheet Dim filter As String Dim targetWorkbook As Workbook, wb As Workbook Dim Ret As Variant Set targetWorkbook = Application.ActiveWorkbook ' get the customer workbook filter = ".xlsx,.xls" caption = "Please select an input file " Ret = Application.GetOpenFilename(filter, , caption) If Ret = False Then Exit Sub Set wb = Workbooks.Open(Ret) On Error GoTo ErrorLine: 'Check for columns var1 = ActiveSheet.Range("1:1").Find("variable1", LookIn:=xlValues, LookAt:=xlWhole, MatchCase:=True).Column var2 = ActiveSheet.Range("1:1").Find("variable2", LookIn:=xlValues, LookAt:=xlWhole, MatchCase:=True).Column var3 = ActiveSheet.Range("1:1").Find("variable3", LookIn:=xlValues, LookAt:=xlWhole, MatchCase:=True).Column ErrorLine: MsgBox ("The selected file is missing a key data column, please upload a correctly formated file.") If Error = True Then ActiveWorkSheet.Close wb.Sheets(1).Move Before:=targetWorkbook.Sheets("Worksheet2") ActiveSheet.Name = "DATA" End Sub

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  • Php string handling triks

    - by Dam
    Hi my question Need to get the 10 word before and 10 words after for the given text . i mean need to start the 10 words before the keyword and end with 10 word after the key word. Given text : "Twenty-three" The main trick : content having some html tags etc .. tags need to keep that tag with this content only . need to display the words from 10before - 10after content is bellow : <div id="hpFeatureBoxInt"><h3><a href="/go/homepage/i/int/news/world/1/-/news/1/hi/world/europe/8592190.stm">Suicide bombings hit Moscow Metro</a></h3><p>Past suicide bombings in Moscow have been blamed on Islamist rebels At least 35 people have been killed after two female suicide bombers blew themselves up on Moscow Metro trains in the morning rush hour,<h2><span class="dy">Top News Story</span></h2> officials say.<img height="150" width="201" alt="Emergency services carry a body from a Metro station in Moscow (29 March 2010)" src="http://wwwimg.bbc.co.uk/feedengine/homepage/images/_47550689_moscowap203_201x150.jpg">Twenty-three died in the first blast at 0756 (0356 GMT) as a<a href="#"> train stood </a>at the central Lubyanka station, beneath the offices of the FSB intelligence agency.About 40 minutes later, a second explosion ripped through a train at Park Kultury, leaving another 12 dead.No-one has said they carried out the worst attack in the capital since 2004. </p><p id="fbilisten"><a href="/go/homepage/i/int/news/heading/-/news/">More from BBC News</a></p></div> Thank you

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  • Validating event usurps button click on Windows Form

    - by triskelion
    I have a ComboBox and a Save button on my Windows Form. When I change the selected value in the ComboBox then click the Save button, the ComboBox validating event fires but the button click is lost. When the selected value is valid this results in the user thinking they have saved the change when in fact they have not. Why is the button click lost if the ComboBox is valid? Is there a work around?

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  • .net exception pool

    - by javier
    I want to create a mecanism in a large .net application to handle all the exceptions in the application, and to save the error messages (in db or log file) so these errors can be fixed, and so we are aware of the problems in the application. Does anyone know a good way of creating a library to handle and process all the exceptions?. Are there any tools around that can simplify my task. What aproach would you suggest me to take.... If you previously implemented something similar to what I want to do, I do want to heard from you Thanks all

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  • Why does "return ERROR" only work with exceptions?

    - by ThreaT
    In the struts.xml I use: <result name="error">error</result> Then in my action I use: addActionError("ERROR RETURNED"); return ERROR; When I submit the form then it just goes to a blank page and does nothing. However, if I FORCE an exception to be thrown in the action then it goes to the error page and shows the ActionError message. So am I doing this wrong? If so, how should I tell struts to show an error page using "if statements" instead of relying solely on expensive try catches? EDIT 1: I'm using struts 2 version: 2.1.8.1 EDIT 2: For example, here is my action code that I'm using to test: String test = ""; int number = 0; try { if (number == 1) { System.out.println("number 1: " + number); test = SUCCESS; } else if (number == 2) { System.out.println("number 2: " + number); addActionError("ERROR RETURNED?"); addActionMessage("TESTTEST"); test = ERROR; } else if (number == 3) { System.out.println("number 3: " + number); addActionError("ERROR RETURNED?"); addActionMessage("TESTTEST"); test = INPUT; } else { System.out.println("number 4: " + number); test = LOGIN; } } catch (Exception e) { addActionError("ERROR RETURNED? " + e); } return test; And here is my JSP code: <s:form action="number_save" method="post"> <s:textfield name="number" label="Enter number" /> </s:form> <s:actionerror /> <s:fielderror /> <s:actionmessage /> EDIT 3: Here is a longer version of my struts.xml: <action name="number" method="numberCreate" class="NumberActionBean"> <result>number.jsp</result> </action> <action name="error"> <result>error.jsp</result> </action> <action name="number_save" method="numberSave" class="NumberActionBean"> <interceptor-ref name="defaultStack"></interceptor-ref> <result name="success" type="redirect">index</result> <result name="input" type="redirect">number</result> <result name="error">error</result> <result name="login" type="redirect">login</result> <result name="none">number</result> </action> EDIT 4: My error.jsp is simply a <s:actionerror /> tag with the general taglibs and html tags...

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  • ThreadExceptionEventHandler and invoking delegates

    - by QmunkE
    If I assign a ThreadExceptionEventHandler to Application.ThreadException, why when I invoke a delegate method using a control on the main application thread are any exceptions thrown by that delegate not triggering the event handler? i.e. static void Main() { ... Application.ThreadException += new System.Threading.ThreadExceptionEventHandler(Application_ThreadException); Application.Run(new Form1()); } static void Application_ThreadException(object sender, System.Threading.ThreadExceptionEventArgs e) { Console.Error.Write("A thread exception occurred!"); } ... private void Form1_Load(object sender, EventArgs e) { Thread syncThread = new Thread(new ThreadStart(this.ThrowException)); syncThread.Start(); } private void ThrowException() { button1.Invoke(new MethodInvoker(delegate { // Not handled by ThreadExceptionEventHandler? throw new Exception(); })); } The context on this is that I have a background thread started from a form which is throwing an unhandled exception which terminates the application. I know this thread is going to be unreliable since it is network connectivity reliant and so subject to being terminated at any point, but I'm just interested as to why this scenario doesn't play out as I expect?

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  • Ruby Methods: return an usage string when insufficient arguments are given

    - by Shyam
    Hi, After creating a serious bunch of classes, with initialize methods, loading them in IRb requires to look back at the code. However, I think it should be easy enough to return a usage message, instead of: ArgumentError: wrong number of arguments (0 for 9) So I prefer to return a string with the human readable arguments, by example using "puts" or just a return of a string. Now I have seen the rescue keyword inside begin-end code, but I wonder how I could catch the ArgumentError when the initialize method is called. Thank you for your answers, feedback and comments!

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  • Help me find article on Multi-threading and Event Handling in Java

    - by JDR
    I once read an article on how to properly write event handlers for multi-threading in Java, but I can't for the life of me find it anymore. It described the pitfalls and potentials for deadlocks that can occur when firing events (not Swing events mind you, but general events like model update notifications). To clarify, the situation would be as such: // let's say this is code from an MVC model somewhere public void setSomeProperty(String myProperty){ if(!this.myProperty.equals(myProperty)){ this.myProperty = myProperty; fireMyPropertyChangedEvent(...); } } The article described how passing control to arbitrary external listener code was a potential cause for deadlock. I now find myself in a situation where I need to fire such events in a multithreaded environment and I would very much like to read the article again to see what it has to say before I continue. Does anyone know the article I'm referring to? I believe it came as a (fairly short) PDF. It started off with an initial naive implementation and incrementally pointed out flaws and improved upon it. It ended with a sort of final proper-way-to-fire-multithreaded-events. I've searched endlessly in my browse history and on google, but all I could find were endless amounts topics on Swing event dispatch threads. Thank you.

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  • GetWindowLongPtr fails if called when handling WM_CREATE

    - by Semen Semenych
    Calling the GetWindowLongPtr function for a dialog box with the DWL_USER parameter fails when done from the WM_CREATE handler. It gives no error (checked that, the return value is always zero), which, according to the MSDN documentation, occurs only if SetWindowLongPtr has not been called previously. However, I call it after registering the window class, and properly call the SetWindowPos after that. Finally, calling GetWindowLongPtr in any other event handler, that is, later than WM_CREATE, works fine. Is there something I'm missing in the initialization sequence, or maybe the messages are sent in some not so obvious order?

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  • How to pass non-fatal warnings from a library

    - by wRAR
    A library function parses a file and returns an object. If a parser encounters unknown data, missing values etc., it shouldn't throw an exception and stop parsing (because this is not fatal), but there should be a way to pass information about these things to a caller (so that warnings can be displayed in the UI, for example). How can these warning be returned? I'm thinking of passing a callback function/object into the library, are there any other possible solutions?

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  • How to handle touch events on UI Controls

    - by Sreelatha
    Hi, I have a query related to Touch events on the UI controls. I have 4 controls on the screen ( UITextField, UISlider, UISwitch, UIButton ). If the user touches any of the control on the screen, I want to fire touchesBegan and touchesEnded events on those controls in which I would implement some code. Please let me know how to fire these events. Thanks in advance, Sreelatha.

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  • How to know the file type of the file which you are forcing the user to download?

    - by Starx
    I am trying to force the user to download a file. For that my script is: $file = "file\this.zip"; header("Cache-Control: public"); header("Content-Description: File Transfer"); header("Content-Disposition: attachment; filename=$file"); header("Content-Type: application/zip"); //This is what I need header("Content-Transfer-Encoding: binary"); readfile($file); The files I am going to upload my not be .zip all the time so I want to know the content type of the image I am going to receive in $file. How to accomplish this

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