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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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  • Handling missing/incomplete data in R

    - by doug
    As you would expect from a DSL aimed at data analysts, R handles missing/incomplete data very well, for instance: Many R functions have an 'na.rm' flag that you can set to 'T' to remove the NAs, but if you want to deal with this before the function call, then: to replace each 'NA' w/ 0: ifelse(is.na(vx), 0, vx) to remove each 'NA': vx = vx[!is.na(a)] to remove entire each row that contains 'NA' from a data frame: dfx = dfx[complete.cases(dfx),] All of these functions remove 'NA' or rows with an 'NA' in them. Sometimes this isn't quite what you want though--making an 'NA'-excised copy of the data frame might be necessary for the next step in the workflow but in subsequent steps you often want those rows back (e.g., to calculate a column-wise statistic for a column that has missing rows caused by a prior call to 'complete cases' yet that column has no 'NA' values in it). to be as clear as possible about what i'm looking for: python/numpy has a class, 'masked array', with a 'mask' method, which lets you conceal--but not remove--NAs during a function call. Is there an analogous function in R?

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  • Eclipse And Linux: Keyboard unusable after gnome-screen-saver

    - by Martijn Courteaux
    Hi, I know this is not programming related. But I can't find any topics on Google or UbuntuForums. So the problem is: When gnome-screensaver starts on the moment Eclipse has the focus and I wake up again my laptop, Eclipse doesn't listen to keyboard-events. To solve this I have to change the focus to another program and then back to Eclipse. Than it works again. This isn't a real problem, but it would be nice if someone can solve it. Thanks

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  • Uncatchable errors in node.js

    - by Peter Burns
    So I'm trying to write a simple TCP socket server that broadcasts information to all connected clients. So when a user connects, they get added to the list of clients, and when the stream emits the close event, they get removed from the client list. This works well, except that sometimes I'm sending a message just as a user disconnects. I've tried wrapping stream.write() in a try/catch block, but no luck. It seems like the error is uncatchable.

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  • Keyboard- and mouse-event transparent widget

    - by Gajender
    When i click a button my main window i want it to become transparent to keyboard and mouse events, i.e. all keyboard and mouse events should pass to any windows below it as if that window is not present there. "Qt::WA_TransparentForMouseEvents" does not work here as this only make child windows transparent to keyboard and mouse events i guess. And my window is main window and i want to pass all event to any window on desktop not just parent window.

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  • Customizing Mail Message in SSIS Event Handler

    - by Eric Ness
    I want to add an email notification to an SSIS 2005 package event handler. I've added a Send Mail task to the event handler. I'd like to customize the email body to include things like the error description. I've tried including @[System::ErrorDescription] in the MessageSource field, but the mail message doesn't include the value of ErrorDescription only the name of the variable.

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  • How should I re-raise a Delphi exception after logging it?

    - by Nik
    Do you know a way to trap, log, and re-raise exception in Delphi code? A simple example: procedure TForm3.Button1Click(Sender: TObject); begin try raise Exception.Create('Bum'); except on E: Exception do begin MyHandleException(E); end; end; end; procedure TForm3.MyHandleException(AException: Exception); begin ShowMessage(AException.Message); LogThis(AException.Message); // raise AException; - this will access violate end; So I need to re-raise it in the except block but I was wondering if there is a better way to write my own method to handle and (on specific conditions) to re-raise exceptions.

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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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  • systematizing error codes for a web app in php?

    - by user151841
    I'm working on a class-based php web app. I have some places where objects are interacting, and I have certain situations where I'm using error codes to communicate to the end user -- typically when form values are missing or invalid. These are situations where exceptions are unwarranted ( and I'm not sure I could avoid the situations with exceptions anyways). In one object, I have some 20 code numbers, each of which correspond to a user-facing message, and a admin/developer-facing message, so both parties know what's going on. Now that I've worked over the code several times, I find that it's difficult to quickly figure out what code numbers in the series I've already used, so I accidentally create conflicting code numbers. For instance, I just did that today with 12, 13, 14 and 15. How can I better organize this so I don't create conflicting error codes? Should I create one singleton class, errorCodes, that has a master list of all error codes for all classes, systematizing them across the whole web app? Or should each object have its own set of error codes, when appropriate, and I just keep a list in the commentary of the object, to use and update that as I go along?

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  • wxPython: How to handle event binding and Show() properly.

    - by Gopal
    Hi all, I'm just starting out with wxPython and this is what I would like to do: a) Show a Frame (with Panel inside it) and a button on that panel. b) When I press the button, a dialog box pops up (where I can select from a choice). c) When I press ok on dialog box, the dialog box should disappear (destroyed), but the original Frame+Panel+button are still there. d) If I press that button again, the dialog box will reappear. My code is given below. Unfortunately, I get the reverse effect. That is, a) The Selection-Dialog box shows up first (i.e., without clicking on any button since the TopLevelframe+button is never shown). b) When I click ok on dialog box, then the frame with button appears. c) Clicking on button again has no effect (i.e., dialog box does not show up again). What am I doing wrong ? It seems that as soon as the frame is initialized (even before the .Show() is called), the dialog box is initialized and shown automatically. I am doing this using Eclipse+Pydev on WindowsXP with Python 2.6 ============File:MainFile.py=============== import wx import MyDialog #This is implemented in another file: MyDialog.py class TopLevelFrame(wx.Frame): def __init__(self,parent,id): wx.Frame.__init__(self,parent,id,"Test",size=(300,200)) panel=wx.Panel(self) button=wx.Button(panel, label='Show Dialog', pos=(130,20), size=(60,20)) # Bind EVENTS --> HANDLERS. button.Bind(wx.EVT_BUTTON, MyDialog.start(self)) # Run the main loop to start program. if __name__=='__main__': app=wx.PySimpleApp() TopLevelFrame(parent=None, id=-1).Show() app.MainLoop() ============File:MyDialog.py=============== import wx def start(parent): inputbox = wx.SingleChoiceDialog(None,'Choose Fruit', 'Selection Title', ['apple','banana','orange','papaya']) if inputbox.ShowModal()==wx.ID_OK: answer = inputbox.GetStringSelection() inputbox.Destroy()

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  • Reverse massive text file in Java

    - by DanJanson
    What would be the best approach to reverse a large text file that is uploaded asynchronously to a servlet that reverses this file in a scalable and efficient way? text file can be massive (gigabytes long) can assume mulitple server/clustered environment to do this in a distributed manner. open source libraries are encouraged to consider I was thinking of using Java NIO to treat file as an array on disk (so that I don't have to treat the file as a string buffer in memory). Also, I am thinking of using MapReduce to break up the file and process it in separate machines. Any input is appreciated. Thanks. Daniel

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  • Is it safe to silently catch ClassCastException when searching for a specific value?

    - by finnw
    Suppose I am implementing a sorted collection (simple example - a Set based on a sorted array.) Consider this (incomplete) implementation: import java.util.*; public class SortedArraySet<E> extends AbstractSet<E> { @SuppressWarnings("unchecked") public SortedArraySet(Collection<E> source, Comparator<E> comparator) { this.comparator = (Comparator<Object>) comparator; this.array = source.toArray(); Collections.sort(Arrays.asList(array), this.comparator); } @Override public boolean contains(Object key) { return Collections.binarySearch(Arrays.asList(array), key, comparator) >= 0; } private final Object[] array; private final Comparator<Object> comparator; } Now let's create a set of integers Set<Integer> s = new SortedArraySet<Integer>(Arrays.asList(1, 2, 3), null); And test whether it contains some specific values: System.out.println(s.contains(2)); System.out.println(s.contains(42)); System.out.println(s.contains("42")); The third line above will throw a ClassCastException. Not what I want. I would prefer it to return false (as HashSet does.) I can get this behaviour by catching the exception and returning false: @Override public boolean contains(Object key) { try { return Collections.binarySearch(Arrays.asList(array), key, comparator) >= 0; } catch (ClassCastException e) { return false; } } Assuming the source collection is correctly typed, what could go wrong if I do this?

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  • keyUp event heard?: Overridden NSView method

    - by Old McStopher
    UPDATED: I'm now overriding the NSView keyUp method from a NSView subclass set to first responder like below, but am still not seeing evidence that it is being called. @implementation svsView - (BOOL)acceptsFirstResponder { return YES; } - (void)keyUp:(NSEvent *)event { //--do key up stuff-- NSLog(@"key up'd!"); } @end --ORIGINAL POST-- I'm new to Cocoa and Obj-C and am trying to do a (void)keyUp: from within the implementation of my controller class (which itself is of type NSController). I'm not sure if this is the right place to put it, though. I have a series of like buttons each set to a unique key equivalent (IB button attribute) and each calls my (IBAction)keyInput method which then passes the identity of each key onto another object. This runs just fine, but I also want to track when each key is released. --ORIGINAL [bad] EXAMPLE-- @implementation svsController //init //IBActions - (IBAction)keyInput:(id)sender { //--do key down stuff-- } - (void)keyUp:(NSEvent *)event { //--do key up stuff-- } @end Upon fail, I also tried the keyUp as an IBAction (instead of void), like the user-defined keyInput is, and hooked it up to the appropriate buttons in Interface Builder, but then keyUp was only called when the keys were down and not when released. (Which I kind of figured would happen.) Pardon my noobery, but should I be putting this method in another class or doing something differently? Wherever it is, though, I need it be able to access objects owned by the controller class. Thanks for any insight you may have.

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  • Handling Types Defined in Plug-ins That Are No Longer Available

    - by Chris
    I am developing a .NET framework application that allows users to maintain and save "projects". A project can consist of components whose types are defined in the assemblies of the framework itself and/or in third-party assemblies that will be made available to the framework via a yet-to-be-built plug-in architecture. When a project is saved, it is simply binary-serialised to file. Projects are portable, so multiple users can load the same project into their own instances of the framework (just as different users may open the same MSWord document in their own local copies of MSWord). What's more, the plug-ins available to one user's framework might not be available to that of another. I need some way of ensuring that when a user attempts to open (i.e. deserialise) a project that includes a type whose defining assembly cannot be found (either because of a framework version incompatibility or the absence of a plug-in), the project still opens but the offending type is somehow substituted or omitted. Trouble is, the research I've done to date does not even hint at a suitable approach. Any ideas would be much appreciated, thanks.

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  • Why use event listeners over function calls?

    - by Organiccat
    I've been studying event listeners lately and I think I've finally gotten them down. Basically, they are functions that are called on another object's method. My question is, why create an event listener when calling the function will work just fine? Example, I want to call player.display_health(), and when this is fired, the method player.get_health() should be fired and stored so that display_health() has access to it. Why should I use an event listener over simply calling the function? Even if display_health() were in another object, this still doesn't appear to be a problem to me. If you have another example that fits the usage better, please let me know. Perhaps particular languages don't benefit from it as much? (Javascript, PHP, ASP?)

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  • Event handling to detect if user clicks a 'Like' button in XFBML page

    - by Simon_Weaver
    I have a Facebook connect app / canvas IFrame app which has a Like control for a fanpage. I'd like to detect when the user clicks the Like button to be able to display additional info (a discount coupon code). I'm using the latest Javascript API but the events that can be handled doesn't seem to include detection of social widget controls. The documentation for the Like Plugin doesn't show any events. However I know its definitely possible because if I have two Like buttons on a page they both instantly update each other if I like or unlike whatever it is.

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  • Handling Application Logic in Multiple AsyncTask onPostExecute()s

    - by stormin986
    I have three simultaneous instances of an AsyncTask for download three files. When two particular ones finish, at the end of onPostExecute() I check a flag set by each, and if both are true, I call startActivity() for the next Activity. I am currently seeing the activity called twice, or something that resembles this type of behavior. Since the screen does that 'swipe left' kind of transition to the next activity, it sometimes does it twice (and when I hit back, it goes back to the same activity). It's obvious two versions of the activity that SHOULD only get called once are being put on the Activity stack. The only way I can find that this is possible is if both AsyncTasks' onPostExecute() executed SO simultaneously that they were virtually running the same lines at the same time, since I set the 'itemXdownloaded' flag to true right before I check for both and call startActivity(). But this is happening enough that it's very hard for me to believe that both downloads are finishing precisely at the same time and having their onPostExecute()s so close together... Any thoughts on what could be going on here? General gist of code (details removed, ignore any syntactical errors I may have edited in): // In onPostExecute() switch (downloadID) { case DL1: dl1complete = true; break; case DL2: dl2complete = true; break; case DL3: dl3complete = true; break; } // If 1 and 2 are done, move on (DL3 still going in background) if ( downloadID != DL3 && dl1complete && dl2complete) { ParentClass.this.startActivity(new Intent(ParentClass.this, NextActivity.class)); }

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  • c# eventhandling error

    - by bragin.www
    i have method private void getValues(object sender, EventArgs e) { int id = int.Parse(dgvTable.Rows[dgvTable.CurrentRow.Index].Cells[0].Value.ToString()); var values = from c in v.db.TotalDoc where c.TotalID == id select c.TotalAmount; dgvValues.DataSource = values; } and datagridview "dgvTable" error at this line dgvTable.CellClick += new EventHadler(getValues); error text is: No overload for 'getValues' matches delegate 'System.EventHandler' please help!

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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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  • performing a javascript event without triggering that event handler

    - by bento
    In my latest code, I have an event handler for a focus on a textarea. When the user clicks on the textarea, that event-handler is triggered which sets some other DOM states based on the selected textarea. However, elsewhere in my program I want to programmatically set the focus of the textarea without triggering that event handler. I know Backbone, for instance, has a way to silently perform an action. My only pseudo-solution is to temporarily set a variable: var silence = true; And then, in my event handler, only perform the logic if silence is false. The handler is still triggered, but the logic doesn't run. Does anyone else know of better strategies for this?

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  • Event handling for a dynamically added user control

    - by francisf
    Hi, I have a user control say SearchVendor.ascx which contains 4 buttons a gridview and another user control. I need to load the control dynamically actually as a modal pop up I get this code VendorProductSearch uc = Page.LoadControl("~/Controls/Proposal/VendorProductSearch.ascx") as VendorProductSearch; uc.ShowVendorProductSearch(true); _tempPlaceHolder.Controls.Add(uc); it works fine the control gets loaded properly but onclick of any button the second time the control disappears ??? I want the dynamically added control to remain until the user clicks on the cancel button Any idea as to how to achive this ? Thanks & Regards, Francis P.

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  • Error handling in the RequestHandler without embedding in URI

    - by hyn
    When a user sends a filled form, I want to print an error message in case there is an input error. One of the GAE sample codes does this by embedding the error message in the URI. Inside the form handler (get): self.redirect('/compose?error_message=%s' % message) and in the handler (get) of redirected URI, gets the message from request: values = { 'error_message': self.request.get('error_message'), ... Is there a way to accomplish the same without embedding the message in the URI?

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  • Capture KeyUp event on form when child control has focus

    - by Jon B
    I need to capture the KeyUp event in my form (to toggle a "full screen mode"). Here's what I'm doing: protected override void OnKeyUp(KeyEventArgs e) { base.OnKeyUp(e); if (e.KeyCode == Keys.F12) this.ToggleFullScreen(); } private void ToggleFullScreen() { // Snazzy code goes here } This works fine, unless a control on the form has focus. In that case, I don't get the event at all (also tried OnKeyDown - no luck there either). I could handle the KeyUp event from the child control, but the controls on the form are generated dynamically, and there may be many of them - each having many children of their own. Is there any way to do this without generating event handlers for every control on the screen (which I certainly could do with a recursive function)?

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  • Handling form from different view and passing form validation through session in django

    - by Mo J. Mughrabi
    I have a requirement here to build a comment-like app in my django project, the app has a view to receive a submitted form process it and return the errors to where ever it came from. I finally managed to get it to work, but I have doubt for the way am using it might be wrong since am passing the entire validated form in the session. below is the code comment/templatetags/comment.py @register.inclusion_tag('comment/form.html', takes_context=True) def comment_form(context, model, object_id, next): """ comment_form() is responsible for rendering the comment form """ # clear sessions from variable incase it was found content_type = ContentType.objects.get_for_model(model) try: request = context['request'] if request.session.get('comment_form', False): form = CommentForm(request.session['comment_form']) form.fields['content_type'].initial = 15 form.fields['object_id'].initial = 2 form.fields['next'].initial = next else: form = CommentForm(initial={ 'content_type' : content_type.id, 'object_id' : object_id, 'next' : next }) except Exception as e: logging.error(str(e)) form = None return { 'form' : form } comment/view.py def save_comment(request): """ save_comment: """ if request.method == 'POST': # clear sessions from variable incase it was found if request.session.get('comment_form', False): del request.session['comment_form'] form = CommentForm(request.POST) if form.is_valid(): obj = form.save(commit=False) if request.user.is_authenticated(): obj.created_by = request.user obj.save() messages.info(request, _('Your comment has been posted.')) return redirect(form.data.get('next')) else: request.session['comment_form'] = request.POST return redirect(form.data.get('next')) else: raise Http404 the usage is by loading the template tag and firing {% comment_form article article.id article.get_absolute_url %} my doubt is if am doing the correct approach or not by passing the validated form to the session. Would that be a problem? security risk? performance issues? Please advise Update In response to Pol question. The reason why I went with this approach is because comment form is handled in a separate app. In my scenario, I render objects such as article and all I do is invoke the templatetag to render the form. What would be an alternative approach for my case? You also shared with me the django comment app, which am aware of but the client am working with requires a lot of complex work to be done in the comment app thats why am working on a new one.

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