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• problem with Using SAX parser

  - by moustafa

  Hi guys i have this small class task that im having trouble with. I need to create a PHP file using SAX to generate the display shown below from an XML file. Im not sure how to Use | to represent its level, where the root element orders is at level zero. This is what the result should look like when i parse it through a SAX parser http://img13.imageshack.us/img13/6950/75914446.jpg This is the XML source code from which i need to generate the display: <orders> <order> <count>37</count> <price>49.99</price> <book> <isbn>0130897930</isbn> <title>Core Web Programming Second Edition</title> <authors> <count>2</count> <author>Marty Hall</author> <author>Larry Brown</author> </authors> </book> </order> <order> <count>1</count> <price>9.95</price> <yacht> <manufacturer>Luxury Yachts, Inc.</manufacturer> <model>M-1</model> <standardFeatures oars="plastic" lifeVests="none">false</standardFeatures> </yacht> </order> <order> <count>3</count> <price>22.22</price> <book> <isbn>B000059Z4H</isbn> <title>Harry Potter and the Order of the Phoenix</title> <authors> <count>1</count> <author>J.K. Rowling</author> </authors> </book> </order>

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• approximating log10[x^k0 + k1]

  - by Yale Zhang

  Greetings. I'm trying to approximate the function Log10[x^k0 + k1], where .21 < k0 < 21, 0 < k1 < ~2000, and x is integer < 2^14. k0 & k1 are constant. For practical purposes, you can assume k0 = 2.12, k1 = 2660. The desired accuracy is 5*10^-4 relative error. This function is virtually identical to Log[x], except near 0, where it differs a lot. I already have came up with a SIMD implementation that is ~1.15x faster than a simple lookup table, but would like to improve it if possible, which I think is very hard due to lack of efficient instructions. My SIMD implementation uses 16bit fixed point arithmetic to evaluate a 3rd degree polynomial (I use least squares fit). The polynomial uses different coefficients for different input ranges. There are 8 ranges, and range i spans (64)2^i to (64)2^(i + 1). The rational behind this is the derivatives of Log[x] drop rapidly with x, meaning a polynomial will fit it more accurately since polynomials are an exact fit for functions that have a derivative of 0 beyond a certain order. SIMD table lookups are done very efficiently with a single _mm_shuffle_epi8(). I use SSE's float to int conversion to get the exponent and significand used for the fixed point approximation. I also software pipelined the loop to get ~1.25x speedup, so further code optimizations are probably unlikely. What I'm asking is if there's a more efficient approximation at a higher level? For example: Can this function be decomposed into functions with a limited domain like log2((2^x) * significand) = x + log2(significand) hence eliminating the need to deal with different ranges (table lookups). The main problem I think is adding the k1 term kills all those nice log properties that we know and love, making it not possible. Or is it? Iterative method? don't think so because the Newton method for log[x] is already a complicated expression Exploiting locality of neighboring pixels? - if the range of the 8 inputs fall in the same approximation range, then I can look up a single coefficient, instead of looking up separate coefficients for each element. Thus, I can use this as a fast common case, and use a slower, general code path when it isn't. But for my data, the range needs to be ~2000 before this property hold 70% of the time, which doesn't seem to make this method competitive. Please, give me some opinion, especially if you're an applied mathematician, even if you say it can't be done. Thanks.

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• Trying to integrate CakePHP and jQuery

  - by user198003

  Trying to integrate CakePHP and jQuery, using next example http://bakery.cakephp.org/articles/view/dynamic-select-boxes-with-ajax-jquery What I want is to when user change first option element, to automaticly fill second select option box with proper values. But, nothing happens, if you can help me why. So, there is a Invoice add form (add.ctp), with next code... <?php echo $form->create('Invoice');?> <?php echo $javascript->link('jquery.js'); $category = array('1' => 'First', '4' => 'Fourth', '7' => 'Seventh'); echo $form->input('client_id', array('options' => $category, 'empty' => 'Choose:')); echo $form->select('clientBank_id', array("Choose category first"), null, null, false); ?> <script> $("#InvoiceClientId").change(function () { $.post('/invoices/listTitleByCategory/' + $(this).val(), function(data) { $("#InvoiceClientBankId").empty().append(data); }, 'html'); }) </script> Also, there is controller (invoices_controller.php): <?php var $name = 'Invoices'; var $helpers = array('Html', 'Form', 'Time', 'Number', 'Javascript'); var $paginate = array('order' => array('Invoice.pinned DESC', 'Invoice.invoiceNumber')); var $components = array('RequestHandler'); function beforeRender(){ // prevent useless warnings for Ajax if($this->RequestHandler->isAjax()){ Configure::write('debug', 0); } } // etc... function listTitleByCategory($category = "") { $this->layout = 'ajax'; $this->beforeRender(); $this->autoRender = false; $data = $this->Invoice->Client->find('list'); echo "<option value=0>just for testing...</option>"; foreach($data as $key => $val) { echo "<option value=$key>$val</option>"; } } ?> Please, if you can help me solving this. Thank you in advance!

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• Exception showing a erroneous web page in a WPF frame

  - by H4mm3rHead

  I have a small application where i need to navigate to an url, I use this method to get the Frame: public override System.Windows.UIElement GetPage(System.Windows.UIElement container) { XmlDocument doc = new XmlDocument(); doc.Load(Location); string webSiteUrl = doc.SelectSingleNode("website").InnerText; Frame newFrame = new Frame(); if (!webSiteUrl.StartsWith("http://")) { webSiteUrl = "http://" + webSiteUrl; } newFrame.Source = new Uri(webSiteUrl); return newFrame; } My problem is now that the page im trying to show generates a error (or so i think), when i load the page in a browser it never fully loads, keeps saying "loading1 element" in the load bar and the green progress line (IE 8) keeps showing. When i attach my debugger i get this error: System.ArgumentException was unhandled Message="Parameter and value pair is not valid. Expected form is parameter=value." Source="WindowsBase" StackTrace: at MS.Internal.ContentType.ParseParameterAndValue(String parameterAndValue) at MS.Internal.ContentType..ctor(String contentType) at MS.Internal.WpfWebRequestHelper.GetContentType(WebResponse response) at System.Windows.Navigation.NavigationService.GetObjectFromResponse(WebRequest request, WebResponse response, Uri destinationUri, Object navState) at System.Windows.Navigation.NavigationService.HandleWebResponse(IAsyncResult ar) at System.Windows.Navigation.NavigationService.<>c__DisplayClassc.<HandleWebResponseOnRightDispatcher>b__8(Object unused) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) ved System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.TranslateAndDispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Application.RunInternal(Window window) at GreenWebPlayerWPF.App.Main() i C:\Development\Hvarregaard\GWDS\GreenWeb\GreenWebPlayerWPF\obj\Debug\App.g.cs:linje 0 at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException: Anyone? Or any way to capture it and respond to it, tried a try/catch around my code, but its not caught - seems something deep inside the guts of the CLR is failing.

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• Changing tabs in android

  - by Pavel

  Hi guys. Can someone please tell me how to change tab by clicking on element INSIDE the tab? I already tried it with global data. The code looks like this: public class Tabs extends TabActivity { int tabNumber = 0; private TabHost tabHost; int returnedTabNumber = 0; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Resources res = getResources(); // Resource object to get Drawables tabHost = getTabHost(); // The activity TabHost TabHost.TabSpec spec; // Resusable TabSpec for each tab Intent intent; // Reusable Intent for each tab // Create an Intent to launch an Activity for the tab (to be reused) intent = new Intent().setClass(this, Tribocracy.class); // Initialize a TabSpec for each tab and add it to the TabHost spec = tabHost.newTabSpec("map").setIndicator("Map", res.getDrawable(R.drawable.ic_tab_artists)) .setContent(intent); tabHost.addTab(spec); // Do the same for the other tabs intent = new Intent().setClass(this, Areas.class); spec = tabHost.newTabSpec("areas").setIndicator("Areas", res.getDrawable(R.drawable.ic_tab_albums)) .setContent(intent); tabHost.addTab(spec); // Do the same for the other tabs intent = new Intent().setClass(this, Settings.class); spec = tabHost.newTabSpec("settings").setIndicator("Settings", res.getDrawable(R.drawable.ic_tab_albums)) .setContent(intent); tabHost.addTab(spec); tabHost.setCurrentTab(tabNumber); } protected void onResume() { super.onResume(); GlobalData globalData = ((GlobalData)getApplicationContext()); returnedTabNumber = globalData.getTabNumber(); tabHost.setCurrentTab(returnedTabNumber); } } The global adapter looks like this: public class GlobalData extends Application { //---------------------------------------------------- private int Point1; //define the vars here private int Point2; //define the vars here private int Point3; //define the vars here private int Point4; //define the vars here private int Point5; //define the vars here private int Point6; //define the vars here private int tabNumber; public int getTabNumber() //getter of the value { return tabNumber; } public int setTabNumber(int number) //setter of the value { tabNumber = number; return tabNumber; } } Now when I'm trying to change tab in my ListActivity tab by clicking on one of the items it doesn't do anything and stays on the ListActivity tab. Perhaps I shouldn't use onResume() here. Basically I want to go to first tab when I click on one of the items in the list. Please help!

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• WPF Datagrid items binding problem

  - by gencay

  I get a problem while displaying a List in WPF-Datagrid. When I do this line ... DocumentList dt = new DocumentList(fileWordList, fileUriType, fileUri, cosineSimilarityRatio, diceSimilarityRatio, extendedJaccardSimilarityRatio); documentList.Add(dt); ... dataGrid1.Items.Add(dt); ... It creates an empty row into dataGrid1 and no text is shown there. my xaml implementation is this: <GroupBox Canvas.Left="-0.003" Canvas.Top="0" Header="Display Results" Height="427.5" Name="groupBox2" Width="645.56"> <toolkit:DataGrid Canvas.Left="137.5" Canvas.Top="240" Height="392" Name="dgrDocumentList" Width="627" ItemsSource="{Binding DocumentList }"> <toolkit:DataGrid.Columns> <toolkit:DataGridTextColumn Header="Type" Binding="{Binding type}" IsReadOnly="True"> </toolkit:DataGridTextColumn> <toolkit:DataGridHyperlinkColumn Header="Uri" Binding="{Binding path}" IsReadOnly="True"> </toolkit:DataGridHyperlinkColumn> <toolkit:DataGridTextColumn Header="Cosine" Binding="{Binding cos}" IsReadOnly="True"> </toolkit:DataGridTextColumn> <toolkit:DataGridTextColumn Header="Dice" Binding="{Binding dice}" IsReadOnly="True"> </toolkit:DataGridTextColumn> <toolkit:DataGridTextColumn Header="Jaccard" Binding="{Binding jaccard}" IsReadOnly="True"> </toolkit:DataGridTextColumn> </toolkit:DataGrid.Columns> </toolkit:DataGrid> </GroupBox> and my DocumentList class class DocumentList { public List<WordList> wordList; public string type; public string path; public double cos; public double dice; public double jaccard; //public static string title; public DocumentList(List<WordList> wordListt, string typee, string pathh, double sm11, double sm22, double sm33) { type = typee; wordList = wordListt; path = pathh; cos = sm11; dice = sm22; jaccard = sm33; } I would like to do that: When i add a new element into documentList instance, would like to see the results on data grid. Thank you in advance.

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• How to get the top keys from a hash by value

  - by Kirs Kringle

  I have a hash that I sorted by values greatest to least. How would I go about getting the top 5? There was a post on here that talked about getting only one value. What is the easiest way to get a key with the highest value from a hash in Perl? I understand that so would lets say getting those values add them to an array and delete the element in the hash and then do the process again? Seems like there should be an easier way to do this then that though. My hash is called %words. use strict; use warnings; use Tk; #Learn to install here: http://factscruncher.blogspot.com/2012/01/easy-way-to-install-tk- on-strawberry.html #Reading in the text file my $file0 = Tk::MainWindow->new->Tk::getOpenFile; open( my $filehandle0, '<', $file0 ) || die "Could not open $file0\n"; my @words; while ( my $line = <$filehandle0> ) { chomp $line; my @word = split( /\s+/, lc($line)); push( @words, @word ); } for (@words) { s/[\,|\.|\!|\?|\:|\;|\"]//g; } #Counting words that repeat; put in hash my %words_count; $words_count{$_}++ for @words; #Reading in the stopwords file my $file1 = "stoplist.txt"; open( my $filehandle1, '<', $file1 ) or die "Could not open $file1\n"; my @stopwords; while ( my $line = <$filehandle1> ) { chomp $line; my @linearray = split( " ", $line ); push( @stopwords, @linearray ); } for my $w ( my @stopwords ) { s/\b\Q$w\E\B//ig; } #Comparing the array to Hash and deleteing stopwords my %words = %words_count; for my $stopwords ( @stopwords ) { delete $words{ $stopwords }; } #Sorting Hash Table my @keys = sort { $words{$b} <=> $words{$a} or "\L$a" cmp "\L$b" } keys %words; #Starting Statistical Work my $value_count = 0; my $key_count = 0; #Printing Hash Table $key_count = keys %words; foreach my $key (@keys) { $value_count = $words{$key} + $value_count; printf "%-20s %6d\n", $key, $words{$key}; } my $value_average = $value_count / $key_count; #my @topwords; #foreach my $key (@keys){ #if($words{$key} > $value_average){ # @topwords = keys %words; # } #} print "\n", "The number of values: ", $value_count, "\n"; print "The number of elements: ", $key_count, "\n"; print "The Average: ", $value_average, "\n\n";

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• Use of text() function when using xPath in dom4j

  - by jlawless

  I have inherited an application that parses xml using dom4j and xPath: The xml being parsed is similar to the following: <cache> <content> <transaction> <page> <widget name="PAGE_ID">WRK_REGISTRATION</widget> <widget name="TRANS_DETAIL_ID">77145</widget> <widget name="GRD_ERRORS" /> </page> <page> <widget name="PAGE_ID">WRK_REGISTRATION</widget> <widget name="TRANS_DETAIL_ID">77147</widget> <widget name="GRD_ERRORS" /> </page> <page> <widget name="PAGE_ID">WRK_PROCESSING</widget> <widget name="TRANS_DETAIL_ID">77152</widget> <widget name="GRD_ERRORS" /> </page> </transaction> </content> </cache> Individual Nodes are being searched using the following: String xPathToGridErrorNode = "//cache/content/transaction/page/widget[@name='PAGE_ID'][text()='WRK_DNA_REGISTRATION']/../widget[@name='TRANS_DETAIL_ID'][text()='77147']/../widget[@name='GRD_ERRORS_TEMP']"; org.dom4j.Element root = null; SAXReader reader = new SAXReader(); Document document = reader.read(new BufferedInputStream(new ByteArrayInputStream(xmlToParse.getBytes()))); root = document.getRootElement(); Node gridNode = root.selectSingleNode(xPathToGridErrorNode); where xmlToParse is a String of xml similar to the excerpt provided above. The code is trying to obtain the GRD_ERROR node for the page with the PAGE_ID and TRANS_DETAIL_ID provided in the xPath. I am seeing an intermittent (~1-2%) failure (returned node is null) of this selectSingleNode request even though the requested node is in the xml being searched. I know there are some gotchas associated with using text()= in xPath and was wondering if there was a better way to format the xPath string for this type of search.

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• How can I check the content of the arrays? Parsing XML file with ObjectiveC

  - by skiria

  I have 3 classes- video { nameVideo, id, description, user... } topic {nameTopic, topicID, NSMutableArray videos; } category {nameCategory, categoryID, NSMUtableArray topics} And then in my app delegate I defined- NSMutableArray categories; I parse an XML file with this code. I try the arrays hierachy, and i think that i don't add any object on the arrays. How can I check it? What's wrong? (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict { if([elementName isEqualToString:@"Videos"]) { //Initialize the array. appDelegate.categories = [[NSMutableArray alloc] init]; } else if ([elementName isEqualToString:@"Category"]) { aCategory = [[Category alloc] init]; aCategory.categoryID = [[attributeDict objectForKey:@"id"] integerValue]; NSLog(@"Reading id category value: %i", aCategory.categoryID); } else if ([elementName isEqualToString:@"Topic"]) { aTopic = [[Topic alloc] init]; aTopic.topicID = [[attributeDict objectForKey:@"id"] integerValue]; NSLog(@"Reading id topic value: %i", aTopic.topicID); } else if ([elementName isEqualToString:@"video"]) { aVideo = [[Video alloc] init]; aVideo.videoID = [[attributeDict objectForKey:@"id"] integerValue]; aVideo.nameTopic = currentNameTopic; aVideo.nameCategory = currentNameCategory; NSLog(@"Reading id video value: %i", aVideo.videoID); } NSLog(@"Processing Element: %@", elementName); } (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string { if(!currentElementValue) currentElementValue = [[NSMutableString alloc] initWithString:string]; else [currentElementValue appendString:string]; NSLog(@"Processing Value: %@", currentElementValue); } (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName { if([elementName isEqualToString:@"Videos"]) return; if ([elementName isEqualToString:@"Category"]) { [appDelegate.categories addObject:aCategory]; [aCategory release]; aCategory = nil; } if ([elementName isEqualToString:@"Topic"]) { [aCategory.topics addObject:aTopic]; //NSLog(@"contador: %i", [aCategory.topics count]); //NSLog(@"contador: %@", aTopic.nameTopic); [aTopic release]; aTopic = nil; } if ([elementName isEqualToString:@"video"]) { [aTopic.videos addObject:aVideo]; NSLog(@"count number videos: %i", [aTopic.videos count]); -- always 0 NSLog(@"NOM CATEGORIA VIDEO: %@", aVideo.urlVideo); -- OK [aVideo release]; aVideo = nil; } if ([elementName isEqualToString:@"nameCategory"]) { //[aCategory setValue:currentElementValue forKey:elementName]; aCategory.nameCategory = currentElementValue; currentNameCategory = currentElementValue; } if ([elementName isEqualToString:@"nameTopic"]) { aTopic.nameTopic = currentElementValue; currentNameTopic = currentElementValue; } else [aVideo setValue:currentElementValue forKey:elementName]; [currentElementValue release]; currentElementValue = nil; }

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• Unsure how to design JavaScript / jQuery functionality which uses XML to create HTML objects

  - by Jack Roscoe

  Hi, I'm using JavScript and jQuery to read an XML document and subsequently use the information from the XML to create HTML objects. The main 'C' nodes in the XML document all have a type attribute, and depending on the type I want to run a function which will create a new html object using the other attributes assigned to that particular 'C' node node. Currently, I have a for loop which extracts each 'C' node from the XML and also it's attributes (e.g. width, height, x, y). Also inside the for loop, I have an if statement which checks the 'type' attribute of the current 'C' node being processed, and depending on the type it will run a different function which will then create a new HTML object with the attributes which have been drawn from the XML. The problem is that there may be more than one 'C' node of the same type, so for example when I'm creating the function that will run when a 'C' node of 'type=1' is detected, I cannot use the 'var p = document.createElement('p')' because if a 'C' node of the same type comes up later in the loop it will clash and override that element with that variable that has just been created. I'm not really sure how to approach this? Here is my entire script. If you need me to elaborate on any parts please ask, I'm sure it's not written in the nicest possible way: var arrayIds = new Array(); $(document).ready(function(){ $.ajax({ type: "GET", url: "question.xml", dataType: "xml", success: function(xml) { $(xml).find("C").each(function(){ arrayIds.push($(this).attr('ID')); }); var svgTag = document.createElement('SVG'); // Create question type objects function ctyp3(x,y,width,height,baC) { alert('test'); var r = document.createElement('rect'); r.x = x; r.y = y; r.width = width; r.height = height; r.fillcolor = baC; svgTag.appendChild(r); } // Extract question data from XML var questions = []; for (j=0; j<arrayIds.length; j++) { $(xml).find("C[ID='" + arrayIds[j] + "']").each(function(){ // pass values questions[j] = { typ: $(this).attr('typ'), width: $(this).find("I").attr('wid'), height: $(this).find("I").attr('hei'), x: $(this).find("I").attr('x'), y: $(this).find("I").attr('x'), baC: $(this).find("I").attr('baC'), boC: $(this).find("I").attr('boC'), boW: $(this).find("I").attr('boW') } alert($(this).attr('typ')); if ($(this).attr('typ') == '3') { ctyp3(x,y,width,height,baC); // alert('pass'); } else { // Add here // alert('fail'); } }); } } }); });

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• How do you combine "Revision Control" with "WorkFlow" for R?

  - by Tal Galili

  Hello all, I remember coming across R users writing that they use "Revision control" (e.g: "Source control"), and I am curious to know: How do you combine "Revision control" with your statistical analysis WorkFlow? Two (very) interesting discussions talk about how to deal with the WorkFlow. But neither of them refer to the revision control element: http://stackoverflow.com/questions/1266279/how-to-organize-large-r-programs http://stackoverflow.com/questions/1429907/workflow-for-statistical-analysis-and-report-writing A Long Update To The Question: Following some of the people's answers, and Dirk's question in the comment, I would like to direct my question a bit more. After reading the Wiki article about "revision control" (which I was previously not familiar with), it was clear to me that when using revision control, what one does is to build a development structure of his code. This structure either leads to a "final product" or to several branches. When building something like, let's say, a website. There is usually one end product you work towards (the website), with some prototypes along the way. But when doing a statistical analysis, the work (to my view) is different. Sometimes you know where you want to get to. But more often, you explore. Explore cleaning the dataset. Explore different methods for statistical analysis, and ask various questions of your data (and I am writing this, knowing how Frank Harrell, and other experience statisticians feels about Data dredging). That is way the WorkFlow question with statistical programming is (in my view) a serious and deep question, raising many issues, The simpler ones are technical: Which revision control software do you use (and why) ? Which IDE do you use(and why) ? The more interesting question are about work process: How do you structure your files? What do you keep as a separate file and what as a revision? or asking in a different way - What should be a "branch" and what should be a "sub project" in your code? For example: When starting to explore your data, should a plot be creating and then erased because it didn't lead any where (but kept as a revision) or should there be a backup file of that path? How you solve this tension was my initial curiosity. The second question is "what might I be missing?". What rules (of thumb) should one follow so to avoid common pitfalls doing statistical programming with version control? In my intuition, I feel that statistical programming is inherently different then software development (I am writing this without being a real expert in statistical programming, and even less so in software development). That's way I am unsure which of the lessons I have read here about version control would be applicable. Thanks a lot, Tal

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• Multi-threaded Pooled Allocators

  - by Darren Engwirda

  I'm having some issues using pooled memory allocators for std::list objects in a multi-threaded application. The part of the code I'm concerned with runs each thread function in isolation (i.e. there is no communication or synchronization between threads) and therefore I'd like to setup separate memory pools for each thread, where each pool is not thread-safe (and hence fast). I've tried using a shared thread-safe singleton memory pool and found the performance to be poor, as expected. This is a heavily simplified version of the type of thing I'm trying to do. A lot has been included in a pseudo-code kind of way, sorry if it's confusing. /* The thread functor - one instance of MAKE_QUADTREE created for each thread */ class make_quadtree { private: /* A non-thread-safe memory pool for int linked list items, let's say that it's * something along the lines of BOOST::OBJECT_POOL */ pooled_allocator<int> item_pool; /* The problem! - a local class that would be constructed within each std::list as the * allocator but really just delegates to ITEM_POOL */ class local_alloc { public : //!! I understand that I can't access ITEM_POOL from within a nested class like //!! this, that's really my question - can I get something along these lines to //!! work?? pointer allocate (size_t n) { return ( item_pool.allocate(n) ); } }; public : make_quadtree (): item_pool() // only construct 1 instance of ITEM_POOL per // MAKE_QUADTREE object { /* The kind of data structures - vectors of linked lists * The idea is that all of the linked lists should share a local pooled allocator */ std::vector<std::list<int, local_alloc>> lists; /* The actual operations - too complicated to show, but in general: * * - The vector LISTS is grown as a quadtree is built, it's size is the number of * quadtree "boxes" * * - Each element of LISTS (each linked list) represents the ID's of items * contained within each quadtree box (say they're xy points), as the quadtree * is grown a lot of ID pop/push-ing between lists occurs, hence the memory pool * is important for performance */ } }; So really my problem is that I'd like to have one memory pool instance per thread functor instance, but within each thread functor share the pool between multiple std::list objects.

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• dynamic module creation

  - by intuited

  I'd like to dynamically create a module from a dictionary, and I'm wondering if adding an element to sys.modules is really the best way to do this. EG context = { a: 1, b: 2 } import types test_context_module = types.ModuleType('TestContext', 'Module created to provide a context for tests') test_context_module.__dict__.update(context) import sys sys.modules['TestContext'] = test_context_module My immediate goal in this regard is to be able to provide a context for timing test execution: import timeit timeit.Timer('a + b', 'from TestContext import *') It seems that there are other ways to do this, since the Timer constructor takes objects as well as strings. I'm still interested in learning how to do this though, since a) it has other potential applications; and b) I'm not sure exactly how to use objects with the Timer constructor; doing so may prove to be less appropriate than this approach in some circumstances. EDITS/REVELATIONS/PHOOEYS/EUREKAE: I've realized that the example code relating to running timing tests won't actually work, because import * only works at the module level, and the context in which that statement is executed is that of a function in the testit module. In other words, the globals dictionary used when executing that code is that of main, since that's where I was when I wrote the code in the interactive shell. So that rationale for figuring this out is a bit botched, but it's still a valid question. I've discovered that the code run in the first set of examples has the undesirable effect that the namespace in which the newly created module's code executes is that of the module in which it was declared, not its own module. This is like way weird, and could lead to all sorts of unexpected rattlesnakeic sketchiness. So I'm pretty sure that this is not how this sort of thing is meant to be done, if it is in fact something that the Guido doth shine upon. The similar-but-subtly-different case of dynamically loading a module from a file that is not in python's include path is quite easily accomplished using imp.load_source('NewModuleName', 'path/to/module/module_to_load.py'). This does load the module into sys.modules. However this doesn't really answer my question, because really, what if you're running python on an embedded platform with no filesystem? I'm battling a considerable case of information overload at the moment, so I could be mistaken, but there doesn't seem to be anything in the imp module that's capable of this. But the question, essentially, at this point is how to set the global (ie module) context for an object. Maybe I should ask that more specifically? And at a larger scope, how to get Python to do this while shoehorning objects into a given module?

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• Java threads not working correctly with linkedlist

  - by user69514

  Hi I am working on the sleeping barber problem. with the addition of having priority customer when they arrive they go in the front of the line and they are the next ones to get a haircut. I'm using a linkedlist and if I see a priority customer I put him in the beginning of the list, if the customer is not priority he goes to the end of the list. then I call the wantHaircut method getting the first element of the list. my problem is that the customer are being processed in the order they arrive, and the priority customer have to wait. here is the code where it all happens. any ideas what I am doing wrong? thanks public void arrivedBarbershop(Customer c){ if(waiting < numChairs && c.isPriority()){ System.out.println("Customer " + c.getID() + ": is a priority customer - SITTING -"); mutex.up(); customer_list.addFirst(c); } else if(waiting >= numChairs && c.isPriority()){ System.out.println("Customer " + c.getID() + ": is a priority customer - STANDING -"); mutex.up(); customer_list.addFirst(c); } else if(waiting < numChairs && !c.isPriority()){ waiting++; System.out.println("Customer " + c.getID() + ": arrived, sitting in the waiting room"); customer_list.addLast(c); customers.up(); // increment waiting customers } else if(waiting >= numChairs && !c.isPriority()) { System.out.println("Customer " + c.getID() + ": went to another barber because waiting room was full - " + waiting + " waiting"); mutex.up(); } if(!customer_list.isEmpty()){ this.wantHairCut(customer_list.removeFirst()); } } public void wantHairCut(Customer c) { mutex.up(); barber.down(); // waits for being allowed in barber chair System.out.println("Customer " + c.getID() + ": getting haircut"); try { /** haircut takes between 1 and 2 seconds **/ Thread.sleep(Barbershop.randomInt(1, 2) * 1000); } catch (InterruptedException e) { } System.out.println("Barber: finished cutting customer " + c.getID() + "'s hair"); c.gotHaircut = true; cutting.up(); // signals cutting has finished /** customer must pay now **/ this.wantToCashout(c); }

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• Differences between matrix implementation in C

  - by tempy

  I created two 2D arrays (matrix) in C in two different ways. I don't understand the difference between the way they're represented in the memory, and the reason why I can't refer to them in the same way: scanf("%d", &intMatrix1[i][j]); //can't refer as &intMatrix1[(i * lines)+j]) scanf("%d", &intMatrix2[(i * lines)+j]); //can't refer as &intMatrix2[i][j]) What is the difference between the ways these two arrays are implemented and why do I have to refer to them differently? How do I refer to an element in each of the arrays in the same way (?????? in my printMatrix function)? int main() { int **intMatrix1; int *intMatrix2; int i, j, lines, columns; lines = 3; columns = 2; /************************* intMatrix1 ****************************/ intMatrix1 = (int **)malloc(lines * sizeof(int *)); for (i = 0; i < lines; ++i) intMatrix1[i] = (int *)malloc(columns * sizeof(int)); for (i = 0; i < lines; ++i) { for (j = 0; j < columns; ++j) { printf("Type a number for intMatrix1[%d][%d]\t", i, j); scanf("%d", &intMatrix1[i][j]); } } /************************* intMatrix2 ****************************/ intMatrix2 = (int *)malloc(lines * columns * sizeof(int)); for (i = 0; i < lines; ++i) { for (j = 0; j < columns; ++j) { printf("Type a number for intMatrix2[%d][%d]\t", i, j); scanf("%d", &intMatrix2[(i * lines)+j]); } } /************** printing intMatrix1 & intMatrix2 ****************/ printf("intMatrix1:\n\n"); printMatrix(*intMatrix1, lines, columns); printf("intMatrix2:\n\n"); printMatrix(intMatrix2, lines, columns); } /************************* printMatrix ****************************/ void printMatrix(int *ptArray, int h, int w) { int i, j; printf("Printing matrix...\n\n\n"); for (i = 0; i < h; ++i) for (j = 0; j < w; ++j) printf("array[%d][%d] ==============> %d\n, i, j, ??????); }

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• How to develop a Jquery plugin to find the first child that match with a selector?

  - by Ivan

  I'm trying to make a Jquery plugin (findFirst()) to find the first child with a given characteristics (something in the middle of the find() and children() functions. For instance, given this markup: <div id="start"> <div> <span>Hello world</span> <ul class="valid-result"> ... </ul> <ul class="valid-result"> <li> <ul class="not-a-result"> ... </ul> </li> </ul> <div> <ul class="valid-result"> ... </ul> </div> </div> </div> If you ask for $("#start").findFirst('ul') it should return all ul lists that I have tagged with the valid-result class, but not the ul with class not-a-result. It is, this function has to find the first elements that matches with a given selector, but not the inner elements that match this selector. This is the first time I try to code a Jquery function, and what I've already read doesn't helps me too much with this. The function I have developed is this: jQuery.fn.findFirst = function (sel) { return this.map(function() { return $(this).children().map(function() { if ($(this).is(sel)) { return $(this); } else { return $(this).findFirst(sel); } }); }); } It works in the sense it tries to return the expected result, but the format it returns the result is very rare for me. I suppose the problem is something I don't understand about Jquery. Here you have the JFiddle where I'm testing. EDIT The expected result after $("#start").findFirst('ul') is a set with all UL that have the class 'valid-result' BUT it's not possible to use this class because it doesn't exist in a real case (it's just to try to explain the result). This is not equivalent to first(), because first returns only one element!

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• HTML-like GUI Framework in Java

  - by wintermute

  I was recently brought onto a project where we are developing a lot GUI elements for BlackBerry devices. The standard RIM APIs are pretty basic, almost never do what is required and are difficult or impossible to extend, so we end up re-implementing chunks of it. Currently the code we have isn't super organized and factored so there are lots of little tricks that get implemented over and over again. I had a thought about how to aid development efforts on this platform and wanted to see if the community could tell me if I'm still sane or if I've gone totally nuts. By far, the biggest organizational problem I've run into is making sure that each screen is laid out properly with proper padding and such. The current approach is to manually keep track of padding like so: protected void sublayout(int width, int height) { final int padding = 5; int y = padding; int x = padding; layoutChild(_someChild, width - padding * 2, height / 3 - padding * 2); setPositionChild(_someChild, x, y); y += _someChild.getHeight() + padding; // Calculate where to start drawing next. /* ... snipped ... */ } As you can see, positioning elements on a screen is a nightmare due to the tedium. I have investigated other GUI frameworks but, for a variety of reasons, it is difficult to find one that suites our purposes. One potential solution that came to me is to create a GUI framework who's API resembles HTML/CSS. This would allow for things like padding, margins, borders and colours to be handled through a sort of CSS API while the content would be organized using the HTML part of the API. It might look something like this: public class OptionsScreen extends Document { public OptionsScreen() { // You would set the style (like CSS style) through the constructor. Div content = new Div(new Style(new Padding(5), Color.BLACK)); // Then build up a tree of elements which can each have their own style's. // Each element knows how to draw itself, but it doesn't have to worry about // manually handling things like padding. // content.addChild(new P("This is a paragraph", new Style(new Padding(), Color.RED))); Ul list = new Ul(); list.addChild(new Li("item 1")); list.addChild(new Li("item 2")); content.addChild(list); addChild(content); } } I can imagine this making it easier to customize the UI of our app (which is very important) with different fonts, colours and layouts. Does this idea belong on The Daily WTF or do you think there is some promise?

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• .live event doesnt work till second click

  - by ChampionChris

  I have 2 list on a page that are linked. When I drag a li element from list 1 to list 2 the live events on list 1 don't work on the first click only second click. Below is the code that adds the li (obj) to list 2. function AddToDropBox(obj) { $(obj).children(".handle").animate({ width: "20px" }).children("strong").fadeOut(); $(obj).children("span:not(.track,.play,.handle,:has(.btn-edit))").fadeOut('fast'); $(obj).children(".play").css("margin-right", "8px"); $(obj).css({ "opacity": "0.0", "width": "284px" }).animate({ opacity: "1.0" }); if ($(".sidebar-drop-box ul").children(".admin-song").length > 0) { $(".dropTitle").fadeOut("fast"); $(".sidebar-drop-box ul.admin-song-list").css("min-height", "0"); } if (typeof SetLinks == 'function') { SetLinks(); } //CBG Changes adds media ID to hidden field //checks id there is a value in field then adds comma if(document.getElementById("ctl00_cphBody_hfRemoveMedia").value==""||document.getElementById("ctl00_cphBody_hfRemoveMedia").value==null) { document.getElementById("ctl00_cphBody_hfRemoveMedia").value=(obj).attr("mediaid"); } else { var localMediaIDs=document.getElementById("ctl00_cphBody_hfRemoveMedia").value; document.getElementById("ctl00_cphBody_hfRemoveMedia").value=localMediaIDs+", "+(obj).attr("mediaid"); } // alert("hfid: "+document.getElementById("ctl00_cphBody_hfRemoveMedia").value); //END CBG Modifications } this is one of the live() events that dont fire until the second click after the drag. This live() event is in a document.ready function(). // Live for deleting. $(".btn-del").live("click", function(e) { DeleteItem(this); $(this).removeClass("btn-del").addClass("btn-add").parents("li").removeClass("alt").addClass("removed"); var oldTxt = $(this).parents("li").find(".status").text(); $(this).parents("li").find(".status").text("Removed").attr("oldstat", oldTxt); $("#timeHolder input[type=hidden]").val(($("#timeHolder input[type=hidden]").val() * 1) - ($(this).parents("li").find(".time").attr("length") * 1)); CalculateAggregates(); isDirty = false; }); EDIT @dreaton.. Im new to jquery and javascript so thanks for the last tip... Im not sure what you mean about cache the query's. ... the delegete feature is giving me this Microsoft JScript runtime error: Object doesn't support this property or method this is the way I have the code $('#ulPlaylist').delegate('.btn-del', 'click', function (e) { DeleteItem(this); $(this).removeClass("btn-del").addClass("btn-add").parents("li").removeClass("alt").addClass("removed"); var oldTxt = $(this).parents("li").find(".status").text(); $(this).parents("li").find(".status").text("Removed").attr("oldstat", oldTxt); $("#timeHolder input[type=hidden]").val(($("#timeHolder input[type=hidden]").val() * 1) - ($(this).parents("li").find(".time").attr("length") * 1)); CalculateAggregates(); isDirty = false; });

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• MATLAB image corner coordinates & referncing to cell arrays

  - by James

  Hi, I am having some problems comparing the elements in different cell arrays. The context of this problem is that I am using the bwboundaries function in MATLAB to trace the outline of an image. The image is of a structural cross section and I am trying to find if there is continuity throughout the section (i.e. there is only one outline produced by the bwboundaries command). Having done this and found where the is more than one section traced (i.e. it is not continuous), I have used the cornermetric command to find the corners of each section. The code I have is: %% Define the structural section as a binary matrix (Image is an I-section with the web broken) bw(20:40,50:150) = 1; bw(160:180,50:150) = 1; bw(20:60,95:105) = 1; bw(140:180,95:105) = 1; Trace = bw; [B] = bwboundaries(Trace,'noholes'); %Traces the outer boundary of each section L = length(B); % Finds number of boundaries if L > 1 disp('Multiple boundaries') % States whether more than one boundary found end %% Obtain perimeter coordinates for k=1:length(B) %For all the boundaries perim = B{k}; %Obtains perimeter coordinates (as a 2D matrix) from the cell array end %% Find the corner positions C = cornermetric(bw); Areacorners = find(C == max(max(C))) % Finds the corner coordinates of each boundary [rowindexcorners,colindexcorners] = ind2sub(size(Newgeometry),Areacorners) % Convert corner coordinate indexes into subcripts, to give x & y coordinates (i.e. the same format as B gives) %% Put these corner coordinates into a cell array Cornerscellarray = cell(length(rowindexcorners),1); % Initialises cell array of zeros for i =1:numel(rowindexcorners) Cornerscellarray(i) = {[rowindexcorners(i) colindexcorners(i)]}; %Assigns the corner indicies into the cell array %This is done so the cell arrays can be compared end for k=1:length(B) %For all the boundaries found perim = B{k}; %Obtains coordinates for each perimeter Z = perim; % Initialise the matrix containing the perimeter corners Sectioncellmatrix = cell(length(rowindexcorners),1); for i =1:length(perim) Sectioncellmatrix(i) = {[perim(i,1) perim(i,2)]}; end for i = 1:length(perim) if Sectioncellmatrix(i) ~= Cornerscellarray Sectioncellmatrix(i) = []; %Gets rid of the elements that are not corners, but keeps them associated with the relevent section end end end This creates an error in the last for loop. Is there a way I can check whether each cell of the array (containing an x and y coordinate) is equal to any pair of coordinates in cornercellarray? I know it is possible with matrices to compare whether a certain element matches any of the elements in another matrix. I want to be able to do the same here, but for the pair of coordinates within the cell array. The reason I don't just use the cornercellarray cell array itself, is because this lists all the corner coordinates and does not associate them with a specific traced boundary.

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• Getting key/value pairs from plist-style xml using simplexml in php

  - by Anthony

  Here is an example bit from the xml file: <array> <dict> <key>Name</key> <string>Joe Smith</string> <key>Type</key> <string>Profile</string> <key>Role</key> <string>User</string> <key>Some Number</key> <integer>1</integer> <key>Some Boolean</key> <true/> </dict> </array> I have two separate goals. The first is to extract an array from the dictnode that would look like: [Name] => Joe Smith [Type] => Profile [Role] => User [Some Number] => 1 [Some Boolean] => true It's not crucial that the boolean be included, so if that adds too much complexity, I'd rather just know how to deal with the others for now. The second goal is to be able to select the value node (<string>, <integer>,etc) so that I can change the value. I would need to select it based on the text value of the preceding key element. I think the following XPath should work: //key[.=$keyname]/following-sibling[1] But I'm not sure. Basically, this whole system that Apple uses seems logical, but totally contrary to the XML is supposed to work. If I ran the world, the original XML would look more like: <dict type="array"> <value key="Name" type="string">Joe Smith</value> <value key="Type" type="string">Profile</value> <value key="Role type="string">User</value> <value key="Some Number" type="integer">1</value> <value key="Some Boolean" type="boolean">true</value> </dict> But since it is fairly logical, I am wondering if I'm missing some obvious way of handling it.

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• jQuery function execute on Button Click and Enter/Return (key)

  - by Alvin Jones

  I'm trying to create a little search box that allows you to search Twitter based on the keyword you enter in the input field. While it's work, it only works if you press the Submit button. I would also like to be able to press the Enter or Return key to initiate the search. I've tried using the .sumbit function and wrapping my input around a form element with no success. Any insight would be greatly appreciate! Live example: http://tinyurl.com/84axyym <script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script> <script> $(document).ready(function(){ function(data) { $('#startSearch').click(function(){ $('#tweets .results').remove(); var searchTerm = 'http://search.twitter.com/search.json?q=' + $('#twitterSearch').val() + '&callback=?' $.getJSON(searchTerm, function(data) { $.each(data.results, function() { $('<div class="results"></div>') .hide() .append('<a class="userPicLink" href="http://twitter.com/' + this.from_user + '">' + '<img class="userImg" src="' + this.profile_image_url + '">' + '</a>') .append('<span class="userName">' + '<a href="http://twitter.com/' + this.from_user + '">' + this.from_user + '</span>') .append('<span class="userText">' + this.text + '</span>') .append('<time class="textTime">' + relTime(this.created_at) + '</time>') .appendTo('#tweets') .fadeIn(); }); }); </script> <body> <label id="searchLabel" for="twitterSearch">Search</label> <input type="search" list="searchSugg" id="twitterSearch" placeholder="css3 animation" required aria-required="true"> <input id="startSearch" type="submit"> <datalist id="searchSugg"> <option value="css3 mulitple backgrounds"> <option value="html5 video"> <option value="responsive web design"> <option value="twitter api"> </datalist> <div id="tweets"> </div> </body>

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• how to remove empty tags in input xml

  - by SGB

  My java module gets a huge input xml from a mainframe. Unfortunately, the mainframe is unable to skip optional elements when it is not a leaf node, with the result that I get a LOT of empty tags in my input : So, <pre><code><SSN>111111111</SSN> <Employment> <Current> <Address> <line1/> <line2/> <line3/> <city/> <state/> <country/> </Address> <Phone> <phonenumber/> <countryCode/> </Phone> </Current> <Previous> <Address> <line1/> <line2/> <line3/> <city/> <state/> <country/> </Address> <Phone> <phonenumber/> <countryCode/> </Phone> </Previous> </Employment> <MaritalStatus>Single</MaritalStatus> </code></pre> should be <SSN>111111111</SSN> <MaritalStatus>Single</MaritalStatus> I use jaxb to unmarshall the input xml string that the mainframe sends it. Is there a clean/ easy way to remove all the empty group tags, or do I have to do this manuall in the code for each element. I have over 35 elements in my input xml, so I would love to it if jaxb itself had a way of doing this automatically? Thanks, SGB

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• Resize AIR app window while dragging

  - by matt lohkamp

  So I've noticed Windows 7 has a disturbing tendency to prevent you from dragging the title bar of windows off the top of the screen. If you try - in this case, using an air app with a draggable area at the bottom of the window, allowing you to push the top of the window up past the screen - it just kicks the window back down far enough that the title bar is at the top of what it considers the 'visible area.' One solution would be to resize the app window as it moves, so that the title bar is always where windows wants it. How would you resize the window while you're dragging it, though? Would you do it like this? dragHitArea.addEventListener(MouseEvent.MOUSE_DOWN, function(e:MouseEvent):void{ stage.nativeWindow.height += 50; stage.nativeWindow.startMove(); stage.nativeWindow.height -= 50; }); see what's going on there? When I click, I'm doing startMove(), which is hooking into the OS' function for dragging a window around. I'm also increasing and decreasing the height of the window by 50 pixels - which should give me no net increase, right? Wrong - the first '.height +=' gets executed, but the '.height -=' after the .startMove() never runs. Why? update - If you're curious, I'm programming an air widget with fly-out menus which expand rightwards and upwards - and since those element can only be displayed within the boundaries of the application window itself (even though the window is set to be chromeless and transparent) I have to expand the application's borders to include the area that the menu 'pops up' into. In the extreme case, with the widget positioned bottom left, and the menus expanded completely across to the right side and top edge of the screen, the application area could very well cover the entire desktop. The problem is, when it's expanded like this, if the user drags it up and to the right, it causes the 'title bar' area of the application window to move above the top edge of the desktop area, where it would normally be unreachable; and Windows automatically re-positions the window back below that edge once the .startMove() operation is completed. So what I want to do is continually resize the height of the application so that the visual effect will be the same for the user, but for the benefit of the operating system the window's title bar will never be above that top boundary of the desktop area.

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• Wierdness debugging Visual Studio C++ 2008

  - by Jeff Dege

  I have a legacy C++ app, that in its most incarnation we've been building with makefiles and VS2003's command-line tool. I'm trying to get it to build using VS2008 and MsBuild. The build is working OK, but I'm getting errors where I'd never seen errors, before, and stepping through in VS2008's debugger only confuses me. The app links a number of static libraries, which fall into two categories: those that are part of the same application suite, and those that are shared between a number of application suites. Originally, I had a .csproj file for each static library, and two .sln files, one for the application suite (including the suite-specific libraries) and one for the non-suite-specific shared libraries. The shared libraries were included in the link, their projects were not included in the application suite .sln. The application instantiates an object from a class that is defined in one of the shared libraries. The class has a member object of a class that wraps a linked list. The constructor of the linked list class sets its "head" pointer to null. When I run the app, and try to add an element to the linked list, I get an error - the head pointer contains the value 0xCCCCCCCC. So I step through with the debugger. And see weirdness. When the current line in the debugger is in a source file belonging to the static library, the head pointer contains 0x00000000. When I step into the constructor, I can see the pointer being set to that value, and when I'm stepped into any other method of the class, I can see that the head pointer still contains 0x00000000. But when I step out into methods that are defined in the application suite .sln, it contains 0xCCCCCCCC. It's not like it's being overwritten. It changes back and forth depending upon which source file I am currently debugging. So I included the shared library's project in the application suite .sln, and now I see the head pointer containing 0xCCCCCCCC all the time. It looks like the constructor of the linked list class is not being called. So now, I'm entirely confused. Anyone have any ideas?

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• Python: How best to parse a simple grammar?

  - by Rosarch

  Ok, so I've asked a bunch of smaller questions about this project, but I still don't have much confidence in the designs I'm coming up with, so I'm going to ask a question on a broader scale. I am parsing pre-requisite descriptions for a course catalog. The descriptions almost always follow a certain form, which makes me think I can parse most of them. From the text, I would like to generate a graph of course pre-requisite relationships. (That part will be easy, after I have parsed the data.) Some sample inputs and outputs: "CS 2110" => ("CS", 2110) # 0 "CS 2110 and INFO 3300" => [("CS", 2110), ("INFO", 3300)] # 1 "CS 2110, INFO 3300" => [("CS", 2110), ("INFO", 3300)] # 1 "CS 2110, 3300, 3140" => [("CS", 2110), ("CS", 3300), ("CS", 3140)] # 1 "CS 2110 or INFO 3300" => [[("CS", 2110)], [("INFO", 3300)]] # 2 "MATH 2210, 2230, 2310, or 2940" => [[("MATH", 2210), ("MATH", 2230), ("MATH", 2310)], [("MATH", 2940)]] # 3 If the entire description is just a course, it is output directly. If the courses are conjoined ("and"), they are all output in the same list If the course are disjoined ("or"), they are in separate lists Here, we have both "and" and "or". One caveat that makes it easier: it appears that the nesting of "and"/"or" phrases is never greater than as shown in example 3. What is the best way to do this? I started with PLY, but I couldn't figure out how to resolve the reduce/reduce conflicts. The advantage of PLY is that it's easy to manipulate what each parse rule generates: def p_course(p): 'course : DEPT_CODE COURSE_NUMBER' p[0] = (p[1], int(p[2])) With PyParse, it's less clear how to modify the output of parseString(). I was considering building upon @Alex Martelli's idea of keeping state in an object and building up the output from that, but I'm not sure exactly how that is best done. def addCourse(self, str, location, tokens): self.result.append((tokens[0][0], tokens[0][1])) def makeCourseList(self, str, location, tokens): dept = tokens[0][0] new_tokens = [(dept, tokens[0][1])] new_tokens.extend((dept, tok) for tok in tokens[1:]) self.result.append(new_tokens) For instance, to handle "or" cases: def __init__(self): self.result = [] # ... self.statement = (course_data + Optional(OR_CONJ + course_data)).setParseAction(self.disjunctionCourses) def disjunctionCourses(self, str, location, tokens): if len(tokens) == 1: return tokens print "disjunction tokens: %s" % tokens How does disjunctionCourses() know which smaller phrases to disjoin? All it gets is tokens, but what's been parsed so far is stored in result, so how can the function tell which data in result corresponds to which elements of token? I guess I could search through the tokens, then find an element of result with the same data, but that feel convoluted... What's a better way to approach this problem?

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