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• How to give the First image in a gallery a different class than the rest of the images - Carrierwave

  - by ChrisBedoya

  I have a model called "Photo" that belongs to a model called "Shoe". I using Carrierwave to upload multiple images. index.html.erb <% shoes.each do |shoe| %> <div class="shoe"> <div class="gallery"> <% shoe.photos.each do |photo| %> <%= link_to image_tag(photo.photo_file.url(:thumb).to_s), photo.photo_file.url.to_s, :class => 'fancybox', :rel => 'gallery' %> <% end %> </div> </div> <% end %> Outputs this: <div class="shoe"> <div class="gallery"> <a class="fancybox" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> <a class="fancybox" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> <a class="fancybox" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> </div> </div> But I want the first image of each gallery to be able to have its own class and the rest of the images to have their own class. Something like this: <a class="firstclass" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> <a class="fancybox" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> <a class="fancybox" href="../nike-kd-6-meteorology-2.jpg" rel="gallery"> <img src="../thumb_nike-kd-6-meteorology-2.jpg"> </a> How can I do this? Also I want each gallery to have its own unique id but when I try to add this: :rel => 'gallery<%= shoe.id %>' I get a Syntax error. Thanks.

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• Trouble passing a string as a SQLite ExecSQL command

  - by Hackbrew

  I keep getting the ERROR: near "PassWord": syntax error when trying to execute the ExecSQL() statement. The command looks good in the output of the text file. In fact, I copied & pasted the command directly into SQLite Database Browser and the commend executed properly. Here's the code that's producing the error: procedure TForm1.Button1Click(Sender: TObject); var i, iFieldSize: integer; sFieldName, sFieldType, sFieldList, sExecSQL: String; names: TStringList; f1: Textfile; begin //Open Source table - Table1 has 8 fields but has only two different field types ftString and Boolean Table1.TableName:= 'PWFile'; Table1.Open; //FDConnection1.ExecSQL('drop table PWFile'); sFieldList := ''; names := TStringList.Create; for i := 0 to Table1.FieldCount - 1 do begin sFieldName := Table1.FieldDefList.FieldDefs[i].Name; sFieldType := GetEnumName(TypeInfo(TFieldType),ord(Table1.FieldDefList.FieldDefs[i].DataType)); iFieldSize := Table1.FieldDefList.FieldDefs[i].Size; if sFieldType = 'ftString' then sFieldType := 'NVARCHAR' + '(' + IntToStr(iFieldSize) + ')'; if sFieldType = 'ftBoolean' then sFieldType := 'INTEGER'; names.Add(sFieldName + ' ' + sFieldType); if sFieldList = '' then sFieldList := sFieldName + ' ' + sFieldType else sFieldList := sFieldList + ', ' + sFieldName + ' ' + sFieldType; end; ListBox1.Items.Add(sFieldList); sExecSQL := 'create table IF NOT EXISTS PWFile (' + sFieldList + ')'; // 08/18/2014 - Entered this to log the SQLite FDConnection1.ExecSQL Command to a file AssignFile(f1, 'C:\Users\Test User\Documents\SQLite_Command.txt'); Rewrite(f1); Writeln(f1, sExecSQL); { insert code here that would require a Flush before closing the file } Flush(f1); { ensures that the text was actually written to file } CloseFile(f1); FDConnection1.ExecSQL(sFieldList); Table1.Close; end; Here's the actual command that gets executed: create table IF NOT EXISTS PWFile (PassWord NVARCHAR(10), PassName NVARCHAR(10), Dept NVARCHAR(10), Active NVARCHAR(1), Admin INTEGER, Shred INTEGER, Reports INTEGER, Maintain INTEGER)

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• Designing different Factory classes (and what to use as argument to the factories!)

  - by devoured elysium

  Let's say we have the following piece of code: public class Event { } public class SportEvent1 : Event { } public class SportEvent2 : Event { } public class MedicalEvent1 : Event { } public class MedicalEvent2 : Event { } public interface IEventFactory { bool AcceptsInputString(string inputString); Event CreateEvent(string inputString); } public class EventFactory { private List<IEventFactory> factories = new List<IEventFactory>(); public void AddFactory(IEventFactory factory) { factories.Add(factory); } //I don't see a point in defining a RemoveFactory() so I won't. public Event CreateEvent(string inputString) { try { //iterate through all factories. If one and only one of them accepts //the string, generate the event. Otherwise, throw an exception. return factories.Single(factory => factory.AcceptsInputString(inputString)).CreateEvent(inputString); } catch (InvalidOperationException e) { throw new InvalidOperationException("No valid factory found to generate this kind of Event!", e); } } } public class SportEvent1Factory : IEventFactory { public bool AcceptsInputString(string inputString) { return inputString.StartsWith("SportEvent1"); } public Event CreateEvent(string inputString) { return new SportEvent1(); } } public class MedicalEvent1Factory : IEventFactory { public bool AcceptsInputString(string inputString) { return inputString.StartsWith("MedicalEvent1"); } public Event CreateEvent(string inputString) { return new MedicalEvent1(); } } And here is the code that runs it: static void Main(string[] args) { EventFactory medicalEventFactory = new EventFactory(); medicalEventFactory.AddFactory(new MedicalEvent1Factory()); medicalEventFactory.AddFactory(new MedicalEvent2Factory()); EventFactory sportsEventFactory = new EventFactory(); sportsEventFactory.AddFactory(new SportEvent1Factory()); sportsEventFactory.AddFactory(new SportEvent2Factory()); } I have a couple of questions: Instead of having to add factories here in the main method of my application, should I try to redesign my EventFactory class so it is an abstract factory? It'd be better if I had a way of not having to manually add EventFactories every time I want to use them. So I could just instantiate MedicalFactory and SportsFactory. Should I make a Factory of factories? Maybe that'd be over-engineering? As you have probably noticed, I am using a inputString string as argument to feed the factories. I have an application that lets the user create his own events but also to load/save them from text files. Later, I might want to add other kinds of files, XML, sql connections, whatever. The only way I can think of that would allow me to make this work is having an internal format (I choose a string, as it's easy to understand). How would you make this? I assume this is a recurrent situation, probably most of you know of any other more intelligent approach to this. I am then only looping in the EventFactory for all the factories in its list to check if any of them accepts the input string. If one does, then it asks it to generate the Event. If you find there is something wrong or awkward with the method I'm using to make this happen, I'd be happy to hear about different implementations. Thanks! PS: Although I don't show it in here, all the different kind of events have different properties, so I have to generate them with different arguments (SportEvent1 might have SportName and Duration properties, that have to be put in the inputString as argument).

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• writing XML with Xerces 3.0.1 and C++ on windows

  - by Jon

  Hi, i have the following function i wrote to create an XML file using Xerces 3.0.1, if i call this function with a filePath of "foo.xml" or "../foo.xml" it works great, but if i pass in "c:/foo.xml" then i get an exception on this line XMLFormatTarget *formatTarget = new LocalFileFormatTarget(targetPath); can someone explain why my code works for relative paths, but not absolute paths please? many thanks. const int ABSOLUTE_PATH_FILENAME_PREFIX_SIZE = 9; void OutputXML(xercesc::DOMDocument* pmyDOMDocument, std::string filePath) { //Return the first registered implementation that has the desired features. In this case, we are after a DOM implementation that has the LS feature... or Load/Save. DOMImplementation *implementation = DOMImplementationRegistry::getDOMImplementation(L"LS"); // Create a DOMLSSerializer which is used to serialize a DOM tree into an XML document. DOMLSSerializer *serializer = ((DOMImplementationLS*)implementation)->createLSSerializer(); // Make the output more human readable by inserting line feeds. if (serializer->getDomConfig()->canSetParameter(XMLUni::fgDOMWRTFormatPrettyPrint, true)) serializer->getDomConfig()->setParameter(XMLUni::fgDOMWRTFormatPrettyPrint, true); // The end-of-line sequence of characters to be used in the XML being written out. serializer->setNewLine(XMLString::transcode("\r\n")); // Convert the path into Xerces compatible XMLCh*. XMLCh *tempFilePath = XMLString::transcode(filePath.c_str()); // Calculate the length of the string. const int pathLen = XMLString::stringLen(tempFilePath); // Allocate memory for a Xerces string sufficent to hold the path. XMLCh *targetPath = (XMLCh*)XMLPlatformUtils::fgMemoryManager->allocate((pathLen + ABSOLUTE_PATH_FILENAME_PREFIX_SIZE) * sizeof(XMLCh)); // Fixes a platform dependent absolute path filename to standard URI form. XMLString::fixURI(tempFilePath, targetPath); // Specify the target for the XML output. XMLFormatTarget *formatTarget = new LocalFileFormatTarget(targetPath); //XMLFormatTarget *myFormTarget = new StdOutFormatTarget(); // Create a new empty output destination object. DOMLSOutput *output = ((DOMImplementationLS*)implementation)->createLSOutput(); // Set the stream to our target. output->setByteStream(formatTarget); // Write the serialized output to the destination. serializer->write(pmyDOMDocument, output); // Cleanup. serializer->release(); XMLString::release(&tempFilePath); delete formatTarget; output->release(); }

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• Step by Step / Deep explain: The Power of (Co)Yoneda (preferably in scala) through Coroutines

  - by Mzk

  some background code /** FunctorStr: ? F[-]. (? A B. (A -> B) -> F[A] -> F[B]) */ trait FunctorStr[F[_]] { self => def map[A, B](f: A => B): F[A] => F[B] } trait Yoneda[F[_], A] { yo => def apply[B](f: A => B): F[B] def run: F[A] = yo(x => x) def map[B](f: A => B): Yoneda[F, B] = new Yoneda[F, B] { def apply[X](g: B => X) = yo(f andThen g) } } object Yoneda { implicit def yonedafunctor[F[_]]: FunctorStr[({ type l[x] = Yoneda[F, x] })#l] = new FunctorStr[({ type l[x] = Yoneda[F, x] })#l] { def map[A, B](f: A => B): Yoneda[F, A] => Yoneda[F, B] = _ map f } def apply[F[_]: FunctorStr, X](x: F[X]): Yoneda[F, X] = new Yoneda[F, X] { def apply[Y](f: X => Y) = Functor[F].map(f) apply x } } trait Coyoneda[F[_], A] { co => type I def fi: F[I] def k: I => A final def map[B](f: A => B): Coyoneda.Aux[F, B, I] = Coyoneda(fi)(f compose k) } object Coyoneda { type Aux[F[_], A, B] = Coyoneda[F, A] { type I = B } def apply[F[_], B, A](x: F[B])(f: B => A): Aux[F, A, B] = new Coyoneda[F, A] { type I = B val fi = x val k = f } implicit def coyonedaFunctor[F[_]]: FunctorStr[({ type l[x] = Coyoneda[F, x] })#l] = new CoyonedaFunctor[F] {} trait CoyonedaFunctor[F[_]] extends FunctorStr[({type l[x] = Coyoneda[F, x]})#l] { override def map[A, B](f: A => B): Coyoneda[F, A] => Coyoneda[F, B] = x => apply(x.fi)(f compose x.k) } def liftCoyoneda[T[_], A](x: T[A]): Coyoneda[T, A] = apply(x)(a => a) } Now I thought I understood yoneda and coyoneda a bit just from the types – i.e. that they quantify / abstract over map fixed in some type constructor F and some type a, to any type B returning F[B] or (Co)Yoneda[F, B]. Thus providing map fusion for free (? is this kind of like a cut rule for map ?). But I see that Coyoneda is a functor for any type constructor F regardless of F being a Functor, and that I don't fully grasp. Now I'm in a situation where I'm trying to define a Coroutine type, (I'm looking at https://www.fpcomplete.com/school/to-infinity-and-beyond/pick-of-the-week/coroutines-for-streaming/part-2-coroutines for the types to get started with) case class Coroutine[S[_], M[_], R](resume: M[CoroutineState[S, M, R]]) sealed trait CoroutineState[S[_], M[_], R] object CoroutineState { case class Run[S[_], M[_], R](x: S[Coroutine[S, M, R]]) extends CoroutineState[S, M, R] case class Done[R](x: R) extends CoroutineState[Nothing, Nothing, R] class CoroutineStateFunctor[S[_], M[_]](F: FunctorStr[S]) extends FunctorStr[({ type l[x] = CoroutineState[S, M, x]})#l] { override def map[A, B](f : A => B) : CoroutineState[S, M, A] => CoroutineState[S, M, B] = { ??? } } } and I think that if I understood Coyoneda better I could leverage it to make S & M type constructors functors way easy, plus I see Coyoneda potentially playing a role in defining recursion schemes as the functor requirement is pervasive. So how could I use coyoneda to make type constructors functors like for example coroutine state? or something like a Pause functor ?

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• How to unit test synchronized code

  - by gillJ

  Hi, I am new to Java and junit. I have the following peice of code that I want to test. Would appreciate if you could send your ideas about what's the best way to go about testing it. Basically, the following code is about electing a leader form a Cluster. The leader holds a lock on the shared cache and services of the leader get resumed and disposed if it somehow looses the lock on the cache. How can i make sure that a leader/thread still holds the lock on the cache and that another thread cannot get its services resumed while the first is in execution? public interface ContinuousService { public void resume(); public void pause(); } public abstract class ClusterServiceManager { private volatile boolean leader = false; private volatile boolean electable = true; private List<ContinuousService> services; protected synchronized void onElected() { if (!leader) { for (ContinuousService service : services) { service.resume(); } leader = true; } } protected synchronized void onDeposed() { if (leader) { for (ContinuousService service : services) { service.pause(); } leader = false; } } public void setServices(List<ContinuousService> services) { this.services = services; } @ManagedAttribute public boolean isElectable() { return electable; } @ManagedAttribute public boolean isLeader() { return leader; } public class TangosolLeaderElector extends ClusterServiceManager implements Runnable { private static final Logger log = LoggerFactory.getLogger(TangosolLeaderElector.class); private String election; private long electionWaitTime= 5000L; private NamedCache cache; public void start() { log.info("Starting LeaderElector ({})",election); Thread t = new Thread(this, "LeaderElector ("+election+")"); t.setDaemon(true); t.start(); } public void run() { // Give the connection a chance to start itself up try { Thread.sleep(1000); } catch (InterruptedException e) {} boolean wasElectable = !isElectable(); while (true) { if (isElectable()) { if (!wasElectable) { log.info("Leadership requested on election: {}",election); wasElectable = isElectable(); } boolean elected = false; try { // Try and get the lock on the LeaderElectorCache for the current election if (!cache.lock(election, electionWaitTime)) { // We didn't get the lock. cycle round again. // This code to ensure we check the electable flag every now & then continue; } elected = true; log.info("Leadership taken on election: {}",election); onElected(); // Wait here until the services fail in some way. while (true) { try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} if (!cache.lock(election, 0)) { log.warn("Cache lock no longer held for election: {}", election); break; } else if (!isElectable()) { log.warn("Node is no longer electable for election: {}", election); break; } // We're fine - loop round and go back to sleep. } } catch (Exception e) { if (log.isErrorEnabled()) { log.error("Leadership election " + election + " failed (try bfmq logs for details)", e); } } finally { if (elected) { cache.unlock(election); log.info("Leadership resigned on election: {}",election); onDeposed(); } // On deposition, do not try and get re-elected for at least the standard wait time. try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} } } else { // Not electable - wait a bit and check again. if (wasElectable) { log.info("Leadership NOT requested on election ({}) - node not electable",election); wasElectable = isElectable(); } try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} } } } public void setElection(String election) { this.election = election; } @ManagedAttribute public String getElection() { return election; } public void setNamedCache(NamedCache nc) { this.cache = nc; }

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• Autoconf -- building with static library (newbie)

  - by EB

  I am trying to migrate my application from manual build to autoconf, which is working very nicely so far. But I have one static library that I can't figure out how to integrate. That library will NOT be located in the usual library locations - the location of the binary (.a file) and header (.h file) will be given as a configure argument. (Notably, even if I move the .a file to /usr/lib or anywhere else I can think of, it still won't work.) It is also not named traditionally (it does not start with "lib" or "l"). Manual compilation is working with these (directory is not predictable - this is just an example): gcc ... -I/home/john/mystuff /home/john/mystuff/helper.a (Uh, I actually don't understand why the .a file is referenced directly, not with -L or anything. Yes, I have a half-baked understanding of building C programs.) So, in my configure.ac, I can use the relevant configure argument to successfully find the header (.h file) using AC_CHECK_HEADER. Inside the AC_CHECK_HEADER I then add the location to CPFLAGS and the #include of the header file in the actual C code picks it up nicely. Given a configure argument that has been put into $location and the name of the needed files are helper.h and helper.a (which are both in the same directory), here is what works so far: AC_CHECK_HEADER([$location/helper.h], [AC_DEFINE([HAVE_HELPER_H], [1], [found helper.h]) CFLAGS="$CFLAGS -I$location"]) Where I run into difficulties is getting the binary (.a file) linked in. No matter what I try, I always get an error about undefined references to the function calls for that library. I'm pretty sure it's a linkage issue, because I can fuss with the C code and make an intentional error in the function calls to that library which produces earlier errors that indicate that the function prototypes have been loaded and used to compile. I tried adding the location that contains the .a file to LDFLAGS and then doing a AC_CHECK_LIB but it is not found. Maybe my syntax is wrong, or maybe I'm missing something more fundamental, which would not be surprising since I'm a newbie and don't really know what I'm doing. Here is what I have tried: AC_CHECK_HEADER([$location/helper.h], [AC_DEFINE([HAVE_HELPER_H], [1], [found helper.h]) CFLAGS="$CFLAGS -I$location"; LDFLAGS="$LDFLAGS -L$location"; AC_CHECK_LIB(helper)]) No dice. AC_CHECK_LIB is looking for -lhelper I guess (or libhelper?) so I'm not sure if that's a problem, so I tried this, too (omit AC_CHECK_LIB and include the .a directly in LDFLAGS), without luck: AC_CHECK_HEADER([$location/helper.h], [AC_DEFINE([HAVE_HELPER_H], [1], [found helper.h]) CFLAGS="$CFLAGS -I$location"; LDFLAGS="$LDFLAGS -L$location/helper.a"]) To emulate the manual compilation, I tried removing the -L but that doesn't help: AC_CHECK_HEADER([$location/helper.h], [AC_DEFINE([HAVE_HELPER_H], [1], [found helper.h]) CFLAGS="$CFLAGS -I$location"; LDFLAGS="$LDFLAGS $location/helper.a"]) I tried other combinations and permutations, but I think I might be missing something more fundamental....

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• how to use window.onload?

  - by Patrick

  I'm refactoring a website using MVC. What was a set of huge pages with javascript, php, html etc etc is becoming a series of controllers and views. I'm trying to do it in a modular way so views are split in 'modules' that I can reuse in other pages when needed eg. "view/searchform displays only one div with the searchform "view/display_events displays a list of events and so on. One of the old pages was supposed to load a google map with a marker on it. Amongst the rest of the code, I can identify the relevant bits as follows <head> <script src="http://maps.google.com/maps?file=api&amp;v=2&amp;key=blablabla" type="text/javascript"></script> <script type="text/javascript"> //<![CDATA[ function load() { if (GBrowserIsCompatible()) { var map = new GMap2(document.getElementById("map")); var point = new GLatLng(<?php echo ($info->lat && $info->lng) ? $info->lat .",". $info->lng : "51.502759,-0.126171"; ?>); map.setCenter(new GLatLng(<?php echo ($info->lat && $info->lng) ? $info->lat .",". $info->lng : "51.502759,-0.126171"; ?>), 15); map.addControl(new GLargeMapControl()); map.addControl(new GScaleControl()); map.addOverlay(new GMarker(point)); var marker = createMarker(point,GIcon(),"CIAO"); map.addOverlay(marker); } } //]]> </script> </head> ...then <body onload="load()" onunload="GUnload()"> ...and finally this div where the map should be displayed <div id="map" style="width: 440px; height: 300px"> </div> Don't know much about js, but my understanding is that a) I have to include the scripts in the view module I'm writing (directly in the HTML? I would prefer to load a separate script) b) I have to trigger that function using the equivalent of body onload... (obviously there's no body tag in my view. In my ignorance I've tried div onload=.... but didn't seem to be working :) What do you suggest I do? I've read about window.onload but don't know what's the correct syntax for that. please keep in mind that other parts of the page include other js functions (eg, google adsense) that are called after the footer.

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• Inbreeding-immune database structure

  - by Nick Savage

  I have an application that requires a "simple" family tree. I would like to be able to perform queries that will give me data for an entire family given one id from a member in the family. I say simple because it does not need to take into account adoption or any other obscurities. The requirements for the application are as follows: Any two people will not be able to breed if they're from the same genetic line Needs to allow for the addition of new family lines (new people with no previous family) Need to be able to pull siblings, parents separately through queries I'm having trouble coming up with the proper structure for the database. So far I've come up with two solutions but they're not very reliable and will probably get out of hand quite quickly. Solution 1 involves placing a family_ids field on the people table and storing a list of unique family ids. Each time two people breed the lists are checked against each other to make sure no ids match and if everything checks out will merge the two lists and set that as the child's family_ids field. Example: Father (family_ids: (null)) breeds with Mother (family_ids: (213, 519)) -> Child (family_ids: (213, 519)) breeds with Random Person (family_ids: (813, 712, 122, 767)) -> Grandchild (family_ids: (213, 519, 813, 712, 122, 767)) And so on and so forth... The problem I see with this is the lists becoming unreasonably large as time goes on. Solution 2 uses cakephp's associations to declare: public $belongsTo = array( 'Father' => array( 'className' => 'User', 'foreignKey' => 'father_id' ), 'Mother' => array( 'className' => 'User', 'foreignKey' => 'mother_id' ) ); Now setting recursive to 2 will fetch the results of the mother and father, along with their mother and father, and so on and so forth all the way down the line. The problem with this route is that the data is in nested arrays and I'm unsure of how to efficiently work through the code. If anyone would be able to steer me in the direction of the most efficient way to handle what I want to achieve that would be tremendously helpful. Any and all help is greatly appreciated and I'll gladly answer any questions anyone has. Thanks a lot.

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• Primary language - C++/Qt, C#, Java?

  - by Airjoe

  I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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• Add class to elements which already have a class

  - by bwstud

  I have a group of divs which I'm dynamically generating when a button is clicked with the class, "brick". This gives them dimension and starting position of top: 0. I'm trying to get them to animate to the bottom of the view using a css transition with a second class assignment which gives them a bottom position: 0;. Can't figure out the syntax for adding a second class to elements with a pre-existing class. On inspection they only show the original class of, "brick". HTML <!DOCTYPE html> <html> <head> <script src="http://code.jquery.com/jquery-2.1.0.min.js"></script> <meta charset="utf-8"> <title>JS Bin</title> </head> <body> <div id="container"> <div id="button" >Click Me</div> </div> </body> </html> CSS #container { width: 100%; height: 100vh; padding: 10vmax; } #button { position: fixed; } .brick { position: relative; top: 0; height: 10vmax; width: 20vmax; background: white; margin: 0; padding: 0; transition: all 1s; } .drop { transition: all 1s; bottom 0; } The offending JS: var brickCount = function() { var count = prompt("How many boxes you lookin' for?"); for(var i=0; i < count; i++) { var newBrick = document.createElement("div"); newBrick.className="brick"; document.querySelector("#container") .appendChild(newBrick); } }; var getBricks = function(){ document.getElementByClass("brick"); }; var changeColor = function(){ getBricks.style.backgroundColor = '#'+Math.floor(Math.random()*16777215).toString(16); }; var addDrop = function() { getBricks.brick = "getBricks.brick" + " drop"; }; var multiple = function() { brickCount(); getBricks(); changeColor(); addDrop(); }; document.getElementById("button").onclick = function() {multiple();}; Thanks!

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• jquery load a specific #Div content from multiple html files

  - by Vikram

  Hello friends I am trying to make a Content Slider for my site. I have multiple HTML files and the structure of these files is like this: <div id="title"><h2>Title of the Slide</h2></div> <div id="image"><a href="http://mylink.com"><img src="image.jpg" width="600" height="300" alt="image"</a></div> <div id="content">Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s.</div> I have been trying to use the following script get content (but no success): <?php function render($position="") { ob_start(); foreach(glob("/slides/*.html") as $fileName) { $fname = basename( $fileName ); $curArr = file($fname); $slides[$fname ]['title'] = $curArr[0]; $slides[$fname ]['image'] = $curArr[1]; $slides[$fname ]['content'] = $curArr[2]; foreach($slides as $key => $value){ ?> <div id="slide-title"> <?php echo $value['title'] ?> </div> <div id="slide-content"> <?php echo $value['image'] ?> </div> <div id="slide-image"> <?php echo $value['content'] ?> </div> <?php }} ?> <?php return ob_get_clean(); } But then I came to know about a jQuery function.... (again no success) jQuery.noConflict(); (function($){ $(document).ready(function () { $('#slide-title').load('slides/slide1.html #title'); $('#slide-content').load('slides/slide1.html #content'); $('#slide-image').load('slides/slide1.html #image'); }); })(jQuery); Now My questions are..... Am I using the right syntax. How do I get the content from multiple files using jQuery. Please Note : My knowledge on Programming is almost '0'. I have just started learning it.

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• Generating Unordered List with PHP + CodeIgniter from a MySQL Database

  - by Tim

  Hello Everyone, I am trying to build a dynamically generated unordered list in the following format using PHP. I am using CodeIgniter but it can just be normal php. This is the end output I need to achieve. <ul id="categories" class="menu"> <li rel="1"> Arts &amp; Humanities <ul> <li rel="2"> Photography <ul> <li rel="3"> 3D </li> <li rel="4"> Digital </li> </ul> </li> <li rel="5"> History </li> <li rel="6"> Literature </li> </ul> </li> <li rel="7"> Business &amp; Economy </li> <li rel="8"> Computers &amp; Internet </li> <li rel="9"> Education </li> <li rel="11"> Entertainment <ul> <li rel="12"> Movies </li> <li rel="13"> TV Shows </li> <li rel="14"> Music </li> <li rel="15"> Humor </li> </ul> </li> <li rel="10"> Health </li> And here is my SQL that I have to work with. -- -- Table structure for table `categories` -- CREATE TABLE IF NOT EXISTS `categories` ( `id` mediumint(8) NOT NULL auto_increment, `dd_id` mediumint(8) NOT NULL, `parent_id` mediumint(8) NOT NULL, `cat_name` varchar(256) NOT NULL, `cat_order` smallint(4) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ; So I know that I am going to need at least 1 foreach loop to generate the first level of categories. What I don't know is how to iterate inside each loop and check for parents and do that in a dynamic way so that there could be an endless tree of children. Thanks for any help you can offer. Tim

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• How can I create a Searchstring for a Google AJAX Search API?

  - by elmaso

  Hello, i have this code to get the search resutls from the api: querygoogle.php: <?php session_start(); // Here's the Google AJAX Search API url for curl. It uses Google Search's site:www.yourdomain.com syntax to search in a specific site. I used $_SERVER['HTTP_HOST'] to find my domain automatically. Change $_POST['searchquery'] to your posted search query $url = 'http://ajax.googleapis.com/ajax/services/search/web?rsz=large&v=1.0&start=20&q=' . urlencode('' . $_POST['searchquery']); // use fopen and fread to pull Google's search results $handle = fopen($url, 'rb'); $body = ''; while (!feof($handle)) { $body .= fread($handle, 8192); } fclose($handle); // now $body is the JSON encoded results. We need to decode them. $json = json_decode($body); // now $json is an object of Google's search results and we need to iterate through it. foreach($json->responseData->results as $searchresult) { if($searchresult->GsearchResultClass == 'GwebSearch') { $formattedresults .= ' <div class="searchresult"> <h3><a href="' . $searchresult->unescapedUrl . '">' . $searchresult->titleNoFormatting . '</a></h3> <p class="resultdesc">' . $searchresult->content . '</p> <p class="resulturl">' . $searchresult->visibleUrl . '</p> </div>'; } } $_SESSION['googleresults'] = $formattedresults; header('Location: ' . $_SERVER['HTTP_REFERER']); exit; ?> search.php <?php session_start(); ?> <form method="post" action="querygoogle.php"> <label for="searchquery"><span class="caption">Search this site</span> <input type="text" size="20" maxlength="255" title="Enter your keywords and click the search button" name="searchquery" /></label> <input type="submit" value="Search" /> </form> <?php if(!empty($_SESSION['googleresults'])) { echo $_SESSION['googleresults']; unset($_SESSION['googleresults']); } ?> but with this code, I cant add a searchstring.. how can i add a search string like search.php?search=keyword ? thanks

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• Why oh why doesn't my asp.net treeview update?

  - by Brendan

  I'm using an ASP.net treeview on a page with a custom XmlDataSource. When the user clicks on a node of the tree, a detailsview pops up and edits a bunch of things about the underlying object. All this works properly, and the underlying object gets updated in my background object-management classes. Yay! However, my treeview just isn't updating the display. Either immediately (which i would like it to), or on full page re-load (which is the minimal useful level i need it to be at). Am i subclassing XmlDataSource poorly? I really don't know. Can anyone point me in a good direction? Thanks! The markup looks about like this (chaff removed): <data:DefinitionDataSource runat="server" ID="DefinitionTreeSource" RootDefinitionID="uri:1"></data:DefinitionDataSource> <asp:TreeView ID="TreeView" runat="server" DataSourceID="DefinitionTreeSource"> <DataBindings> <asp:TreeNodeBinding DataMember="definition" TextField="name" ValueField="id" /> </DataBindings> </asp:TreeView> <asp:DetailsView ID="DetailsView1" runat="server" AutoGenerateRows="False" DataKeyNames="Id" DataSourceID="DefinitionSource" DefaultMode="Edit"> <Fields> <asp:BoundField DataField="Name" HeaderText="Name" HeaderStyle-Wrap="false" SortExpression="Name" /> <asp:CommandField ShowCancelButton="False" ShowInsertButton="True" ShowEditButton="True" ButtonType="Button" /> </Fields> </asp:DetailsView> And the DefinitionTreeSource code looks like this: public class DefinitionDataSource : XmlDataSource { public string RootDefinitionID { get { if (ViewState["RootDefinitionID"] != null) return ViewState["RootDefinitionID"] as String; return null; } set { if (!Object.Equals(ViewState["RootDefinitionID"], value)) { ViewState["RootDefinitionID"] = value; DataBind(); } } } public DefinitionDataSource() { } public override void DataBind() { base.DataBind(); setData(); } private void setData() { String defXML = "<?xml version=\"1.0\" ?>"; Test.Management.TestManager.Definition root = Test.Management.TestManager.Definition.GetDefinitionById(RootDefinitionID); if (root != null) this.Data = defXML + root.ToXMLString(); else this.Data = defXML + "<definition id=\"null\" name=\"Set Root Node\" />"; } } }

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• Simplifying const Overloading?

  - by templatetypedef

  Hello all- I've been teaching a C++ programming class for many years now and one of the trickiest things to explain to students is const overloading. I commonly use the example of a vector-like class and its operator[] function: template <typename T> class Vector { public: T& operator[] (size_t index); const T& operator[] (size_t index) const; }; I have little to no trouble explaining why it is that two versions of the operator[] function are needed, but in trying to explain how to unify the two implementations together I often find myself wasting a lot of time with language arcana. The problem is that the only good, reliable way that I know how to implement one of these functions in terms of the other is with the const_cast/static_cast trick: template <typename T> const T& Vector<T>::operator[] (size_t index) const { /* ... your implementation here ... */ } template <typename T> T& Vector<T>::operator[] (size_t index) { return const_cast<T&>(static_cast<const Vector&>(*this)[index]); } The problem with this setup is that it's extremely tricky to explain and not at all intuitively obvious. When you explain it as "cast to const, then call the const version, then strip off constness" it's a little easier to understand, but the actual syntax is frightening,. Explaining what const_cast is, why it's appropriate here, and why it's almost universally inappropriate elsewhere usually takes me five to ten minutes of lecture time, and making sense of this whole expression often requires more effort than the difference between const T* and T* const. I feel that students need to know about const-overloading and how to do it without needlessly duplicating the code in the two functions, but this trick seems a bit excessive in an introductory C++ programming course. My question is this - is there a simpler way to implement const-overloaded functions in terms of one another? Or is there a simpler way of explaining this existing trick to students? Thanks so much!

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• XML and XSD - use element name as replacement of xsi:type for polymorphism

  - by disown

  Taking the W3C vehicle XSD as an example: <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://cars.example.com/schema" xmlns:target="http://cars.example.com/schema"> <complexType name="Vehicle" abstract="true"/> <complexType name="Car"> <complexContent> <extension base="target:Vehicle"/> ... </complexContent> </complexType> <complexType name="Plane"> <complexContent> <extension base="target:Vehicle"/> <sequence> <element name="wingspan" type="integer"/> </sequence> </complexContent> </complexType> </schema> , and the following definition of 'meansOfTravel': <complexType name="MeansOfTravel"> <complexContent> <sequence> <element name="transport" type="target:Vehicle"/> </sequence> </complexContent> </complexType> <element name="meansOfTravel" type="target:MeansOfTravel"/> With this definition you need to specify the type of your instance using xsi:type, like this: <meansOfTravel> <transport xsi:type="Plane"> <wingspan>3</wingspan> </transport> </meansOfTravel> I would just like to acheive a 'name of type' - 'name of element' mapping so that this could be replaced with just <meansOfTravel> <plane> <wingspan>3</wingspan> </plane> </meansOfTravel> The only way I could do this until now is by making it explicit: <complexType name="MeansOfTravel"> <sequence> <choice> <element name="plane" type="target:Plane"/> <element name="car" type="target:Car"/> </choice> </sequence> </complexType> <element name="meansOfTravel" type="target:MeansOfTravel"/> But this means that I have to list all possible sub-types in the 'MeansOfTravel' complex type. Is there no way of making the XML parser assume that you mean a 'Plane' if you call the element 'plane'? Or do I have to make the choice explicit? I would just like to keep my design DRY - if you have any other suggestions (like groups or so) - i would love to hear them.

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• General workflow to allow multiple OpenIDs to be associated with one app account

  - by BobTodd

  I have a (typical?) scenario: that my app's users can use multiple openids mapped to one app account (like stackoverflow). For me the unique thing on the account is the email address, so this binds openids to the profile. Question is, how to allow a user to start using a second openid once one is setup. I am asking as I have read that it is a security hole to allow automatic account openid syncing simply based on the provider-supplied email address as someone could easily spoof someone's email address to create a spoof openid and falsely access the account (how I am not sure) - although this seems to be exactly how stack operates. See options a. and b. below. Problem for me with a. is what happens if the original openid no longer works for whatever reason - how would you set-up a new openid? Would b. be more acceptable if we used email verification? Does anyone have an article detailing a "standard" way (set of user stories) for this - it seems to be an increasingly popular way to authenticate. I have tried to detail this in a rough decision tree... 1. My Site > authentication landing page - user chooses an openid (facebook, google, myopenid etc), redirection > 2. Provider site returns with token (includes user registering a new openid, logging in or is already logged in to Provider site) 3. My Site > use token id to lookup user 3.1 Profile exists? Yes > authenticate. ends. No > 3.1.1 was email address supplied by provider? Yes > lookup user by email address 3.1.1.1 Profile exists? Yes > a. error message - please login with existing openid and associate this openid (from special page) Yes > b. or associate this openid with existing profile automatically. authenticate. ends. No > Register profile. With registration email address follow 3.1.1, except this time where email is unique, we will associate openid. ends

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• Why do we have reinterpret_cast in C++ when two chained static_cast can do it's job?

  - by Nawaz

  Say I want to cast A* to char* and vice-versa, we have two choices (I mean, many of us think we've two choices, because both seems to work! Hence the confusion!): struct A { int age; char name[128]; }; A a; char *buffer = static_cast<char*>(static_cast<void*>(&a)); //choice 1 char *buffer = reinterpret_cast<char*>(&a); //choice 2 Both work fine. //convert back A *pA = static_cast<A*>(static_cast<void*>(buffer)); //choice 1 A *pA = reinterpret_cast<A*>(buffer); //choice 2 Even this works fine! So why do we have reinterpret_cast in C++ when two chained static_cast can do it's job? Some of you might think this topic is a duplicate of the previous topics such as listed at the bottom of this post, but it's not. Those topics discuss only theoretically, but none of them gives even a single example demonstrating why reintepret_cast is really needed, and two static_cast would surely fail. I agree, one static_cast would fail. But how about two? If the syntax of two chained static_cast looks cumbersome, then we can write a function template to make it more programmer-friendly: template<class To, class From> To any_cast(From v) { return static_cast<To>(static_cast<void*>(v)); } And then we can use this, as: char *buffer = any_cast<char*>(&a); //choice 1 char *buffer = reinterpret_cast<char*>(&a); //choice 2 //convert back A *pA = any_cast<A*>(buffer); //choice 1 A *pA = reinterpret_cast<A*>(buffer); //choice 2 Also, see this situation where any_cast can be useful: Proper casting for fstream read and write member functions. So my question basically is, Why do we have reinterpret_cast in C++? Please show me even a single example where two chained static_cast would surely fail to do the same job? Which cast to use; static_cast or reinterpret_cast? Cast from Void* to TYPE* : static_cast or reinterpret_cast

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• When saving a model with has_one or has_many associations, which side of the association is saved fi

  - by SeeBees

  I have three simplified models: class Team < ActiveRecord::Base has_many :players has_one :coach end class Player < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end class Coach < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end I use the following code to test these models: t = Team.new team.coach = Coach.new team.save! team.save! returns true. But in another test: t = Team.new team.players << Player.new team.save! team.save! gives the following error: > ActiveRecord::RecordInvalid: > Validation failed: Players is invalid > from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/validations.rb:1090:in > `save_without_dirty!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/dirty.rb:87:in `save_without_transactions!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in > `transaction' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:182:in > `transaction' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:208:in > `rollback_active_record_state!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from (irb):14 I figured out that when team.save! is called, it first calls player.save!. player needs to validate the presence of the id of the associated team. But at the time player.save! is called, team hasn't been saved yet, and therefore, team_id doesn't yet exist for player. This fails the player's validation, so the error occurs. But on the other hand, team is saved before coach.save!, otherwise the first example will get the same error as the second one. So I've concluded that when a has_many bs, a.save! will save bs prior to a. When a has_one b, a.save! will save a prior to b. If I am right, why is this the case? It doesn't seem logical to me. Why do has_one and has_many association have different order in saving? Any ideas? And is there any way I can change the order? Say I want to have the same saving order for both has_one and has_many. Thanks.

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• Is there a way to make PHP's SplHeap recalculate? (aka: add up-heap to SplHeap?)

  - by md2k7

  I am using an SplHeap to hold graph nodes of a tree with directed edges that will be traversed from the leaves to the root. For this, I precalculate the "fan-in" of nodes and put them into the heap so that I can always retrieve the node with the smallest fan-in (0) from it. After visiting a node, I reduce the fan-in of its successor by 1. Then obviously, the heap needs to be recalculated because the successor is now in the wrong place there. I have tried recoverFromCorruption(), but it doesn't do anything and keeps the heap in the wrong order (node with larger fanIn stays in front of smaller fanIn). As a workaround, I'm now creating a new heap after each visit, amounting to a full O(N*log(N)) sort each time. It should be possible, however, to make up-heap operations on the changed heap entry until it's in the right position in O(log(N)). The API for SplHeap doesn't mention an up-heap (or deletion of an arbitrary element - it could then be re-added). Can I somehow derive a class from SplHeap to do this or do I have to create a pure PHP heap from scratch? EDIT: Code example: class VoteGraph { private $nodes = array(); private function calculateFanIn() { /* ... */ } // ... private function calculateWeights() { $this->calculateFanIn(); $fnodes = new GraphNodeHeap(); // heap by fan-in ascending (leaves are first) foreach($this->nodes as $n) { // omitted: filter loops $fnodes->insert($n); } // traversal from leaves to root while($fnodes->valid()) { $node = $fnodes->extract(); // fetch a leaf from the heap $successor = $this->nodes[$node->successor]; // omitted: actual job of traversal $successor->fanIn--; // will need to fix heap (sift up successor) because of this //$fnodes->recoverFromCorruption(); // doesn't work for what I want // workaround: rebuild $fnodes from scratch $fixedHeap = new GraphNodeHeap(); foreach($fnodes as $e) $fixedHeap->insert($e); $fnodes = $fixedHeap; } } } class GraphNodeHeap extends SplHeap { public function compare($a, $b) { if($a->fanIn === $b->fanIn) return 0; else return $a->fanIn < $b->fanIn ? 1 : -1; } }

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• Urgent help needed on How to update NSMutableDictionary. My code doesn't work.

  - by dawatson833

  I've populated an array using. arrSettings = [[NSMutableArray alloc] initWithContentsOfFile:[self settingsPath]]; The file is a plist with the root as an array and then a dictionary with three three keys defined as number. I've also tried setting the keys to string. I display the values in the plist file on a view using. diaper = [[arrSettings objectAtIndex:0] objectForKey:@"Diaper Expenses"]; oil = [[arrSettings objectAtIndex:0] objectForKey:@"Oil Used"]; tree = [[arrSettings objectAtIndex:0] objectForKey:@"Wood Used"]; This code works fine, the values in the dictionary are assigned to the variables and they are displayed. The user can make changes and then press a save button. I use this code to extract the dictionary part of the array so I can update it. The assignment to editDictionary works. I've double checked the key names including case and that is correct. editDictionary = [[NSMutableDictionary alloc] init]; editDictionary = [arrSettings objectAtIndex:0]; NSNumber *myNumber = [NSNumber numberWithFloat:diaperAmount]; [editDictionary setValue:myNumber forKey:@"Diaper Expenses"]; myNumber = [NSNumber numberWithFloat:oilAmount]; [editDictionary setValue:myNumber forKey:@"Oil Used"]; myNumber = [NSNumber numberWithFloat:treeAmount]; [editDictionary setValue:myNumber forKey:@"Wood Used"]; In this example I've used a nsnumber. But I've also tried the xxxAmount field as part of SetValue instead of creating a NSNumber. Neither implementation works. Several strange things happen. Sometimes the first two setvalue statements work, but the last setvalue fails with a EXC_BAD_ACCESS failure. Other times the first setValue fails with the same error. I have no idea why the first two sometimes work. I'm at a loss of what to do next. I've tried several implentations and none of them work. Also, in the debugger how can I display the editDictionary elements. I can see editDictionary, but I don't know how to display the individual elements.

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• Custom cell in list in Flash AS3

  - by Stian Flatby

  I am no expert in Flash, and I need some quick help here, without needing to learn everything from scratch. Short story, I have to make a list where each cell contains an image, two labels, and a button. List/Cell example: img - label - label - button img - label - label - button As a Java-programmer, I have tried to quicly learn the syntax and visualness of Flash and AS3, but with no luck so far. I have fairly understood the basics of movie clips etc. I saw a tutorial on how to add a list, and add some text to it. So I dragged in a list, and in the code went list.addItem({label:"hello"}); , and that worked ofc. So i thought if I double-clicked the MC of the list, i would get to tweak some things. In there I have been wandering around different halls of cell-renderers etc. I have now come to the point that I entered the CellRenderer_skinUp or something, and customized it to my liking. When this was done, I expected i could use list.addItem(); and get an empty "version" of my cell, with the img, labels and the button. But AS3 expects an input in addItem. From my object-oriented view, I am thinking that i have to create an object of the cell i have made, but i have no luck reaching it.. I tried to go var test:CellRenderer = list.listItem; list.addItem(test); ..But with no luck. This is just for funsies, but I really want to make this work, however not so much that I am willing to read up on ALOT of Flash and AS3. I felt that I was closing in on the prize, but the compiler expected a semicolon after the variable (list.addItem({test:something});). Note: If possible, I do NOT want this: list.addItem({image:"src",label:"text",label"text",button:"text"}); Well.. It actually is what I want, but I would really like to custom-draw everything. Does anyone get what I am trying to do, and has any answers for me? Am I approaching this the wrong way? I have searched the interwebs for custom list-cells, but with no luck. Please, any guiding here is appreciated! Sti

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• How do I get around this lambda expression outer variable issue?

  - by panamack

  I'm playing with PropertyDescriptor and ICustomTypeDescriptor (still) trying to bind a WPF DataGrid to an object, for which the data is stored in a Dictionary. Since if you pass WPF DataGrid a list of Dictionary objects it will auto generate columns based on the public properties of a dictionary (Comparer, Count, Keys and Values) my Person subclasses Dictionary and implements ICustomTypeDescriptor. ICustomTypeDescriptor defines a GetProperties method which returns a PropertyDescriptorCollection. PropertyDescriptor is abstract so you have to subclass it, I figured I'd have a constructor that took Func and an Action parameters that delegate the getting and setting of the values in the dictionary. I then create a PersonPropertyDescriptor for each Key in the dictionary like this: foreach (string s in this.Keys) { var descriptor = new PersonPropertyDescriptor( s, new Func<object>(() => { return this[s]; }), new Action<object>(o => { this[s] = o; })); propList.Add(descriptor); } The problem is that each property get's its own Func and Action but they all share the outer variable s so although the DataGrid autogenerates columns for "ID","FirstName","LastName", "Age", "Gender" they all get and set against "Gender" which is the final resting value of s in the foreach loop. How can I ensure that each delegate uses the desired dictionary Key, i.e. the value of s at the time the Func/Action is instantiated? Much obliged. Here's the rest of my idea, I'm just experimenting here these are not 'real' classes... // DataGrid binds to a People instance public class People : List<Person> { public People() { this.Add(new Person()); } } public class Person : Dictionary<string, object>, ICustomTypeDescriptor { private static PropertyDescriptorCollection descriptors; public Person() { this["ID"] = "201203"; this["FirstName"] = "Bud"; this["LastName"] = "Tree"; this["Age"] = 99; this["Gender"] = "M"; } //... other ICustomTypeDescriptor members... public PropertyDescriptorCollection GetProperties() { if (descriptors == null) { var propList = new List<PropertyDescriptor>(); foreach (string s in this.Keys) { var descriptor = new PersonPropertyDescriptor( s, new Func<object>(() => { return this[s]; }), new Action<object>(o => { this[s] = o; })); propList.Add(descriptor); } descriptors = new PropertyDescriptorCollection(propList.ToArray()); } return descriptors; } //... other other ICustomTypeDescriptor members... } public class PersonPropertyDescriptor : PropertyDescriptor { private Func<object> getFunc; private Action<object> setAction; public PersonPropertyDescriptor(string name, Func<object> getFunc, Action<object> setAction) : base(name, null) { this.getFunc = getFunc; this.setAction = setAction; } // other ... PropertyDescriptor members... public override object GetValue(object component) { return getFunc(); } public override void SetValue(object component, object value) { setAction(value); } }

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• What does Apache need to support both mysqli and PDO?

  - by Nathan Long

  I'm considering changing some PHP code to use PDO for database access instead of mysqli (because the PDO syntax makes more sense to me and is database-agnostic). To do that, I'd need both methods to work while I'm making the changeover. My problem is this: so far, either one or the other method will crash Apache. Right now I'm using XAMPP in Windows XP, and PHP Version 5.2.8. Mysqli works fine, and so does this: $dbc = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password); echo 'Connected to database'; $sql = "SELECT * FROM `employee`"; But this line makes Apache crash: $dbc->query($sql); I don't want to redo my entire Apache or XAMPP installation, but I'd like for PDO to work. So I tried updating libmysql.dll from here, as oddvibes recommended here. That made my simple PDO query work, but then mysqli queries crashed Apache. (I also tried the suggestion after that one, to update php_pdo_mysql.dll and php_pdo.dll, to no effect.) Test Case I created this test script to compare PDO vs mysqli. With the old copy of libmysql.dll, it crashes if $use_pdo is true and doesn't if it's false. With the new copy of libmysql.dll, it's the opposite. if ($use_pdo){ $dbc = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password); echo 'Connected to database<br />'; $sql = "SELECT * FROM `employee`"; $dbc->query($sql); foreach ($dbc->query($sql) as $row){ echo $row['firstname'] . ' ' . $row['lastname'] . "<br>\n"; } } else { $dbc = @mysqli_connect($hostname, $username, $password, $dbname) OR die('Could not connect to MySQL: ' . mysqli_connect_error()); $sql = "SELECT * FROM `employee`"; $result = @mysqli_query($dbc, $sql) or die(mysqli_error($dbc)); while ($row = mysqli_fetch_array($result,MYSQLI_ASSOC)) { echo $row['firstname'] . ' ' . $row['lastname'] . "<br>\n"; } } What does Apache need in order to support both methods of database query?

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