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  • Getting an exception when trying to use extension method with SortedDictionary... why?

    - by Polaris878
    I'm trying to place custom objects into a sorted dictionary... I am then trying to use an extension method (Max()) on this sorted dictionary. However, I'm getting the exception: "At least one object must implement IComparable". I don't understand why I'm getting that, as my custom object obviously implements IComparable. Here is my code: public class MyDate : IComparable<MyDate> { int IComparable<MyDate>.CompareTo(MyDate obj) { if (obj != null) { if (this.Value.Ticks < obj.Value.Ticks) { return 1; } else if (this.Value.Ticks == obj.Value.Ticks) { return 0; } else { return -1; } } } public MyDate(DateTime date) { this.Value = date; } public DateTime Value; } class Program { static void Main(string[] args) { SortedDictionary<MyDate, int> sd = new SortedDictionary<MyDate,int>(); sd.Add(new MyDate(new DateTime(1)), 1); sd.Add(new MyDate(new DateTime(2)), 2); Console.WriteLine(sd.Max().Value); // Throws exception!! } } What on earth am I doing wrong???

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  • Need a workaround to filter on related model and aggregated fields in Django

    - by parxier
    I opened a ticket for this problem. In a nutshell here is my model: class Plan(models.Model): cap = models.IntegerField() class Phone(models.Model): plan = models.ForeignKey(Plan, related_name='phones') class Call(models.Model): phone = models.ForeignKey(Phone, related_name='calls') cost = models.IntegerField() I want to run a query like this one: Phone.objects.annotate(total_cost=Sum('calls__cost')).filter(total_cost__gte=0.5*F('plan__cap')) Unfortunately Django generates bad SQL: SELECT "app_phone"."id", "app_phone"."plan_id", SUM("app_call"."cost") AS "total_cost" FROM "app_phone" INNER JOIN "app_plan" ON ("app_phone"."plan_id" = "app_plan"."id") LEFT OUTER JOIN "app_call" ON ("app_phone"."id" = "app_call"."phone_id") GROUP BY "app_phone"."id", "app_phone"."plan_id" HAVING SUM("app_call"."cost") >= 0.5 * "app_plan"."cap" and errors with: ProgrammingError: column "app_plan.cap" must appear in the GROUP BY clause or be used in an aggregate function LINE 1: ...."plan_id" HAVING SUM("app_call"."cost") >= 0.5 * "app_plan".... Is there any workaround apart from running raw SQL?

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  • Avoiding mass propagation of properties and events for exposure to ViewModels.

    - by firoso
    I have an MVVM application I am developing that is to the point where I'm ready to start putting together a user interface (my client code is largely functional) I'm now running into the issue that I'm trying to get my application data to where I need it so that it can be consumed by the view model and then bound to the view. Unfortunately, it seems that I've either got a few structural oversights, or I'm just going to have to face the reality that I need to be propogating events and raising excessive amounts of errors to notify view models that thier properties have changed. Let me go into some examples of my issue: I have a class "Unit" contained in a class "Test", contained in a class "Session" contained in a class "TestManager" which is contained in "TestDataModel" which is utilized by "TestViewModel" which is databound to by my "TestView" .... WHOA. Now, consider that Unit (the bottom of the heiarchy) has a property called "Results" that is updated periodically, I want to expose that to my viewmodel and then databind it to my view, trouble is, the only way I can really think to do this is to perpetuate events WAY up a chain that say "I've been updated!" and then request the new value... This seems like an aweful way to do this. Alternatively, I could register a static event and raise it, and have the appropriate "Unit view model" grab the event and request the update. This SEEMS better... but... static events? Is that a taboo idea? Also, having an expression like: TestDataModel.TestManager.Session.Test.Unit.Results[i] Seems REALLY gross to have on a View Model. I know this all reeks of a bad design issue, but I can't figure out what I did wrong? Should I be using more singleton/container controlled lifetimes type objects? Register object instances with static helper containers? Obviously these are hard questions to answer without being intimate with the existing structure, but if you've run into situations like this, what did you do to refactor? Should I just live with this, add mass events, and propogate them?

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  • Trouble decoding JSON string with PHP

    - by Anthony
    I'm trying to send an array of objects from JS to PHP using JSON. I have an array of players as follows: var player; var players = new Array(); //loop for number of players player = new Object(); player.id = theID; players[i] = player; Then my AJAX call looks like this: JSONplayers = JSON.stringify(players); $.ajax({ type: "POST", url: "php/ajax_send_players.php", data: { "players" : JSONplayers } On the PHP side the decode function looks like this $players = $_REQUEST['players']; echo var_dump($players); $players = json_decode($players); echo 'players: ' .$players. '--'. $players[0] . '--'. $players[0]->id; Debugging in chrome, the JSON players var looks like this before it is sent: JSONplayers: "[{"id":"Percipient"},{"id":"4"}]" And when I vardump in PHP it looks OK, giving this: string(40) "[{\"id\":\"Percipient\"},{\"id\":\"4\"}]" But I can't access the PHP array, and the echo statement about starting with players: outputs this: players: ---- Nothing across the board...maybe it has something to do with the \'s in the array, I am new to this and might be missing something very simple. Any help would be greatly appreciated. note I've also tried json_decode($players, true) to get it as an assoc array but get similar results.

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  • Dependency injection in constructors

    - by andre
    Hello everyone. I'm starting a new project and setting up the base to work on. A few questions have risen and I'll probably be asking quite a few in here, hopefully I'll find some answers. First step is to handle dependencies for objects. I've decided to go with the dependency injection design pattern, to which I'm somewhat new, to handle all of this for the application. When actually coding it I came across a problem. If a class has multiple dependencies and you want to pass on multiple dependencies via the constructor (so that they cannot be changed after you instantiate the object). How do you do it without passing an array of dependencies, using call_user_func_array(), eval() or Reflection? This is what i'm looking for: <?php class DI { public function getClass($classname) { if(!$this->pool[$classname]) { # Load dependencies $deps = $this->loadDependencies($classname); # Here is where the magic should happen $instance = new $classname($dep1, $dep2, $dep3); # Add to pool $this->pool[$classname] = $instance; return $instance; } else { return $this->pool[$classname]; } } } Again, I would like to avoid the most costly methods to call the class. Any other suggestions?

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  • What's the best way of accessing a DRb object (e.g. Ruby Queue) from Scala (and Java)?

    - by Tom Morris
    I have built a variety of little scripts using Ruby's very simple Queue class, and share the Queue between Ruby and JRuby processes using DRb. It would be nice to be able to access these from Scala (and maybe Java) using JRuby. I've put together something Scala and the JSR-223 interface to access jruby-complete.jar. import javax.script._ class DRbQueue(host: String, port: Int) { private var engine = DRbQueue.factory.getEngineByName("jruby") private var invoker = engine.asInstanceOf[Invocable] engine.eval("require \"drb\" ") private var queue = engine.eval("DRbObject.new(nil, \"druby://" + host + ":" + port.toString + "\")") def isEmpty(): Boolean = invoker.invokeMethod(this.queue, "empty?").asInstanceOf[Boolean] def size(): Long = invoker.invokeMethod(this.queue, "length").asInstanceOf[Long] def threadsWaiting: Long = invoker.invokeMethod(this.queue, "num_waiting").asInstanceOf[Long] def offer(obj: Any) = invoker.invokeMethod(this.queue, "push", obj.asInstanceOf[java.lang.Object]) def poll(): Any = invoker.invokeMethod(this.queue, "pop") def clear(): Unit = { invoker.invokeMethod(this.queue, "clear") } } object DRbQueue { var factory = new ScriptEngineManager() } (It conforms roughly to java.util.Queue interface, but I haven't declared the interface because it doesn't implement the element and peek methods because the Ruby class doesn't offer them.) The problem with this is the type conversion. JRuby is fine with Scala's Strings - because they are Java strings. But if I give it a Scala Int or Long, or one of the other Scala types (List, Set, RichString, Array, Symbol) or some other custom type. This seems unnecessarily hacky: surely there has got to be a better way of doing RMI/DRb interop without having to use JSR-223 API. I could either make it so that the offer method serializes the object to, say, a JSON string and takes a structural type of only objects that have a toJson method. I could then write a Ruby wrapper class (or just monkeypatch Queue) to would parse the JSON. Is there any point in carrying on with trying to access DRb from Java/Scala? Might it just be easier to install a real message queue? (If so, any suggestions for a lightweight JVM-based MQ?)

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  • Initial capacity of collection types, i.e. Dictionary, List

    - by Neil N
    Certain collection types in .Net have an optional "Initial Capacity" constructor param. i.e. Dictionary<string, string> something = new Dictionary<string,string>(20); List<string> anything = new List<string>(50); I can't seem to find what the default initial capacity is for these objects on MSDN. If I know I will only be storing 12 or so items in a dictionary, doesn't it make sense to set the initial capacity to something like 20? My reasoning is, assuming the capacity grows like it does for a StringBuiler, which doubles each time the capacity is hit, and each re-allocation is costly, why not pre-set the size to something you know will hold your data, with some extra room just in case? If the initial capacity is 100, and I know I will only need a dozen or so, it seems as though the rest of that allocated RAM is allocated for nothing. Please spare me the "premature optimization" speil for the O(n^n)th time. I know it won't make my apps any faster or save any meaningful amount of memory, this is mostly out of curiosity.

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  • Why doesn't java.lang.Number implement Comparable?

    - by Julien Chastang
    Does anyone know why java.lang.Number does not implement Comparable? This means that you cannot sort Numbers with Collections.sort which seems to me a little strange. Post discussion update: Thanks for all the helpful responses. I ended up doing some more research about this topic. The simplest explanation for why java.lang.Number does not implement Comparable is rooted in mutability concerns. For a bit of review, java.lang.Number is the abstract super-type of AtomicInteger, AtomicLong, BigDecimal, BigInteger, Byte, Double, Float, Integer, Long and Short. On that list, AtomicInteger and AtomicLong to do not implement Comparable. Digging around, I discovered that it is not a good practice to implement Comparable on mutable types because the objects can change during or after comparison rendering the result of the comparison useless. Both AtomicLong and AtomicInteger are mutable. The API designers had the forethought to not have Number implement Comparable because it would have constrained implementation of future subtypes. Indeed, AtomicLong and AtomicInteger were added in Java 1.5 long after java.lang.Number was initially implemented. Apart from mutability, there are probably other considerations here too. A compareTo implementation in Number would have to promote all numeric values to BigDecimal because it is capable of accommodating all the Number sub-types. The implication of that promotion in terms of mathematics and performance is a bit unclear to me, but my intuition finds that solution kludgy.

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  • IOS : BAD ACCESS when trying to add a new Entity object

    - by Maverick447
    So i'm using coredata to model my relationships . This is the model in brief Type A can have one or more types of type B Type B has a inverse relationship of being associated with one of type A Type B can have one or more types of type C Type C has a inverse relationship of being associated with one of type B From a UI standpoint , I have a Navigation controller with controllers that successively sets up the first A object (VC-1) , then another viewcontroller (VC-2) creates a B object ( I pass in the A object to this controller) and the B object is added to the A object . Similarly the same thing happens with B and C . The third Viewcontroller (VC3) first creates a C object and assigns it to the passed B Object . Also between these viewcontrollers the managedObjectCOntext is also passed . SO my use case is such that while viewcontroller (VC-3) is the top controller a button action will keep creating multiple objects of type C and add them to the same type B object that was passed . Also as part of this function I save the managedObject context after saving each type C . e.g. code in viewcontroller 3 - (void) SaveNewTypeC { TypeC *newtypeC = (Question*)[NSEntityDescription insertNewObjectForEntityForName:@"TypeC" inManagedObjectContext:managedObjectContext]; [newtypeC setProp1:] ; [newtypeC setProp2:] .. .. **[typeBObject addTypeCInTypeBObject:newtypeC];** [section setTotalCObjectCount:[ NSNumber numberWithInt:typeCIndex++]]; NSError *error = nil; if (![managedObjectContext save:&error]) { // Handle error NSLog(@"Unresolved error %@, %@, %@", error, [error userInfo],[error localizedDescription]); exit(-1); // Fail } [newtypeC release]; } - (IBAction)selectedNewButton:(id)sender { [self SaveNewTypeC]; [self startRepeatingTimer]; } The BAD ACCESS seems to appear when the bold line above executes Relating to some HashValue . Any clues on resolving this would be helpful .

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  • Copy constructor called even when returning by reference?

    - by Johnyy
    Hi, I am testing the return of local objects by reference. My original test went well but something else happens unexpected. #include <iostream> using namespace std; class MyInt { public: MyInt(int i){ value = new int(i); } ~MyInt(){ delete value; } int getValue(){ return *value; } MyInt(const MyInt &b){ cout<<"Copy"<<endl; } private: int* value; }; MyInt& returnref(){ MyInt a(10); cout<<"Returning from returnref()"<<endl; return a; } int main(){ MyInt a = returnref(); cout<<a.getValue()<<endl; return 0; } My console prints "Returning from ..." then "Copy" then a random value. My understanding of pass by reference is that it does not need to make any copy. Why is it not doing what I expected?

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  • How would I instruct extconf.rb to use additional g++ optimization flags, and which are advisable?

    - by mohawkjohn
    I'm using Rice to write a C++ extension for a Ruby gem. The extension is in the form of a shared object (.so) file. This requires 'mkmf-rice' instead of 'mkmf', but the two (AFAIK) are pretty similar. By default, the compiler uses the flags -g -O2. Personally, I find this kind of silly, since it's hard to debug with any optimization enabled. I've resorted to editing the Makefile to take out the flags I don't like (e.g., removing -fPIC -shared when I need to debug using main() instead of Ruby's hooks). But I figure there's got to be a better way. I know I can just do $CPPFLAGS += " -DRICE" to add additional flags. But how do I remove things without editing the Makefile directly? A secondary question: what optimizations are safe for shared objects loaded by Ruby? Can I do things like -funroll-loops? What do you all recommend? It's a scientific computing project, so the faster the better. Memory is not much of an issue. Many thanks!

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  • Passing a paramter/object to a ruby unit/test before running it using TestRunner

    - by Nahir Khan
    I'm building a tool that automates a process then runs some tests on it's own results then goes to do some other stuff. In trying to clean up my code I have created a separate file that just has the test cases class. Now before I can run these tests, I have to pass the class a couple of parameters/objects before they can be run. Now the problem is that I can't seem to find a way to pass a parameter/object to the test class. Right now I am thinking to generate a Yaml file and read it in the test class but it feels "wrong" to use a temporary file for this. If anyone has a nicer solution that would be great! *********Edit******* Example Code of what I am doing right now: #!/usr/bin/ruby require 'test/unit/ui/console/testrunner' require 'yaml' require 'TS_SampleTestSuite' automatingSomething() importantInfo = getImportantInfo() File.open('filename.yml', 'w') do |f| f.puts importantInfo.to_yaml end Test::Unit::UI::Console::TestRunner.run(TS_SampleTestSuite) Now in the example above TS_SampleTestSuite needs importantInfo, so the first "test case" is a method that just reads in the information from the Yaml file filname.yml. I hope that clears up some confusion.

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  • d3: Coloring Multiple Lines from Nested Data

    - by diet_coke
    I'm currently assembling some line graphs with circles at the datapoints from arrays of JSON objects formatted like so: var data = [{ "name": "metric1", "datapoints": [ [10.0, 1333519140], [48.0, 1333519200] ] }, { "name": "metric2", "datapoints": [ [48.0, 1333519200], [12.0, 1333519260] ] }] I want to have a color for each metric, so I'm trying to color them based on the index of the object within the array data. The code I have currently for just placing the circles looks like: // We bind an svg group to each metric. var metric_groups = this.vis.selectAll("g.metric_group") .data(data).enter() .append("g") .attr("class", "metric_group"); // Then bind a circle for each datapoint. var circles = metric_groups.selectAll("circle") .data(function(d) { return d.datapoints; }); circles.enter().append("circle") .attr("r", 3.5); Now if I change that last bit to something like: circles.enter().append("circle") .attr("r", 3.5); .style("fill", function(d,i) { return i%2 ? "red" : "blue"; } I get alternating red and blue circles, as could be expected. Taking some advice from Nested Selections : 'Nesting and Index', I tried: circles.enter().append("circle") .attr("r", 3.5); .style("fill", function(d,i,j) { return j%2 ? "red" : "blue"; } Which doesn't work (j is undefined), presumably because we are in the named property datapoints, rather than an array element. How might I go about doing the coloring that I want without changing my data structure? Thanks!

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  • Processing velocity-vectors during collision as neatly as possible

    - by DevEight
    Hello. I'm trying to create a good way to handle all possible collisions between two objects. Typically one will be moving and hitting the other, and should then "bounce" away. What I've done so far (I'm creating a typical game where you have a board and bounce a ball at bricks) is to check if the rectangles intersect and if they do, invert the Y-velocity. This is a really ugly and temporary solution that won't work in the long haul and since this is kind of processing is very common in games I'd really like to find a great way of doing this for future projects aswell. Any links or helpful info is appreciated. Below is what my collision-handling function looks like right now. protected void collision() { #region Boundaries if (bal.position.X + bal.velocity.X >= viewportRect.Width || bal.position.X + bal.velocity.X <= 0) { bal.velocity.X *= -1; } if (bal.position.Y + bal.velocity.Y <= 0) { bal.velocity.Y *= -1; } #endregion bal.rect = new Rectangle((int)bal.position.X+(int)bal.velocity.X-bal.sprite.Width/2, (int)bal.position.Y-bal.sprite.Height/2+(int)bal.velocity.Y, bal.sprite.Width, bal.sprite.Height); player.rect = new Rectangle((int)player.position.X-player.sprite.Width/2, (int)player.position.Y-player.sprite.Height/2, player.sprite.Width, player.sprite.Height); if (bal.rect.Intersects(player.rect)) { bal.position.Y = player.position.Y - player.sprite.Height / 2 - bal.sprite.Height / 2; if (player.position.X != player.prevPos.X) { bal.velocity.X -= (player.prevPos.X - player.position.X) / 2; } bal.velocity.Y *= -1; } foreach (Brick b in brickArray.list) { b.rect.X = Convert.ToInt32(b.position.X-b.sprite.Width/2); b.rect.Y = Convert.ToInt32(b.position.Y-b.sprite.Height/2); if (bal.rect.Intersects(b.rect)) { b.recieveHit(); bal.velocity.Y *= -1; } } brickArray.removeDead(); }

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  • subquery in join with doctrine dql

    - by Martijn de Munnik
    I want to use DQL to create a query which looks like this in SQL: select e.* from e inner join ( select uuid, max(locale) as locale from e where locale = 'nl_NL' or locale = 'nl' group by uuid ) as e_ on e.uuid = e_.uuid and e.locale = e_.locale I tried to use QueryBuilder to generate the query and subquery. I think they do the right thing by them selves but I can't combine them in the join statement. Does anybody now if this is possible with DQL? I can't use native SQL because I want to return real objects and I don't know for which object this query is run (I only know the base class which have the uuid and locale property). $subQueryBuilder = $this->_em->createQueryBuilder(); $subQueryBuilder ->addSelect('e.uuid, max(e.locale) as locale') ->from($this->_entityName, 'e') ->where($subQueryBuilder->expr()->in('e.locale', $localeCriteria)) ->groupBy('e.uuid'); $queryBuilder = $this->_em->createQueryBuilder(); $queryBuilder ->addSelect('e') ->from($this->_entityName, 'e') ->join('('.$subQueryBuilder.') as', 'e_')->join ->where('e.uuid = e_.uuid') ->andWhere('e.locale = e_.locale');

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  • How to design app to be modular / support plugins

    - by Lee
    I'm currently in the process of refactoring my webplayer so that we'll be more easily able to run it on our other internet radio stations. Much of the setup between these players will be very similar, however, some will need to have different UI plugins / other plugins. Currently in the webplayer I do something like this in it's init(): _this.ui = new UI(); _this.ui.playlist = new Playlist(); _this.ui.channelDropdown = new ChannelDropdown(); _this.ui.timecode = ne Timecode(); etc etc This works fine but that blocks me into requiring those objects at run time. What I'd like to do is be able to add those based on the stations needs. Basically my question is, do I need to add some kind of "addPlugin()" functionality here? And if I do that, do I need to constantly check from my WebPlayer object if that plugin exists before it attempts to use it? Like... if (_hasPlugin('playlist')) this.plugins.playlist.add(track); I apologize if some of this might not be clear... really trying to get my head wrapped around all of this. I feel I'm closer but I'm still stuck. Any advice on how I should proceed with this would be greatly appreciated. Thanks in advance, Lee

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  • Extend DOMElement object

    - by Comma
    How could I exdend objects provided with Document Object Model? Seems that there is no way according to this [issue][2]. class Application_Model_XmlSchema extends DOMElement { const ELEMENT_NAME = 'schema'; /** * @var DOMElement */ private $_schema; /** * @param DOMDocument $document * @return void */ public function __construct(DOMDocument $document) { $this->setSchema($document->getElementsByTagName(self::ELEMENT_NAME)->item(0)); } /** * @param DOMElement $schema * @return void */ public function setSchema(DOMElement $schema){ $this->_schema = $schema; } /** * @return DOMElement */ public function getSchema(){ return $this->_schema; } /** * @param string $name * @param array $arguments * @return mixed */ public function __call($name, $arguments) { if (method_exists($this->_schema, $name)) { return call_user_func_array( array($this->_schema, $name), $arguments ); } } } $version = $this->getRequest()->getParam('version', null); $encoding = $this->getRequest()->getParam('encoding', null); $source = 'http://www.w3.org/2001/XMLSchema.xsd'; $document = new DOMDocument($version, $encoding); $document->load($source); $xmlSchema = new Application_Model_XmlSchema($document); $xmlSchema->getAttribute('version'); I got an error: Warning: DOMElement::getAttribute(): Couldn't fetch Application_Model_XmlSchema in C:\Nevermind.php on line newvermind

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  • multiple clients - one server connection with sockets tcp/ip c# .net

    - by jagse
    Hello guys, I need to develop a client server system where I can have multiple clients communicating with one server at the same time. I want to communicate xml serialized objects and also need to send and receive other commands to invoke methods. Now, I am just starting with socket programming in C# and .Net and found that the asynchronous I/O is the way to go so that the methods dont block the execution of code. Also there are many examples of how to make a simple client server system. So I have a basic understanding of how that works. Anyway, what still is not clear to me is how I can set up a server which can manage connections to multiple clients? Can I just create a new socket per connection and then store those in some kind of list? Do I need some kind of multiplexing to achieve this? Do I have to listen at multiple ports? What`s the best way here? And the other thing is if I need to develop my own protocol to differentiate between what I am actually sending over the network -- xml serialized object or a command which might be just a string encoded in ascII or something. Or would I develop my own protocol just to send these commands? Any kind of help is apreciated! If someone knows a good book which covers this sort of stuff, let me know. Cheers I forgot to mention that some of my clients which are supposed to communicate with my server will be pda and I therefore use the compact framework... So this might bring in some restrictions...

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  • What is the difference between a restful route method for getting an index vs. creating a new object

    - by Jason
    According to rake routes, there's the same path for getting an index of objects as there is for creating a new object: cars GET /cars(.:format) {:controller=>"plugs", :what=>"car", :action=>"index"} POST /cars(.:format) {:controller=>"plugs", :what=>"car", :action=>"create"} Obviously, the HTTP verb is what distinguishes between them. I want the "create" version of the cars_path method, not the "index" version. My question is what route method do you invoke to choose the one you want? I'm telling cucumber what path to generate with this: when /the car plug preview page for "(.+)"/ cars_path(:action => :create, :method => :post) ...but it always chooses the "index" action, not "create". I've tried lots of combinations for the hash argument following cars_path and nothing changes it from choosing "index" instead of "create". I'll get an error like this: cars_url failed to generate from {:controller=>"plugs", :method=>:post, :what=>"car", :action=>"create"}, expected: {:controller=>"plugs", :what=>"car", :action=>"index"}, diff: {:method=>:post, :action=>"index"} (ActionController::RoutingError) This seems like a very simple question but I've had no luck googling for it, so could use some advice. Thanks.

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  • Referencing not-yet-defined variables - Java

    - by user2537337
    Because I'm tired of solving math problems, I decided to try something more engaging with my very rusty (and even without the rust, very basic) Java skills. I landed on a super-simple people simulator, and thus far have been having a grand time working through the various steps of getting it to function. Currently, it generates an array of people-class objects and runs a for loop to cycle through a set of actions that alter the relationships between them, which I have stored in a 2d integer array. When it ends, I go look at how much they all hate each other. Fun stuff. Trouble has arisen, however, because I would like the program to clearly print what action is happening when it happens. I thought the best way to do this would be to add a string, description, to my "action" class (which stores variables for the actor, reactor, and the amount the relationship changes). This works to a degree, in that I can print a generic message ("A fight has occurred!") with no problem. However, ideally I would like it to be a little more specific ("Person A has thrown a rock at Person B's head!"). This latter goal is proving more difficult: attempting to construct an action with a description string that references actor and reactor gets me a big old error, "Cannot reference field before it is defined." Which makes perfect sense. I believe I'm not quite in programmer mode, because the only other way I can think to do this is an unwieldy switch statement that negates the need for each action to have its own nicely-packaged description. And there must be a neater way. I am not looking for examples of code, only a push in the direction of the right concept to handle this.

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  • How to change value inside a JSON string.

    - by Jeremy Roy
    I have a JSON string array of objects like this. [{"id":"4","rank":"adm","title":"title 1"}, {"id":"2","rank":"mod","title":"title 2"}, {"id":"5","rank":"das","title":"title 3"}, {"id":"1","rank":"usr","title":"title 4"}, {"id":"3","rank":"ref","title":"title 5"}] I want to change the title value of it, once the id is matching. So if my variable myID is 5, I want to change the title "title 5" to new title, and so on. And then I get the new JSON array to $("#rangArray").val(jsonStr); Something like $.each(jsonStr, function(k,v) { if (v==myID) { this.title='new title'; $("#myTextArea").val(jsonStr); } }); Here is the full code. $('img.delete').click(function() { var deltid = $(this).attr("id").split('_'); var newID = deltid[1]; var jsonStr = JSON.stringify(myArray); $.each(jsonStr, function(k,v) { if (v==newID) { // how to change the title jsonStr[k].title = 'new title'; alert(jsonStr); $("#rangArray").val(jsonStr); } }); }); The above is not working. Any help please?

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  • java: libraries for immutable functional-style data structures

    - by Jason S
    This is very similar to another question (Functional Data Structures in Java) but the answers there are not particularly useful. I need to use immutable versions of the standard Java collections (e.g. HashMap / TreeMap / ArrayList / LinkedList / HashSet / TreeSet). By "immutable" I mean immutable in the functional sense (e.g. purely functional data structures), where updating operations on the data structure do not change the original data, but instead return a new instance of the same kind of data structure. Also typically new and old instances of the data structure will share immutable data to be efficient in time and space. From what I can tell my options include: Functional Java Scala Clojure but I'm not sure whether any of these are particularly appealing to me. I have a few requirements/desirements: the collections in question should be usable directly in Java (with the appropriate libraries in the classpath). FJ would work for me; I'm not sure if I can use Scala's or Clojure's data structures in Java w/o having to use the compilers/interpreters from those languages and w/o having to write Scala or Clojure code. Core operations on lists/maps/sets should be possible w/o having to create function objects with confusing syntaxes (FJ looks slightly iffy) They should be efficient in time and space. I'm looking for a library which ideally has done some performance testing. FJ's TreeMap is based on a red-black tree, not sure how that rates. Documentation / tutorials should be good enough so someone can get started quickly using the data structures. FJ fails on that front. Any suggestions?

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  • ios UITableView reloadData don't increase content height

    - by Zoltan Varadi
    I'm facing a strange error in my iOS app and haven't been able to figure out the reason why. In my UITableView i can add new cells, so i refresh the array that is the datasource and call reloadData. Everything works without error. The numberOfRowsInSection is called again, and it's value is one more than it's previous value was. The new cell even gets inserted at the bottom of the tableview, but i cant scroll down to it. I only know that it's there because the tableview bounces and i can see it. I'm guessing the tableview's content height is not getting increased for some reason, but i have no idea why. I'm using iOS 6 btw. Any help is very much appreciated! Thanks, Zoli EDIT, answers for Srikanth's questions: How is data getting added. There's an NSArray containing objects of a specific type. The array.count is the number of the number of cells. This NSArray gets its values from a database query. When you say, you are refreshing the array, what do you mean. By refreshing the array i mean i execute a new query in the database and put the results of this query into an NSArray. this will be the tableview's datasource array. Like this: dataSourceArray = [dbManager executeQuery]; [tableView reloadData]; Are you adding the data within the same view controller Yes. Can you show some code as to what you are doing See above. Is the table view at the root of the view controllers view or is it within another view The tableview is the main view's first child. Can you try adding data to the array at the beginning, so that you can view the cell being added at the top. I don't understand what you mean.

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  • Whose fault is a NullReferenceException?

    - by stefan.at.wpf
    I'm currently working on a class which exposes an internal List through a property. The List shall and can be modified. The problem is, entries in the internal list could be set to null from outside the class. My code actually looks like this: class ClassWithList { List<object> _list = new List<object>(); // get accessor, which however returns the reference to the list, // therefore the list can be modified (this is intended) public List<object> Data { get { return _list; } } private void doSomeWorkWithTheList() { foreach(object obj in _list) // do some work with the objects in the list without checking for null. } } So now in the doSomeWorkWithTheList() I could always check whether the current list entry is null or I could just asume that the person using this class doesn't have the great idea to set entries to null. So finally the questions end up in: Whose fault is a NullReferenceException in this case? Is it the fault of the class developer not checking everything for null (which would make code generally - not only in this class - more complex) or is it the fault of the user of this class, as setting a List entry to null doesn't really make sense? I'd tend to generally not check values for null except in some really special cases. Is this a bad style or de facto standard / standard in praxis? I know there's probably no ultimate answer for this, I'm just missing enough experience for such thing and therefore wondering what other developers think about such cases and want to hear what's done in reality about checking null (or not).

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  • Best method to select an object from another unknown jQuery object

    - by Yosi
    Lets say I have a jQuery object/collection stored in a variable named obj, which should contain a DOM element with an id named target. I don't know in advance if target will be a child in obj, i.e.: obj = $('<div id="parent"><div id="target"></div></div>'); or if obj equals target, i.e.: obj = $('<div id="target"></div>'); or if target is a top-level element inside obj, i.e.: obj = $('<div id="target"/><span id="other"/>'); I need a way to select target from obj, but I don't know in advance when to use .find and when to use .filter. What would be the fastest and/or most concise method of extracting target from obj? What I've come up with is: var $target = obj.find("#target").add(obj.filter("#target")); UPDATE I'm adding solutions to a JSPERF test page to see which one is the best. Currently my solution is still the fastest. Here is the link, please run the tests so that we'll have more data: http://jsperf.com/jquery-selecting-objects

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