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  • How can one describe a rock-paper-scissors relationship between 3 items?

    - by Madara Uchiha
    Let's say I have the following structure: abstract class Hand {} class Rock extends Hand {} class Paper extends Hand {} class Scissors extends Hand {} The goal is to make a function (or a method) Hand::compareHands(Hand $hand1, Hand $hand2), which would return the winning hand in a rock-paper-scissors match. That would be very easy with a bunch of ifs, but the point is to have a more robust structure, that's relying on polymorphism rather than on procedural code. P.S. this is done in actual production code, if someone is asking. This isn't some sort of challenge or homework. (It's not really rock-paper-scissors, but you get the point).

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  • Implementing hoverIntent for Drop Down Menu (coming from click_event)

    - by stormeTrooper
    I've just recently started programming, I was hoping for some help. I have a drop down menu that was originally activated by click_event, however I want to now implement hoverIntent in order to make the menu drop. The issue I am having now is being able to use the menu, because whenever I invoke the menu now, once I leave the area that activates the menu, the menu closes. If you could explain to me like I'm five, I'd appreciate it, thanks :) The code I am using as follows: JavaScript: function setupUserConfigMenu() { $('.user_profile_btn').hoverIntent( function (event) { $('#user_settings_dropdown').animate({height:['toggle', 'swing'] }, 225); }, function (event) { $('#user_settings_dropdown').animate({height:['toggle', 'swing'] }, 225); }) } HTML: <li> <a href="<%= "#" %>" class="user_profile_btn" title="Your profile page"><%= truncate(current_user.full_name || current_user.name, :length => 28) %> <div class="arrow_down"></div></a> <ul id="user_settings_dropdown"> <li> <a href="<%= current_user.get_url(true) %>"> <%= image_tag current_user.get_thumb_url, :size => "30x30" %> <div> <%= truncate(current_user.full_name || current_user.name, :length => 40) %> <br> View profile </div> </a> </li> <div class="grey_line"></div> <li class="settings_list_item"> <%= link_to "Settings", edit_user_registration_path %> </li> <li class="settings_list_item"> <%= link_to "About", "/about" %> </li> <li class="settings_list_item"> <%= link_to "Logout", destroy_user_session_path, :method => :delete %> </li> </ul> </li>

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  • Is a many-to-many relationship with extra fields the right tool for my job?

    - by whichhand
    Previously had a go at asking a more specific version of this question, but had trouble articulating what my question was. On reflection that made me doubt if my chosen solution was correct for the problem, so this time I will explain the problem and ask if a) I am on the right track and b) if there is a way around my current brick wall. I am currently building a web interface to enable an existing database to be interrogated by (a small number of) users. Sticking with the analogy from the docs, I have models that look something like this: class Musician(models.Model): first_name = models.CharField(max_length=50) last_name = models.CharField(max_length=50) dob = models.DateField() class Album(models.Model): artist = models.ForeignKey(Musician) name = models.CharField(max_length=100) class Instrument(models.Model): artist = models.ForeignKey(Musician) name = models.CharField(max_length=100) Where I have one central table (Musician) and several tables of associated data that are related by either ForeignKey or OneToOneFields. Users interact with the database by creating filtering criteria to select a subset of Musicians based on data the data on the main or related tables. Likewise, the users can then select what piece of data is used to rank results that are presented to them. The results are then viewed initially as a 2 dimensional table with a single row per Musician with selected data fields (or aggregates) in each column. To give you some idea of scale, the database has ~5,000 Musicians with around 20 fields of related data. Up to here is fine and I have a working implementation. However, it is important that I have the ability for a given user to upload there own annotation data sets (more than one) and then filter and order on these in the same way they can with the existing data. The way I had tried to do this was to add the models: class UserDataSets(models.Model): user = models.ForeignKey(User) name = models.CharField(max_length=100) description = models.CharField(max_length=64) results = models.ManyToManyField(Musician, through='UserData') class UserData(models.Model): artist = models.ForeignKey(Musician) dataset = models.ForeignKey(UserDataSets) score = models.IntegerField() class Meta: unique_together = (("artist", "dataset"),) I have a simple upload mechanism enabling users to upload a data set file that consists of 1 to 1 relationship between a Musician and their "score". Within a given user dataset each artist will be unique, but different datasets are independent from each other and will often contain entries for the same musician. This worked fine for displaying the data, starting from a given artist I can do something like this: artist = Musician.objects.get(pk=1) dataset = UserDataSets.objects.get(pk=5) print artist.userdata_set.get(dataset=dataset.pk) However, this approach fell over when I came to implement the filtering and ordering of query set of musicians based on the data contained in a single user data set. For example, I could easily order the query set based on all of the data in the UserData table like this: artists = Musician.objects.all().order_by(userdata__score) But that does not help me order by the results of a given single user dataset. Likewise I need to be able to filter the query set based on the "scores" from different user data sets (eg find all musicians with a score 5 in dataset1 and < 2 in dataset2). Is there a way of doing this, or am I going about the whole thing wrong?

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  • CSS overflow : list in a div

    - by Felicita
    I have an image gallery and I dont want give an extra class to third list item: <div class="row"> <ul class="rowUl"> <li>ssss</li> <li>ssss</li> <li>ssss</li> </ul> </div> and css .row { width: 620px; clear: both; overflow: hidden; } .rowUl { width: 645px; float: left; } .rowUl li { width: 220px; float: left; } but the third list item drop in other row. How can I solve this without extra class?

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  • How to pass data to a C++0x lambda function that will run in a different thread?

    - by Dimitri C.
    In our company we've written a library function to call a function asynchronously in a separate thread. It works using a combination of inheritance and template magic. The client code looks as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, &DemoThread::SomeFunction, stringToPassByValue); Since the introduction of lambda functions I'd like to use it in combination with lambda functions. I'd like to write the following client code: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=]() { const std::string someCopy = stringToPassByValue; }); Now, with the Visual C++ 2010 this code doesn't work. What happens is that the stringToPassByValue is not copied. Instead the "capture by value" feature passes the data by reference. The result is that if the function is executed after stringToPassByValue has gone out of scope, the application crashes as its destructor is called already. So I wonder: is it possible to pass data to a lambda function as a copy? Note: One possible solution would be to modify our framework to pass the data in the lambda parameter declaration list, as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=](const std::string stringPassedByValue) { const std::string someCopy = stringPassedByValue; } , stringToPassByValue); However, this solution is so verbose that our original function pointer solution is both shorter and easier to read. Update: The full implementation of AsyncCall is too big to post here. In short, what happens is that the AsyncCall template function instantiates a template class holding the lambda function. This class is derived from a base class that contains a virtual Execute() function, and upon an AsyncCall() call, the function call class is put on a call queue. A different thread then executes the queued calls by calling the virtual Execute() function, which is polymorphically dispatched to the template class which then executes the lambda function.

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  • JPA entitylisteners and @embeddable

    - by seanizer
    I have a class hierarchy of JPA entities that all inherit from a BaseEntity class: @MappedSuperclass @EntityListeners( { ValidatorListener.class }) public abstract class BaseEntity implements Serializable { // other stuff } I want all entities that implement a given interface to be validated automatically on persist and/or update. Here's what I've got. My ValidatorListener: public class ValidatorListener { private enum Type { PERSIST, UPDATE } @PrePersist public void checkPersist(final Object entity) { if (entity instanceof Validateable) { this.check((Validateable) entity, Type.PERSIST); } } @PreUpdate public void checkUpdate(final Object entity) { if (entity instanceof Validateable) { this.check((Validateable) entity, Type.UPDATE); } } private void check(final Validateable entity, final Type persist) { switch (persist) { case PERSIST: if (entity instanceof Persist) { ((Persist) entity).persist(); } if (entity instanceof PersistOrUpdate) { ((PersistOrUpdate) entity).persistOrUpdate(); } break; case UPDATE: if (entity instanceof Update) { ((Update) entity).update(); } if (entity instanceof PersistOrUpdate) { ((PersistOrUpdate) entity).persistOrUpdate(); } break; default: break; } } } and here's my Validateable interface that it checks against (the outer interface is just a marker, the inner contain the methods): public interface Validateable { interface Persist extends Validateable { void persist(); } interface PersistOrUpdate extends Validateable { void persistOrUpdate(); } interface Update extends Validateable { void update(); } } All of this works, however I would like to extend this behavior to Embeddable classes. I know two solutions: call the validation method of the embeddable object manually from the entity validation method: public void persistOrUpdate(){ // validate my own properties first // then manually validate the embeddable property: myEmbeddable.persistOrUpdate(); // this works but I'd like something that I don't have to call manually } use reflection, checking all properties to see if their type is of one of their interface types. This would work, but it's not pretty. Is there a more elegant solution?

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  • Appropriate uses of Monad `fail` vs. MonadPlus `mzero`

    - by jberryman
    This is a question that has come up several times for me in the design code, especially libraries. There seems to be some interest in it so I thought it might make a good community wiki. The fail method in Monad is considered by some to be a wart; a somewhat arbitrary addition to the class that does not come from the original category theory. But of course in the current state of things, many Monad types have logical and useful fail instances. The MonadPlus class is a sub-class of Monad that provides an mzero method which logically encapsulates the idea of failure in a monad. So a library designer who wants to write some monadic code that does some sort of failure handling can choose to make his code use the fail method in Monad or restrict his code to the MonadPlus class, just so that he can feel good about using mzero, even though he doesn't care about the monoidal combining mplus operation at all. Some discussions on this subject are in this wiki page about proposals to reform the MonadPlus class. So I guess I have one specific question: What monad instances, if any, have a natural fail method, but cannot be instances of MonadPlus because they have no logical implementation for mplus? But I'm mostly interested in a discussion about this subject. Thanks! EDIT: One final thought occured to me. I recently learned (even though it's right there in the docs for fail) that monadic "do" notation is desugared in such a way that pattern match failures, as in (x:xs) <- return [] call the monad's fail. It seems like the language designers must have been strongly influenced by the prospect of some automatic failure handling built in to haskell's syntax in their inclusion of fail in Monad.

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  • Is there a g++ equivalent to Visual Studio's __declspec(novtable)?

    - by ceretullis
    Is there a g++ equivalent to Visual Studio's __declspec(novtable) argument? Basically, in a pure virtual base class the __declspec(novtable) argument can be used to suppress the creation of a vtable for the base class as well as vtable initialization/deinitialization code in the contstructor/destructor respectively. E.g., class __declspec(novtable) PureVirtualBaseClass { public: PureVirtualBaseClass(){} virtual ~PureVirtualBaseClass() = 0; }; See Paul DiLascia's article for more info. Also see my related question.

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  • How could I implement a fuzzy time date replacer using Knockout?

    - by rball
    I'd like to implement what this plugin does using jQuery: https://github.com/rmm5t/jquery-timeago A short description of that plugin: This will turn all abbr elements with a class of timeago and an ISO 8601 timestamp in the title (conforming to the datetime design pattern microformat): <abbr class="timeago" title="2011-12-17T09:24:17Z">December 17, 2011</abbr> Into something like this: <abbr class="timeago" title="December 17, 2011">about 1 day ago</abbr> Except using knockout my markup looks like this: <abbr data-bind="attr: { title: Posted }" class="timeago"></abbr> I think something isn't synced up because nothing is happening even if I put the call to timeago within the viewmodel itself. I'm guessing I need a subscriber that's attached to the observable "Posted" but I'm not sure how to set that up.

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  • text-transform cannot change/be overwritten? (css)

    - by Radek
    I am studying css and I do not understand why some OTHER text and line 2 has red underline effect on them. I thought I either changed it for class others or reset it to none for class line2 I tried `text-decoration:none' for both .line2 and .others and the text was still red underlined. <html> <head> <style type="text/css"> .line {color:red; text-transform:uppercase; text-decoration:underline;} .line2 {color:blue; text-transform:none;} .others {color:black; text-transform:lowercase; text-decoration:blink; font-weight:bold;} </style> </head> <body> <div class='line'> line 1 <div class='others'><BR>some OTHER text<BR></DIV> <div class='line2'> <BR>line 2 </div> </div> </body> </html>

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  • How to make Event visible?

    - by eflles
    Inside a Silverlight library project I have a public event, which is not visible for other classes. How can I make the event visible? When I try the following code, I can not locate the event in the "ReceivingClass". .dll - file: Public Class MyClass Public Event MyEvent(ByVal sender As Object, ByVal e As EventArgs) Public Sub OnStart() RaiseEvent MyEvent(Me, new EventArgs) End Sub End Class Silverlight app: Imports MyClass Public Class ReceivingClass Public Sub New() Dim myClass As new MyClass AddHandler myClass.MyEvent, AddressOf Me.EventHandler End Sub Private Sub EventHandler(ByVal sender As Object, ByVal e As EventArgs) 'Handle Event End Sub End Class

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  • What is Ruby's double-colon (::) all about?

    - by Meltemi
    I'd probably be able to answer this for myself if "::" wasn't so hard to Google. Didn't see anything on SO so thought I'd try my luck. What is this double-colon :: all about? I see it everywhere in Rails: class User < ActiveRecord::Base or… ActionController::Routing::Routes.draw do |map| I found a definition from this guy: The :: is a unary operator that allows: constants, instance methods and class methods defined within a class or module, to be accessed from anywhere outside the class or module. but that just leads to more questions. What good is scope (private, protected) if you can just use :: to expose anything?

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  • use JQuery to get a list of classes

    - by John
    Hi I have a un-ordered (ul) html list. Each li item has 1 or more classes attached to it. I want to go through this ul list and get all the (distinct) classes. Then from this list create a list of checkboxes who's value matches that of the class and also who's label matches that of the class. One checkbox for each class. What is the best way to do this using JQuery? Thanks

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  • How to configure Spring-DM OSGi service for new instance per call?

    - by Bhav
    I'm starting to delve into using Spring DM and OSGi services in an RCP application. I've created a service which is used by another bundle in the RCP application. It does a lookup of the service via calls to getBundleContext().getServiceReference() using the explicit bundle names and service class names. I'm not using DI anywhere yet. The issue I'm running into is that the service that is returned in the requesting bundle is a singleton. At times I notice a threading issue since it is a "stateful" service. How do I configure the application to get back a new service instance with each call? Here is my spring xml file contents which registers the service: <bean id="myServBean" class="com.xyz.ClassImpl"/> <osgi:service ref="myServBean" class="com.xyz.Class"/>

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  • CultureManager issue

    - by Serge
    I have a bug I don't understand. While the following works fine: Resources.Classes.AFieldFormula.DirectFieldFormula this one throws an exception: new ResourceManager(typeof(Resources.Classes.AFieldFormula)).GetString("DirectFieldFormula"); Could not find any resources appropriate for the specified culture or the neutral culture. Make sure \"Resources.Classes.AFieldFormula.resources\" was correctly embedded or linked into assembly \"MygLogWeb\" at compile time, or that all the satellite assemblies required are loadable and fully signed. How comes? Resource designer.cs file: //------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:4.0.30319.18408 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ namespace Resources.Classes { using System; /// <summary> /// A strongly-typed resource class, for looking up localized strings, etc. /// </summary> // This class was auto-generated by the StronglyTypedResourceBuilder // class via a tool like ResGen or Visual Studio. // To add or remove a member, edit your .ResX file then rerun ResGen // with the /str option, or rebuild your VS project. [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "4.0.0.0")] [global::System.Diagnostics.DebuggerNonUserCodeAttribute()] [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()] public class AFieldFormula { private static global::System.Resources.ResourceManager resourceMan; private static global::System.Globalization.CultureInfo resourceCulture; [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")] internal AFieldFormula() { } /// <summary> /// Returns the cached ResourceManager instance used by this class. /// </summary> [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)] public static global::System.Resources.ResourceManager ResourceManager { get { if (object.ReferenceEquals(resourceMan, null)) { global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("MygLogWeb.Classes.AFieldFormula", typeof(AFieldFormula).Assembly); resourceMan = temp; } return resourceMan; } } /// <summary> /// Overrides the current thread's CurrentUICulture property for all /// resource lookups using this strongly typed resource class. /// </summary> [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)] public static global::System.Globalization.CultureInfo Culture { get { return resourceCulture; } set { resourceCulture = value; } } /// <summary> /// Looks up a localized string similar to Direct field. /// </summary> public static string DirectFieldFormula { get { return ResourceManager.GetString("DirectFieldFormula", resourceCulture); } } } }

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  • How can I sync three classes?

    - by TheMachineCharmer
    class Foo { Bar b; List<Foo> Neighbours; } class Bar { Spam s; List<Bar> Neighbours; } class Spam { List<string> Neighbours; } Each of these classes have AddNeighbour,RemoveNeighbour methods. User can add/remove Neighbours from any of the class at random. I want these three objects to be in sync. How can I do this?

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  • Get Mail with PHP and IMAP in Gmail just loading

    - by Oscar Godson
    I'm not sure why. Ive tried a bunch of different code. Wrote it myself, and copied other people's tutorials but every bit of code it's loading forever and eventually stops due to script processing times on the server. Does anyone know why? Oh, and IMAP is turned on, i get IMAP / Exchange on my iPhone from this same account fine. And IMAP is turned on in my version of PHP (checked with phpinfo they all say enabled.) <?php /* connect to gmail */ $hostname = '{imap.gmail.com:993/imap/ssl}INBOX'; $username = '[email protected]'; $password = 'xxxxxx'; /* try to connect */ $inbox = imap_open($hostname,$username,$password) or die('Cannot connect to Gmail: ' . imap_last_error()); /* grab emails */ $emails = imap_search($inbox,'ALL'); /* if emails are returned, cycle through each... */ if($emails) { /* begin output var */ $output = ''; /* put the newest emails on top */ rsort($emails); /* for every email... */ foreach($emails as $email_number) { /* get information specific to this email */ $overview = imap_fetch_overview($inbox,$email_number,0); $message = imap_fetchbody($inbox,$email_number,2); /* output the email header information */ $output.= '<div class="toggler '.($overview[0]->seen ? 'read' : 'unread').'">'; $output.= '<span class="subject">'.$overview[0]->subject.'</span> '; $output.= '<span class="from">'.$overview[0]->from.'</span>'; $output.= '<span class="date">on '.$overview[0]->date.'</span>'; $output.= '</div>'; /* output the email body */ $output.= '<div class="body">'.$message.'</div>'; } echo $output; } /* close the connection */ imap_close($inbox); ?

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  • How to limit setAccessible to only "legitimate" uses?

    - by polygenelubricants
    The more I learned about the power of setAccessible, the more astonished I am at what it can do. This is adapted from my answer to the question (Using reflection to change static final File.separatorChar for unit testing). import java.lang.reflect.*; public class EverythingIsTrue { static void setFinalStatic(Field field, Object newValue) throws Exception { field.setAccessible(true); Field modifiersField = Field.class.getDeclaredField("modifiers"); modifiersField.setAccessible(true); modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL); field.set(null, newValue); } public static void main(String args[]) throws Exception { setFinalStatic(Boolean.class.getField("FALSE"), true); System.out.format("Everything is %s", false); // "Everything is true" } } You can do truly outrageous stuff: public class UltimateAnswerToEverything { static Integer[] ultimateAnswer() { Integer[] ret = new Integer[256]; java.util.Arrays.fill(ret, 42); return ret; } public static void main(String args[]) throws Exception { EverythingIsTrue.setFinalStatic( Class.forName("java.lang.Integer$IntegerCache") .getDeclaredField("cache"), ultimateAnswer() ); System.out.format("6 * 9 = %d", 6 * 9); // "6 * 9 = 42" } } Presumably the API designers realize how abusable setAccessible can be, but must have conceded that it has legitimate uses to provide it. So my questions are: What are the truly legitimate uses for setAccessible? Could Java has been designed as to NOT have this need in the first place? What would the negative consequences (if any) of such design be? Can you restrict setAccessible to legitimate uses only? Is it only through SecurityManager? How does it work? Whitelist/blacklist, granularity, etc? Is it common to have to configure it in your applications?

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  • Can I make PDOStatement->fetchObject not use non-member variables?

    - by threendib
    Lets say I have a class like this: Class User { var $id var $name; } And I run a query using PDO in php like so: $stm = $db->prepare('select * from users where id = :id'); $r = $stm->execute(array(':id' => $id)); $user = $r->fetchObject('User'); If I vardump my user object it has all kinds of other fields in it that I have not defined in the User class. Obviously I could make my query specific so that it only gives me back the fields I need/want. But if I don't want to do that is there any way to make this work the way I want it to? I like the idea of fetchObject, because it's one line of code to create this object and set member variables for me. I just don't want it to set variables I haven't defined in my class.

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  • How to call window developed in C# through FindWindow api.

    - by Sagar Mane
    Hello All, I am new to C# and xaml code. I have one sample code which implemented in C#. when I have reviewed xaml file I got <Window x:Class="test.MainWindow">. So does test.MainWindow indicate the class name for this window. I am trying to invoke this window from other application which is developed in win 32. I am trying to pass this class name to FindWindow("test.MainWindow",NULL) ,but it fails. does anything missing over there. how I can change the class name of window developed in C#? Thanks, Sagar

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  • Get dragged / saved items state back from Sql Server

    - by user571507
    Ok i saw many post's on how to serialize the value of dragged items to get hash and they tell how to save them. Now the question is how do i persist the dragged items the next time when user log's in using the has value that i got eg: <ul class="list"> <li id="id_1"> <div class="item ui-corner-all ui-widget ui-widget-content"> </div> </li> <li id="id_2"> <div class="item ui-corner-all ui-widget ui-widget-content"> </div> </li> <li id="id_3"> <div class="item ui-corner-all ui-widget ui-widget-content"> </div> </li> <li id="id_4"> <div class="item ui-corner-all ui-widget"> </div> </li> </ul> which on serialize will give "id[]=1&id[]=2&id[]=3&id[]=4" Now think that i saved it to Sql server database in a single field called SortOrder. Now how do i get the items to these order again ? the code to make these sort is below,without which people didn't know which library i had used to sort and serialize <script type="text/javascript"> $(document).ready(function() { $(".list li").css("cursor", "move"); $(".list").sortable(); }); </script>

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  • push(ing)_back objects pointers within a loop

    - by Jose Manuel Albornoz
    Consider the following: I have a class CDevices containing, amongst others, a string member class CDevice { public: CDevice(void); ~CDevice(void); // device name std::string Device_Name; etc... } and somewhere else in my code I define another class that contains a vector of pointers to CDevices class CDevice; class CServers { public: CServers(void); ~CServers(void); // Devices vector vector<CDevice*> Devices; etc... } The problem appears in the following lines in my main.c pDevice = new CDevice; pDevice->Device_Name = "de"; Devices.push_back(pDevice); pDevice->Device_Name = " revolotiunibus"; Devices.push_back(pDevice); pDevice->Device_Name = " orbium"; Devices.push_back(pDevice); pDevice->Device_Name = " coelestium"; Devices.push_back(pDevice); for(int i = 0; i < (int)Devices.size(); ++i) cout << "\nLoad name = " << Devices.at(i)->Device_Name << endl; The output I get is " coelestium" repeated four times: each time I push_back a new element into the vector all of the already existing elements take the value of the one which has just been added. I have also tried using iterators to recover each element in the vector with the same results. Could someone please tell me what's wrong here? Thankx

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  • Creating a new object destroys an older object with different name in C++

    - by Mikael
    First question here! So, I am having some problems with pointers in Visual C++ 2008. I'm writing a program which will control six cameras and do some processing on them so to clean things up I have created a Camera Manager class. This class handles all operations which will be carried out on all the cameras. Below this is a Camera class which interacts with each individual camera driver and does some basic image processing. Now, the idea is that when the manager is initialised it creates two cameras and adds them to a vector so that I can access them later. The catch here is that when I create the second camera (camera2) the first camera's destructor is called for some reason, which then disconnects the camera. Normally I'd assume that the problem is somewhere in the Camera class, but in this case everything works perfectly as long as I don't create the camera2 object. What's gone wrong? CameraManager.h: #include "stdafx.h" #include <vector> #include "Camera.h" class CameraManager{ std::vector<Camera> cameras; public: CameraManager(); ~CameraManager(); void CaptureAll(); void ShowAll(); }; CameraManager.cpp: #include "stdafx.h" #include "CameraManager.h" CameraManager::CameraManager() { printf("Camera Manager: Initializing\n"); [...] Camera *camera1 = new Camera(NodeInfo,1, -44,0,0); cameras.push_back(*camera1); // Adding the following two lines causes camera1's destructor to be called. Why? Camera *camera2 = new Camera(NodeInfo,0, 44,0,0); cameras.push_back(*camera2); printf("Camera Manager: Ready\n"); }

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  • Best way to implement game loop without freezing UI thread

    - by Matt H
    I'm trying to make a simple 2D game in Java. So far I have a JFrame, with a menubar, and a class which extends JPanel and overrides it's paint method. Now, I need to get a game loop going, where I will update the position of images and so on. However, I'm stuck at how best to achieve this. Should I use multi-threading, because surely, if you put an infinite loop on the main thread, the UI (and thus my menu bar) will freeze up? Here's my code so far: import java.awt.Color; import java.awt.Graphics; import javax.swing.JPanel; @SuppressWarnings("serial") public class GameCanvas extends JPanel { public void paint(Graphics g) { while (true) { g.setColor(Color.DARK_GRAY); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } } } import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; @SuppressWarnings("serial") public class Main extends JFrame { GameCanvas canvas = new GameCanvas(); final int FRAME_HEIGHT = 400; final int FRAME_WIDTH = 400; public static void main(String args[]) { new Main(); } public Main() { super("Game"); JMenuBar menuBar = new JMenuBar(); JMenu fileMenu = new JMenu("File"); JMenuItem startMenuItem = new JMenuItem("Pause"); menuBar.add(fileMenu); fileMenu.add(startMenuItem); super.add(canvas); super.setVisible(true); super.setSize(FRAME_WIDTH, FRAME_WIDTH); super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); super.setJMenuBar(menuBar); } } Any pointers/tips? Also, where should I put my loop? In my main class, or my GameCanvas class? Any help is appreciated, thanks.

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