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  • UIVIewController not released when view is dismissed

    - by Nelson Ko
    I have a main view, mainWindow, which presents a couple of buttons. Both buttons create a new UIViewController (mapViewController), but one will start a game and the other will resume it. Both buttons are linked via StoryBoard to the same View. They are segued to modal views as I'm not using the NavigationController. So in a typical game, if a person starts a game, but then goes back to the main menu, he triggers: [self dismissViewControllerAnimated:YES completion:nil ]; to return to the main menu. I would assume the view controller is released at this point. The user resumes the game with the second button by opening another instance of mapViewController. What is happening, tho, is some touch events will trigger methods on the original instance (and write status updates to them - therefore invisible to the current view). When I put a breakpoint in the mapViewController code, I can see the instance will be one or the other (one of which should be released). I have tried putting a delegate to the mainWindow clearing the view: [self.delegate clearMapView]; where in the mainWindow - (void) clearMapView{ gameWindow = nil; } I have also tried self.view=nil; in the mapViewController. The mapViewController code contains MVC code, where the model is static. I wonder if this may prevent ARC from releasing the view. The model.m contains: static CanShieldModel *sharedInstance; + (CanShieldModel *) sharedModel { @synchronized(self) { if (!sharedInstance) sharedInstance = [[CanShieldModel alloc] init]; return sharedInstance; } return sharedInstance; } Another post which may have a lead, but so far not successful, is UIViewController not being released when popped I have in ViewDidLoad: // checks to see if app goes inactive - saves. [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(resignActive) name:UIApplicationWillResignActiveNotification object:nil]; with the corresponding in ViewDidUnload: [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationWillResignActiveNotification object:nil]; Does anyone have any suggestions? EDIT: - (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{ NSString *identifier = segue.identifier; if ([identifier isEqualToString: @"Start Game"]){ gameWindow = (ViewController *)[segue destinationViewController]; gameWindow.newgame=-1; gameWindow.delegate = self; } else if ([identifier isEqualToString: @"Resume Game"]){ gameWindow = (ViewController *)[segue destinationViewController]; gameWindow.newgame=0; gameWindow.delegate = self;

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  • How do I create a thread-safe write-once read-many value in Java?

    - by Software Monkey
    This is a problem I encounter frequently in working with more complex systems and which I have never figured out a good way to solve. It usually involves variations on the theme of a shared object whose construction and initialization are necessarily two distinct steps. This is generally because of architectural requirements, similar to applets, so answers that suggest I consolidate construction and initialization are not useful. By way of example, let's say I have a class that is structured to fit into an application framework like so: public class MyClass { private /*ideally-final*/ SomeObject someObject; MyClass() { someObject=null; } public void startup() { someObject=new SomeObject(...arguments from environment which are not available until startup is called...); } public void shutdown() { someObject=null; // this is not necessary, I am just expressing the intended scope of someObject explicitly } } I can't make someObject final since it can't be set until startup() is invoked. But I would really like it to reflect it's write-once semantics and be able to directly access it from multiple threads, preferably avoiding synchronization. The idea being to express and enforce a degree of finalness, I conjecture that I could create a generic container, like so: public class WoRmObject<T> { private T object; WoRmObject() { object=null; } public WoRmObject set(T val) { object=val; return this; } public T get() { return object; } } and then in MyClass, above, do: private final WoRmObject<SomeObject> someObject; MyClass() { someObject=new WoRmObject<SomeObject>(); } public void startup() { someObject.set(SomeObject(...arguments from environment which are not available until startup is called...)); } Which raises some questions for me: Is there a better way, or existing Java object (would have to be available in Java 4)? Is this thread-safe provided that no other thread accesses someObject.get() until after it's set() has been called. The other threads will only invoke methods on MyClass between startup() and shutdown() - the framework guarantees this. Given the completely unsynchronized WoRmObject container, it is ever possible under either JMM to see a value of object which is neither null nor a reference to a SomeObject? In other words, does has the JMM always guaranteed that no thread can observe the memory of an object to be whatever values happened to be on the heap when the object was allocated.

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  • Strategies for "Always-Connected" Windows Client Data Architecture

    - by magz2010
    Hi. Let me start by saying: this is my 1st post here, this is a bit lenghty, and I havent done Windows Forms development in years....with that in mind please excuse me if this isn't directly a programming question and please bear with me as I really need the help!! I have been asked to develop a Windows Forms app for our company that talks to a central (local area network) Linux Server hosting a PostgreSQL database. The app is to allow users to authenticate themselves into the system and thereafter conduct the usual transactions with the PG database. Ordinarily, I would propose writing a webforms app against Mono, but the clients need to utilise local resources such as USB peripheral devices, so that is out of the question. While it might not seem clear, my questions are italised below: Dilemma #1: The application is meant to be always connected. How should I structure my DAL/BLL - Should this reside on the server or with the client? Dilemma #2: I have been reading up on Client Application Services (CAS), and it seems like a great fit for authentication, as everything is exposed via URIs. I know that a .NET Data Provider exists for PostgreSQL, but not too sure if CAS will all work on a Linux (Debian) server? Believe me, I would get my hands dirty and try myself, but I need to come up with a logical design first before resources are allocated to me for "trial purposes"! Dilemma #3: If the DAL/BLL is to reside on the server, is there any way I can create data services, and expose only these services to authenticated clients. There is a (security) requirement whereby a connection string with username and password to the database cannot be present on any client machines...even if security on the database side is quite rigid. I'm guessing that the only way for this to work would be to create the various CRUD data service methods that are exposed by an ASP.NET app, and have the WindowsForms make a request for data or persist data to the ASP.NET app (thru a URI) and have that return a resultset or value. Would I be correct in assuming this? Should I be looking into WCF Data Services? and will WCF work with a non-SQL Server database? Thank you for taking the time out to read this, but know that I am desperately seeking any advice on this! THANKS A MILLION!!!!

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  • Why does every thread in my application use a different hibernate session?

    - by Ittai
    Hi, I have a web-application which uses hibernate and for some reason every thread (httprequest or other threads related to queueing) uses a different session. I've implemented a HibernateSessionFactory class which looks like this: public class HibernateSessionFactory { private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>(); private static Configuration configuration = new AnnotationConfiguration(); private static org.hibernate.SessionFactory sessionFactory; static { try { configuration.configure(configFile); sessionFactory = configuration.buildSessionFactory(); } catch (Exception e) {} } private HibernateSessionFactory() {} public static Session getSession() throws HibernateException { Session session = (Session) threadLocal.get(); if (session == null || !session.isOpen()) { if (sessionFactory == null) { rebuildSessionFactory();//This method basically does what the static init block does } session = (sessionFactory != null) ? sessionFactory.openSession(): null; threadLocal.set(session); } return session; } //More non relevant methods here. Now from my testing it seems that the threadLocal member is indeed initialized only once when the class is first loaded by the JVM but for some reason when different threads access the getSession() method they use different sessions. When a thread first accesses this class (Session) threadLocal.get(); will return null but as expected all other access requests will yeild the same session. I'm not sure how this can be happening as the threadLocal variable is final and the method threadLocal.set(session) is only used in the above context (which I'm 99.9% sure has to yeild a non null session as I would have encountered a NullPointerException at a different part of my app). I'm not sure this is relevant but these are the main parts of my hibernate.cfg.xml file: <hibernate-configuration> <session-factory> <property name="connection.url">someURL</property> <property name="connection.driver_class"> com.microsoft.sqlserver.jdbc.SQLServerDriver</property> <property name="dialect">org.hibernate.dialect.SQLServerDialect</property> <property name="hibernate.connection.isolation">1</property> <property name="hibernate.connection.username">User</property> <property name="hibernate.connection.password">Password</property> <property name="hibernate.connection.pool_size">10</property> <property name="show_sql">false</property> <property name="current_session_context_class">thread</property> <property name="hibernate.hbm2ddl.auto">update</property> <property name="hibernate.cache.use_second_level_cache">false</property> <property name="hibernate.cache.provider_class">org.hibernate.cache.NoCacheProvider</property> <!-- Mapping files --> I'd appreciate any help granted and of course if anyone has any questions I'd be happy to clarify. Ittai

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  • Upgrading Entity Framework 1.0 to 4.0 to include foreign keys

    - by duthiega
    Currently I've been working with Entity Framework 1.0 which is located under a service façade. Below is one of the save methods I've created to either update or insert the device in question. This currently works but, I can't help feel that its a bit of a hack having to set the referenced properties to null then re-attach them just to get an insert to work. The changedDevice already holds these values, so why do I need to assign them again. So, I thought I'll update the model to EF4. That way I can just directly access the foreign keys. However, on doing this I've found that there doesn't seem to be an easy way to add the foreign keys except by removing the entity from the diagram and re-adding it. I don't want to do this as I've already been through all the entity properties renaming them from the DB column names. Can anyone help? /// <summary> /// Saves the non network device. /// </summary> /// <param name="nonNetworkDeviceDto">The non network device dto.</param> public void SaveNonNetworkDevice(NonNetworkDeviceDto nonNetworkDeviceDto) { using (var context = new AssetNetworkEntities2()) { var changedDevice = TransformationHelper.ConvertNonNetworkDeviceDtoToEntity(nonNetworkDeviceDto); if (!nonNetworkDeviceDto.DeviceId.Equals(-1)) { var originalDevice = context.NonNetworkDevices.Include("Status").Include("NonNetworkType").FirstOrDefault( d => d.DeviceId.Equals(nonNetworkDeviceDto.DeviceId)); context.ApplyAllReferencedPropertyChanges(originalDevice, changedDevice); context.ApplyCurrentValues(originalDevice.EntityKey.EntitySetName, changedDevice); } else { var maxNetworkDevice = context.NonNetworkDevices.OrderBy("it.DeviceId DESC").First(); changedDevice.DeviceId = maxNetworkDevice.DeviceId + 1; var status = changedDevice.Status; var nonNetworkType = changedDevice.NonNetworkType; changedDevice.Status = null; changedDevice.NonNetworkType = null; context.AttachTo("DeviceStatuses", status); if (nonNetworkType != null) { context.AttachTo("NonNetworkTypes", nonNetworkType); } changedDevice.Status = status; changedDevice.NonNetworkType = nonNetworkType; context.AddToNonNetworkDevices(changedDevice); } context.SaveChanges(); } }

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  • SQL Invalid Object Name 'AddressType'

    - by salvationishere
    I am getting the above error in my VS 2008 C# method when I try to invoke the SQL getColumnNames stored procedure from VS. This SP accepts one input parameter, the table name, and works successfully from SSMS. Currently I am selecting the AdventureWorks AddressType table for it to pull the column names from this table. I can see teh AdventureWorks table available in VS from my Server Explorer / Data Connection. And I see both the AddressType table and getColumnNames SP showing in Server Explorer. But I am still getting this error listed above. Here is the C# code snippet I use to execute this: public static DataTable DisplayTableColumns(string tt) { SqlDataReader dr = null; string TableName = tt; string connString = "Data Source=.;AttachDbFilename=\"C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\DATA\AdventureWorks_Data.mdf\";Initial Catalog=AdventureWorks;Integrated Security=True;Connect Timeout=30;User Instance=False"; string errorMsg; SqlConnection conn2 = new SqlConnection(connString); SqlCommand cmd = conn2.CreateCommand(); try { cmd.CommandText = "dbo.getColumnNames"; cmd.CommandType = CommandType.StoredProcedure; cmd.Connection = conn2; SqlParameter parm = new SqlParameter("@TableName", SqlDbType.VarChar); parm.Value = TableName; parm.Direction = ParameterDirection.Input; cmd.Parameters.Add(parm); conn2.Open(); dr = cmd.ExecuteReader(); } catch (Exception ex) { errorMsg = ex.Message; } And when I examine the errorMsg it says the following: " at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)\r\n at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)\r\n at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)\r\n at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)\r\n at System.Data.SqlClient.SqlDataReader.ConsumeMetaData()\r\n at System.Data.SqlClient.SqlDataReader.get_MetaData()\r\n at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)\r\n at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async)\r\n at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result)\r\n at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method)\r\n at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method)\r\n at System.Data.SqlClient.SqlCommand.ExecuteReader()\r\n at ADONET_namespace.ADONET_methods.DisplayTableColumns(String tt) in C:\Documents and Settings\Admin\My Documents\Visual Studio 2008\Projects\AddFileToSQL\AddFileToSQL\ADONET methods.cs:line 35" Where line 35 is dr = cmd.ExecuteReader();

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  • SAX parser does not resolve filename

    - by phantom-99w
    Another day, another strange error with SAX, Java, and friends. I need to iterate over a list of File objects and pass them to a SAX parser. However, the parser fails because of an IOException. However, the various File object methods confirm that the file does indeed exist. The output which I get: 11:53:57.838 [MainThread] DEBUG DefaultReactionFinder - C:\project\trunk\application\config\reactions\TestReactions.xml 11:53:57.841 [MainThread] ERROR DefaultReactionFinder - C:\project\trunk\application\config\reactions\null (The system cannot find the file specified) So the problem is obviously that null in the second line. I've tried nearly all variations of passing the file as a parameter to the parser, including as a String (both from getAbsolutePath() and entered by hand), as a URI and, even more weirdly, as a FileInputStream (for this I get the same error, except that the entire relative path gets reported as null, so C:\project\trunk\null). All that I can think of is that the SAXParserFactory is incorrectly configured. I have no idea what is wrong, though. Here is the code concerned: SAXParserFactory factory = SAXParserFactory.newInstance(); factory.setValidating(true); try { parser = factory.newSAXParser(); } catch (ParserConfigurationException e) { throw new InstantiationException("Error configuring an XML parser. Given error message: \"" + e.getMessage() + "\"."); } catch (SAXException e) { throw new InstantiationException("Error creating a SAX parser. Given error message: \"" + e.getMessage() + "\"."); } ... for (File f : fileLister.getFileList()) { logger.debug(f.getAbsolutePath()); try { parser.parse(f, new ReactionHandler(input)); //FileInputStream fs = new FileInputStream(f); //parser.parse(fs, new ReactionHandler(input)); //fs.close(); } catch (IOException e) { logger.error(e.getMessage()); throw new ReactionNotFoundException("An error occurred processing file \"" + f + "\"."); } ... } I have made no special provisions to provide a custom SAX parser implementation: I use the system default. Any help would be greatly appreciated!

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  • calling startActivity() inside of a instance method - causing a NullPointerException

    - by Cole
    Heya - I'm trying to call startActivity() from a class that extends AsyncTask in the onPostExecute(). Here's the flow: Class that extends AsyncTask: protected void onPostExecute() { Login login = new Login(); login.pushCreateNewOrChooseExistingFormActivity(); } Class that extends Activity: public void pushCreateNewOrChooseExistingFormActivity() { // start the CreateNewOrChooseExistingForm Activity Intent intent = new Intent(Intent.ACTION_VIEW); **ERROR_HERE*** intent.setClassName(this, CreateNewOrChooseExistingForm.class.getName()); startActivity(intent); } And I get this error… every time: 03-17 16:04:29.579: ERROR/AndroidRuntime(1503): FATAL EXCEPTION: main 03-17 16:04:29.579: ERROR/AndroidRuntime(1503): java.lang.NullPointerException 03-17 16:04:29.579: ERROR/AndroidRuntime(1503): at android.content.ContextWrapper.getPackageName(ContextWrapper.java:120) 03-17 16:04:29.579: ERROR/AndroidRuntime(1503): at android.content.ComponentName.(ComponentName.java:62) 03-17 16:04:29.579: ERROR/AndroidRuntime(1503): at android.content.Intent.setClassName(Intent.java:4850) 03-17 16:04:29.579: ERROR/AndroidRuntime(1503): at com.att.AppName.Login.pushCreateNewOrChooseExistingFormActivity(Login.java:47) For iOS developers - I'm just trying to push a new view controller on to a navigational controller's stack a la pushViewController:animated:. Which apparently - is hard to do on this platform. Any ideas? Thanks in advance! UPDATE - FIXED: per @Falmarri advice, i managed to resolve this issue. first of all, i'm no longer calling Login login = new Login(); to create a new login object. bad. bad. bad. no cookie. instead, when preparing to call .execute(), this tutorial suggests passing the applicationContext to the class the executes the AsyncTask, for my purposes, as shown below: CallWebServiceTask task = new CallWebServiceTask(); // pass the login object to the task task.applicationContext = login; // execute the task in the background, passing the required params task.execute(login); now, in onPostExecute(), i can get to my Login objects methods like so: ((Login) applicationContext).pushCreateNewOrChooseExistingFormActivity(); ((Login) applicationContext).showLoginFailedAlert(result.get("httpResponseCode").toString()); ... hope this helps someone else out there! especially iOS developers transistioning over to Android...

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  • making a password-only auth with bcrypt and mongoose

    - by user3081123
    I want to create service that let you login only with password. You type a password and if this password exists - you are logged in and if it's not - username is generated and password is encrypted. I'm having some misunderstandings and hope someone would help me to show where I'm mistaken. I guess, it would look somewhat like this in agularjs First we receive a password in login controller. $scope.signup = function() { var user = { password: $scope.password, }; $http.post('/auth/signup', user); }; Send it via http.post and get in in our node server file. We are provided with a compare password bcrypt function userSchema.methods.comparePassword = function(candidatePassword, cb) { bcrypt.compare(candidatePassword, this.password, function(err, isMatch) { if (err) return cb(err); cb(null, isMatch); }); }; So right now we are creating function to catch our http request app.post('/auth/signup', function(req, res, next) { Inside we use a compair password function to realize if such password exists or not yet. So we have to encrypt a password with bcrypt to make a comparison First we hash it same way as in .pre var encPass; bcrypt.genSalt(10, function(err, salt) { if (err) return next(err); bcrypt.hash(req.body.password, salt, function(err, hash) { if (err) return next(err); encPass=hash; )}; )}; We have encrypted password stored in encPass so now we follow to finding a user in database with this password User.findOne({ password: encPass }, function(err, user) { if (user) { //user exists, it means we should pass an ID of this user to a controller to display it in a view. I don't know how. res.send({user.name}) //like this? How should controller receive this? With $http.post? } else { and now if user doesn't exist - we should create it with user ID generated by my function var nUser = new User({ name: generId(), password: req.body.password }); nUser.save(function(err) { if (err) return next(err); )}; )}; )}; Am I doing anything right? I'm pretty new to js and angular. If so - how do I throw a username back at controller? If someone is interested - this service exists for 100+ symbol passphrases so possibility of entering same passphrase as someone else is miserable. And yeah, If someone logged in under 123 password - the other guy will log in as same user if he entered 123 password, but hey, you are warned to make a big passphrase. So I'm confident about the idea and I only need a help with understanding and realization.

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  • use simplexml to get attributes of elements

    - by user1291894
    I am trying to parse an xml file with a soap envelope from a web service using php. I would like to use SoapClient, but I get an error back that 'page must be viewed over secure channel SSL', which I think is an issue on their end, so I gave up on that. Currently I am using curl to get a result back. Then I put it into a simplexml object like so: <?php $xml = @simplexml_load_string($result, NULL, NULL, "http://schemas.xmlsoap.org/soap/envelope/"); $xml->registerXPathNamespace('xs', 'http://www.w3.org/2001/XMLSchema'); $output = $xml->xpath('//soap:Body'); ?> I now have this: Array ( [0] => SimpleXMLElement Object ( [GetDocumentListResponse] => SimpleXMLElement Object ( [GetDocumentListResult] => <NewDataSet> <xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata"> <xs:element name="_x0023_temp_list"> <xs:complexType> <xs:attribute name="tran_datetime" type="xs:string" /> <xs:attribute name="sender" type="xs:string" /> <xs:attribute name="doc_type_num" type="xs:string" /> <xs:attribute name="doc_date" type="xs:string" /> <xs:attribute name="doc_num" type="xs:string" /> <xs:attribute name="doc_sys_no" type="xs:string" /> <xs:attribute name="is_new" type="xs:string" /> </xs:complexType> </xs:element> <xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:UseCurrentLocale="true"> <xs:complexType> <xs:choice minOccurs="0" maxOccurs="unbounded"> <xs:element ref="_x0023_temp_list" /> </xs:choice> </xs:complexType> </xs:element> </xs:schema> <_x0023_temp_list tran_datetime="2012-03-22T13:37:17.237" sender="webservice" doc_type_num="100" doc_date="2012-03-22T13:37:17.253" doc_num="12345" doc_sys_no="1234567" is_new="1" /> </NewDataSet> ) ) ) I am able to loop through this object and get to the part between the "NewDataSet" tags, but I can't seem to get to the individual elements. What I need is the attributes in the last tag that starts with _x0023_temp_list. I'm not sure if the tag is always going to be named that, so I will probably also have to deal with getting attributes from the tag with the xs namespace as well. I've read quite a few other posts and have tried several different methods of getting the info and so far nothing has seemed to work.

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  • initializing a vector of custom class in c++

    - by Flamewires
    Hey basically Im trying to store a "solution" and create a vector of these. The problem I'm having is with initialization. Heres my class for reference class Solution { private: // boost::thread m_Thread; int itt_found; int dim; pfn_fitness f; double value; std::vector<double> x; public: Solution(size_t size, int funcNo) : itt_found(0), x(size, 0.0), value(0.0), dim(30), f(Eval_Functions[funcNo]) { for (int i = 1; i < (int) size; i++) { x[i] = ((double)rand()/((double)RAND_MAX))*maxs[funcNo]; } } Solution() : itt_found(0), x(31, 0.0), value(0.0), dim(30), f(Eval_Functions[1]) { for (int i = 1; i < 31; i++) { x[i] = ((double)rand()/((double)RAND_MAX))*maxs[1]; } } Solution operator= (Solution S) { x = S.GetX(); itt_found = S.GetIttFound(); dim = S.GetDim(); f = S.GetFunc(); value = S.GetValue(); return *this; } void start() { value = f (dim, x); } /* plus additional getter/setter methods*/ } Solution S(30, 1) or Solution(2, 5) work and initalizes everything, but I need X of these solution objects. std::vector<Solution> Parents(X) will create X solutions with the default constructor and i want to construct using the (int, int) constructor. Is there any easy(one liner?) way to do this? Or would i have to do something like: size_t numparents = 10; vector<Solution> Parents; Parents.reserve(numparents); for (int i = 0; i<(int)numparents; i++) { Solution S(31, 0); Parents.push_back(S); }

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  • C++ game designing & polymorphism question

    - by Kotti
    Hi! I'm trying to implement some sort of 'just-for-me' game engine and the problem's plot goes the following way: Suppose I have some abstract interface for a renderable entity, e.g. IRenderable. And it's declared the following way: interface IRenderable { // (...) // Suppose that Backend is some abstract backend used // for rendering, and it's implementation is not important virtual void Render(Backend& backend) = 0; }; What I'm doing right now is something like declaring different classes like class Ball : public IRenderable { virtual void Render(Backend& backend) { // Rendering implementation, that is specific for // the Ball object // (...) } }; And then everything looks fine. I can easily do something like std::vector<IRenderable*> items, push some items like new Ball() in this vector and then make a call similiar to foreach (IRenderable* in items) { item->Render(backend); } Ok, I guess it is the 'polymorphic' way, but what if I want to have different types of objects in my game and an ability to manipulate their state, where every object can be manipulated via it's own interface? I could do something like struct GameState { Ball ball; Bonus bonus; // (...) }; and then easily change objects state via their own methods, like ball.Move(...) or bonus.Activate(...), where Move(...) is specific for only Ball and Activate(...) - for only Bonus instances. But in this case I lose the opportunity to write foreach IRenderable* simply because I store these balls and bonuses as instances of their derived, not base classes. And in this case the rendering procedure turns into a mess like ball.Render(backend); bonus.Render(backend); // (...) and it is bad because we actually lose our polymorphism this way (no actual need for making Render function virtual, etc. The other approach means invoking downcasting via dynamic_cast or something with typeid to determine the type of object you want to manipulate and this looks even worse to me and this also breaks this 'polymorphic' idea. So, my question is - is there some kind of (probably) alternative approach to what I want to do or can my current pattern be somehow modified so that I would actually store IRenderable* for my game objects (so that I can invoke virtual Render method on each of them) while preserving the ability to easily change the state of these objects? Maybe I'm doing something absolutely wrong from the beginning, if so, please point it out :) Thanks in advance!

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  • How to page multiple data sets in ASP.NET MVC

    - by REA_ANDREW
    On a single view I will have three sets of paged data. Which means for each model I will have The Objects The Page Index The Page Size My initial thought was for example: public class PagedModel<T> where T:class { public IList<T> Objects { get; set; } public int ModelPageIndex { get; set; } public int ModelPageSize { get; set; } } Then having a model which is to be supplied to the action as for example: public class TypesViewModel { public PagedModel<ObjectA> Types1 { get; set; } public PagedModel<ObjectB> Typed2 { get; set; } public PagedModel<ObjectC> Types3 { get; set; } } So if I then for example have the Index view inherit from the type: System.Web.Mvc.ViewPage<uk.co.andrewrea.forum.Web.Models.TypesViewModel> Now my initial aciton method for the index is simply: public ActionResult Index() { var forDisplayPurposes = new TypesViewModel(); return View(forDisplayPurposes); } If I then want to page, it is here where I am struggling to decide which action to take. Lets say that I select the next page of the Types2 PageModel. What should the action look like for this in order to return the new view showing the second page of the Types2 PageModel I was thinking possibly to duplicate the action but use it with POST [AcceptVerbs(HttpVerbs.Post)] public ActionResult Index(TypesViewModel model) { return View(model); } Is this a good way to approach it. I understand there is always Session, but I was just wondering how such a thing is achieved currently out there. If any best methods have been mutually accepted and things. So simply, one page with multiple paged models. How to persist the data for each using a wrapper model. Which way should you pass in the model and which way should you page the data, i.e. Form Post Lastly, I have seen the routes take this into account i.e. {controller}/{action}/{id}/{pageindex}/{pagesize} but this only accounts for one model and I do not really wwant to repeat the pagesize and pageindex values for the number of models I have inside the wrapper model. Thanks for your time!! Andrew

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  • PHP Session Class and $_SESSION Array

    - by Gianluca Bargelli
    Hello, i've implemented this custom PHP Session Class for storing sessions into a MySQL database: class Session { private $_session; public $maxTime; private $database; public function __construct(mysqli $database) { $this->database=$database; $this->maxTime['access'] = time(); $this->maxTime['gc'] = get_cfg_var('session.gc_maxlifetime'); session_set_save_handler(array($this,'_open'), array($this,'_close'), array($this,'_read'), array($this,'_write'), array($this,'_destroy'), array($this,'_clean') ); register_shutdown_function('session_write_close'); session_start();//SESSION START } public function _open() { return true; } public function _close() { $this->_clean($this->maxTime['gc']); } public function _read($id) { $getData= $this->database->prepare("SELECT data FROM Sessions AS Session WHERE Session.id = ?"); $getData->bind_param('s',$id); $getData->execute(); $allData= $getData->fetch(); $totalData = count($allData); $hasData=(bool) $totalData >=1; return $hasData ? $allData['data'] : ''; } public function _write($id, $data) { $getData = $this->database->prepare("REPLACE INTO Sessions VALUES (?, ?, ?)"); $getData->bind_param('sss', $id, $this->maxTime['access'], $data); return $getData->execute(); } public function _destroy($id) { $getData=$this->database->prepare("DELETE FROM Sessions WHERE id = ?"); $getData->bind_param('S', $id); return $getData->execute(); } public function _clean($max) { $old=($this->maxTime['access'] - $max); $getData = $this->database->prepare("DELETE FROM Sessions WHERE access < ?"); $getData->bind_param('s', $old); return $getData->execute(); } } It works well but i don't really know how to properly access the $_SESSION array: For example: $db=new DBClass();//This is a custom database class $session=new Session($db->getConnection()); if (isset($_SESSION['user'])) { echo($_SESSION['user']);//THIS IS NEVER EXECUTED! } else { $_SESSION['user']="test"; Echo("Session created!"); } At every page refresh it seems that $_SESSION['user'] is somehow "resetted", what methods can i apply to prevent such behaviour?

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  • Problem separating C++ code in header, inline functions and code.

    - by YuppieNetworking
    Hello all, I have the simplest code that I want to separate in three files: Header file: class and struct declarations. No implementations at all. Inline functions file: implementation of inline methods in header. Code file: normal C++ code for more complicated implementations. When I was about to implement an operator[] method, I couldn't manage to compile it. Here is a minimal example that shows the same problem: Header (myclass.h): #ifndef _MYCLASS_H_ #define _MYCLASS_H_ class MyClass { public: MyClass(const int n); virtual ~MyClass(); double& operator[](const int i); double operator[](const int i) const; void someBigMethod(); private: double* arr; }; #endif /* _MYCLASS_H_ */ Inline functions (myclass-inl.h): #include "myclass.h" inline double& MyClass::operator[](const int i) { return arr[i]; } inline double MyClass::operator[](const int i) const { return arr[i]; } Code (myclass.cpp): #include "myclass.h" #include "myclass-inl.h" #include <iostream> inline MyClass::MyClass(const int n) { arr = new double[n]; } inline MyClass::~MyClass() { delete[] arr; } void MyClass::someBigMethod() { std::cout << "Hello big method that is not inlined" << std::endl; } And finally, a main to test it all: #include "myclass.h" #include <iostream> using namespace std; int main(int argc, char *argv[]) { MyClass m(123); double x = m[1]; m[1] = 1234; cout << "m[1]=" << m[1] << endl; x = x + 1; return 0; } void nothing() { cout << "hello world" << endl; } When I compile it, it says: main.cpp:(.text+0x1b): undefined reference to 'MyClass::MyClass(int)' main.cpp:(.text+0x2f): undefined reference to 'MyClass::operator[](int)' main.cpp:(.text+0x49): undefined reference to 'MyClass::operator[](int)' main.cpp:(.text+0x65): undefined reference to 'MyClass::operator[](int)' However, when I move the main method to the MyClass.cpp file, it works. Could you guys help me spot the problem? Thank you.

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  • How do you programmatically set a Style on a View?

    - by Greg
    I would like to do something like this: <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_cotent" style="@style/SubmitButtonType" /> But in code The xml approach works fine provided that SubmitButtonType is defined. Now what I assume happens is that the appt parser runs through this xml, generates an AttributeSet. That AttributeSet when passed to context/theme#obtainStyledAttributes() will have the style ref mask anything that is not written inline in this tag. Great that's fine! Now how do we do this programmatically. Button, as well as other View types, has a constructor that has the form: <Widget>(Context context, AttributeSet set, int defStyle). So I thought this would work. Button button = new Button(context, null, R.style.SubmitButtonType); However, I am finding that defStyle is badly documented as it really should be written to be a resourceId to an attribute (from R.attrs) that will be passed to obtainStyledAttributes() as the attribute resource, and not the style resource. After looking at the code, all the view implementations seem to pass 0 as the styleRef. I don't see the harm in having it passed as both the attr and the style resource (more flexible and negligible overhead) However I might be approaching this all wrong. How do you do this in code then other than by setting each individual element of the style to the specific widget you want to style (only possible by looking a the code to see what param maps to which method or set of methods). The only way I have found to do this is: <declare-styleable> <attr name="totallyAdhoc_attribute_just_for_this_case" format="reference"> </declare-styleable> <style name="MyAlreadyExistantTheme" > ... ... <item name="totallyAdhoc_attribute_just_for_this_case">@style/SubmitButtonType</item> </style> And instead of passing R.style.SubmitButtonType as defStyle, I pass the new R.attr.totallyAdhoc_attribute_just_for_this_case. Button button = new Button(context, null, R.attr.totallyAdhoc_attribute_just_for_this_case); This works but sounds way too complicated.

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  • Wierdness debugging Visual Studio C++ 2008

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

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  • Unable to read data from the transport connection: the connection was closed

    - by webdreamer
    The exception is Remoting Exception - Authentication Failure. The detailed message says "Unable to read data from the transport connection: the connection was closed." I'm having trouble with creating two simple servers that can comunicate as remote objects in C#. ServerInfo is just a class I created that holds the IP and Port and can give back the address. It works fine, as I used it before, and I've debugged it. Also the server is starting just fine, no exception is thrown, and the channel is registered without problems. I'm using Forms to do the interfaces, and call some of the methods on the server, but didn't find any problems in passing the parameters from the FormsApplication to the server when debugging. All seems fine in that chapter. public ChordServerProgram() { RemotingServices.Marshal(this, "PADIBook"); nodeInt = 0; } public void startServer() { try { serverChannel = new TcpChannel(serverInfo.Port); ChannelServices.RegisterChannel(serverChannel, true); } catch (Exception e) { Console.WriteLine(e.ToString()); } } I run two instances of this program. Then startNode is called on one of the instances of the application. The port is fine, the address generated is fine as well. As you can see, I'm using the IP for localhost, since this server is just for testing purposes. public void startNode(String portStr) { IPAddress address = IPAddress.Parse("127.0.0.1"); Int32 port = Int32.Parse(portStr); serverInfo = new ServerInfo(address, port); startServer(); //node = new ChordNode(serverInfo,this); } Then, in the other istance, through the interface again, I call another startNode method, giving it a seed server to get information from. This is where it goes wrong. When it calls the method on the seedServer proxy it just got, a RemotingException is thrown, due to an authentication failure. (The parameter I'll want to get is the node, I'm just using the int to make sure the ChordNode class has nothing to do with this error.) public void startNode(String portStr, String seedStr) { IPAddress address = IPAddress.Parse("127.0.0.1"); Int32 port = Int32.Parse(portStr); serverInfo = new ServerInfo(address, port); IPAddress addressSeed = IPAddress.Parse("127.0.0.1"); Int32 portSeed = Int32.Parse(seedStr); ServerInfo seedInfo = new ServerInfo(addressSeed, portSeed); startServer(); ChordServerProgram seedServer = (ChordServerProgram)Activator.GetObject(typeof(ChordServerProgram), seedInfo.GetFullAddress()); // node = new ChordNode(serverInfo,this); int seedNode = seedServer.nodeInt; // node.chordJoin(seedNode.self); }

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  • C++ vector and segmentation faults

    - by Headspin
    I am working on a simple mathematical parser. Something that just reads number = 1 + 2; I have a vector containing these tokens. They store a type and string value of the character. I am trying to step through the vector to build an AST of these tokens, and I keep getting segmentation faults, even when I am under the impression my code should prevent this from happening. Here is the bit of code that builds the AST: struct ASTGen { const vector<Token> &Tokens; unsigned int size, pointer; ASTGen(const vector<Token> &t) : Tokens(t), pointer(0) { size = Tokens.size() - 1; } unsigned int next() { return pointer + 1; } Node* Statement() { if(next() <= size) { switch(Tokens[next()].type) { case EQUALS : Node* n = Assignment_Expr(); return n; } } advance(); } void advance() { if(next() <= size) ++pointer; } Node* Assignment_Expr() { Node* lnode = new Node(Tokens[pointer], NULL, NULL); advance(); Node* n = new Node(Tokens[pointer], lnode, Expression()); return n; } Node* Expression() { if(next() <= size) { advance(); if(Tokens[next()].type == SEMICOLON) { Node* n = new Node(Tokens[pointer], NULL, NULL); return n; } if(Tokens[next()].type == PLUS) { Node* lnode = new Node(Tokens[pointer], NULL, NULL); advance(); Node* n = new Node(Tokens[pointer], lnode, Expression()); return n; } } } }; ... ASTGen AST(Tokens); Node* Tree = AST.Statement(); cout << Tree->Right->Data.svalue << endl; I can access Tree->Data.svalue and get the = Node's token info, so I know that node is getting spawned, and I can also get Tree->Left->Data.svalue and get the variable to the left of the = I have re-written it many times trying out different methods for stepping through the vector, but I always get a segmentation fault when I try to access the = right node (which should be the + node) Any help would be greatly appreciated.

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  • How do I create/use a Fluent NHibernate convention to map UInt32 properties to an SQL Server 2008 da

    - by dommer
    I'm trying to use a convention to map UInt32 properties to a SQL Server 2008 database. I don't seem to be able to create a solution based on existing web sources, due to updates in the way Fluent NHibernate works - i.e. examples are out of date. Here's my code as it currently stands (which, when I try to expose the schema, fails due to SQL Server not supporting UInt32). Apologies for the code being a little long, but I'm not 100% sure what is relevant to the problem, so I'm erring on the side of caution. I think I'll need a relatively comprehensive example, as I don't seem to be able to pull the pieces together into a working solution, at present. FluentConfiguration configuration = Fluently.Configure() .Database(MsSqlConfiguration.MsSql2008 .ConnectionString(connectionString)) .Mappings(mapping => mapping.AutoMappings.Add( AutoMap.AssemblyOf<Product>() .Conventions.Add<UInt32UserTypeConvention>())); configuration.ExposeConfiguration(x => new SchemaExport(x).Create(false, true)); namespace NHibernateTest { public class UInt32UserTypeConvention : UserTypeConvention<UInt32UserType> { // Empty. } } namespace NHibernateTest { public class UInt32UserType : IUserType { // Public properties. public bool IsMutable { get { return false; } } public Type ReturnedType { get { return typeof(UInt32); } } public SqlType[] SqlTypes { get { return new SqlType[] { SqlTypeFactory.Int32 }; } } // Public methods. public object Assemble(object cached, object owner) { return cached; } public object DeepCopy(object value) { return value; } public object Disassemble(object value) { return value; } public new bool Equals(object x, object y) { return (x != null && x.Equals(y)); } public int GetHashCode(object x) { return x.GetHashCode(); } public object NullSafeGet(IDataReader rs, string[] names, object owner) { int? i = (int?)NHibernateUtil.Int32.NullSafeGet(rs, names[0]); return (UInt32?)i; } public void NullSafeSet(IDbCommand cmd, object value, int index) { UInt32? u = (UInt32?)value; int? i = (Int32?)u; NHibernateUtil.Int32.NullSafeSet(cmd, i, index); } public object Replace(object original, object target, object owner) { return original; } } }

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  • Java replacement for C macros

    - by thkala
    Recently I refactored the code of a 3rd party hash function from C++ to C. The process was relatively painless, with only a few changes of note. Now I want to write the same function in Java and I came upon a slight issue. In the C/C++ code there is a C preprocessor macro that takes a few integer variables names as arguments and performs a bunch of bitwise operations with their contents and a few constants. That macro is used in several different places, therefore its presence avoids a fair bit of code duplication. In Java, however, there is no equivalent for the C preprocessor. There is also no way to affect any basic type passed as an argument to a method - even autoboxing produces immutable objects. Coupled with the fact that Java methods return a single value, I can't seem to find a simple way to rewrite the macro. Avenues that I considered: Expand the macro by hand everywhere: It would work, but the code duplication could make things interesting in the long run. Write a method that returns an array: This would also work, but it would repeatedly result into code like this: long tmp[] = bitops(k, l, m, x, y, z); k = tmp[0]; l = tmp[1]; m = tmp[2]; x = tmp[3]; y = tmp[4]; z = tmp[5]; Write a method that takes an array as an argument: This would mean that all variable names would be reduced to array element references - it would be rather hard to keep track of which index corresponds to which variable. Create a separate class e.g. State with public fields of the appropriate type and use that as an argument to a method: This is my current solution. It allows the method to alter the variables, while still keeping their names. It has the disadvantage, however, that the State class will get more and more complex, as more macros and variables are added, in order to avoid copying values back and forth among different State objects. How would you rewrite such a C macro in Java? Is there a more appropriate way to deal with this, using the facilities provided by the standard Java 6 Development Kit (i.e. without 3rd party libraries or a separate preprocessor)?

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  • NVIDIA graphics driver in Ubuntu 12.04

    - by user924501
    So my overall goal is that I want to be able to code with CUDA enabled applications. However, upon many days of searching, using installation walkthroughs, and reinstalling countless times after driver failure... I'm now here as a last resort. I cannot get Ubuntu 12.04 LTS to install the NVIDIA 295.59 driver for my GeForce GT 540M NVIDIA graphics card. My main system specs is as follows... (I believe having the Intel processor may be the problem) DELL Laptop XPS L502X Intel® Core™ i7-2620M CPU @ 2.70GHz × 4 Intel Integrated Graphics 64 bit NVIDIA GeForce GT 540M Ubuntu 12.04 LTS All other specs are irrelevant unless I forgot something? Methods Tried: aptitude install nvidia-current (all packages) Results: Nothing really happened. Nothing in the additional drivers menu appeared, nor was the NVIDIA X Server settings application allowing access because it thought there was no NVIDIA X Server installed. Downloaded driver from nvidia.com. Set nomodeset in the grub boot menu through /boot/grub/grub.cfg Went to console and turned off lightdm. Installed the driver, but it said the pre-install failed? (mean anything?) Started up lightdm again. Results: NVIDIA X Server settings still didn't notice it. Even tried to do nvidia-xconfig multiple times. I also went into the config file to make sure the driver setting said "nvidia". aptitude install nvidia-173 (all packages) Results: Couldn't find the xorg-video-abi-10 virtual package. It was nowhere to be found and the ubuntu forums everywhere had no answers. Lots of people were having this problem. This is easily done in windows, simply download the driver and debug in visual studio with no problems at all. I'd like clear step-by-step instructions on how I should go about this. I'm relatively new to linux but I can find my way around pretty well so you aren't talking to a straight-up beginner. Also, if you think another thread may have the answer please post because I was having a hard time looking for my specific type of problem. TL;DR I want to have access to my GPU so I can code with CUDA while in Ubuntu 12.04 on my 64 bit laptop that also has Intel integrated graphics on the processor. Solution: sudo apt-add-repository ppa:ubuntu-x-swat/x-updates && sudo apt-get update && sudo apt-get upgrade && sudo apt-get install nvidia-current

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  • Difference between Cloud and Virtualization

    - by Akash Kava
    Ops: This does not belong to ServerFault because it focuses on Programing Architecture. I have following questions regarding differences between Cloud and Virtualization.. How Cloud is different then Virtualization? Currently I tried to find out pricing of Rackspace, Amazone and all similar cloud providers, I found that our current 6 dedicated servers came cheaper then their pricing. So how one can claim cloud is cheaper? Is it cheaper only in comparison of normal hosting? We re organized our infrastructure in virtual environment to reduce or configuration overhead at time of failure, we did not have to rewrite any peice of code that is already written for earlier setup. So moving to virtualization does not require any re programming. But cloud is absoltely different and it will require entire reprogramming right? Is it really worth to recode when our current IT costs are 3-4 times lower then cloud hosting including raid backups and all sort of clustering for high availability? New programming architecture means new overheads of training staff, new methods of testing and new deployment schemes, does it justify over "on demand resource usage" words of cloud? We are having current development architecture with simple Server side ASP.NET WebServices with no local context and on client side Flex/Silverlight which offers pretty good REST architecture and its highly scalable. How does cloud differs from REST model of deployment? On storage, SQL Server or MySQL offers pretty good replication and high availibility then what is advantage in cloud? Data guarantee, one of our vendor hosting some other customer's app on cloud (one of most used), lost Entire Hard Disk (the virtual) and entire module in first 6 months. Second provider said its your duty to take backup, fine I agree, but no provider gives SLA for data guarantee, they give 99% uptime. However in most business apps, uptime is less important then data integrity. In our 10 years of dedicated hosting experience we had only one hard disk crash. This makes me little skeptical to go for cloud and loosing control over data. And I feel its just a big marketing buzz to sell virtulization in different form. Size of data, currently all providers charge very heavy for large data, if you are hosting only below 100GB cloud can be good alternative, but I think virtual servers and dedicated servers above 100GB to few TBs are still cheaper. Why would want to pay so high on cloud when there is no data guarentee as well as it doesnt say anything about redundancy. (I wish SO had something for spell check for Internet Explorer, sorry for wrong spellings in my post)

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  • Minutia on Objective-C Categories and Extensions.

    - by Matt Wilding
    I learned something new while trying to figure out why my readwrite property declared in a private Category wasn't generating a setter. It was because my Category was named: // .m @interface MyClass (private) @property (readwrite, copy) NSArray* myProperty; @end Changing it to: // .m @interface MyClass () @property (readwrite, copy) NSArray* myProperty; @end and my setter is synthesized. I now know that Class Extension is not just another name for an anonymous Category. Leaving a Category unnamed causes it to morph into a different beast: one that now gives compile-time method implementation enforcement and allows you to add ivars. I now understand the general philosophies underlying each of these: Categories are generally used to add methods to any class at runtime, and Class Extensions are generally used to enforce private API implementation and add ivars. I accept this. But there are trifles that confuse me. First, at a hight level: Why differentiate like this? These concepts seem like similar ideas that can't decide if they are the same, or different concepts. If they are the same, I would expect the exact same things to be possible using a Category with no name as is with a named Category (which they are not). If they are different, (which they are) I would expect a greater syntactical disparity between the two. It seems odd to say, "Oh, by the way, to implement a Class Extension, just write a Category, but leave out the name. It magically changes." Second, on the topic of compile time enforcement: If you can't add properties in a named Category, why does doing so convince the compiler that you did just that? To clarify, I'll illustrate with my example. I can declare a readonly property in the header file: // .h @interface MyClass : NSObject @property (readonly, copy) NSString* myString; @end Now, I want to head over to the implementation file and give myself private readwrite access to the property. If I do it correctly: // .m @interface MyClass () @property (readonly, copy) NSString* myString; @end I get a warning when I don't synthesize, and when I do, I can set the property and everything is peachy. But, frustratingly, if I happen to be slightly misguided about the difference between Category and Class Extension and I try: // .m @interface MyClass (private) @property (readonly, copy) NSString* myString; @end The compiler is completely pacified into thinking that the property is readwrite. I get no warning, and not even the nice compile error "Object cannot be set - either readonly property or no setter found" upon setting myString that I would had I not declared the readwrite property in the Category. I just get the "Does not respond to selector" exception at runtime. If adding ivars and properties is not supported by (named) Categories, is it too much to ask that the compiler play by the same rules? Am I missing some grand design philosophy?

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  • Passing variables, creating instances, self, The mechanics and usage of classes: need explenation

    - by Baf
    I've been sitting over this the whole day and Im a little tired already so please excuse me being brief. Im new to python. I just rewrrote a working program, into a bunch of functions in a class and everzthings messed up. I dont know if its me but Im very surprised i couldn t find a beginners tutorial on how to handle classes on the web so I have a few questions. First of all, in the init section of the class i have declared a bunch of variables with self.variable=something. Is it correct that i should be able to access/modify these variables in every function of the class by using self.variable in that function? In other words by declaring self.variable i have made these variables, global variables in the scope of the class right? If not how do i handle self. ? Secondly how do i correctly pass arguments to the class? some example code would be cool. thirdly how do i call a function of the class outside of the class scope? some example code would be cool. fouthly how do I create an Instance of the class INITIALCLASS in another class OTHERCLASS, passing variables from OTHERCLASS to INITIALCLASS? some example code would be cool. I Want to call a function from OTHERCLASS with arguments from INITIALCLASS. What Ive done so far is. class OTHERCLASS(): def __init__(self,variable1,variable2,variable3): self.variable1=variable1 self.variable2=variable2 self.variable3=variable3 def someotherfunction(self): something=somecode(using self.variable3) self.variable2.append(something) print self.variable2 def somemorefunctions(self): self.variable2.append(variable1) class INITIALCLASS(): def __init__(self): self.variable1=value1 self.variable2=[] self.variable3='' self.DoIt=OTHERCLASS(variable1,variable2,variable3) def somefunction(self): variable3=Somecode #tried this self.DoIt.someotherfunctions() #and this DoIt.someotherfunctions() I clearly havent understood how to pass variables to classes or how to handle self, when to use it and when not, I probably also havent understood how to properly create an isntance of a class. In general i havent udnerstood the mechanics of classes So please help me and explain it to me like i have no Idea( which i dont it seems). Or point me to a thorough video, or readable tutorial. All i find on the web is super simple examples, that didnt help me much. Or just very short definitions of classes and class methods instances etc. I can send you my original code if you guys want, but its quite long. Thanks for the Help Much appreciated!

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