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• Switching textstorage of NSTextViews back and forth

  - by Jakob Dam Jensen

  I'm trying to make a feature in a product which gives the user the ability to split a textview into two. The way this is done is by removing the textview from it's superview, making a NSSplitView and adding the textview as well as a new NSTextView instance to this splitview. Lastly I make these two textviews share the same textstorage in order to make them share the same content. It works great. But the problem is when I want to make one of the two textviews change textstorage. The replaceTextStorage method in NSLayoutManager causes both NSTextView to change textStorage. The API documentation states: replaceTextStorage: All NSLayoutManager objects sharing the original NSTextStorage object then share the new one. This method makes all the adjustments necessary to keep these relationships intact, unlike setTextStorage:. So it makes sense that it would do this. But the question is how do I make it possible to have two (or more) textviews first share the same storage and after that having them using their own? I've tried replacing the layoutManager and even making new instances of NSTextViews but no luck... Any suggestions?

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• how to restart a Thread?

  - by wizztjh

  It is a RMI Server object , so many sethumanActivity() might be run , how do i make sure the previous changeToFalse thread will be stop or halt before the new changeToFalse run? t. interrupt ? Basically when sethumanActivity() is invoke , the humanActivity will be set to true , but a thread will be run to set it back to false. But I am thinking for how to disable or kill the thread when another sethumanActivity() invoked? public class VitaminDEngine implements VitaminD { public boolean humanActivity = false; changeToFalse cf = new changeToFalse(); Thread t = new Thread(cf); private class changeToFalse implements Runnable{ @Override public void run() { try { Thread.sleep(4000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } humanActivity = false; } } @Override public void sethumanActivity() throws RemoteException { // TODO Auto-generated method stub humanActivity = true; t.start(); } public boolean gethumanActivity() throws RemoteException { // TODO Auto-generated method stub return humanActivity; } } Edited after the help of SOer package smartOfficeJava; import java.rmi.RemoteException; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class VitaminDEngine implements VitaminD { public volatile boolean humanActivity = false; changeToFalse cf = new changeToFalse(); ExecutorService service = Executors.newSingleThreadExecutor(); private class changeToFalse implements Runnable{ @Override public void run() { try { Thread.sleep(4000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } humanActivity = false; } } @Override public synchronized void sethumanActivity() throws RemoteException { humanActivity = true; service.submit(cf); } public synchronized boolean gethumanActivity() throws RemoteException { return humanActivity; } }

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• How to interrupt a thread performing a blocking socket connect?

  - by Jason R

  I have some code that spawns a pthread that attempts to maintain a socket connection to a remote host. If the connection is ever lost, it attempts to reconnect using a blocking connect() call on its socket. Since the code runs in a separate thread, I don't really care about the fact that it uses the synchronous socket API. That is, until it comes time for my application to exit. I would like to perform some semblance of an orderly shutdown, so I use thread synchronization primitives to wake up the thread and signal for it to exit, then perform a pthread_join() on the thread to wait for it to complete. This works great, unless the thread is in the middle of a connect() call when I command the shutdown. In that case, I have to wait for the connect to time out, which could be a long time. This makes the application appear to take a long time to shut down. What I would like to do is to interrupt the call to connect() in some way. After the call returns, the thread will notice my exit signal and shut down cleanly. Since connect() is a system call, I thought that I might be able to intentionally interrupt it using a signal (thus making the call return EINTR), but I'm not sure if this is a robust method in a POSIX threads environment. Does anyone have any recommendations on how to do this, either using signals or via some other method? As a note, the connect() call is down in some library code that I cannot modify, so changing to a non-blocking socket is not an option.

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• how do call a polymorphic function from an agnostic function?

  - by sds

  I have a method foo void foo (String x) { ... } void foo (Integer x) { ... } and I want to call it from a method which does not care about the argument: void bar (Iterable i) { ... for (Object x : i) foo(x); // this is the only time i is used ... } the code above complains that that foo(Object) is not defined and when I add void foo (Object x) { throw new Exception; } then bar(Iterable<String>) calls that instead of foo(String) and throws the exception. How do I avoid having two textually identical definitions of bar(Iterable<String>) and bar(Iterable<Integer>)? I thought I would be able to get away with something like <T> void bar (Iterable<T> i) { ... for (T x : i) foo(x); // this is the only time i is used ... } but then I get cannot find foo(T) error.

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• NetBeans parameter fill after code completion

  - by byte

  This is a particularly annoying problem I'm having, and I can't be the only one to have issue with it. In NetBeans, when you type part of a method, then hit CTRL-SPACE, it displays the code-completion popup, whereupon you can hit tab to finish out the word. This is great, and pretty much how all IDE's operate. Example: Thread.sl < CTRL-SPACE Thread.sleep Yay! Problem is that in this context, once you type in a paren, it auto-fills the parameters for the method with their default names, and inserts a closing paren (regardless of whether you have disabled the option to automatically close them on the preferences page for code completion). This behavior is NOT present if you had manually typed out the full name. How is this helpful to anyone? You've got to type over it your actual variable that you will be passing, and NetBeans gives you no option to prevent the closing paren on code-completion. Does anyone have a way to solve this issue, without having to dive into the netbeans source and build it just for this minor of an issue?

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• Implementing Excel 2003 COM Add-in UDF in Asyc Programming model using C#(VS 2005)

  - by Venu

  Hi: I am trying to implement a UDF using Excel COM Add-in(2003) with Visual Studio 2005 in C#. I would like to implement the UDF using async programming. The UDF is a slow operation as its results are fetched from a server. As an illustration(not a real world example),the following UDF works fine without any issue: public double mul(double number1, double number2) { return number1 * number2; } How can I do the same functionality in an async way: For example, I would like the UDF return immediately and later when the results are available from a server, I would like to update the desired cells. // This method returns immediately. public object mul(double number1, double number2) { return "calculating"; } // This method of a worker thread will update the results. public OnResultsAvailable(object result) { // Question: how should I update the cells that triggerred the calcualtions above? } Constraints: I cannot use Excel RTD as I have to work with existing codebase written using Excel C# COM Add-in. Thanks for the help. -Venu

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• DB2 Driver Connection Hanging in Glassfish Connection Pool

  - by Ant

  We have an intermittent issue around the DB2 used from a Glassfish connection pool. What happens is this: Under situations where the database (DB2 on ZOS) is under stress, our application (which is a multi-threaded application using connections to DB2 via a Glassfish connection pool) stops doing anything. The following are observed: 1) Looking at the server using JConsole, we can see a thread waiting indefinitely in the DB2 driver's getConnection() method. We can also see that it has gained a lock on a Vector within the driver. Several other threads are also calling the getConnection() method in the driver, and are hanging waiting for the lock on the Vector to be released. 2) Looking at the database itself, we can see that there are connections from the Glassfish server open and waiting to be used. It seems that there is some sort of mismatch between the connection pool on Glassfish and the connections actually open to DB2. Has anyone come across this issue before? Or something similar? If you need any more information that I haven't provided, then please let me know!

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• Resolve php endless recursion issue

  - by Matt

  Hey all, I'm currently running into an endless recursion situation. I'm implementing a message service that calls various object methods.. it's quite similar to observer pattern.. Here's whats going on: Dispatcher.php class Dispatcher { ... public function message($name, $method) { // Find the object based on the name $object = $this->findObjectByName($name); // Slight psuedocode.. for ease of example if($this->not_initialized($object)) $object = new $object(); // This is where it locks up. } return $object->$method(); ... } class A { function __construct() { $Dispatcher->message("B", "getName"); } public function getName() { return "Class A"; } } class B { function __construct() { // Assume $Dispatcher is the classes $Dispatcher->message("A", "getName"); } public function getName() { return "Class B"; } } It locks up when neither object is initialized. It just goes back and forth from message each other and no one can be initialized. I'm looking for some kind of queue implementation that will make messages wait for each other.. One where the return values still get set. I'm looking to have as little boilerplate code in class A and class B as possible Any help would be immensely helpful.. Thanks! Matt Mueller

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• Resolve php "deadlock"

  - by Matt

  Hey all, I'm currently running into a situation that I guess would be called deadlock. I'm implementing a message service that calls various object methods.. it's quite similar to observer pattern.. Here's whats going on: Dispatcher.php Dispatcher.php <? class Dispatcher { ... public function message($name, $method) { // Find the object based on the name $object = $this->findObjectByName($name); // Slight psuedocode.. for ease of example if($this->not_initialized($object)) $object = new $object(); // This is where it locks up. } return $object->$method(); ... } class A { function __construct() { $Dispatcher->message("B", "getName"); } public function getName() { return "Class A"; } } class B { function __construct() { // Assume $Dispatcher is the classes $Dispatcher->message("A", "getName"); } public function getName() { return "Class B"; } } ?> It locks up when neither object is initialized. It just goes back and forth from message each other and no one can be initialized. Any help would be immensely helpful.. Thanks! Matt Mueller

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• jsf messed up links

  - by Mateusz

  I'm new to JSF. My application is working, but I'm confused with links in browser when using controller. BTW, there is also PrimeFaces in my app so don't be suprised with p: tags. Let's say I have 'list' and 'show' pages with controller doing redirection between them. First I'm on http://localhost:8080/y/r/conversation/list.xhtml page. There is link created with line <p:commandLink action="#{lazyConversationBean.doShow(conv)}" ajax="false" value="View"/>. lazyConversationBean acts here as my Controller. There is method: public String doShow(Conversation c) { this.setSelectedConversation(c); return "view"; } from which I got redirected to ...... again http://localhost:8080/y/r/conversation/list.xhtml (browser shows it) even when it's correct http://localhost:8080/y/r/conversation/view.xhtml page. There I have link <p:commandButton action="#{lazyConversationBean.doList()}" ajax="false" value="Back to list"/> and again controller has method: public String doList() { return "list"; } from which I got redirected to ... yeah, you guessed right ... http://localhost:8080/y/r/conversation/view.xhtml (that is again what browser shows) even when again it is correct http://localhost:8080/y/r/conversation/list.xhtml page. It seams as browser link area is always one step behind page currently being displayed. I don't even know if it's some incorrect behaviour as I have no idea how to query google for this :D Just for test I did this short tutorial, where netbeans created whole stack of code on one of my entities, and behaviour was the same, so it's not PrimeFaces magic related. Can you tell my why it happens, and how to fix it? Users likes to copy correct links ;)

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• How do I tell if an action is a lambda expression?

  - by Keith

  I am using the EventAgregator pattern to subscribe and publish events. If a user subscribes to the event using a lambda expression, they must use a strong reference, not a weak reference, otherwise the expression can be garbage collected before the publish will execute. I wanted to add a simple check in the DelegateReference so that if a programmer passes in a lambda expression and is using a weak reference, that I throw an argument exception. This is to help "police" the code. Example: eventAggregator.GetEvent<RuleScheduler.JobExecutedEvent>().Subscribe ( e => resetEvent.Set(), ThreadOption.PublisherThread, false, // filter event, only interested in the job that this object started e => e.Value1.JobDetail.Name == jobName ); public DelegateReference(Delegate @delegate, bool keepReferenceAlive) { if (@delegate == null) throw new ArgumentNullException("delegate"); if (keepReferenceAlive) { this._delegate = @delegate; } else { //TODO: throw exception if target is a lambda expression _weakReference = new WeakReference(@delegate.Target); _method = @delegate.Method; _delegateType = @delegate.GetType(); } } any ideas? I thought I could check for @delegate.Method.IsStatic but I don't believe that works... (is every lambda expression a static?)

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• Can it be done in a more elegant way with the Swing Timer?

  - by Roman

  Bellow is the code for the simplest GUI countdown. Can the same be done in a shorter and more elegant way with the usage of the Swing timer? import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.SwingUtilities; public class CountdownNew { static JLabel label; // Method which defines the appearance of the window. public static void showGUI() { JFrame frame = new JFrame("Simple Countdown"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); label = new JLabel("Some Text"); frame.add(label); frame.pack(); frame.setVisible(true); } // Define a new thread in which the countdown is counting down. public static Thread counter = new Thread() { public void run() { for (int i=10; i>0; i=i-1) { updateGUI(i,label); try {Thread.sleep(1000);} catch(InterruptedException e) {}; } } }; // A method which updates GUI (sets a new value of JLabel). private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater( new Runnable() { public void run() { label.setText("You have " + i + " seconds."); } } ); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { showGUI(); counter.start(); } }); } }

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• Unable to Get a Correct Time when I am Calling serverTime using jquery.countdown.js + Asp.net ?

  - by user312891

  When i am calling the below function I unable to get a correct Answer. Both var Shortly and newTime having same time one coming from the client site other sync with server. http://keith-wood.name/countdown.html I am waiting from your response. Thanks $(function() { var shortly = new Date('April 9, 2010 20:38:10'); var newTime = new Date('April 9, 2010 20:38:10'); //for loop divid /// $('#defaultCountdown').countdown({ until: shortly, onExpiry: liftOff, onTick: watchCountdown, serverSync: serverTime }); $('#div1').countdown({ until: newTime }); }); function serverTime() { var time = null; $.ajax({ type: "POST", //Page Name (in which the method should be called) and method name url: "Default.aspx/GetTime", // If you want to pass parameter or data to server side function you can try line contentType: "application/json; charset=utf-8", dataType: "json", data: "{}", async: false, //else If you don't want to pass any value to server side function leave the data to blank line below //data: "{}", success: function(msg) { //Got the response from server and render to the client time = new Date(msg.d); alert(time); }, error: function(msg) { time = new Date(); alert('1'); } }); return time; }

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• How can I provide users with the functionality of the DBUnit DatabaseOperation methods from a web in

  - by reckoner

  I am currently updating a java-based web application which allows database developers to create stored procedure regression test suites for database testing. Currently, for test setup, execution and clean-up stages, the user is provided with text boxes where they are able to enter SQL code which is executed by the isql command. I would like to extend the application to use DB Unit’s DatabaseOperation methods to provide more ways to setup the state of the database than just SQL statements. The main reason for using Db Unit rather than just SQL statements is to be able to create and store xml and xls DataSets on a server where they can be associated with their test cases and used for data setup. My question is: How can I provide users with the functionality of the DBUnit DatabaseOperation methods from a web interface? I have considered: Creating a simple programming language and a parser to read some simple syntax involving the DB Unit method names which accept a parameter being the file location to an xml or xls DataSet. I was thinking of allowing the user to register the files they need with the web app which would catalogue them and provide each file with an identifier which could passed as a parameter to the methods in this simple programming language. Creating an XML DTD which provides the user with the ability to specify operations and parameters. If I went this approach, how can I execute the methods and their parameters that I parse from the XML document? Creating a table in the database which stores the method and a FK relation to a catalogued DataSet file, however I don’t think this would be good solution due to the fact that data entry would be tedious. Thanks for your help.

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• .NET Web Service hydrate custom class

  - by row1

  I am consuming an external C# Web Service method which returns a simple calculation result object like this: [Serializable] public class CalculationResult { public string Name { get; set; } public string Unit { get; set; } public decimal? Value { get; set; } } When I add a Web Reference to this service in my ASP .NET project Visual Studio is kind enough to generate a matching class so I can easily consume and work with it. I am using Castle Windsor and I may want to plug in other method of getting a calculation result object, so I want a common class CalculationResult (or ICalculationResult) in my solution which all my objects can work with, this will always match the object returned from the external Web Service 1:1. Is there anyway I can tell my Web Service client to hydrate a particular class instead of its generated one? I would rather not do it manually: foreach(var fromService in calcuationResultsFromService) { ICalculationResult calculationResult = new CalculationResult() { Name = fromService.Name }; yield return calculationResult; } Edit: I am happy to use a Service Reference type instead of the older Web Reference.

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• C# Hiding, overriding and calling function from base class.

  - by Lukasz Lysik

  I'm learning C# and I encountered the following problem. I have two classes: base and derived: class MyBase { public void MyMethod() { Console.WriteLine("MyBase::MyMethod()"); } } class MyDerived: MyBase { public void MyMethod() { Console.WriteLine("MyDerived::MyMethod()"); } } For now, without virtual and override key words. When I compile this I get the warning (which is of course expected) that I try to hide MyMethod from MyBase class. What I want to do is to call the method from the base class having an instance of derived class. I do this like this: MyDerived myDerived = new MyDerived(); ((MyBase)myDerived).MyMethod(); It works fine when I do not specify any virtual, etc. keywords in the methods. I tried to put combination of the keywords and I got the following results: | MyBase::MyMethod | MyDerived::MyMethod | Result printed on the console | | -----------------|---------------------|-------------------------------| | - | - | MyBase::MyMethod() | | - | new | MyBase::MyMethod() | | virtual | new | MyBase::MyMethod() | | virtual | override | MyDerived::MyMethod() | I hope the table is clear to you. I have two questions: Is it the correct way to call the function from the base class (((MyBase)myDerived).MyMethod();)? I know about base keyword, but it can be called only from the inside of the derived class. Is it right? Why in the last case (with virtual and override modifiers) the method which was called came from the derived class? Would you please explain that?

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• Awkward looking uses of Contract.ValueAtReturn()

  - by devoured elysium

  I am designing a method that will add an element to an internal list. The structure of the class is something along the lines of: class MyCustomerDatabase { private IList<Customer> _customers = new List<Customer>(); public int NumberOfCustomers { get { return _customers; } } public void AddCustomer(Customer customer) { _customers.Add(customer); } } Now, I was thinking of adding a Contract.Ensures() about the size of the _customers growing by 1 with this call. The problem is that I end up with some weird looking code: public void AddCustomer(Customer customer) { int numberOfCustomersAtReturn; Contract.Ensures(Contract.ValueAtReturn<int>(out numberOfCustomersAtReturn) == Contract.OldValue<int>(NumberOfCustomers) + 1); _customers.Add(customer); numberOfCustomersAtReturn = NumberOfCustomers; } The main problem is that properties are in fact methods, so you can't just reference them direcly when using Contract.ValueAtReturn() as its only parameter accepts variables as out. The situation gets even odder if I want to achieve the same but this time with a method that should return a value: public int MyReturningMethod() { ... return abc(); //abc will add by one the number of customers in list } //gets converted to public int MyReturningMethod() { int numberOfCustomersAtReturn; Contract.Ensures(Contract.ValueAtReturn<int>(out numberOfCustomersAtReturn) == Contract.OldValue<int>(NumberOfCustomers) + 1); int returnValue = abc(); numberOfCustomersAtReturn = NumberOfCustomers; return returnValue; } This seems pretty clumsy :( Code Contracts should aim to get things clearer and this seems right the opposite. Am I doing something wrong? Thanks

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• Why do case class companion objects extend FunctionN?

  - by retronym

  When you create a case class, the compiler creates a corresponding companion object with a few of the case class goodies: an apply factory method matching the primary constructor, equals, hashCode, and copy. Somewhat oddly, this generated object extends FunctionN. scala> case class A(a: Int) defined class A scala> A: (Int => A) res0: (Int) => A = <function1> This is only the case if: There is no manually defined companion object There is exactly one parameter list There are no type arguments The case class isn't abstract. Seems like this was added about two years ago. The latest incarnation is here. Does anyone use this, or know why it was added? It increases the size of the generated bytecode a little with static forwarder methods, and shows up in the #toString() method of the companion objects: scala> case class A() defined class A scala> A.toString res12: java.lang.String = <function0>

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• Get number of posts in a topic PHP

  - by Wayne

  How do I get to display the number of posts on a topic like a forum. I used this... (how very noobish): function numberofposts($n) { $sql = "SELECT * FROM posts WHERE topic_id = '" . $n . "'"; $result = mysql_query($sql) or die(mysql_error()); $count = mysql_num_rows($result); echo number_format($count); } The while loop of listing topics: <div class="topics"> <div class="topic-name"> <p><?php echo $row['topic_title']; ?></p> </div> <div class="topic-posts"> <p><?php echo numberofposts($row['topic_id']); ?></p> </div> </div> Although it is a bad method of doing this... All I need is to know what would be the best method, don't just point me out to a website, do it here, because I'm trying to learn much. Okay? :D Thanks.

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• How to get MySQL database to appear on index.php

  - by Teddy Truong

  Hi, I have a submission form on my website (index.php) and I have the data(user submissions) being stored into a MySQL database. Right now, I have the user submitting a post and then the page directs them to an update.php which shows what they inputed. However, I want all of the data in the database in MySQL to be shown on the index.php. It's a lot like a comment system. User submits a post... and sees their post above the other submitted posts all on the same page. I think I'm missing AJAX... ? Here is the code for index.php <div align="center"> <p>&nbsp;</p> <h2 align="center" class="Title"><em><strong>REDACTED</strong></em></h2> <form id="form1" name="form1" method="post" action="update.php"> <hr /> <label><br /> <form action="update.php" method="post"> REDACTED: <input type="text" name="text" /> <input type="submit" /> </form> </label> </form> </div> On update.php I have this: ?php $text = $_POST['text']; $myString = "REDACTED"; mysql_connect ("db----.net", "-----3", "------------") or die ('Error: ' . mysql_error()); mysql_select_db ("-----------"); $query="INSERT INTO TextArea (ID, text) VALUES ('NULL', '".$text."')"; mysql_query($query) or die ('Error updating database'); echo " $myString "," $text "; ?> Thanks a lot!

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• How to use the LINQ where expression?

  - by NullReference

  I'm implementing the service \ repository pattern in a new project. I've got a base interface that looks like this. Everything works great until I need to use the GetMany method. I'm just not sure how to pass a LINQ expression into the GetMany method. For example how would I simply sort a list of objects of type name? nameRepository.GetMany( ? ) public interface IRepository<T> where T : class { void Add(T entity); void Update(T entity); void Delete(T entity); void Delete(Expression<Func<T, bool>> where); T GetById(long Id); T GetById(string Id); T Get(Expression<Func<T, bool>> where); IEnumerable<T> GetAll(); IEnumerable<T> GetMany(Expression<Func<T, bool>> where); } public virtual IEnumerable<T> GetMany(Expression<Func<T, bool>> where) { return dbset.Where(where).ToList(); }

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• Losing URI segments when paginating with CodeIgniter

  - by Danny Herran

  I have a /payments interface where the user should be able to filter via price range, bank, and other stuff. Those filters are standard select boxes. When I submit the filter form, all the post data goes to another method called payments/search. That method performs the validation, saves the post values into a session flashdata and redirects the user back to /payments passing the flashdata name via URL. So my standard pagination links with no filters are exactly like this: payments/index/20/ payments/index/40/ payments/index/60/ And if you submit the filter form, the returning URL is: payments/index/0/b48c7cbd5489129a337b0a24f830fd93 This works just great. If I change the zero for something else, it paginates just fine. The only issue however is that the << 1 2 3 4 page links wont keep the hash after the pagination offset. CodeIgniter is generating the page links ignoring that additional uri segment. My uri_segment config is already set to 3: $config['uri_segment'] = 3; I cannot set the page offset to 4 because that hash may or may not exists. Any ideas of how can I solve this? Is it mandatory for CI to have the offset as the last segment in the uri? Maybe I am trying an incorrect approach, so I am all ears. Thank you folks.

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• Change classes instantiated with loadNibNamed

  - by Nick H247

  I am trying to change the class of objects created with a nib with the iPhone SDK. The reason for this is; i dont know until runtime what the class is that i want the nib object to be (though they will have the same UIView based super class), and i dont want to create a different nib for every eventuality - as the .nib will be the same for each, apart from the class of one object. I have been successful, with a couple of methods, but either have some knock on effects or am unsure of how safe the methods I have used are: Method 1: Override alloc, on the super class and set a c variable to the class I require: + (id) alloc { if (theClassIWant) { id object = [theClassIWant allocWithZone:NSDefaultMallocZone()]; theClassIWant = nil; return object; } return [BaseClass allocWithZone:NSDefaultMallocZone()]; } this works well, and i assume is 'reasonably' safe, though if I alloc a subclass myself (without setting 'theClassIWant') - an object of the base class is created. I also dont really like the idea of overriding alloc... Method 2: use object_setClass(self,theClassIWant) in initWithCoder (before calling initWithCoder on the super class): - (id) initWithCoder:(NSCoder *)aDecoder { if (theClassIWant) { // the framework doesn't like this: //[self release]; //self = [theClassIWant alloc]; // whoa now! object_setClass(self,theClassIWant); theClassIWant = nil; return [self initWithCoder:aDecoder]; } if (self = [super initWithCoder:aDecoder]) { ... this also works well, but not all the subclasses are necessarily going to be the same size as the super class, so this could be very unsafe! To combat this i tried releasing and re-allocing to the correct type within initWithCoder, but i got the following error from the framework: "This coder requires that replaced objects be returned from initWithCoder:" dont quite get what this means! i am replacing an object in initWithCoder... Any comments on the validity of these methods, or suggestions of improvements or alternatives welcome!

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• Indentation control while developing a small python like language

  - by sap

  Hello, I'm developing a small python like language using flex, byacc (for lexical and parsing) and C++, but i have a few questions regarding scope control. just as python it uses white spaces (or tabs) for indentation, not only that but i want to implement index breaking like for instance if you type "break 2" inside a while loop that's inside another while loop it would not only break from the last one but from the first loop as well (hence the number 2 after break) and so on. example: while 1 while 1 break 2 'hello world'!! #will never reach this. "!!" outputs with a newline end 'hello world again'!! #also will never reach this. again "!!" used for cout end #after break 2 it would jump right here but since I don't have an "anti" tab character to check when a scope ends (like C for example i would just use the '}' char) i was wondering if this method would the the best: I would define a global variable, like "int tabIndex" on my yacc file that i would access in my lex file using extern. then every time i find a tab character on my lex file i would increment that variable by 1. when parsing on my yacc file if i find a "break" keyword i would decrement by the amount typed after it from the tabIndex variable, and when i reach and EOF after compiling and i get a tabIndex != 0 i would output compilation error. now the problem is, whats the best way to see if the indentation got reduced, should i read \b (backspace) chars from lex and then reduce the tabIndex variable (when the user doesn't use break)? another method to achieve this? also just another small question, i want every executable to have its starting point on the function called start() should i hardcode this onto my yacc file? sorry for the long question any help is greatly appreciated. also if someone can provide an yacc file for python would be nice as a guideline (tried looking on Google and had no luck). thanks in advance.

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• WPF-Can a XAML object be a source as well as a target for bindings?

  - by iambic77

  I was wondering if it's possible to have a TextBlock as a target and a source? Basically I have a bunch of entities which have simple relationships to other entities (like Entity1 Knows Entity3, Entity3 WorksAt Entity2 etc.) I have a Link class that stores SourceEntity, Relationship and TargetEntity details. What I want to be able to do is to select an entity then display the relationships related to that entity, with the target entities of each relationship listed underneath the relationship names. When an entity is selected, an ObservableCollection is populated with the Links for that particular entity (SelectedEntityLinks<Link>). Because each entity could have the same relationship to more than one target entity (Entity1 could know both Entity3 and Entity4 for eg.), I've created a method GetThisRelationshipEntities() that takes a relationship name as a parameter, looks through SelectedEntityLinks for relationship names that match the parameter, and returns an ObservableCollection with the target entities of that relationship. Hope I'm making this clear. In my xaml I have a WrapPanel to display each relationship name in a TextBlock: <TextBlock x:Name="relationship" Text="{Binding Path=Relationship.Name}" /> Then underneath that another Textblock which should display the results of GetThisRelationshipEntities(String relationshipName). So I want the "relationship" TextBlock to both get its Text from the binding I've shown above, but also to provide its Text as a parameter to the GetThisRelationshipEntities() method which I've added to <UserControl.Resources> as an ObjectDataProvider. Sorry if this is a bit wordy but I hope it's clear. Any pointers/advice would be great. Many thanks.

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