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  • I need to get form data from multiple forms on one page using $_POST

    - by CDeanMartin
    My project is a menu that displays daily specials at a cafe. The Pointy Haired Boss(PHB) needs to add/remove items from the menu on a daily basis, so I stored all dishes with MySQL, and created a page which will load all menu items as buttons. When clicked, the button will UPDATE the item, turning it on or off. I need form data to detect which button was pressed, so my query knows which $menuItem to UPDATE. That is the purpose of the hidden fields. <html><head></head> <body> <html><head></head> <body> <?php include("getElement.php"); $keys = array_keys($_POST); echo $keys[0]; echo $keys[1]; //if(isset($_POST["menuItem"])){ //toggleItem($_POST["menuItem"]); //echo print_r(array_keys($_POST));} ?> <form name="b" action="scratchpad.php" method="post" > <input type="hidden" name="b" value="Cajun Gumbo"/> <input type="submit" style="color:blue" value="Cajun Gumbo" /> </form> <form name="a" action="scratchpad.php" method="post" > <input type="hidden" name="a" value="Guacomole Burger"/> <input type="submit" style="color:blue" value="Guacomole Burger" /> </form> </body> </html> Can I get $_POST to identify which button was pressed?

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  • Servlet Mapping Help - Possible to Avoid Referencing Context Name?

    - by AJ
    Hi all, I am working on a Spring application and trying to get my URL mapping correct. What I would like to have work is the following: http://localhost:8080/idptest -> doesn't work But instead, I have to reference the context name in my URL in order to resolve the mapping: http://localhost:8080/<context_name>/idptest -> works How can I avoid the requirement of referencing the context name in my URL without using a rewrite/proxy engine e.g. Apache? Here is the servlet definition and mapping from my web.xml: <servlet> <servlet-name>idptest</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/conf/idptest.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>idptest</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> Here's the outline of my controller (showing annotations for request mappings): @Controller @RequestMapping("/idptest") public class MyController { @RequestMapping(method=RequestMethod.GET) public String setupForm(Model model){ MyObject someObject = new MyObject(); model.addAttribute("someObject", someObject); return "myform"; } @RequestMapping(method = RequestMethod.POST) public String processSubmit(@ModelAttribute("someObject") MyObject someObject) throws Exception { // POST logic... } } Thanks!

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  • C++ Multiple inheritance with interfaces?

    - by umanga
    Greetings all, I come from Java background and I am having difficulty with multiple inheritance. I have an interface called IView which has init() method.I want to derive a new class called PlaneViewer implementing above interface and extend another class. (QWidget). My implementation is as: IViwer.h (only Header file , no CPP file) : #ifndef IVIEWER_H_ #define IVIEWER_H_ class IViewer { public: //IViewer(); ///virtual //~IViewer(); virtual void init()=0; }; #endif /* IVIEWER_H_ */ My derived class. PlaneViewer.h #ifndef PLANEVIEWER_H #define PLANEVIEWER_H #include <QtGui/QWidget> #include "ui_planeviewer.h" #include "IViewer.h" class PlaneViewer : public QWidget , public IViewer { Q_OBJECT public: PlaneViewer(QWidget *parent = 0); ~PlaneViewer(); void init(); //do I have to define here also ? private: Ui::PlaneViewerClass ui; }; #endif // PLANEVIEWER_H PlaneViewer.cpp #include "planeviewer.h" PlaneViewer::PlaneViewer(QWidget *parent) : QWidget(parent) { ui.setupUi(this); } PlaneViewer::~PlaneViewer() { } void PlaneViewer::init(){ } My questions are: Is it necessary to declare method init() in PlaneViewer interface also , because it is already defined in IView? 2.I cannot complie above code ,give error : PlaneViewer]+0x28): undefined reference to `typeinfo for IViewer' collect2: ld returned 1 exit status Do I have to have implementation for IView in CPP file?

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  • A monkey could do this better - Access to and availability of private member functions in C++

    - by David
    I am wandering the desert of my brain. I'm trying to write something like the following: class MyClass { // Peripherally Related Stuff public: void TakeAnAction(int oneThing, int anotherThing) { switch(oneThing){ case THING_A: TakeThisActionWith(anotherThing); break; //cases THINGS_NOT_A: }; private: void TakeThisActionWith(int thing) { string outcome = new string; outcome = LookUpOutcome(thing); // Do some stuff based on outcome return; } string LookUpOutcome(int key) { string oc = new string; oc = MyPrivateMap[key]; return oc; } map<int, string> MyPrivateMap; Then in the .cc file where I am actually using these things, while compiling the TakeAnAction section, it [CC, the solaris compiler] throws an an error: 'The function LookUpOutcome must have a prototype' and bombs out. In my header file, I have declared 'string LookUpOutcome(int key);' in the private section of the class. I have tried all sorts of variations. I tried to use 'this' for a little while, and it gave me 'Can only use this in non-static member function.' Sadly, I haven't declared anything static and these are all, putatively, member functions. I tried it [on TakeAnAction and LookUp] when I got the error, but I got something like, 'Can't access MyPrivateMap from LookUp'. MyPrivateMap could be made public and I could refer to it directly, I guess, but my sensibility says that is not the right way to go about this [that means that namespace scoped helper functions are out, I think]. I also guess I could just inline the lookup and subsequent other stuff, but my line-o-meter goes on tilt. I'm trying desperately not to kludge it.

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  • Reloading the model of a TTTableViewController

    - by user341338
    My problem is that I have a Register Controller and a Login Controller. The Login Screen displays a Login Screen or a Logout Screen depending if a user is logged in. Now when a user registers, does not close the app, and then goes to the Login Screen it will still display a Login Screen, although there is a logged in user already. This is because the Screen is created when the application loads and does not change afterwards. I tried doing this: - (id)init { if (self = [super init]) { [self invalidateModel]; [self reload]; but that did not work, since it is only called on the first init. then i tried: - (void)viewDidLoad { [self invalidateModel]; [self reload]; } But that method had the same problem. Then I found this method: - (TTNavigationMode)navigationModeForURL:(NSString*)URL; with the following options: typedef enum { TTNavigationModeNone, TTNavigationModeCreate, // a new view controller is created each time TTNavigationModeShare, // a new view controller is created, cached and re-used TTNavigationModeModal, // a new view controller is created and presented modally TTNavigationModeExternal, // an external app will be opened } TTNavigationMode; It seems like TTNavigationModeCreate would be the right thing to use, but I have no clue how to use it. Any help? Thnx.

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  • missing rake tasks ??

    - by richard moss
    hi I have ran gem install rails and am running 2.3.4 but i am missing some rake tasks like 'db' and 'gems' if i run rake -T i get the following tasks. How can i get all the others ? rake apache2 # Build Apache 2 module rake clean # Remove compiled files rake clobber # Remove all generated files rake default # Build everything rake doc # Generate all documentation rake doxygen # Generate Doxygen C++ API documentation if ... rake doxygen:clobber # Remove generated Doxygen C++ API documenta... rake doxygen:force # Force generation of Doxygen C++ API docume... rake fakeroot # Create a fakeroot, useful for building nat... rake nginx # Build Nginx helper server rake package # Build all the packages rake package:clean # Remove package products rake package:debian # Create a Debian package rake package:force # Force a rebuild of the package files rake package:gem # Build the gem file passenger-2.2.4.gem rake rdoc # Build the rdoc HTML Files rake rdoc:clobber # Remove rdoc products rake rdoc:force # Force a rebuild of the RDOC files rake sloccount # Run 'sloccount' to see how much code Passe... rake test # Run all unit tests and integration tests rake test:cxx # Run unit tests for the Apache 2 and Nginx ... rake test:integration # Run all integration tests rake test:integration:apache2 # Run Apache 2 integration tests rake test:integration:nginx # Run Nginx integration tests rake test:oxt # Run unit tests for the OXT library rake test:rcov # Run coverage tests for the Ruby libraries rake test:restart # Run the 'restart' integration test infinit... rake test:ruby If anyone knows why this has happened, how i can fix it or anything else that could help, please let me know thanks alot rick

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  • Extension methods for encapsulation and reusability

    - by tzaman
    In C++ programming, it's generally considered good practice to "prefer non-member non-friend functions" instead of instance methods. This has been recommended by Scott Meyers in this classic Dr. Dobbs article, and repeated by Herb Sutter and Andrei Alexandrescu in C++ Coding Standards (item 44); the general argument being that if a function can do its job solely by relying on the public interface exposed by the class, it actually increases encapsulation to have it be external. While this confuses the "packaging" of the class to some extent, the benefits are generally considered worth it. Now, ever since I've started programming in C#, I've had a feeling that here is the ultimate expression of the concept that they're trying to achieve with "non-member, non-friend functions that are part of a class interface". C# adds two crucial components to the mix - the first being interfaces, and the second extension methods: Interfaces allow a class to formally specify their public contract, the methods and properties that they're exposing to the world. Any other class can choose to implement the same interface and fulfill that same contract. Extension methods can be defined on an interface, providing any functionality that can be implemented via the interface to all implementers automatically. And best of all, because of the "instance syntax" sugar and IDE support, they can be called the same way as any other instance method, eliminating the cognitive overhead! So you get the encapsulation benefits of "non-member, non-friend" functions with the convenience of members. Seems like the best of both worlds to me; the .NET library itself providing a shining example in LINQ. However, everywhere I look I see people warning against extension method overuse; even the MSDN page itself states: In general, we recommend that you implement extension methods sparingly and only when you have to. So what's the verdict? Are extension methods the acme of encapsulation and code reuse, or am I just deluding myself?

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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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  • Write Null/Nothing value with Databinding

    - by clawson
    I have extended a MaskedTextBox component to add some functionality. The text property of the extended MaskedTextBox is bound to a DateTime? property and the format of binding is set to a time format of "HH:mm:ss" (i.e. 24hr time). So that this masked text box will capture the display a time. The extra functionality I have added is to make the component readonly unless the component is double clicked or the enter button is pressed (the back color of the control helps to inform the users if the component is locked/readonly or not). When the enter button is pressed I also suspend the bindings so that bound data is updated the users input won't be lost. The information is then written back to the value and databindings resumed when the user presses the enter key again. This all works fine up to here, with values written and displayed as would be expected. However, I also want to write the null or nothing value to the DateTime? property if the user hasn't entered any text (or invalid text but let's just stick with no text) when enter key is pressed to submit the new value. Unlike with other valid entries in the MaskedTextBox, with no text entered when i execute: Me.DataBindings("Text").WriteValue() (when 'locking' the MaskedTextBox) it then branches to the bound properties Get method as I step into each line of code in the debugger (as opposed to the Set method with other valid entries) How can I write this null/nothing/"" value to the DateTime? property when no text "" is entered into the MaskedTextBox? Thanks for the help!

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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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  • 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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  • Redirecting to a Facelet is not working when extending FaceletViewHandler

    - by Abel Morelos
    I'm overriding the handleRenderResponse method defined in com.sun.facelets.FaceletViewHandler: protected void handleRenderException(FacesContext context, Exception ex) I'm overriding this method so I can redirect the user to a custom error page (which contain the desired look and feel and other stuff). This is the way I'm trying to String errorPage = "/error.xhtml"; String contextPath = context.getExternalContext().getRequestContextPath(); String errorPagePath = contextPath+errorPage; context.getExternalContext().redirect(errorPagePath); The previous code is what I'm using to perform the redirect to this custom error page. Anyway, when I perform the redirect I'm prompted with a download dialog (this is with Internet Explorer, in Firefox the page does not display properly or as I would expect). I tried changing "/error.xhtml" to "/error.jsf" but in that case I get a 404 error. Somehow I think that the XHTML file is not being handled to the Facelets ViewHandler after the redirect, if I open the downloaded xhtml file I can see that the EL expressions were not resolved and the the ui tags were not handled. I don't have problems with other pages in my application, only when doing the redirect programatically. Important data from my web.xml: facelets.VIEW_MAPPINGS is set to *.xhtml javax.faces.DEFAULT_SUFFIX is set to .xhtml servlet-mapping for the "Faces Servlet" is ".jsf" and "/faces/"

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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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  • RoR: Replace_html with partial and collection not functioning

    - by Jack
    I am trying to create a tabbed interface using the prototype helper method "replace_html." I have three different partials I am working with. The first one is the 'main tab' and it is loaded automatically like so: <div id = "grid"> <% things_today = things.find_things_today %> <%= render :partial => "/todaything", :collection => things_today, :as =>:thing %> </div> ...which works fine. Similarly, I have a _tomorrowthing partial which would replace the content in the 'grid' div like so: <%things_tomorrow = things.find_things_tomorrow%> <%= link_to_function('Tomorrow',nil, :id=>'tab') do |page| page.replace_html 'grid' , :partial => '/tomorrowthing',:collection => things_tomorrow, :as => :thing end %> If I click on this tab nothing happens at all. Using firebug, the only errors I find are a missing ) after argument list which is contained in the Element.update block where the link_to_function is called. What am I doing wrong?

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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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  • 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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  • Declare module name of classes for logging

    - by Space_C0wb0y
    I currently am adding some features to our logging-library. One of these is the possibility to declare a module-name for a class that automatically gets preprended to any log-messages writing from within that class. However, if no module-name is provided, nothing is prepended. Currently I am using a trait-class that has a static function that returns the name. template< class T > struct ModuleNameTrait { static std::string Value() { return ""; } }; template< > struct ModuleNameTrait< Foo > { static std::string Value() { return "Foo"; } }; This class can be defined using a helper-macro. The drawback is, that the module-name has to be declared outside of the class. I would like this to be possible within the class. Also, I want to be able to remove all logging-code using a preprocessor directive. I know that using SFINAE one can check if a template argument has a certain member, but since other people, that are not as friendly with templates as I am, will have to maintain the code, I am looking for a much simpler solution. If there is none, I will stick with the traits approach. Thanks in advance!

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  • What does the JS function 'postMessage()' do when called on an html object tag?

    - by Stephano
    I was recently searching for a way to call the print function on a PDF I was displaying in adobe air. I solved this problem with a little help from this fellow, and by calling postMessage on my PDF like so: //this is the HTML I use to view my PDF <object id="PDFObj" data="test.pdf" type="application/pdf"/> ... //this actionscript lives in my air app var pdfObj:Object = htmlLoader.window.document.getElementById("PDFObj"); pdfObj.postMessage([message]); I've tried this in JavaScript as well, just to be sure it wasn't adobe sneaking in and helping me out... var obj = document.getElementById("PDFObj"); obj.postMessage([message]); Works well in JavaScript and in ActionScript. I looked up what the MDC had to say about postMessage, but all I found was window.postMessage. Now, the code works like a charm, and postMessage magically sends my message to my PDF's embedded JavaScript. However, I'm still not sure how I'm doing this. I found adobe talking about this method, but not really explaining it: HTML-PDF communication basics JavaScript in an HTML page can send a message to JavaScript in PDF content by calling the postMessage() method of the DOM object representing the PDF content. Any ideas how this is accomplished?

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  • BinaryWriterWith7BitEncoding & BinaryReaderWith7BitEncoding

    - by Tim
    Mr. Ayende wrote in his latest blog post about an implementation of a queue. In the post he's using two magical files: BinaryWriterWith7BitEncoding & BinaryReaderWith7BitEncoding BinaryWriterWith7BitEncoding can write both int and long? using the following method signatures: void WriteBitEncodedNullableInt64(long? value) & void Write7BitEncodedInt(int value) and BinaryReaderWith7BitEncoding can read the values written using the following method signatures: long? ReadBitEncodedNullableInt64() and int Read7BitEncodedInt() So far I've only managed to find a way to read the 7BitEncodedInt: protected int Read7BitEncodedInt() { int value = 0; int byteval; int shift = 0; while(((byteval = ReadByte()) & 0x80) != 0) { value |= ((byteval & 0x7F) << shift); shift += 7; } return (value | (byteval << shift)); } I'm not too good with byte shifting - does anybody know how to read and write the 7BitEncoded long? and write the int ?

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  • JUnit confusion: use 'extend Testcase' or '@Test' ?

    - by Rabarberski
    I've found the proper use (or at least the documentation) of JUnit very confusing. This question serves both as a future reference and as a real question. If I've understood correctly, there are two main approaches to create and run a JUnit test: Approach A: create a class that extends TestCase, and start test methods with the word test. When running the class as a JUnit Test (in Eclipse), all methods starting with the word test are automatically run. import junit.framework.TestCase; public class DummyTestA extends TestCase { public void testSum() { int a = 5; int b = 10; int result = a + b; assertEquals(15, result); } } Approach B: create a 'normal' class and prepend a @Test annotation to the method. Note that you do NOT have to start the method with the word test. import org.junit.*; import static org.junit.Assert.*; public class DummyTestB { @Test public void Sum() { int a = 5; int b = 10; int result = a + b; assertEquals(15, result); } } Mixing the two seems not to be a good idea, see e.g. this stackoverflow question: Now, my questions(s): What is the preferred approach, or when would you use one instead of the other? Approach B allows for testing for exceptions by extending the @Test annotation like in @Test(expected = ArithmeticException.class). But how do you test for exceptions when using approach A? When using approach A, you can group a number of test classes in a test suite. TestSuite suite = new TestSuite("All tests");<br/> suite.addTestSuite(DummyTestA.class); suite.addTestSuite(DummyTestAbis.class);` But this can't be used with approach B (since each testclass should subclass TestCase). What is the proper way to group tests for approach B?

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  • Comparing two images from the clipboard class

    - by VeXe
    In a C# winform app. I'm writing a Clipboard log manager that logs test to a log file, (everytime a Ctrl+c/x is pressed the copied/cut text gets appended to the file) I also did the same for images, that is, if you press "prtScreen", the screen shot you took will also go to a folder. I do that by using a timer, inside I have something which 'looks' like this: if (Clipboard.ContainsImage()) { if (IsClipboardUpdated()) { LogData(); UpdateLastClipboardData(); } } This is how the rest of the methods look like: public void UpdateLastClipboardData() { // ... other updates LastClipboardImage = Clipboard.GetImage(); } // This is how I determine if there's a new image in the clipboard... public bool IsClipboardUpdated() { return (LastClipboardImage != Clipboard.GetImage()); } public void LogData() { Clipboard.GetImage().Save(ImagesLogFolder + "\\Image" + now_hours + "_" + now_mins + "_" + now_secs + ".jpg"); } The problem is: inside the update method, "LastClipboardImage != Clipboard.GetImage()" is always returning true! I even did the following inside the update method: Image img1 = Clipboard.GetImage(); Image img2 = Clipboard.GetImage(); Image img3 = img2; bool b1 = img1 == img2; // this returned false. WHY?? bool b2 = img3 == img2; // this returned true. Makes sense. Please help, the comparison isn't working... why?

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  • Moving inserted container element if possible

    - by doublep
    I'm trying to achieve the following optimization in my container library: when inserting an lvalue-referenced element, copy it to internal storage; but when inserting rvalue-referenced element, move it if supported. The optimization is supposed to be useful e.g. if contained element type is something like std::vector, where moving if possible would give substantial speedup. However, so far I was unable to devise any working scheme for this. My container is quite complicated, so I can't just duplicate insert() code several times: it is large. I want to keep all "real" code in some inner helper, say do_insert() (may be templated) and various insert()-like functions would just call that with different arguments. My best bet code for this (a prototype, of course, without doing anything real): #include <iostream> #include <utility> struct element { element () { }; element (element&&) { std::cerr << "moving\n"; } }; struct container { void insert (const element& value) { do_insert (value); } void insert (element&& value) { do_insert (std::move (value)); } private: template <typename Arg> void do_insert (Arg arg) { element x (arg); } }; int main () { { // Shouldn't move. container c; element x; c.insert (x); } { // Should move. container c; c.insert (element ()); } } However, this doesn't work at least with GCC 4.4 and 4.5: it never prints "moving" on stderr. Or is what I want impossible to achieve and that's why emplace()-like functions exist in the first place?

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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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  • 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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  • 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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