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  • Django template can't see CSS files

    - by Technical Bard
    I'm building a django app and I can't get the templates to see the CSS files... My settings.py file looks like: MEDIA_ROOT = os.path.join(os.path.abspath(os.path.dirname(__file__)), 'media') MEDIA_URL = '/media/' I've got the CSS files in /mysite/media/css/ and the template code contains: <link rel="stylesheet" type="text/css" href="/media/css/site_base.css" />` then, in the url.py file I have: # DEVELOPMENT ONLY (r'^media/(?P<path>.*)$', 'django.views.static.serve', {'document_root': '/media'}), but the development server serves the plain html (without styles). What am I doing wrong?

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  • gtk_window_fullscreen problem

    - by sterh
    Hello, I need in full screen window functional in my gtk+ application. I try to use gtk_window_fullscreen(GtkWindow* Window): I have function: static void full_screen(MainWin *mw) { gtk_window_fullscreen((GtkWindow*)mw); } When i try to call this function i see error: Gtk-CRITICAL **: gtk_window_fullscreen: assertion `GTK_IS_WINDOW (window)' failed What's wrong? Thank you

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  • .NET Reflection: How to call method of interface without creating instance?

    - by jitm
    I have situation where I have to call method of interface using reflection, like this object x = null; MethodInfo method = interfaceExists.GetMethod("ShutDown"); method.Invoke(x, new object[] { 4 }) As you can see I do not create instance of object! And, as I can supposed, I receive exception Non-static method requires a target And Question, Can I call method of interface using reflection without creating instance of interface and if YES, How I can do it ?

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  • cellForRowAtIndexPath not being called, but rowsInSections is and it's delegate is set

    - by Jhorra
    I searched around prior to posting this and made sure I hadn't missed anything obvious, though I have a feeling I am missing something basic. I'm using this as a sidebar navigation view. I tried making them static cells and pre-populating them, but they were blank that way as well. When I do it this way I can see everything gets called except that. I've tried deleting it and re-adding it. #import "acxSideBarController.h" @interface acxSideBarController () @end @implementation acxSideBarController @synthesize sidebarDelegate = _sidebarDelegate; - (id)initWithStyle:(UITableViewStyle)style { self = [super initWithStyle:style]; if (self) { // Custom initialization } return self; } - (void)viewDidLoad { [super viewDidLoad]; if ([self.sidebarDelegate respondsToSelector:@selector(lastSelectedIndexPathForSidebarViewController:)]) { NSIndexPath *indexPath = 0; [self.tableView selectRowAtIndexPath:indexPath animated:NO scrollPosition:UITableViewScrollPositionNone]; } self.tableView.backgroundColor = [UIColor underPageBackgroundColor]; self.tableView.dataSource = self; self.tableView.delegate = self; } - (void)viewDidUnload { [super viewDidUnload]; } - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { return (interfaceOrientation == UIInterfaceOrientationPortrait); } #pragma mark - Table view data source - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 3; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { if(section == 0) return 2; else if(section == 1) return 1; else return 1; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"linkCell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; } NSString *name = @""; if(indexPath.section == 1) name = @"Inbox"; else if(indexPath.section == 2) name = @"Logout"; else { if(indexPath.row == 0) name = @"Roster"; else if(indexPath.row == 1) name = @"Environmental Variables"; } cell.textLabel.text = name; cell.textLabel.textColor = [UIColor darkTextColor]; return cell; } - (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section { if(section == 0) return @"Students"; else if(section == 1) return @"Communication"; else return @" "; } #pragma mark - Table view delegate - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { if (self.sidebarDelegate) { [self.sidebarDelegate acxSideBarController:self atIndexPath:indexPath]; } } @end If it's helpful here's the header file #import <UIKit/UIKit.h> @protocol acxSideBarControllerDelegate; @interface acxSideBarController : UITableViewController @property (nonatomic, assign) id <acxSideBarControllerDelegate> sidebarDelegate; @end @protocol acxSideBarControllerDelegate <NSObject> - (void)acxSideBarController:(acxSideBarController *)acxSideBarController atIndexPath:(NSIndexPath *)indexPath; @optional - (NSIndexPath *)lastSelectedIndexPathForacxSideBarController:(acxSideBarController *)acxSideBarController; @end

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  • C# equivalent of NaN or IsNumeric

    - by johnc
    This seems like a fairly simple question, and I'm surprised not to have required it before. What is the most efficient way of testing a string input is a numeric (or conversely Not A Number). I guess I can do a Double.Parse or a regex (see below) public static bool IsNumeric(this string value) { return Regex.IsMatch(value, "^\\d+$"); } but I was wondering if there was a implemented way to do it, such as javascript's NaN() or IsNumeric() (was that VB, I can't remember).

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  • Error CS0103: The name 'Class1' does not exist in the current context

    - by Mad coder.
    In my website I created a class e.g. Class1.cs in App_Code folder when I am trying to load default page which is using this Class file I am getting the following error CS0103: The name 'Class1' does not exist in the current context for the code String something = Class1.item1(text1.Text, text2.Text); and Class1.cs consists of protected static string item1(string a, string b) { //some action here return null; } Everything works fine in my VS2010 but when I host the website in my server I am getting this issue.

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  • iphone :- i have one webservice in that Authentication require

    - by Heart PAL
    hello, i have one webservice given by my client ... problem is this webservise require Authentication...without username and password no one get data from this url...so how can i do authentication this webservice . this is same like u r gling to login to facebook or twitter then first we enter username and password for authenticate . how can i do this same. i have username and password for this webservise can i pass this static data in code ?

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  • How to convert this procedural programming to object-oriented programming?

    - by manus91
    I have a source code that is needed to be converted by creating classes, objects and methods. So far, I've just done by converting the initial main into a separate class. But I don't know what to do with constructor and which variables are supposed to be private. This is the code : import java.util.*; public class Card{ private static void shuffle(int[][] cards){ List<Integer> randoms = new ArrayList<Integer>(); Random randomizer = new Random(); for(int i = 0; i < 8;) { int r = randomizer.nextInt(8)+1; if(!randoms.contains(r)) { randoms.add(r); i++; } } List<Integer> clonedList = new ArrayList<Integer>(); clonedList.addAll(randoms); Collections.shuffle(clonedList); randoms.addAll(clonedList); Collections.shuffle(randoms); int i=0; for(int r=0; r < 4; r++){ for(int c=0; c < 4; c++){ cards[r][c] = randoms.get(i); i++; } } } public static void play() throws InterruptedException { int ans = 1; int preview; int r1,c1,r2,c2; int[][] cards = new int[4][4]; boolean[][] cardstatus = new boolean[4][4]; boolean gameover = false; int moves; Scanner input = new Scanner(System.in); do{ moves = 0; shuffle(cards); System.out.print("Enter the time(0 to 5) in seconds for the preview of the answer : "); preview = input.nextInt(); while((preview<0) || (preview>5)){ System.out.print("Invalid time!! Re-enter time(0 - 5) : "); preview = input.nextInt(); } preview = 1000*preview; System.out.println(" "); for (int i =0; i<4;i++){ for (int j=0;j<4;j++){ System.out.print(cards[i][j]); System.out.print(" "); } System.out.println(""); System.out.println(""); } Thread.sleep(preview); for(int b=0;b<25;b++){ System.out.println(" "); } for(int r=0;r<4;r++){ for(int c=0;c<4;c++){ System.out.print("*"); System.out.print(" "); cardstatus[r][c] = false; } System.out.println(""); System.out.println(" "); } System.out.println(""); do{ do{ System.out.print("Please insert the first card row : "); r1 = input.nextInt(); while((r1<1) || (r1>4)){ System.out.print("Invalid coordinate!! Re-enter first card row : "); r1 = input.nextInt(); } System.out.print("Please insert the first card column : "); c1 = input.nextInt(); while((c1<1) || (c1>4)){ System.out.print("Invalid coordinate!! Re-enter first card column : "); c1 = input.nextInt(); } if(cardstatus[r1-1][c1-1] == true){ System.out.println("The card is already flipped!! Select another card."); System.out.println(""); } }while(cardstatus[r1-1][c1-1] != false); do{ System.out.print("Please insert the second card row : "); r2 = input.nextInt(); while((r2<1) || (r2>4)){ System.out.print("Invalid coordinate!! Re-enter second card row : "); r2 = input.nextInt(); } System.out.print("Please insert the second card column : "); c2 = input.nextInt(); while((c2<1) || (c2>4)){ System.out.print("Invalid coordinate!! Re-enter second card column : "); c2 = input.nextInt(); } if(cardstatus[r2-1][c2-1] == true){ System.out.println("The card is already flipped!! Select another card."); } if((r1==r2)&&(c1==c2)){ System.out.println("You can't select the same card twice!!"); continue; } }while(cardstatus[r2-1][c2-1] != false); r1--; c1--; r2--; c2--; System.out.println(""); System.out.println(""); System.out.println(""); for(int r=0;r<4;r++){ for(int c=0;c<4;c++){ if((r==r1)&&(c==c1)){ System.out.print(cards[r][c]); System.out.print(" "); } else if((r==r2)&&(c==c2)){ System.out.print(cards[r][c]); System.out.print(" "); } else if(cardstatus[r][c] == true){ System.out.print(cards[r][c]); System.out.print(" "); } else{ System.out.print("*"); System.out.print(" "); } } System.out.println(" "); System.out.println(" "); } System.out.println(""); if(cards[r1][c1] == cards[r2][c2]){ System.out.println("Cards Matched!!"); cardstatus[r1][c1] = true; cardstatus[r2][c2] = true; } else{ System.out.println("No cards match!!"); } Thread.sleep(2000); for(int b=0;b<25;b++){ System.out.println(""); } for(int r=0;r<4;r++){ for(int c=0;c<4;c++){ if(cardstatus[r][c] == true){ System.out.print(cards[r][c]); System.out.print(" "); } else{ System.out.print("*"); System.out.print(" "); } } System.out.println(""); System.out.println(" "); } System.out.println(""); System.out.println(""); System.out.println(""); gameover = true; for(int r=0;r<4;r++){ for( int c=0;c<4;c++){ if(cardstatus[r][c]==false){ gameover = false; break; } } if(gameover==false){ break; } } moves++; }while(gameover != true); System.out.println("Congratulations, you won!!"); System.out.println("It required " + moves + " moves to finish it."); System.out.println(""); System.out.print("Would you like to play again? (1=Yes / 0=No) : "); ans = input.nextInt(); }while(ans == 1); } } The main class is: import java.util.*; public class PlayCard{ public static void main(String[] args) throws InterruptedException{ Card game = new Card(); game.play(); } } Should I simplify the Card class by creating other classes? Through this code, my javadoc has no constructtor. So i need help on this!

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  • read length of string from stdin

    - by teoz
    I want to take a string from stdin but I don't want a static array of fixed size I know that scanf need something where save the stdin input, but I can't do something like this: char string[10] scanf("%s",string); becouse I need to know before how long will be the string in order to allocate the right memory space. Can you help me to resolve this problem?

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  • Truth tables in code? How to structure state machine?

    - by HanClinto
    I have a (somewhat) large truth table / state machine that I need to implement in my code (embedded C). I anticipate the behavior specification of this state machine to change in the future, and so I'd like to keep this easily modifiable in the future. My truth table has 4 inputs and 4 outputs. I have it all in an Excel spreadsheet, and if I could just paste that into my code with a little formatting, that would be ideal. I was thinking I would like to access my truth table like so: u8 newState[] = decisionTable[input1][input2][input3][input4]; And then I could access the output values with: setOutputPin( LINE_0, newState[0] ); setOutputPin( LINE_1, newState[1] ); setOutputPin( LINE_2, newState[2] ); setOutputPin( LINE_3, newState[3] ); But in order to get that, it looks like I would have to do a fairly confusing table like so: static u8 decisionTable[][][][][] = {{{{ 0, 0, 0, 0 }, { 0, 0, 0, 0 }}, {{ 0, 0, 0, 0 }, { 0, 0, 0, 0 }}}, {{{ 0, 0, 1, 1 }, { 0, 1, 1, 1 }}, {{ 0, 1, 0, 1 }, { 1, 1, 1, 1 }}}}, {{{{ 0, 1, 0, 1 }, { 1, 1, 1, 1 }}, {{ 0, 1, 0, 1 }, { 1, 1, 1, 1 }}}, {{{ 0, 1, 1, 1 }, { 0, 1, 1, 1 }}, {{ 0, 1, 0, 1 }, { 1, 1, 1, 1 }}}}; Those nested brackets can be somewhat confusing -- does anyone have a better idea for how I can keep a pretty looking table in my code? Thanks! Edit based on HUAGHAGUAH's answer: Using an amalgamation of everyone's input (thanks -- I wish I could "accept" 3 or 4 of these answers), I think I'm going to try it as a two dimensional array. I'll index into my array using a small bit-shifting macro: #define SM_INPUTS( in0, in1, in2, in3 ) ((in0 << 0) | (in1 << 1) | (in2 << 2) | (in3 << 3)) And that will let my truth table array look like this: static u8 decisionTable[][] = { { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 1, 1 }, { 0, 1, 1, 1 }, { 0, 1, 0, 1 }, { 1, 1, 1, 1 }, { 0, 1, 0, 1 }, { 1, 1, 1, 1 }, { 0, 1, 0, 1 }, { 1, 1, 1, 1 }, { 0, 1, 1, 1 }, { 0, 1, 1, 1 }, { 0, 1, 0, 1 }, { 1, 1, 1, 1 }}; And I can then access my truth table like so: decisionTable[ SM_INPUTS( line1, line2, line3, line4 ) ] I'll give that a shot and see how it works out. I'll also be replacing the 0's and 1's with more helpful #defines that express what each state means, along with /**/ comments that explain the inputs for each line of outputs. Thanks for the help, everyone!

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  • How to style a label with a colon

    - by Allan
    I have a details view window in WPF and a label may look like this. <Label Content="{x:Static properties:Resources.Reference}" /> So that is obtains it content from my property Resource. How can transform/format the content so it has a colon after each label item. e.g. instead of the content simply displaying Reference I want it to transform to Reference:

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  • Contravariant Delegates Value Types

    - by ChloeRadshaw
    Can anyone shed light on why contravariance does not work with C# value types? The below does not work private delegate Asset AssetDelegate(int m); internal string DoMe() { AssetDelegate aw = new AssetDelegate(DelegateMethod); aw(32); return "Class1"; } private static House DelegateMethod(object m) { return null; }

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  • zend_application showing blank page

    - by daniel
    Hi, I'm using Zend_Application to bootstrap my app. class Bootstrap extends Zend_Application_Bootstrap_Bootstrap { public static $frontController = null; public static $registry = null; protected function _initEnvironment() { ini_set('display_errors', true); //date_default_timezone_set('Europe/London'); } protected function _initRegistry() { self::$registry = new Zend_Registry(array(), ArrayObject::ARRAY_AS_PROPS); Zend_Registry::setInstance(self::$registry); } protected function _initConfiguration() { $config = new Zend_Config_Ini( BASE_PATH . '/data/server/settings.ini', APPLICATION_ENV ); self::$registry->configuration = $config; } protected function _initLogging() { $config = self::$registry->configuration; $logger = new Zend_Log(new Zend_Log_Writer_Stream($config->logging->file)); Zend_Registry::set('logger', $logger); } protected function _initFrontController() { self::$frontController = Zend_Controller_Front::getInstance(); self::$frontController->throwExceptions(true); self::$frontController->returnResponse(true); self::$frontController->setControllerDirectory( APPLICATION_PATH .'/controllers' ); self::$frontController->setParam('registry', self::$registry); return self::$frontController; } protected function _initView() { $config = self::$registry->configuration; $view = new Zend_View; $viewRenderer = new Zend_Controller_Action_Helper_ViewRenderer($view); Zend_Controller_Action_HelperBroker::addHelper($viewRenderer); Zend_Layout::startMvc( array( 'layoutPath' => APPLICATION_PATH . "/layouts/scripts", 'layout' => "layout" ) ); return $view; } protected function _initDatabase() { $config = self::$registry->configuration; $params = array('host' => $config->database->hostname, 'username' => $config->database->username, 'password' => $config->database->password, 'dbname' => $config->database->database); $db = Zend_Db::factory($config->database->type, $params); Zend_Registry::set('db', $db); } protected function _initPlaceholders() { $view = $this->getResource('View'); $view->doctype('XHTML1_STRICT'); $view->headTitle('Greplin') ->setSeparator(' / '); $view->headLink()->prependStylesheet('/src/css/header.css'); $view->headScript()->prependFile('/js/site.js'); return $view; } } When I run the app I get a blank page. Filenames / paths are intact. If I add die() to the bottom of my layout.phtml, I get the page. Something is resetting the headers and sending a blank page. My error reporting is on and I get unrelated errors. What could this be?! Thanks!

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  • Converting C source to C++

    - by Barry Kelly
    How would you go about converting a reasonably large (300K), fairly mature C codebase to C++? The kind of C I have in mind is split into files roughly corresponding to modules (i.e. less granular than a typical OO class-based decomposition), using internal linkage in lieu private functions and data, and external linkage for public functions and data. Global variables are used extensively for communication between the modules. There is a very extensive integration test suite available, but no unit (i.e. module) level tests. I have in mind a general strategy: Compile everything in C++'s C subset and get that working. Convert modules into huge classes, so that all the cross-references are scoped by a class name, but leaving all functions and data as static members, and get that working. Convert huge classes into instances with appropriate constructors and initialized cross-references; replace static member accesses with indirect accesses as appropriate; and get that working. Now, approach the project as an ill-factored OO application, and write unit tests where dependencies are tractable, and decompose into separate classes where they are not; the goal here would be to move from one working program to another at each transformation. Obviously, this would be quite a bit of work. Are there any case studies / war stories out there on this kind of translation? Alternative strategies? Other useful advice? Note 1: the program is a compiler, and probably millions of other programs rely on its behaviour not changing, so wholesale rewriting is pretty much not an option. Note 2: the source is nearly 20 years old, and has perhaps 30% code churn (lines modified + added / previous total lines) per year. It is heavily maintained and extended, in other words. Thus, one of the goals would be to increase mantainability. [For the sake of the question, assume that translation into C++ is mandatory, and that leaving it in C is not an option. The point of adding this condition is to weed out the "leave it in C" answers.]

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  • SSI or PHP Include()?

    - by Ozzy
    Hi all, basically i am launching a site soon and i predict ALOT of traffic. For scenarios sake, lets say i will have 1m uniques a day. The data will be static but i need to have includes aswell I will only include a html page inside another html page, nothing dynamic (i have my reasons that i wont disclose to keep this simple) My question is, performance wise what is faster or

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  • Any way to allow classes implementing IEntity and downcast to have operator == comparisons?

    - by George Mauer
    Basically here's the issue. All entities in my system are identified by their type and their id. new Customer() { Id = 1} == new Customer() {Id = 1}; new Customer() { Id = 1} != new Customer() {Id = 2}; new Customer() { Id = 1} != new Product() {Id = 1}; Pretty standard scenario. Since all Entities have an Id I define an interface for all entities. public interface IEntity { int Id { get; set;} } And to simplify creation of entities I make public abstract class BaseEntity<T> : where T : IEntity { int Id { get; set;} public static bool operator ==(BaseEntity<T> e1, BaseEntity<T> e2) { if (object.ReferenceEquals(null, e1)) return false; return e1.Equals(e2); } public static bool operator !=(BaseEntity<T> e1, BaseEntity<T> e2) { return !(e1 == e2); } } where Customer and Product are something like public class Customer : BaseEntity<Customer>, IEntity {} public class Product : BaseEntity<Product>, IEntity {} I think this is hunky dory. I think all I have to do is override Equals in each entity (if I'm super clever, I can even override it only once in the BaseEntity) and everything with work. So now I'm expanding my test coverage and find that its not quite so simple! First of all , when downcasting to IEntity and using == the BaseEntity< override is not used. So what's the solution? Is there something else I can do? If not, this is seriously annoying. Upadate It would seem that there is something wrong with my tests - or rather with comparing on generics. Check this out [Test] public void when_created_manually_non_generic() { // PASSES! var e1 = new Terminal() {Id = 1}; var e2 = new Terminal() {Id = 1}; Assert.IsTrue(e1 == e2); } [Test] public void when_created_manually_generic() { // FAILS! GenericCompare(new Terminal() { Id = 1 }, new Terminal() { Id = 1 }); } private void GenericCompare<T>(T e1, T e2) where T : class, IEntity { Assert.IsTrue(e1 == e2); } Whats going on here? This is not as big a problem as I was afraid, but is still quite annoying and a completely unintuitive way for the language to behave. Update Update Ah I get it, the generic implicitly downcasts to IEntity for some reason. I stand by this being unintuitive and potentially problematic for my Domain's consumers as they need to remember that anything happening within a generic method or class needs to be compared with Equals()

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  • Java converting to Jython-Getting a class object within itself

    - by Bggreen
    I am attempting to convert Java code to Jython and am using the apache Log and LogFactory imports. I am attempting to emulate Foo.class in Jython The chunk of code is as follows: in Java import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; public class MyClass { private static final Log log = LogFactory.getLog(MyClass.class); public MyClass(Document dom) { //code } How can I emulate this same behavior of MyClass.class in Jython/Python?

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  • Solving a cyclical dependency in Ninject (Compact Framework)

    - by Alex
    I'm trying to use Ninject for dependency injection in my MVP application. However, I have a problem because I have two types that depend on each other, thus creating a cyclic dependency. At first, I understand that it was a problem, because I had both types require each other in their constructors. Therefore, I moved one of the dependencies to a property injection instead, but I'm still getting the error message. What am I doing wrong? This is the presenter: public class LoginPresenter : Presenter<ILoginView>, ILoginPresenter { public LoginPresenter( ILoginView view ) : base( view ) { } } and this is the view: public partial class LoginForm : Form, ILoginView { [Inject] public ILoginPresenter Presenter { private get; set; } public LoginForm() { InitializeComponent(); } } And here's the code that causes the exception: static class Program { /// <summary> /// The main entry point for the application. /// </summary> [MTAThread] static void Main() { // Show the login form Views.LoginForm loginForm = Kernel.Get<Views.Interfaces.ILoginView>() as Views.LoginForm; Application.Run( loginForm ); } } The exception happens on the line with the Kernel.Get<>() call. Here it is: Error activating ILoginPresenter using binding from ILoginPresenter to LoginPresenter A cyclical dependency was detected between the constructors of two services. Activation path: 4) Injection of dependency ILoginPresenter into property Presenter of type LoginForm 3) Injection of dependency ILoginView into parameter view of constructor of type LoginPresenter 2) Injection of dependency ILoginPresenter into property Presenter of type LoginForm 1) Request for ILoginView Suggestions: 1) Ensure that you have not declared a dependency for ILoginPresenter on any implementations of the service. 2) Consider combining the services into a single one to remove the cycle. 3) Use property injection instead of constructor injection, and implement IInitializable if you need initialization logic to be run after property values have been injected. Why doesn't Ninject understand that since one is constructor injection and the other is property injection, this can work just fine? I even read somewhere looking for the solution to this problem that Ninject supposedly gets this right as long as the cyclic dependency isn't both in the constructors. Apparently not, though. Any help resolving this would be much appreciated.

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  • MySQL - Calculating fields on the fly vs storing calculated data

    - by Christian Varga
    Hi Everyone, I apologise if this has been asked before, but I can't seem to find an answer to a question that I have about calculating on the fly vs storing fields in a database. I read a few articles that suggested it was preferable to calculate when you can, but I would just like to know if that still applies to the following 2 examples. Example 1. Say you are storing data relating to a car. You store the fuel tank size in litres, and how many litres it uses per 100km. You also want to know how many KMs it can travel, which can be calculated from the tank size and economy. I see 2 ways of doing this: When a car is added or updated, calculate the amount of KMs and store this as a static field in the database. Every time a car is accessed, calculate the amount of KMs on the fly. Because the cars economy/tank size doesn't change (although it could be edited), the KMs is a pretty static value. I don't see why we would calculate it every single time the car is accessed. Wouldn't this waste cpu time as opposed to simply storing it in a separate field in the database and calculating only when a car is added or updated? My next example, which is almost an entirely different question (but on the same topic), relates to counting children. Let's say we have a app which has categories and items. We have a view where we display all the categories, and a count of all the items inside each category. Again, I'm wondering what's better. To perform a MySQL query to count all the items in each category every single time the page is accessed? Or store the count in a field in the categories table and update when an item is added / deleted? I know it is redundant to store anything that can be calculated, but I worry that calculating fields or counting records might be slow as opposed to storing the data in a field. If it's not then please let me know, I just want to learn about when to use either method. On a small scale I guess it wouldn't matter either way, but apps like Facebook, would they really count the amount of friends you have every time someone views your profile or would they just store it as a field? I'd appreciate any responses to both of these scenarios, and any resource that might explain the benefits of calculating vs storing. Thanks in advance, Christian

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  • Android Camera takePicture function does not call Callback function

    - by Tomáš 'Guns Blazing' Frcek
    I am working on a custom Camera activity for my application. I was following the instruction from the Android Developers site here: http://developer.android.com/guide/topics/media/camera.html Everything seems to works fine, except the Callback function is not called and the picture is not saved. Here is my code: public class CameraActivity extends Activity { private Camera mCamera; private CameraPreview mPreview; private static final String TAG = "CameraActivity"; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.camera); // Create an instance of Camera mCamera = getCameraInstance(); // Create our Preview view and set it as the content of our activity. mPreview = new CameraPreview(this, mCamera); FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview); preview.addView(mPreview); Button captureButton = (Button) findViewById(R.id.button_capture); captureButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Log.v(TAG, "will now take picture"); mCamera.takePicture(null, null, mPicture); Log.v(TAG, "will now release camera"); mCamera.release(); Log.v(TAG, "will now call finish()"); finish(); } }); } private PictureCallback mPicture = new PictureCallback() { @Override public void onPictureTaken(byte[] data, Camera camera) { Log.v(TAG, "Getting output media file"); File pictureFile = getOutputMediaFile(); if (pictureFile == null) { Log.v(TAG, "Error creating output file"); return; } try { FileOutputStream fos = new FileOutputStream(pictureFile); fos.write(data); fos.close(); } catch (FileNotFoundException e) { Log.v(TAG, e.getMessage()); } catch (IOException e) { Log.v(TAG, e.getMessage()); } } }; private static File getOutputMediaFile() { String state = Environment.getExternalStorageState(); if (!state.equals(Environment.MEDIA_MOUNTED)) { return null; } else { File folder_gui = new File(Environment.getExternalStorageDirectory() + File.separator + "GUI"); if (!folder_gui.exists()) { Log.v(TAG, "Creating folder: " + folder_gui.getAbsolutePath()); folder_gui.mkdirs(); } File outFile = new File(folder_gui, "temp.jpg"); Log.v(TAG, "Returnng file: " + outFile.getAbsolutePath()); return outFile; } } After clicking the Button, I get logs: "will now take picture", "will now release camera" and "will now call finish". The activity finishes succesfully, but the Callback function was not called during the mCamera.takePicture(null, null, mPicture); function (There were no logs from the mPicture callback or getMediaOutputFile functions) and there is no file in the location that was specified. Any ideas? :) Much thanks!

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  • What is the best approach to use different CFLAGS for the same source files?

    - by evilsocket
    Hello, i need to build the same source tree twice, 1 - with normal cflags to build the project binary 2 - with cflags plus -fPIC to build a static library that would be some sort of SDK to develop project dynamic modules. Using only one Makefile, what is the best approach to accomplish this? It would be nice to do some sort of : all: $(OBJECTS) lib_rule: $(OBJECTS) CFLAGS += -fPIC .cpp.o: $(CC) -c $< -o $@ $(CFLAGS) But obviously it can't be done. Thanks

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