instance

I'm having a hard time wrapping my head around this concept. I'll take the quote exactly from the book: Class objects also inherit from the classes above them in the hierarchy. But because they don’t have instance variables (only instances do), they inherit only methods. Correct me if I'm wrong, but a class object would be this: NSString *aString = [[NSString alloc]initWithString:@"abc.."]; The class object in this case is *aString -- am I correct so far? The thing that confuses me is the second sentence in the quote above, "But because they don’t have instance variables (only instances do),

Μy Mainclass creates a simple QmainWindows like this: class mcManageUiC(QtGui.QMainWindow): def __init__(self): super(mcManageUiC, self).__init__() self.initUI() def initUI(self): self.show() And at the end of my file I launch it like this: def main(): app = QtGui.QApplication(sys.argv) renderManagerVar = mcManageUiC() sys.exit(app.exec_()) if __name__ == '__main__': main() My problem is that each time i source it, it launches a new window. I would like to know if there is a way to detect existence of previous class instance in my script (so that I close the old one or avoid launching a new

I am trying to create a method inside class, that will instantiate class that is currently in. But I would also need that from this method to work correctly in all extended classes. As I have learned from this thread , it's not good to use self keyword for this task. So obvious choice would be using static keyword. But, I've come across different method that also works. Example: class SimpleClass { private $arg; public function __construct( $arg ){ $this->arg = $arg; } public function getArg(){return $this->arg;} public function setArg($arg){$this->arg = $arg;} public function staticInstance()

I'm trying to call a static magic function ( __callStatic ) from a member of its child class. Problem being, it goes to the non-static __call instead. <?php ini_set("display_errors", true); class a { function __call($method, $params) { echo "instance"; } static function __callStatic($method, $params) { echo "static"; } } class b extends a { function foo() { echo static::bar(); // === echo self::bar(); // === echo a::bar(); // === echo b::bar(); } } $b = new b(); echo phpversion()."<br />"; $b->foo(); ?> Output: 5.3.6 instance How can I make it display "static"? If you remove the magic method '

I have a PHP script that is called in 2 ways from a Dojo Ajax xhrGet call. The first time it is called with an "init" argument which causes the script to create an instance of the StateList class and read in a file of state names. session_start(); @include('StateList.php'); require_once('phplog.php'); //start executing here $comd=$_GET['nexturl']; if($comd=="init") { $st = new StateList("../data/statestxt.txt"); $_SESSION['statefile'] = $st; } The second and further times, another xhrGet call passes a "getstate" argument and the following code tries to get the instance ofr the StateList class

I've created the following class with the main method, which creates new instance of Application and instances of ApplicationModel , ApplicationView and ApplicationController for this particular Application . public class Application { // Variables private ApplicationSettings settings; private ApplicationModel model; private ApplicationView view; private ApplicationController controller; // Constructor public Application() { settings = new ApplicationSettings(); model = new ApplicationModel(); view = new ApplicationView(model); controller = new ApplicationController(); } // Main method public

There can be many activities in application and the last launched activity stay on top of stack and on pressing back it finish the current activity.I have a sequence of Activity and here is the flow .. if we have A,B, C(1) ,D, C(2) ... Activity C(1) and C(2) are two different instance of Activity C launched while navigating the application .So what is requisite is to clear all the instance of activity C and the result should be when I finish C(2) I should have left with these stack A,B,D . What should I do . IMP -I want to keep the C(1) alive in stack until unless I finish the C(2) as I could