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  • Active Record like functionality on array instance variable

    - by rube_noob
    I would like to write a module that provides active record like functionality on an array instance variable. Examples of its use would be x = Container.new x.include(ContainerModule) x.elements << Element.new x.elements.find id module ContainerModule def initialize(*args) @elements = [] class << @elements def <<(element) #do something with the Container... super(element) end def find(id) #find an element using the Container's id self #=> #<Array..> but I need #<Container..> end end super(*args) end end The problem is that I need the Container object within these methods. Any reference to self will return the Array, not the Container object. Is there any way to do this? Thanks!

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  • QT4 Designer - Implement Widget

    - by MOnsDaR
    I'm currently trying to get into QT4 and figure out a workflow for myself. While trying to create a widget which allows the user to connect to a hostname:port some questions appeared. The widget itself contains a LineEdit for entering the hostname, a SpinBox for entering the port and a PushButton which should emit a connect(QString hostname, unsigned int port) signal. In QTDesigner I created the necessary Form. It is saved as a .ui-File. Now the big question is how could I implement the widget? Is there a place in QTDesigner where I could add my signal to the Widget? Where could I add custom Properties? I've learned in another tutorial, which showed how to create a Widget in C++, how signals, slots, Q_PROPERTIES etc are defined and added to the widget. But there is no sourcecode in QTDesigner. Another option would be to generate sourcecode using uic. But the header says, that another generate would overwrite any changes to the sourcefiles. So how can I create a QT-widget completely with my own signals, slots and properties by using the QTDesigner for creating the UI and not having to recode everything whenever the UI is changing. Is there some kind of Roundtrip-Engineering? If thats not possible: Whats the sense of creating a Widget with QTDesigner then?

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  • Getting started with microcontroller programming

    - by Trix
    I'm a fairly good programmer, knowledgeable in C, C++, Python, Ruby and PHP. I'd like to get started with microcontroller programming. I do know nothing about this topic. Microcontrollers are minimal computers on little circuit boards, right? I'm pretty new to electronics too, do I need to be an expert in it to do stuff with microcontrollers? What can I do with them? Would e.g.: A Pacman or Tetris game on an LCD be possible and not too hard? Where should I start? Basically I want to program something really small I can then take with me. This is my only real goal. Are microcontrollers the right thing for this, or are there better solutions? I'd like to do this for fun and as a hobby, I don't want to become a professional in it.

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  • Restore previously serialized JFrame-object, how?

    - by elementz
    Hi all. I have managed to serialize my very basic GUI-object containing a JTextArea and a few buttons to a file 'test.ser'. Now, I would like to completely restore the previously saved state from 'test.ser', but seem to have a misconception of how to properly deserialize an objects state. The class MyFrame creates the JFrame and serializes it. public class MyFrame extends JFrame implements ActionListener { // Fields JTextArea textArea; String title; static MyFrame gui = new MyFrame(); private static final long serialVersionUID = 1125762532137824262L; /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub gui.run(); } // parameterless default contructor public MyFrame() { } // constructor with title public MyFrame(String title) { } // creates Frame and its Layout public void run() { JFrame frame = new JFrame(title); JPanel panel_01 = new JPanel(); JPanel panel_02 = new JPanel(); JTextArea textArea = new JTextArea(20, 22); textArea.setLineWrap(true); JScrollPane scrollPane = new JScrollPane(textArea); scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED); panel_01.add(scrollPane); // Buttons JButton saveButton = new JButton("Save"); saveButton.addActionListener(this); JButton loadButton = new JButton("Load"); loadButton.addActionListener(this); panel_02.add(loadButton); panel_02.add(saveButton); // Layout frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(BorderLayout.CENTER, panel_01); frame.getContentPane().add(BorderLayout.SOUTH, panel_02); frame.setSize(300, 400); frame.setVisible(true); } /* * */ public void serialize() { try { ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("test.ser")); oos.writeObject(gui); oos.close(); } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } } public void actionPerformed(ActionEvent ev) { System.out.println("Action received!"); gui.serialize(); } } Here I try to do the deserialization: public class Deserialize { static Deserialize ds; static MyFrame frame; public static void main(String[] args) { try { ObjectInputStream ois = new ObjectInputStream(new FileInputStream("test.ser")); frame = (MyFrame) ois.readObject(); ois.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } Maybe somebody could point me into the direction where my misconception is? Thx in advance!

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  • Choosing a Java IDE for homework assignments

    - by Andrew
    Can anyone recommend a light Java IDE that doesn't require you to make new projects each time you want to compile and run a program? I just want to be able to open java files and compile and run them. I have already tried Eclipse and NetBeans but both require you to make a new project each time you want to compile and run a program. Making a new project is fine for large scale projects but for small school assignments this just makes the process more tedious. Thanks

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  • Avoiding string copying in Lua

    - by Matt Sheppard
    Say I have a C program which wants to call a very simple Lua function with two strings (let's say two comma separated lists, returning true if the lists intersect at all, false if not). The obvious way to do this is to push them onto the stack with lua_pushstring, which works fine, however, from the doc it looks like lua_pushstring but makes a copy of the string for Lua to work with. That means that to cross over to the Lua function is going to require two string copies which I could avoid by rewriting the Lua function in C. Is there any way to arrange things so that the existing C strings could be reused on the Lua side for the sake of performance (or would the strcpy cost pale into insignificance anyway)? From my investigation so far (my first couple of hours looking seriously at Lua), lite userdata seems like the sort of thing I want, but in the form of a string.

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  • How to use SQLite3 with Java

    - by Bruce
    I am trying to build a simple java program which creates a db file, then a table and inserts dummy values in the table. I found this page http://www.zentus.com/sqlitejdbc/index.html and tried out the example given on the page but I am getting the following error - Exception in thread "main" java.lang.NoClassDefFoundError: Test Caused by: java.lang.ClassNotFoundException: Test at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) Could not find the main class: Test. Program will exit.

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  • Java newbie problem: package with private access

    - by HH
    Pack.java imports pack.TestPack; but it cannot access it. I cannot understand why it cannot access the class despite the import. Error Pack.java:7: TestPack() is not public in pack.TestPack; cannot be accessed from outside package System.out.println(new TestPack().getHello()); ^ 1 error Pack.java import pack.TestPack; import java.io.*; public class Pack { public static void main(String[] args){ System.out.println(new TestPack().getHello()); } } TestPack.java package pack; import java.util.*; import java.io.*; public class TestPack { private String hello="if you see me, you ar inside class TestPack"; public String getHello(){return hello;} TestPack(){} }

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  • Why do I get "mysql_query(): supplied argument is not a valid"

    - by Brian Ojeda
    Why do I get a "mysql_query(): supplied argument is not a valid" for the first... $r = mysql_query($q, $connection); In the following code... $bId = trim($_POST['bId']); $title = trim($_POST['title']); $story = trim($_POST['story']); $q = "SELECT * "; $q .= "FROM " . DB_NAME . ".`blog` "; $q .= "WHERE `blog`.`id` = {$bId}"; $r = mysql_query($q, $connection); //confirm_query($r); if (mysql_num_rows($r) == 1) { $q = "UPDATE " . DB_NAME . ".`blog` SET `title` = '{$title}', `story` = '{$story}' WHERE `id` = {$bId}"; $r = mysql_query($q, $connection); if (mysql_affected_rows() == 1) { //Successful $data['success'] = true; $date['errors'] = false; $date['message'] = "You are the Greatest!"; } else { //Fail $data['success'] = false; $data['error'] = true; $date['message'] = "You can't do it fool!"; } } I also get an "mysql_num_rows(): supplied argument is not a valid MySQL result resource" error too. Side notes: I am using 1&1 Hosting (worst hosting ever), custom .htaccess file with one line text to enable PHP 5.2 (only why with 1&1 Hosting).

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  • C# Using singleton instead of a global static instance

    - by Farstucker
    I ran into a problem today and a friend recommended I use a global static instance or more elegantly a singleton pattern. I spent a few hours reading about singletons but a few things still escape me. Background: What Im trying to accomplish is creating an instance of an API and use this one instance in all my classes (as opposed to making a new connection, etc). There seems to be about 100 ways of creating a singleton but with some help from yoda I found some thread safe examples. ..so given the following code: public sealed class Singleton { public static Singleton Instance { get; private set; } static Singleton() { Instance = new Singleton(); } } How/Where would you instantiate the this new class and how should it be called from a separate class? Thanks for your help.

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  • Initialize a Variable Again.

    - by SoulBeaver
    That may sound a little confusing. Basically, I have a function CCard newCard() { /* Used to store the string variables intermittantly */ std::stringstream ssPIN, ssBN; int picker1, picker2; int pin, bankNum; /* Choose 5 random variables, store them in stream */ for( int loop = 0; loop < 5; ++loop ) { picker1 = rand() % 8 + 1; picker2 = rand() % 8 + 1; ssPIN << picker1; ssBN << picker2; } /* Convert them */ ssPIN >> pin; ssBN >> bankNum; CCard card( pin, bankNum ); return card; } that creates a new CCard variable and returns it to the caller CCard card = newCard(); My teacher advised me that doing this is a violation of OOP principles and has to be put in the class. He told me to use this method as a constructor. Which I did: CCard::CCard() { m_Sperre = false; m_Guthaben = rand() % 1000; /* Work */ /* Convert them */ ssPIN >> m_Geheimzahl; ssBN >> m_Nummer; } All variables with m_ are member variables. However, the constructor works when I initialize the card normally CCard card(); at the start of the program. However, I also have a function, that is supposed to create a new card and return it to the user, this function is now broken. The original command: card = newCard(); isn't available anymore, and card = new CCard(); doesn't work. What other options do I have? I have a feeling using the constructor won't work, and that I probably should just create a class method newCard, but I want to see if it is somehow at all possible to do it the way the teacher wanted. This is creating a lot of headaches for me. I told the teacher that this is a stupid idea and not everything has to be classed in OOP. He has since told me that Java or C# don't allow code outside of classes, which sounds a little incredible. Not sure that you can do this in C++, especially when templated functions exist, or generic algorithms. Is it true that this would be bad code for OOP in C++ if I didn't force it into a class?

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  • Java: print field in an image of other class?

    - by HH
    DirectoryReader.java public class DirectoryReader { public static void main(String[] args) { File myFile = new File(path); FileObject fileThing = new FileObject(myFile); //How to print the value of the hello-field from fileThing? } } FileObject.java public class FileObject { FileObject (File fileThing) { String hello = "Hello Cosmos!"; } }

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  • taking integer input in java

    - by ruchir patwa
    I am actually new to java programming and am finding it difficult to take integer input and storing it in variables...i would like it if someone could tell me how to do it or provide with an example like adding two numbers given by the user..

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  • finally and return

    - by abson
    In the below example, class ex8 { public void show() { try { int a=10/0; return;} catch(ArithmeticException e) { System.out.println(e); return ;} finally { System.out.println("Finally"); } } public static void main(String[] args) { new ex8().show(); } } the output is: java.lang.ArithmeticException: / by zero Finally How is it that Finally gets printed in spite of return statement in catch?

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  • What's wrong with this jQuery example?

    - by Sven Larson
    The following jQuery example should put some text into the div, but it doesn't. I tried Firefox, Google Chrome and Internet Explorer. <html> <head> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js" language="javascript"></script> <script language="javascript"> $(window).load(function() { $('adiv').html('<p>hello world</p>'); alert('done'); }); </script> </head> <body> <div id="adiv"> </div> </body> </html> Sorry, this might be stupid, but I'm stuck.

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  • K&R Exercise 1-21 - Mental incomprehension.

    - by asdfg
    The "impossible" K&R exercise. "Write a program entab that replaces strings of blanks by the minimum number of tabs and blanks to achieve the same spacing. Use the same tab stops, say every n columns. Should n be a variable or a symbolic parameter?" The problem I'm having is, I'm unsure about how to even do this correctly. I know it's not very explanatory, but that's pretty much the problem here. Most of the examples I've seen have counted a number of blanks, and replaced those series with a tab, but this isn't what its asking, I reckon I understand what its asking, but currently feel unable to do this. Could anyone help :)

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  • PDO using singleton stored as class properity

    - by Misiur
    Hi again. OOP drives me crazy. I can't move PDO to work. Here's my DB class: class DB extends PDO { public function &instance($dsn, $username = null, $password = null, $driver_options = array()) { static $instance = null; if($instance === null) { try { $instance = new self($dsn, $username, $password, $driver_options); } catch(PDOException $e) { throw new DBException($e->getMessage()); } } return $instance; } } It's okay when i do something like this: try { $db = new DB(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(DBException $e) { echo $e->getMessage(); } But this: try { $db = DB::instance(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(DBException $e) { echo $e->getMessage(); } Does nothing. I mean, even when I use wrong password/username, I don't get any exception. Second thing - I have class which is "heart" of my site: class Core { static private $instance; public $db; public function __construct() { if(!self::$instance) { $this->db = DB::instance(DB_TYPE.':hpost='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } return self::$instance; } private function __clone() { } } I've tried to use "new DB" inside class, but this: $r = $core->db->query("SELECT * FROM me_config"); print_r($r->fetch()); Return nothing. $sql = "SELECT * FROM me_config"; print_r($core->db->query($sql)); I get: PDOStatement Object ( [queryString] => SELECT * FROM me_config ) I'm really confused, what am I doing wrong?

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  • How do I stop a routed event from triggering on specific places in XAML?

    - by cfouche
    I have the following situation: A stackpanel contains a number of elements, including some that are contained in a GroupBox. So something like this: <StackPanel x:Name="stackpanel" Background="White"> <TextBlock Text="TextBlock"/> <TextBlock Text="Another TextBlock"/> <!--plus a load of other elements and controls--> <GroupBox Header="GroupBoxHeader"> <TextBlock Text="Text inside GroupBox"/> </GroupBox> </StackPanel> I want a MouseDown in the stackpanel to trigger some Storyboard, so I've added an EventTrigger, like this: <EventTrigger RoutedEvent="Mouse.MouseDown" SourceName="stackpanel"> <BeginStoryboard Storyboard="{StaticResource OnMouseDown1}"/> </EventTrigger> This is almost right, but the thing is - I don't want the MouseDown to be picked up by the GroupBox's header or border, only by its content. In other words, I want the Storyboard to begin when someone does a mousedown on anything inside the StackPanel, except GroupBox headers and borders. Is there some way of doing this? (I've tried setting e.Handled to true on the GroupBox, but then its content doesn't pick up the mousedown anymore either.)

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  • What benefits can Java developer have from moving to a *NIX platform?

    - by dave-keiture
    Hi everyone, A friend of mine is a Java developer, who's using *NIX for ages. He claims that *NIX is for real Java geeks, whereas WIN is for dummies (and I'm one of them, according to him) and girls. When I ask him to argue his position, and explain, what's so good for Java developer on *NIX, he starts talking about console, wget, curl and grep. But sorry, wget and curl analogues exist for the WIN platform as well. As for the console - I'm using FAR Commander, and have access to the command line when I need. Moreover, even if I decide moving to *NIX, I will certainly use Netbeans or Eclipse on it, so there will be no big difference. Guys, who use Java on *NIX, could you please give me some real killer examples, when *NIX (any util or technique) dramatically increases Java development productivity (in the way the hints are given in "The Pragmatic Programmer"), or, which is also important, gives more fun from the process. Thanks in advance!

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  • Running iPython from the OSX terminal.

    - by Az
    So I'm going through the matplotlib documentation and prepared to use the iPython interactive Python shell with ipython -pylab. However I get this: Az's MBP:~ Az$ ipython -pylab -bash: ipython: command not found Did I fail to install iPython? I used easy_install as advised. Any ideas?

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