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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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  • Break a class in twain, or impose an interface for restricted access?

    - by bedwyr
    What's the best way of partitioning a class when its functionality needs to be externally accessed in different ways by different classes? Hopefully the following example will make the question clear :) I have a Java class which accesses a single location in a directory allowing external classes to perform read/write operations to it. Read operations return usage stats on the directory (e.g. available disk space, number of writes, etc.); write operations, obviously, allow external classes to write data to the disk. These methods always work on the same location, and receive their configuration (e.g. which directory to use, min disk space, etc.) from an external source (passed to the constructor). This class looks something like this: public class DiskHandler { public DiskHandler(String dir, int minSpace) { ... } public void writeToDisk(String contents, String filename) { int space = getAvailableSpace(); ... } public void getAvailableSpace() { ... } } There's quite a bit more going on, but this will do to suffice. This class needs to be accessed differently by two external classes. One class needs access to the read operations; the other needs access to both read and write operations. public class DiskWriter { DiskHandler diskHandler; public DiskWriter() { diskHandler = new DiskHandler(...); } public void doSomething() { diskHandler.writeToDisk(...); } } public class DiskReader { DiskHandler diskHandler; public DiskReader() { diskHandler = new DiskHandler(...); } public void doSomething() { int space = diskHandler.getAvailableSpace(...); } } At this point, both classes share the same class, but the class which should only read has access to the write methods. Solution 1 I could break this class into two. One class would handle read operations, and the other would handle writes: // NEW "UTILITY" CLASSES public class WriterUtil { private ReaderUtil diskReader; public WriterUtil(String dir, int minSpace) { ... diskReader = new ReaderUtil(dir, minSpace); } public void writeToDisk(String contents, String filename) { int = diskReader.getAvailableSpace(); ... } } public class ReaderUtil { public ReaderUtil(String dir, int minSpace) { ... } public void getAvailableSpace() { ... } } // MODIFIED EXTERNALLY-ACCESSING CLASSES public class DiskWriter { WriterUtil diskWriter; public DiskWriter() { diskWriter = new WriterUtil(...); } public void doSomething() { diskWriter.writeToDisk(...); } } public class DiskReader { ReaderUtil diskReader; public DiskReader() { diskReader = new ReaderUtil(...); } public void doSomething() { int space = diskReader.getAvailableSpace(...); } } This solution prevents classes from having access to methods they should not, but it also breaks encapsulation. The original DiskHandler class was completely self-contained and only needed config parameters via a single constructor. By breaking apart the functionality into read/write classes, they both are concerned with the directory and both need to be instantiated with their respective values. In essence, I don't really care to duplicate the concerns. Solution 2 I could implement an interface which only provisions read operations, and use this when a class only needs access to those methods. The interface might look something like this: public interface Readable { int getAvailableSpace(); } The Reader class would instantiate the object like this: Readable diskReader; public DiskReader() { diskReader = new DiskHandler(...); } This solution seems brittle, and prone to confusion in the future. It doesn't guarantee developers will use the correct interface in the future. Any changes to the implementation of the DiskHandler could also need to update the interface as well as the accessing classes. I like it better than the previous solution, but not by much. Frankly, neither of these solutions seems perfect, but I'm not sure if one should be preferred over the other. I really don't want to break the original class up, but I also don't know if the interface buys me much in the long run. Are there other solutions I'm missing?

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  • Getting input and output from a jar file run from java class?

    - by Jack L.
    Hi, I have a jar file that runs this code: public class InputOutput { /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { boolean cont = true; BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); while (cont) { System.out.print("Input something: "); String temp = in.readLine(); if (temp.equals("end")) { cont = false; System.out.println("Terminated."); } else System.out.println(temp); } } } I want to program another java class that executes this jar file and can get the input and send output to it. Is it possible? The current code I have is this but it is not working: public class JarTest { /** * Test input and output of jar files * @author Jack */ public static void main(String[] args) { try { Process io = Runtime.getRuntime().exec("java -jar InputOutput.jar"); BufferedReader in = new BufferedReader(new InputStreamReader(io.getInputStream())); OutputStreamWriter out = new OutputStreamWriter(io.getOutputStream()); boolean cont = true; BufferedReader consolein = new BufferedReader(new InputStreamReader(System.in)); while (cont) { String temp = consolein.readLine(); out.write(temp); System.out.println(in.readLine()); } } catch (IOException e) { e.printStackTrace(); } } } Thanks for your help

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  • Associating an object with another object for GC clearup

    - by thecoop
    Is there any way of associating an object instance (object A) with a second object (object B) in a generalised way, so that when B gets collected A becomes eligable for collection? The same behaviour that would happen if B had an instance variable pointing to A, but without explicitly changing the class definition of B, and being able to do this in a dynamic way? The same sort of effect could be done by using the Component.Disposed event in a funky way, but I don't want to make B disposable EDIT I'm basically creating a cache of objects that are associated with a single 'root' object, and I don't want the cache to be static, as there can be lots of root objects using different caches, so lots of memory will be used up when a root object is no longer used but the cached objects are still around. So, I want a collection of cached objects to be associated with each 'root' object, without changing the root object definition. Sort of like metadata of an extra object reference attached to each root object instance. That way, each collection will get collected when the root object is collected, and not hang around like they would if a static cache was used.

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  • Gui problem after rewriting to MVC

    - by trevor_nise
    I'm practicing MVC style programming. I have a Mastermind game in a single file, working with no problems (maybe apart of the fact that "Check" button is invisible at start). http://paste.pocoo.org/show/226726/ But when I've rewritten it to model, view, controller files - when I click on empty Pin (that should be updated, and repainted with new color) - noting happens. Can anybody see any problems here ? I've tried placing repaint() in different places, but it simply does not work at all :/ Main : public class Main { public static void main(String[] args){ Model model = new Model(); View view = new View("Mastermind", 400, 590, model); Controller controller = new Controller(model, view); view.setVisible(true); } } Model : import java.util.Random; public class Model{ static final int LINE = 5, SCORE = 10, OPTIONS = 20; Pin pins[][] = new Pin[21][LINE]; int combination[] = new int[LINE]; int curPin = 0; int turn = 1; Random generator = new Random(); int repaintPin; boolean pinsRepaint=false; int pinsToRepaint; boolean isUpdate = true, isPlaying = true, isRowFull = false; static final int HIT_X[] = {270,290,310,290,310}, HIT_Y[] = {506,496,496,516,516}; public Model(){ for ( int i=0; i < SCORE; i++ ){ for ( int j = 0; j < LINE; j++ ){ pins[i][j] = new Pin(20,0); pins[i][j].setPosition(j*50+30,510-i*50); pins[i+SCORE][j] = new Pin(8,0); pins[i+SCORE][j].setPosition(HIT_X[j],HIT_Y[j]-i*50); } } for ( int i=0; i < LINE; i++ ){ pins[OPTIONS][i] = new Pin( 20, i+2 ); pins[OPTIONS][i].setPosition( 370,i * 50 + 56); } } void fillHole(int color) { pins[turn-1][curPin].setColor(color+1); pinsRepaint = true; pinsToRepaint = turn; curPin = (curPin+1) % LINE; if (curPin == 0){ isRowFull = true; } pinsRepaint = false; pinsToRepaint = 0; } void check() { int junkPins[] = new int[LINE], junkCode[] = new int[LINE]; int pinCount = 0, pico = 0; for ( int i = 0; i < LINE; i++ ) { junkPins[i] = pins[turn-1][i].getColor(); junkCode[i] = combination[i]; } for ( int i = 0; i < LINE; i++ ){ if (junkPins[i]==junkCode[i]) { pins[turn+SCORE][pinCount].setColor(1); pinCount++; pico++; junkPins[i] = 98; junkCode[i] = 99; } } for ( int i = 0; i < LINE; i++ ){ for ( int j = 0; j < LINE; j++ ) if (junkPins[i]==junkCode[j]) { pins[turn+SCORE][pinCount].setColor(2); pinCount++; junkPins[i] = 98; junkCode[j] = 99; j = LINE; } } pinsRepaint = true; pinsToRepaint = turn + SCORE; pinsRepaint = false; pinsToRepaint=0; if ( pico == LINE ){ isPlaying = false; } else if ( turn >= 10 ){ isPlaying = false; } else{ curPin = 0; isRowFull = false; turn++; } } void combination() { for ( int i = 0; i < LINE; i++ ){ combination[i] = generator.nextInt(6) + 1; } } } class Pin{ private int color, X, Y, radius; public Pin(){ X = 0; Y = 0; radius = 0; color = 0; } public Pin( int r,int c ){ X = 0; Y = 0; radius = r; color = c; } public int getX(){ return X; } public int getY(){ return Y; } public int getRadius(){ return radius; } public void setRadius(int r){ radius = r; } public void setPosition( int x,int y ){ this.X = x ; this.Y = y ; } public void setColor( int c ){ color = c; } public int getColor() { return color; } } View: import java.awt.*; import javax.swing.*; public class View extends Frame{ Model model; JButton checkAnswer; private JPanel button; private static final Color COLORS[] = {Color.black, Color.white, Color.red, Color.yellow, Color.green, Color.blue, new Color(7, 254, 250)}; public View(String name, int w, int h, Model m){ model = m; setTitle( name ); setSize( w,h ); setResizable( false ); this.setLayout(new BorderLayout()); button = new JPanel(); button.setSize( new Dimension(400, 100)); button.setVisible(true); checkAnswer = new JButton("Check"); checkAnswer.setSize( new Dimension(200, 30)); button.add( checkAnswer ); this.add( button, BorderLayout.SOUTH); button.setVisible(true); } @Override public void paint( Graphics g ) { g.setColor( new Color(238, 238, 238)); g.fillRect( 0,0,400,590); for ( int i=0; i < model.pins.length; i++ ) { paintPins(model.pins[i][0],g); paintPins(model.pins[i][1],g); paintPins(model.pins[i][2],g); paintPins(model.pins[i][3],g); paintPins(model.pins[i][4],g); } } @Override public void update( Graphics g ) { if ( model.isUpdate ) { paint(g); } else { model.isUpdate = true; paintPins(model.pins[model.repaintPin-1][0],g); paintPins(model.pins[model.repaintPin-1][1],g); paintPins(model.pins[model.repaintPin-1][2],g); paintPins(model.pins[model.repaintPin-1][3],g); paintPins(model.pins[model.repaintPin-1][4],g); } } void repaintPins( int pin ) { model.repaintPin = pin; model.isUpdate = false; repaint(); } public void paintPins(Pin p, Graphics g ){ int X = p.getX(); int Y = p.getY(); int color = p.getColor(); int radius = p.getRadius(); int x = X-radius; int y = Y-radius; if (color > 0){ g.setColor( COLORS[color]); g.fillOval( x,y,2*radius,2*radius ); } else{ g.setColor( new Color(238, 238, 238) ); g.drawOval( x,y,2*radius-1,2*radius-1 ); } g.setColor( Color.black ); g.drawOval( x,y,2*radius,2*radius ); } } Controller: import java.awt.*; import java.awt.event.*; public class Controller implements MouseListener, ActionListener { private Model model; private View view; public Controller(Model m, View v){ model = m; view = v; view.addWindowListener( new WindowAdapter(){ public void windowClosing(WindowEvent e){ System.exit(0); } }); view.addMouseListener(this); view.checkAnswer.addActionListener(this); model.combination(); } public void actionPerformed( ActionEvent e ) { if(e.getSource() == view.checkAnswer){ if(model.isRowFull){ model.check(); } } } public void mousePressed(MouseEvent e) { Point mouse = new Point(); mouse = e.getPoint(); if (model.isPlaying){ if (mouse.x > 350) { int button = 1 + (int)((mouse.y - 32) / 50); if ((button >= 1) && (button <= 5)){ model.fillHole(button); if(model.pinsRepaint){ view.repaintPins( model.pinsToRepaint ); } } } } } public void mouseClicked(MouseEvent e) {} public void mouseReleased(MouseEvent e){} public void mouseEntered(MouseEvent e) {} public void mouseExited(MouseEvent e) {} }

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  • Native functions throw UnsatisfiedLinkError in custom view, despite working in main activity

    - by Mark Ingram
    For some reason I can only call native functions from my main activity and not any custom views that I've created. Here is an example file (I followed a tutorial, but renamed the classes http://mindtherobot.com/blog/452/android-beginners-ndk-setup-step-by-step/) See the usage of the native function "getNewString". package com.example.native; import android.app.Activity; import android.app.AlertDialog; import android.content.Context; import android.graphics.Bitmap; import android.graphics.Canvas; import android.os.Bundle; import android.view.View; public class NativeTestActivity extends Activity { static { System.loadLibrary("nativeTest"); } private native String getNewString(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.setContentView(new BitmapView(this)); String hello = getNewString(); // This line works fine new AlertDialog.Builder(this).setMessage(hello).show(); } } class BitmapView extends View { static { System.loadLibrary("nativeTest"); } private native String getNewString(); public BitmapView(Context context) { super(context); String hello = getNewString(); // This line throws the UnsatisfiedLinkError new AlertDialog.Builder(this.getContext()).setMessage(hello).show(); } } How can I call native functions in my custom views? I've built the application as an Android 2.2 app. I'm running the application on my HTC Desire. I have the latest SDK (9) and latest NDK (r5).

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  • Do I really need bindParam?

    - by sandelius
    Hi there! I'm trying to do a little PDO CRUD to learn some PDO. I have a question about bindParam. Here's my update method right now: public static function update($conditions = array(), $data = array(), $table = '') { self::instance(); // Late static bindings (PHP 5.3) $table = ($table === '') ? self::table() : $table; // Check which data array we want to use $values = (empty($data)) ? self::$_fields : $data; $sql = "UPDATE $table SET "; foreach ($values as $f => $v) { $sql .= "$f = ?, "; } // let's build the conditions self::build_conditions($conditions); // fix our WHERE, AND, OR, LIKE conditions $extra = self::$condition_string; // querystring $sql = rtrim($sql, ', ') . $extra; // let's merge the arrays into on $v_val = array_values($values); $c_val = array_values($conditions); $array = array_merge($v_val, self::$condition_array); $stmt = self::$db->prepare($sql); return $stmt->execute($array); } in my "self::$condition_array" I get all the right values from the ?. SO the query looks like this: UPDATE table SET this = ?, another = ? WHERE title = ? AND time = ? as you can see I dont use bindParams instead I pass the right values in the right order ($array) directly into the execute($array) method. This works like a charm BUT is it safe not use use bindParam here? If not then how can I do it? Thanks from Sweden Tobias

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  • why DataColumn AllowDbNull is true even if oracle db does not allow null

    - by matti
    Hi. I have column SomeId in table SomeLink. When I look with tOra or Sql Plus Worksheet both state: tOra: Column name Data type Default Null Comment SOMEID INTEGER {null} NOT NULL {null} Sql Plus: SOMEID NOT NULL NUMBER(38) I have authored a method that's intended to give default values to all NOT NULL fields that don't have values: public static void GetDefaultValuesForNonNullColumns(DataRow row) { foreach(DataColumn col in row.Table.Columns) { if (Convert.IsDBNull(row[col]) && !col.AllowDBNull) { if (ColumnIsNumeric(col.DataType)) row[col] = 0; else if (col.DataType == typeof(DateTime)) row[col] = DateTime.Now; else if (col.DataType == typeof(String)) row[col] = string.Empty; else if (col.DataType == typeof(Char)) row[col] = ' '; else throw new Exception(string.Format("Unsupported column type: {0}", col.DataType)); } } } When SOMEID is handled in loop the AllowDBNull = true. I really can't understand. The table is created in DataSet like this: _someLinkAdptr = _dbFactory.CreateDataAdapter(); _someLinkAdptr.SelectCommand = _dbFactory.CreateCommand(); _someLinkAdptr.SelectCommand.Connection = _cnctn; _someLinkAdptr.SelectCommand.CommandText = GetSomeLinkSelectTxtAndParams(_someLinkAdptr.SelectCommand, UndefinedValue.ToString(), UndefinedValue.ToString()); Select command returns no rows. The idea is that I can then use commandbuilder to get InsertCommand without building it myself. The row is added to dataset's table like this: private static void CreateDocLink(int anId, int anotherId) { DataRow row = _someDataSet.Tables["SomeLink"].NewRow(); row["AnId"] = anId; row["AnotherId"] = anotherId; Utility.GetDefaultValuesForNonNullColumns(row); _someDataSet.Tables["SomeLink"].Rows.Add(row); } When DataAdapter is updated to oracle db I get: ORA-01400: cannot insert NULL into (SOMESCHEMA.SOMELINK.SOMEID) Cheers & BR -Matti

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  • Good practice to create extension methods that apply to System.Object?

    - by Christian
    Hello, I'm wondering whether I should create extension methods that apply on the object level or whether they should be located at a lower point in the class hierarchy. What I mean is something along the lines of: public static string SafeToString(this Object o) { if (o == null || o is System.DBNull) return ""; else { if (o is string) return (string)o; else return ""; } } public static int SafeToInt(this Object o) { if (o == null || o is System.DBNull) return 0; else { if (o.IsNumeric()) return Convert.ToInt32(o); else return 0; } } //same for double.. etc I wrote those methods since I have to deal a lot with database data (From the OleDbDataReader) that can be null (shouldn't, though) since the underlying database is unfortunately very liberal with columns that may be null. And to make my life a little easier, I came up with those extension methods. What I'd like to know is whether this is good style, acceptable style or bad style. I kinda have my worries about it since it kinda "pollutes" the Object-class. Thank you in advance & Best Regards :) Christian P.S. I didn't tag it as "subjective" intentionally.

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  • Beginner: 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. Now I tried to deserialize like so: public class Deserialize { static Deserialize ds; MyFrame frame; public static void main(String[] args) { try { ds.deserialize(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public void deserialize() throws ClassNotFoundException { 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(); } } } Maybe somebody could point me into the direction where my misconception is? Thx in advance!

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  • What is the best method for updating all changed data in EF 4?

    - by Soul_Master
    I try to create some method that can update any changed data from changed Data object (this object is generated by ASP.NET MVC) to old Data object (this object is retrieved from current data in DBMS) like the following code. public static bool UpdateSomeData(SomeEntities context, SomeModelType changedData) { var oldData = GetSomeModelTypeById(context, changedData.ID); UpdateModel(oldData, changedData); return context.SaveChanges() > 0; } I try to create method for saving any changed data without affects other unchanged data like the following source code. public static void UpdateModel<TModel>(TModel oldData, TModel changedData) { foreach (var pi in typeof(TModel).GetProperties() .Where ( // Ignore Change ID property for security reason x => x.Name.ToUpper() != "ID" && x.CanRead && x.CanWrite && ( // It must be primitive type or Guid x.PropertyType.FullName.StartsWith("System") && !x.PropertyType.FullName.StartsWith("System.Collection") && !x.PropertyType.FullName.StartsWith("System.Data.Entity.DynamicProxies") ) ) { var oldValue = pi.GetValue(oldData, null); var newValue = pi.GetValue(changedData, null); if (!oldValue.Equals(newValue)) { pi.SetValue(oldData, newValue, null); } } } I am not sure about the above method because it is so ugly method for updating data. From recent bug, it realizes me that if you update some property like Navigation Properties (related data from other table), it will remove current record from database. I don't understand why it happened. But it is very dangerous for me. So, do you have any idea for this question to ensure me about updating data from ASP.NET MVC? Thanks,

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  • Webfaction apache + mod_wsgi + django configuration issue

    - by Dmitry Guyvoronsky
    A problem that I stumbled upon recently, and, even though I solved it, I would like to hear your opinion of what correct/simple/adopted solution would be. I'm developing website using Django + python. When I run it on local machine with "python manage.py runserver", local address is http://127.0.0.1:8000/ by default. However, on production server my app has other url, with path - like "http://server.name/myproj/" I need to generate and use permanent urls. If I'm using {% url view params %}, I'm getting paths that are relative to / , since my urls.py contains this urlpatterns = patterns('', (r'^(\d+)?$', 'myproj.myapp.views.index'), (r'^img/(.*)$', 'django.views.static.serve', {'document_root': settings.MEDIA_ROOT + '/img' }), (r'^css/(.*)$', 'django.views.static.serve', {'document_root': settings.MEDIA_ROOT + '/css' }), ) So far, I see 2 solutions: modify urls.py, include '/myproj/' in case of production run use request.build_absolute_uri() for creating link in views.py or pass some variable with 'hostname:port/path' in templates Are there prettier ways to deal with this problem? Thank you. Update: Well, the problem seems to be not in django, but in webfaction way to configure wsgi. Apache configuration for application with URL "hostname.com/myapp" contains the following line WSGIScriptAlias / /home/dreamiurg/webapps/pinfont/myproject.wsgi So, SCRIPT_NAME is empty, and the only solution I see is to get to mod_python or serve my application from root. Any ideas?

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  • Django does not load internal .css files

    - by Rubén Jiménez
    I have created a Django project in local which runs without any kind of problem. But, after an annoying and difficult Cherokee + uWSGI installation on Amazon AWS, my project does not show Django .css internal files. http://f.cl.ly/items/2Q2W3I3R0X1n2X3v0q2P/django_error.jpg <-- /Admin/ looks like The image is a screen of my /admin/, which should have a different style, but .css files are not loaded. [pid: 23206|app: 0|req: 19/19] 83.49.10.217 () {56 vars in 1121 bytes} [Sun Apr 15 05:50:24 2012] GET /static/admin/css/base.css = generated 2896 bytes in 6 msecs (HTTP/1.1 404) 1 headers in 51 bytes (1 switches on core 0) [pid: 23206|app: 0|req: 20/20] 83.49.10.217 () {56 vars in 1125 bytes} [Sun Apr 15 05:50:24 2012] GET /static/admin/css/login.css = generated 2899 bytes in 5 msecs (HTTP/1.1 404) 1 headers in 51 bytes (1 switches on core 0) This is a log from Cherokee. I don't understand why it is looking for the .css files in that path. Cherokee should be searching the files in Django original directory so i didn't change .css files in my project. Any advice? Thanks a lot.

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  • Why am I having this InstantiationException in Java when accessing final local variables?

    - by Oscar Reyes
    I was playing with some code to make a "closure like" construct ( not working btw ) Everything looked fine but when I tried to access a final local variable in the code, the exception InstantiationException is thrown. If I remove the access to the local variable either by removing it altogether or by making it class attribute instead, no exception happens. The doc says: InstantiationException Thrown when an application tries to create an instance of a class using the newInstance method in class Class, but the specified class object cannot be instantiated. The instantiation can fail for a variety of reasons including but not limited to: - the class object represents an abstract class, an interface, an array class, a primitive type, or void - the class has no nullary constructor What other reason could have caused this problem? Here's the code. comment/uncomment the class attribute / local variable to see the effect (lines:5 and 10 ). import javax.swing.*; import java.awt.event.*; import java.awt.*; class InstantiationExceptionDemo { //static JTextField field = new JTextField();// works if uncommented public static void main( String [] args ) { JFrame frame = new JFrame(); JButton button = new JButton("Click"); final JTextField field = new JTextField();// fails if uncommented button.addActionListener( new _(){{ System.out.println("click " + field.getText()); }}); frame.add( field ); frame.add( button, BorderLayout.SOUTH ); frame.pack();frame.setVisible( true ); } } class _ implements ActionListener { public void actionPerformed( ActionEvent e ){ try { this.getClass().newInstance(); } catch( InstantiationException ie ){ throw new RuntimeException( ie ); } catch( IllegalAccessException ie ){ throw new RuntimeException( ie ); } } } Is this a bug in Java? edit Oh, I forgot, the stacktrace ( when thrown ) is: Caused by: java.lang.InstantiationException: InstantiationExceptionDemo$1 at java.lang.Class.newInstance0(Class.java:340) at java.lang.Class.newInstance(Class.java:308) at _.actionPerformed(InstantiationExceptionDemo.java:25)

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  • what are all the Optimize tricks that you know for asp.net code ?

    - by Aristos
    After some time of many code programming on asp.net, I discover the very big speed different between string and StringBuilder. I know that is very common and known but I just mention it for start. The second think that I have found to speed up the code, is to use the const, and not the static, for declare my configuration constants value (especial the strings). With the const, the compiler not create new object, but just place the value, on the point that you have ask it, but with the static declaration, is create a new memory object and keep its on the memory. My third trick, is when I search for string, I use hash values, and not the string itself. For example, if I need a List<string SomeValues, and place inside strings that I need to search them, I prefer to use List<int SomeHashValue, and I use the hash value to locate the strings. My forth thought that I was wandering, is if is better to place big strings in one line, or separate them in different lines with the + symbol to be more easy to read out. I make some tests and see that the compiler make a good job is some split the string, in many lines, using the + symbol. What other tricks/tips do you know and use on your programming to make it run faster, and maybe use less memory. Well I know, that some times, to make something run faster, you need more memory, more cache. My priority is on speed. Because Speed Counts.

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  • Getting my head around object oriented programing

    - by nLL
    I am entry level .Net developer and using it to develop web sites. I started with classic asp and last year jumped on the ship with a short C# book. As I developed I learned more and started to see that coming from classic asp I always used C# like scripting language. For example in my last project I needed to encode video on the webserver and wrote a code like public class Encoder { Public static bool Encode(string videopath) { ...snip... return true; } } While searching samples related to my project I’ve seen people doing this public class Encoder { Public static Encode(string videopath) { EncodedVideo encoded = new EncodedVideo(); ...snip... encoded.EncodedVideoPath = outputFile; encoded.Success = true; ...snip... } } public class EncodedVideo { public string EncodedVideoPath { get; set; } public bool Success { get; set; } } As I understand second example is more object oriented but I don’t see the point of using EncodedVideo object. Am I doing something wrong? Does it really necessary to use this sort of code in a web app?

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  • volatile keyword seems to be useless?

    - by Finbarr
    import java.util.concurrent.CountDownLatch; import java.util.concurrent.atomic.AtomicInteger; public class Main implements Runnable { private final CountDownLatch cdl1 = new CountDownLatch(NUM_THREADS); private volatile int bar = 0; private AtomicInteger count = new AtomicInteger(0); private static final int NUM_THREADS = 25; public static void main(String[] args) { Main main = new Main(); for(int i = 0; i < NUM_THREADS; i++) new Thread(main).start(); } public void run() { int i = count.incrementAndGet(); cdl1.countDown(); try { cdl1.await(); } catch (InterruptedException e1) { e1.printStackTrace(); } bar = i; if(bar != i) System.out.println("Bar not equal to i"); else System.out.println("Bar equal to i"); } } Each Thread enters the run method and acquires a unique, thread confined, int variable i by getting a value from the AtomicInteger called count. Each Thread then awaits the CountDownLatch called cdl1 (when the last Thread reaches the latch, all Threads are released). When the latch is released each thread attempts to assign their confined i value to the shared, volatile, int called bar. I would expect every Thread except one to print out "Bar not equal to i", but every Thread prints "Bar equal to i". Eh, wtf does volatile actually do if not this?

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  • Improving field get and set performance with ASM

    - by ng
    I would like to avoid reflection in an open source project I am developing. Here I have classes like the following. public class PurchaseOrder { @Property private Customer customer; @Property private String name; } I scan for the @Property annotation to determine what I can set and get from the PurchaseOrder reflectively. There are many such classes all using java.lang.reflect.Field.get() and java.lang.reflect.Field.set(). Ideally I would like to generate for each property an invoker like the following. public interface PropertyAccessor<S, V> { public void set(S source, V value); public V get(S source); } Now when I scan the class I can create a static inner class of PurchaseOrder like so. static class customer_Field implements PropertyAccessor<PurchaseOrder, Customer> { public void set(PurchaseOrder order, Customer customer) { order.customer = customer; } public Customer get(PurchaseOrder order) { return order.customer; } } With these I totally avoid the cost of reflection. I can now set and get from my instances with native performance. Can anyone tell me how I would do this. A code example would be great. I have searched the net for a good example but can find nothing like this. The ASM examples are pretty poor also. The key here is that I have an interface that I can pass around. So I can have various implementations, perhaps one with Java Reflection as a default, one with ASM, and maybe one with Javassist? Any help would be greatly appreciated.

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  • Send Click Message to another application process

    - by Nazar
    Hi Guys I have a scenario, i need to send click events to an independent application. I started that application with the following code. private Process app; app = new Process(); app.StartInfo.FileName = app_path; app.StartInfo.WorkingDirectory = dir_path; app.Start(); Now i want to send Mouse click message to that applicaiton, I have specific coordinates in relative to application window. How can i do it using Windows Messaging or any other technique. I used [DllImport("user32.dll")] private static extern void mouse_event(UInt32 dwFlags, UInt32 dx, UInt32 dy, UInt32 dwData, IntPtr dwExtraInfo); It works well but cause the pointer to move as well. So not fit for my need. Then i use. [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)] static extern IntPtr SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam); It works well for minimize maximize, but do not work for mouse events. The codes for mousevents i am using are, WM_LBUTTONDOWN = 0x201, //Left mousebutton down WM_LBUTTONUP = 0x202, //Left mousebutton up WM_LBUTTONDBLCLK = 0x203, //Left mousebutton doubleclick WM_RBUTTONDOWN = 0x204, //Right mousebutton down WM_RBUTTONUP = 0x205, //Right mousebutton up WM_RBUTTONDBLCLK = 0x206, //Right mousebutton do Thanks for the help in advance, and waiting for feedback.

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  • Deploying to a clustered weblogic application server or Red Hat Linux

    - by user510210
    I am developing an application with following software stack: XHTML / CSS / ExtJS / DWR / Javascript (Presentation Layer) EJB 3.0 / Spring MVC Hibernate / Hibernate Spatial My application works well in a single server development environment. But deploying to clustered weblogic environment on Red Hat does not work and results in the following exception: ============================================================================================ org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from ServletContext resource [/WEB-INF/applicationContext.xml]; nested exception is java.lang.NoSuchMethodError: Caused by: java.lang.NoSuchMethodError: at org.apache.xerces.impl.dv.xs.XSSimpleTypeDecl.applyFacets(Unknown Source) at org.apache.xerces.impl.dv.xs.XSSimpleTypeDecl.applyFacets1(Unknown Source) at org.apache.xerces.impl.dv.xs.BaseSchemaDVFactory.createBuiltInTypes(Unknown Source) at org.apache.xerces.impl.dv.xs.SchemaDVFactoryImpl.createBuiltInTypes(Unknown Source) at org.apache.xerces.impl.dv.xs.SchemaDVFactoryImpl.(Unknown Source) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at java.lang.Class.newInstance0(Class.java:355) at java.lang.Class.newInstance(Class.java:308) at org.apache.xerces.impl.dv.ObjectFactory.newInstance(Unknown Source) at org.apache.xerces.impl.dv.SchemaDVFactory.getInstance(Unknown Source) at org.apache.xerces.impl.dv.SchemaDVFactory.getInstance(Unknown Source) at org.apache.xerces.impl.xs.SchemaGrammar$BuiltinSchemaGrammar.(Unknown Source) at org.apache.xerces.impl.xs.SchemaGrammar.(Unknown Source) at org.apache.xerces.impl.xs.XMLSchemaValidator.(Unknown Source) at org.apache.xerces.parsers.XML11Configuration.configurePipeline(Unknown Source) at org.apache.xerces.parsers.XIncludeAwareParserConfiguration.configurePipeline(Unknown Source) at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source) at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source) at org.apache.xerces.parsers.XMLParser.parse(Unknown Source) at org.apache.xerces.parsers.DOMParser.parse(Unknown Source) at org.apache.xerces.jaxp.DocumentBuilderImpl.parse(Unknown Source) at org.springframework.beans.factory.xml.DefaultDocumentLoader.loadDocument(DefaultDocumentLoader.java:76) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:351) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:303) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:280) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:131) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:147) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:124) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:93) at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:101) at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:390) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:327) at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:244) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:187) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:50) at weblogic.servlet.internal.EventsManager$FireContextListenerAction.run(EventsManager.java:481) at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321) at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121) at weblogic.servlet.internal.EventsManager.notifyContextCreatedEvent(EventsManager.java:181) at weblogic.servlet.internal.WebAppServletContext.preloadResources(WebAppServletContext.java:1801) at weblogic.servlet.internal.WebAppServletContext.start(WebAppServletContext.java:3042) at weblogic.servlet.internal.WebAppModule.startContexts(WebAppModule.java:1374) at weblogic.servlet.internal.WebAppModule.start(WebAppModule.java:455) at weblogic.application.internal.flow.ModuleStateDriver$3.next(ModuleStateDriver.java:205) at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:37) at weblogic.application.internal.flow.ModuleStateDriver.start(ModuleStateDriver.java:60) at weblogic.application.internal.flow.ScopedModuleDriver.start(ScopedModuleDriver.java:201) at weblogic.application.internal.flow.ModuleListenerInvoker.start(ModuleListenerInvoker.java:118) at weblogic.application.internal.flow.ModuleStateDriver$3.next(ModuleStateDriver.java:205) at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:37) at weblogic.application.internal.flow.ModuleStateDriver.start(ModuleStateDriver.java:60) at weblogic.application.internal.flow.StartModulesFlow.activate(StartModulesFlow.java:28) at weblogic.application.internal.BaseDeployment$2.next(BaseDeployment.java:630) at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:37) at weblogic.application.internal.BaseDeployment.activate(BaseDeployment.java:206) at weblogic.application.internal.EarDeployment.activate(EarDeployment.java:53) at weblogic.application.internal.DeploymentStateChecker.activate(DeploymentStateChecker.java:161) at weblogic.deploy.internal.targetserver.AppContainerInvoker.activate(AppContainerInvoker.java:79) at weblogic.deploy.internal.targetserver.BasicDeployment.activate(BasicDeployment.java:184) at weblogic.deploy.internal.targetserver.BasicDeployment.activateFromServerLifecycle(BasicDeployment.java:361) at weblogic.management.deploy.internal.DeploymentAdapter$1.doActivate(DeploymentAdapter.java:52) at weblogic.management.deploy.internal.DeploymentAdapter.activate(DeploymentAdapter.java:196) at weblogic.management.deploy.internal.AppTransition$2.transitionApp(AppTransition.java:31) at weblogic.management.deploy.internal.ConfiguredDeployments.transitionApps(ConfiguredDeployments.java:233) at weblogic.management.deploy.internal.ConfiguredDeployments.activate(ConfiguredDeployments.java:170) at weblogic.management.deploy.internal.ConfiguredDeployments.deploy(ConfiguredDeployments.java:124) at weblogic.management.deploy.internal.DeploymentServerService.resume(DeploymentServerService.java:174) at weblogic.management.deploy.internal.DeploymentServerService.start(DeploymentServerService.java:90) at weblogic.t3.srvr.SubsystemRequest.run(SubsystemRequest.java:64) at weblogic.work.ExecuteThread.execute(ExecuteThread.java:201) at weblogic.work.ExecuteThread.run(ExecuteThread.java:173) ============================================================================================ My initial thought is that there is a clash in the Xerces library being used. But I could use any feedback.

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  • How do i change this method to get strings instead of ints

    - by David
    here is the original code: public static int getInt () { Scanner in = new Scanner (System.in) ; if (in.hasNextInt()) { int a = in.nextInt() ; return a ; } else { System.out.println ("try again:") ; return getInt () ; } } This checks and sees if the input it receives is an int. If it is then it returns the int, if not it tells you to try again and re-runs. This is what i tried to do to change it: public static String getIns () { Scanner in = new Scanner (System.in) ; if (in.hasNextString()) { String a = in.nextString() ; return a ; } else { System.out.println ("try again:") ; return getIns () ; } } This doesn't work though. I looked through the documentation for the scanner class and i think the problem is that there is no such method as in.hasNextString or in.nextString What methods from the scanner class can i use to do what i intend these to do?

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  • problem with image gallery using fancybox jquery

    - by Alexander
    I am trying to use fancybox for one of my image galery and my code is the following.. this is the code for my Gallery.aspx where it inherits from a master page... For some reason it doesn't work.. can you guys tell me what the problem is? <%@ Page Title="" Language="C#" MasterPageFile="~/Global.Master" AutoEventWireup="true" CodeBehind="Gallery.aspx.cs" Inherits="Permias.Gallery" %> <asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server"> <script src="jquery.js" type="text/javascript"></script> <script type="text/javascript" src="http://code.jquery.com/jquery-1.4.2.min.js"></script> <script type="text/javascript" src="./fancybox/jquery.fancybox-1.3.1.pack.js"></script> <script type="text/javascript" src="./fancybox/jquery.easing-1.3.pack.js"></script> <script type="text/javascript" src="./fancybox/jquery.mousewheel-3.0.2.pack.js"></script> <link rel="stylesheet" href="./fancybox/jquery.fancybox-1.3.1.css" type="text/css" media="screen" /> </asp:Content> <asp:Content ID="Content3" ContentPlaceHolderID="splash" runat="server"> <div id="splash">&nbsp;</div> </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server"> <a class="grouped_elements" rel="group1" href="http://farm5.static.flickr.com/4058/4252054277_f0fa91e026.jpg"><img src="http://farm5.static.flickr.com/4058/4252054277_f0fa91e026.jpg" alt=""/></a> </asp:Content>

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  • Problem when copying array of different types using Arrays.copyOf

    - by Shervin
    I am trying to create a method that pretty much takes anything as a parameter, and returns a concatenated string representation of the value with some delimiter. public static String getConcatenated(char delim, Object ...names) { String[] stringArray = Arrays.copyOf(names, names.length, String[].class); //Exception here return getConcatenated(delim, stringArray); } And the actual method public static String getConcatenated(char delim, String ... names) { if(names == null || names.length == 0) return ""; StringBuilder sb = new StringBuilder(); for(int i = 0; i < names.length; i++) { String n = names[i]; if(n != null) { sb.append(n.trim()); sb.append(delim); } } //Remove the last delim return sb.substring(0, sb.length()-1).toString(); } And I have the following JUnit test: final String two = RedpillLinproUtils.getConcatenated(' ', "Shervin", "Asgari"); Assert.assertEquals("Result", "Shervin Asgari", two); //OK final String three = RedpillLinproUtils.getConcatenated(';', "Shervin", "Asgari"); Assert.assertEquals("Result", "Shervin;Asgari", three); //OK final String four = RedpillLinproUtils.getConcatenated(';', "Shervin", null, "Asgari", null); Assert.assertEquals("Result", "Shervin;Asgari", four); //OK final String five = RedpillLinproUtils.getConcatenated('/', 1, 2, null, 3, 4); Assert.assertEquals("Result", "1/2/3/4", five); //FAIL However, the test fails on the last part with the exception: java.lang.ArrayStoreException at java.lang.System.arraycopy(Native Method) at java.util.Arrays.copyOf(Arrays.java:2763) Can someone spot the error?

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  • dynamic row height

    - by Prasanna Venkatesh
    static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@""]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } //cell.backgroundView = [[[CustomCell alloc] init] autorelease]; cell.selectedBackgroundView = [[[CustomCell alloc] init] autorelease]; // At end of function, right before return cell: cell.textLabel.backgroundColor = [UIColor clearColor]; // Configure the cell. UILabel *myLabel1 = [[UILabel alloc] initWithFrame:CGRectMake(-30, 3, 300, 22)]; UILabel *myLabel2 = [[UILabel alloc] initWithFrame:CGRectMake(10, 22, 310, 200)]; UILabel *myLabel3 = [[UILabel alloc] initWithFrame:CGRectMake(0, 170, 300, 20)]; Book *aBook = [appDelegate.books objectAtIndex:indexPath.row]; myLabel1.text=aBook.title; myLabel2.text=aBook.description; myLabel3.text=aBook.pubDate; NSString *desc = aBook.description; if ([desc isEqualToString:nil]) { NSLog(@"nullll lll "); } //myLabel2.textAlignment=UITextAlignmentCenter; myLabel2.numberOfLines=5; myLabel2.textColor=[UIColor blueColor]; myLabel2.lineBreakMode=UILineBreakModeWordWrap; myLabel2.font=[UIFont systemFontOfSize:14]; myLabel3.numberOfLines=1; myLabel1.numberOfLines=1; myLabel1.textColor=[UIColor redColor]; myLabel1.font=[UIFont systemFontOfSize:20]; myLabel1.shadowColor=[UIColor redColor]; myLabel1.backgroundColor=[UIColor grayColor]; [cell.contentView addSubview:myLabel1]; [cell.contentView addSubview:myLabel2]; [cell.contentView addSubview:myLabel3]; hi guys! i have this following code, i want to display this from xml file. now its working but static row height. if the xml file dont have data then it leaves it as blank. so i want to change row height according to the data i provide using the mylabel1,2,3.text

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  • How to include all objects of an archive in a shared object?

    - by Didier Trosset
    When compiling our project, we create several archives (static libraries), say liby.a and libz.a that each contains an object file defining a function y_function() and z_function(). Then, these archives are joined in a shared object, say libyz.so, that is one of our main distributable target. g++ -fPIC -c -o y.o y.cpp ar cr liby.a y.o g++ -fPIC -c -o z.o z.cpp ar cr libz.a z.o g++ -shared -L. -ly -lz -o libyz.so When using this shared object into the example program, say x.c, the link fails because of an undefined references to functions y_function() and z_function(). g++ x.o -L. -lyz -o xyz It works however when I link the final executable directly with the archives (static libraries). g++ x.o -L. -ly -lz -o xyz My guess is that the object files contained in the archives are not linked into the shared library because they are not used in it. How to force inclusion? Edit: Inclusion can be forced using --whole-archive ld option. But if results in compilation errors: g++ -shared '-Wl,--whole-archive' -L. -ly -lz -o libyz.so /usr/lib/libc_nonshared.a(elf-init.oS): In function `__libc_csu_init': (.text+0x1d): undefined reference to `__init_array_end' /usr/bin/ld: /usr/lib/libc_nonshared.a(elf-init.oS): relocation R_X86_64_PC32 against undefined hidden symbol `__init_array_end' can not be used when making a shared object /usr/bin/ld: final link failed: Bad value Any idea where this comes from?

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