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  • ROR heroku PostGres issue

    - by oelbrenner
    getting error: ActiveRecord::StatementInvalid (PGError: ERROR: argument of HAVING must be type boolean, not type timestamp without time zone controller code snippet: def inactive @number_days = params[:days].to_i || 90 @clients = Client.find(:all, :include = :appointments, :conditions = ["clients.user_id = ? AND appointments.start_time <= ?", current_user.id, @number_days.days.ago], :group = 'client_id', :having = 'MAX(appointments.start_time)' ) end

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  • Getting a specific bit value in a byte string

    - by ignoramus
    There is a byte at a specific index in a byte string which represents eight flags; one flag per bit in the byte. If a flag is set, its corresponding bit is 1, otherwise its 0. For example, if I've got b'\x21' the flags would be 0001 0101 # Three flags are set at indexes 3, 5 and 7 # and the others are not set What would be the best way to get each bit value in that byte, so I know whether a particular flag is set or not? (Preferably using bitwise operations)

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  • Android remote service doesn't call service methods

    - by tarantel
    Hello, I'm developing a GPS tracking software on android. I need IPC to control the service from different activities. So I decide to develop a remote service with AIDL. This wasn't a big problem but now it's always running into the methods of the interface and not into those of my service class. Maybe someone could help me? Here my ADIL file: package test.de.android.tracker interface ITrackingServiceRemote { void startTracking(in long trackId); void stopTracking(); void pauseTracking(); void resumeTracking(in long trackId); long trackingState(); } And the here a short version of my service class: public class TrackingService extends Service implements LocationListener{ private LocationManager mLocationManager; private TrackDb db; private long trackId; private boolean isTracking = false; @Override public void onCreate() { super.onCreate(); mNotificationManager = (NotificationManager) this .getSystemService(NOTIFICATION_SERVICE); mLocationManager = (LocationManager) getSystemService(LOCATION_SERVICE); db = new TrackDb(this.getApplicationContext()); } @Override public void onStart(Intent intent, int startId) { super.onStart(intent, startId); } @Override public void onDestroy(){ //TODO super.onDestroy(); } @Override public IBinder onBind(Intent intent){ return this.mBinder; } private IBinder mBinder = new ITrackingServiceRemote.Stub() { public void startTracking(long trackId) throws RemoteException { TrackingService.this.startTracking(trackId); } public void pauseTracking() throws RemoteException { TrackingService.this.pauseTracking(); } public void resumeTracking(long trackId) throws RemoteException { TrackingService.this.resumeTracking(trackId); } public void stopTracking() throws RemoteException { TrackingService.this.stopTracking(); } public long trackingState() throws RemoteException { long state = TrackingService.this.trackingState(); return state; } }; public synchronized void startTracking(long trackId) { // request updates every 250 meters or 0 sec this.trackId = trackId; mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 250, this); isTracking = true; } public synchronized long trackingState() { if(isTracking){ return trackId; } else return -1; } public synchronized void stopTracking() { if(isTracking){ mLocationManager.removeUpdates(this); isTracking = false; } else Log.i(TAG, "Could not stop because service is not tracking at the moment"); } public synchronized void resumeTracking(long trackId) { if(!isTracking){ this.trackId = trackId; mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 250, this); isTracking = true; } else Log.i(TAG, "Could not resume because service is tracking already track " + this.trackId); } public synchronized void pauseTracking() { if(isTracking){ mLocationManager.removeUpdates(this); isTracking = false; } else Log.i(TAG, "Could not pause because service is not tracking at the moment"); } public void onLocationChanged(Location location) { //TODO } For easier access from the client I wrote a ServiceManager class which sets up the ServiceConnection and you can call the service methods. Here my code for this: public class TrackingServiceManager{ private static final String TAG = "TrackingServiceManager"; private ITrackingServiceRemote mService = null; private Context mContext; private Boolean isBound = false; private ServiceConnection mServiceConnection; public TrackingServiceManager(Context ctx){ this.mContext = ctx; } public void start(long trackId) { if (isBound && mService != null) { try { mService.startTracking(trackId); } catch (RemoteException e) { Log.e(TAG, "Could not start tracking!",e); } } else Log.i(TAG, "No Service bound! 1"); } public void stop(){ if (isBound && mService != null) { try { mService.stopTracking(); } catch (RemoteException e) { Log.e(TAG, "Could not stop tracking!",e); } } else Log.i(TAG, "No Service bound!"); } public void pause(){ if (isBound && mService != null) { try { mService.pauseTracking(); } catch (RemoteException e) { Log.e(TAG, "Could not pause tracking!",e); } } else Log.i(TAG, "No Service bound!"); } public void resume(long trackId){ if (isBound && mService != null) { try { mService.resumeTracking(trackId); } catch (RemoteException e) { Log.e(TAG, "Could not resume tracking!",e); } } else Log.i(TAG, "No Service bound!"); } public float state(){ if (isBound && mService != null) { try { return mService.trackingState(); } catch (RemoteException e) { Log.e(TAG, "Could not resume tracking!",e); return -1; } } else Log.i(TAG, "No Service bound!"); return -1; } /** * Method for binding the Service with client */ public boolean connectService(){ mServiceConnection = new ServiceConnection() { @Override public void onServiceConnected(ComponentName name, IBinder service) { TrackingServiceManager.this.mService = ITrackingServiceRemote.Stub.asInterface(service); } } @Override public void onServiceDisconnected(ComponentName name) { if (mService != null) { mService = null; } } }; Intent mIntent = new Intent("test.de.android.tracker.action.intent.TrackingService"); this.isBound = this.mContext.bindService(mIntent, mServiceConnection, Context.BIND_AUTO_CREATE); return this.isBound; } public void disconnectService(){ this.mContext.unbindService(mServiceConnection); this.isBound = false; } } If i now try to call a method from an activity for example start(trackId) nothing happens. The binding is OK. When debugging it always runs into the startTracking() in the generated ITrackingServiceRemote.java file and not into my TrackingService class. Where is the problem? I can't find anything wrong. Thanks in advance! Tobias

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  • Recommended textbook for machine-level programming?

    - by Norman Ramsey
    I'm looking at textbooks for an undergraduate course in machine-level programming. If the perfect book existed, this is what it would look like: Uses examples written in C or assembly language, or both. Covers machine-level operations such as two's-complement integer arithmetic, bitwise operations, and floating-point arithmetic. Explains how caches work and how they affect performance. Explains machine instructions or assembly instructions. Bonus if the example assembly language includes x86; triple bonus if it includes x86-64 (aka AMD64). Explains how C values and data structures are represented using hardware registers and memory. Explains how C control structures are translated into assembly language using conditional and unconditional branch instructions. Explains something about procedure calling conventions and how procedure calls are implemented at the machine level. Books I might be interested in would probably have the words "machine organization" or "computer architecture" in the title. Here are some books I'm considering but am not quite happy with: Computer Systems: A Programmer's Perspective by Randy Bryant and Dave O'Hallaron. This is quite a nice book, but it's a book for a broad, shallow course in systems programming, and it contains a great deal of material my students don't need. Also, it is just out in a second edition, which will make it expensive. Computer Organization and Design: The Hardware/Software Interface by Dave Patterson and John Hennessy. This is also a very nice book, but it contains way more information about how the hardware works than my students need. Also, the exercises look boring. Finally, it has a show-stopping bug: it is based very heavily on MIPS hardware and the use of a MIPS simulator. My students need to learn how to use DDD, and I can't see getting this to work on a simulator. Not to mention that I can't see them cross-compiling their code for the simulator, and so on and so forth. Another flaw is that the book mentions the x86 architecture only to sneer at it. I am entirely sympathetic to this point of view, but news flash! You guys lost! Write Great Code Vol I: Understanding the Machine by Randall Hyde. I haven't evaluated this book as thoroughly as the other two. It has a lot of what I need, but the translation from high-level language to assembler is deferred to Volume Two, which has mixed reviews. My students will be annoyed if I make them buy a two-volume series, even if the price of those two volumes is smaller than the price of other books. I would really welcome other suggestions of books that would help students in a class where they are to learn how C-language data structures and code are translated to machine-level data structures and code and where they learn how to think about performance, with an emphasis on the cache.

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  • What is the need of collection framework in java?

    - by JavaUser
    Hi, What is the need of Collection framework in Java since all the data operations(sorting/adding/deleting) are possible with Arrays and moreover array is suitable for memory consumption and performance is also better compared with Collections. Can anyone point me a real time data oriented example which shows the difference in both(array/Collections) of these implementations. Thx

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  • What is the best way, if possible, to send information from a Java PrintStream to a JTextPane?

    - by Daniel Reeves
    In Java, I have a package that translates XML metadata from one standard to another. This package is ultimately accessed through a single function and sends all of its output through a PrintStream object. The output sent is just a status of each file and whether or not it was translated. This is pretty fine and dandy if I'm just printing to System.out, but I'm actually wanting to print this to a JTextPane while it translates (kind of like a progress text box). It wouldn't be a big deal to just print the status after it was done translating the XML, but since there may be thousands of XML files, that's just not feasible. One thing that I've tried is to use a thread that takes all of the information from the PrintStream (which is attached to a ByteArrayOutputStream) and let it send any new information to the text pane. Unfortunately, this still sends the information all at once at the end of the translation. This does work correctly for System.out. Here's the code that does the translation and tries to show the output: public class ConverterGUI extends javax.swing.JFrame { boolean printToResultsBox = false; PrintStream printStream = null; ByteArrayOutputStream baos = null; private class ResultsPrinter implements Runnable { public ResultsPrinter() { baos = new ByteArrayOutputStream(); printStream = new PrintStream(baos); } public void run() { String tempString = ""; while (printToResultsBox) { try { if (!baos.toString().equals(tempString)) { tempString = baos.toString(); resultsBox.setText(tempString); } } catch (Exception ex) { } } } } ... ResultsPrinter rp = new ResultsPrinter(); Thread thread = new Thread(rp); thread.start(); // Do the translation. try { printToResultsBox = true; boolean success = false; TranslationEngine te = new TranslationEngine(); // fileOrFolderToConvert is a text box in the GUI. // linkNeeded and destinationFile are just parameters for the translation process. success = te.translate(fileOrFolderToConvert.getText(), linkNeeded, destinationFile, printStream); if (success) { printStream.println("File/folder translation was a success."); } resultsBox.setText(baos.toString()); } catch (Exception ex) { printStream.println("File translation failed."); } finally { printToResultsBox = false; } ... } Ultimately, this code prints out to the JTextPane just fine after all the translation is done but not during. Any suggestions? Do I need to change the PrintStream to something else?

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  • How to output JOINed tables?

    - by ilhan
    $id=(int)$_GET["id"]; $result = mysql_query("SELECT questionstable.*, categorytable.name FROM questionstable INNER JOIN categorytable ON categorytable.id = questionstable.category WHERE id=$id"); $row = mysql_fetch_assoc($result); Warning: mysql_fetch_assoc() expects parameter 1 to be resource, boolean given in C:\Program Files\EasyPHP-5.3.4.0\www\scsoru.php on line 33

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  • Understanding Haskell's filter

    - by dmindreader
    I understand that Haskell's filter is a high order function (meaning a function that takes another function as a parameter) that goes through a list checking which element fulfills certain boolean condition. I don't quite understand its definition: filter:: (a->Bool)->[a]->[a] filter p [] = [] filter p (x:y) | p x = x:filter p y | otherwise = filter p y I understand that if I pass an empty list to the function, it would just return an empty list, but how do I read the last two lines?

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  • Python vs. Java performance (runtime speed)

    - by Bijan
    Ignoring all the characteristics of each languages and focusing SOLELY on speed, which language is better performance-wise? You'd think this would be a rather simple question to answer, but I haven't found a decent one. I'm aware that some types of operations may be faster with python, and vice-versa, but I cannot find any detailed information on this. Can anyone shed some light on the performance differences?

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  • NSOperation inside NSOperationQueue not being executed

    - by Martin Garcia
    I really need help here. I'm desperate at this point. I have NSOperation that when added to the NSOperationQueue is not being triggered. I added some logging to see the NSOperation status and this is the result: Queue operations count = 1 Queue isSuspended = 0 Operation isCancelled? = 0 Operation isConcurrent? = 0 Operation isFinished? = 0 Operation isExecuted? = 0 Operation isReady? = 1 Operation dependencies? = 0 The code is very simple. Nothing special. LoadingConflictEvents_iPad *loadingEvents = [[LoadingConflictEvents_iPad alloc] initWithNibName:@"LoadingConflictEvents_iPad" bundle:[NSBundle mainBundle]]; loadingEvents.modalPresentationStyle = UIModalPresentationFormSheet; loadingEvents.conflictOpDelegate = self; [self presentModalViewController:loadingEvents animated:NO]; [loadingEvents release]; ConflictEventOperation *operation = [[ConflictEventOperation alloc] initWithParameters:wiLr.formNumber pWI_ID:wiLr.wi_id]; [queue addOperation:operation]; NSLog(@"Queue operations count = %d",[queue operationCount]); NSLog(@"Queue isSuspended = %d",[queue isSuspended]); NSLog(@"Operation isCancelled? = %d",[operation isCancelled]); NSLog(@"Operation isConcurrent? = %d",[operation isConcurrent]); NSLog(@"Operation isFinished? = %d",[operation isFinished]); NSLog(@"Operation isExecuted? = %d",[operation isExecuting]); NSLog(@"Operation isReady? = %d",[operation isReady]); NSLog(@"Operation dependencies? = %d",[[operation dependencies] count]); [operation release]; Now my operation do many things on the main method, but the problem is never being called. The main is never executed. The most weird thing (believe me, I'm not crazy .. yet). If I put a break point in any NSLog line or in the creation of the operation the main method will be called and everything will work perfectly. This have been working fine for a long time. I have been making some changes recently and apparently something screw things up. One of those changes was to upgrade the device to iOS 5.1 SDK (iPad). To add something, I have the iPhone (iOS 5.1) version of this application that use the same NSOperation object. The difference is in the UI only, and everything works fine. Any help will be really appreciated. Regards,

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  • High speed matrix manipulation in c#?

    - by Donnie
    I'm working on some image manipulation code in c# and need to do some matrix operations (specifically 2D convolution). I have the code written in matlab which uses the conv2 function ... is there a library for C# / .NET that does good high-speed matrix manipulations? I'd be fine if it requires some specific GPU and does the matrix math on-GPU if that's what it takes.

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  • Android Couchdb - libcouch and IPC Aidl Services

    - by dirtySanchez
    I am working on a native CouchdDB app with android. Now just this week CouchOne released libcouch, described as "Library files needed to interact with CouchDB on Android": couchone_libcouch@Github It is a basic app that installs CouchDB if the CouchDB service (that comes with CouchDB if it was installed previously) can't be bound to. To be more precise, as I understand it: libcouch estimates CouchDb's presence on the device by trying to bind to a IPC Service from CouchDB and through that service wants communicate with CouchDB. Please see the method "attemptLaunch()" at CouchAppLauncher.class for reviewing this: public void attemptLaunch() { Log.i(TAG,"1.) called attemptLaunch"); Intent intent = new Intent(ICouchService.class.getName()); Log.i(TAG,"1.a) setup Intent"); Boolean canStart = bindService(intent, couchServiceConn, Context.BIND_AUTO_CREATE); Log.i(TAG,"1.b bound service. canStart: " + Boolean.toString(canStart)); if (!canStart) { setContentView(R.layout.install_couchdb); TextView label = (TextView) findViewById(R.id.install_couchdb_text); Button btn = (Button) this.findViewById(R.id.install_couchdb_btn); String text = getString(R.string.app_name) + " requires Apache CouchDB to be installed."; label.setText(text); // Launching the market will fail on emulators btn.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { launchMarket(); finish(); } }); } } The question(s) I have about this are: libcouch never is able to "find" a previously installed CouchDB. It always attempts to install CouchDB from the market. This is because it never actually is able to bind to the CouchDBService. As I understand the purpose auf AIDL generated service interfaces, the actual service that intends to offer it's IPC to other applications should make use of AIDL. In this case the AIDL has been moved to the application that is trying to bind to the remote service, which is libcouch in this case. Reviewing the commits the AIDL files have just been moved out of that repository to libcouch. For complete linkage, here's the link to the Android CouchDB sources: github.com/couchone/libcouch-android Now, I could be completely wrong in my findings, it could also be lincouch's Manifest that s missing something, but I am really looking forward to get some answers!

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  • java filenames filter pattern

    - by Sergey
    Hello, I need to implement File[] files = getFiles( String folderName, String ptrn ); Where ptrn is a command prompt style pattern like "*2010*.txt" I'm familar with FilenameFilter class, but can't implement public boolean accept(File dir, String filename) because String.matches() doesn't accept such patterns. Thanks!

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  • Built-in precedence for Expression Trees?

    - by jdk
    I'm unable to find the .NET FCL built-in concept of precedence to leverage while constructing Expression Trees. Ref System.Linq.Expressions Namespace. Is this something that must be handled manually in code, or is it somehow implicit and I'm not recognizing it, maybe through helper methods or classes? I want to apply it to math operations to ensure 3 + 5 * 10 results in 53 instead of 80.

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  • List of objects plus a tag

    - by MC
    I want to store a list of objects, lets say of type Car, but with an additional 'tag' property eg a boolean True/False which does not belong on the Car class. What is the best way to accomplish this? I need to pass the result between methods.

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  • ToolStripMenuItems and Drag and Drop

    - by Paul
    I need to implement "Drag and Drop" operations for the ToolStripMenuItems. Everything works fine only with ToolStripMenuItems on the first level. I mean I can't move menu item from a submenu to other one. But I can move submenu to top-level menu. I noticed that DragEnter event isn't arise for submenus. Initialization is the same for all menu-items. What is wrong? :(

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  • How to compute the dot product?

    - by WizardOfOdds
    I have the following piece of pseudo-C/Java/C# code: int a[]= { 30, 20 }; int b[] = { 40, 50 }; int c[] = {12, 12}; How do I compute the sign of the dot-product AB . AC? I'm only interested in the sign, so I have: boolean signABxAC = ? Now concretely what do I write to get the sign of the dot-product AB . AC?

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  • JSF inner datatable not respecting rendered condition of outer table.

    - by Marc
    <h:dataTable cellpadding="0" cellspacing="0" styleClass="list_table" id="OuterItems" value="#{valueList.values}" var="item" border="0"> <h:column rendered="#{item.typeA"> <h:dataTable cellpadding="0" cellspacing="0" styleClass="list_table" id="InnerItems" value="#{item.options}" var="option" border="0"> <h:column > <h:outputText value="Option: #{option.displayValue}"/> </h:column> </h:dataTable> </h:column> <h:column rendered="#{item.typeB"> <h:dataTable cellpadding="0" cellspacing="0" styleClass="list_table" id="InnerItems" value="#{item.demands}" var="demand" border="0"> <h:column > <h:outputText value="Demand: #{demand.displayValue}"/> </h:column> </h:dataTable> </h:column> </h:dataTable> public class Item{ ... public boolean isTypeA(){ return this instanceof TypeA; } public boolean isTypeB(){ return this instanceof TypeB; } ... } public class typeA extends Item(){ ... public List getOptions(){ .... } ... } public class typeB extends Item(){ ... public List getDemands(){ ... } .... } I'm having an issue with JSF. I've abstracted the problem out here, and I'm hoping someone can help me understand how what I'm doing fails. I'm looping over a list of Items. These Items are actually instances of the subclasses TypeA and TypeB. For Type A, I want to display the options, for Type B I want to display the demands. When rendering the page for the first time, this works fine. However, when I post back to the page for some action, I get an error: [3/26/10 12:52:32:781 EST] 0000008c SystemErr R javax.faces.FacesException: Error getting property 'options' from bean of type TypeB at com.sun.faces.lifecycle.ApplyRequestValuesPhase.execute(ApplyRequestValuesPhase.java:89) at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java(Compiled Code)) at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:91) at com.ibm.faces.portlet.FacesPortlet.processAction(FacesPortlet.java:193) My grasp on the JSF lifecyle is very rough. At this point, i understand there is an error in the ApplyRequestValues Phases which is very early and so the previous state is restored and nothing changes. What I don't understand is that in order to fufill the condition for rendering "item.typeA" that object has to be an instance of TypeA. But here, it looks like that object passed the condition even though it was an instance of TypeB. It is like it is evaluating the inner dataTable (InnerItems) before evaluating the outer (outerItems). My working assumption is that I just don't understand how/when the rendered attribute is actually evaluated.

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  • implement bank using python programming

    - by prajakta
    Write software for a bank. The program should be menu driven with the facility for bank employees to perform various operations. It should be written using all concepts of Object Oriented programming. You should be able to save your data in a file and read it back (because the bank people will shut down their computers when they go home :p ) Guidelines: The program may select to implement classes like Bank, Account, Savings Account, Fixed Deposit account, Customer, Depositor, Borrower, Transaction, etc.

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  • Wierd typeloadexception "Bad flags on delegate constructor."

    - by Marcus
    Hi, Anybody seen this exception before, Google doesn't have a single post regarding the exception. The code that raises the error is a simple add. Items.Add(item); System.TypeLoadException: Bad flags on delegate constructor. at System.Windows.Forms.ListView.Sort() at System.Windows.Forms.ListView.InsertItems(Int32 displayIndex, ListViewItem[] items, Boolean checkHosting) at System.Windows.Forms.ListView.ListViewNativeItemCollection.Add(ListViewItem value) at System.Windows.Forms.ListView.ListViewItemCollection.Add(ListViewItem value)

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  • How do I use an Entity Framework 4 model without a real database?

    - by Ivan
    I don't need any data to be stored. I'd like an application to start, create an Entity Framework entities container based on the model I've designed but having no data records in it, then generate some data (from user input and other input sources), work with it and discard all the data on close, without propagating any data operations made with EF contect to a real database hosted on server or in a file. How do I implement such a pattern? I use Entity Framework 4 and Visual Studio 2010.

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