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  • Sqlalchemy layout with WSGI application

    - by TheDude
    I'm working on writing a small WSGI application using Bottle and SqlAlchemy and am confused on how the "layout" of my application should be in terms of SqlAlchemy. My confusion is with creating engines and sessions. My understanding is that I should only create one engine with the 'create_engine' method. Should I be creating an engine instance in the global namespace in some sort of singleton pattern and creating sessions based off of it? How have you done this in your projects? Any insight would be appreciated. The examples in the documentation dont seem to make this entirely clear (unless I'm missing something obvious). Any thoughts?

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  • memristor is a new paradigm (fourth element in integrated circuits)? [closed]

    - by lsalamon
    The memristor will bring a new paradigm of programming, opened enormous opportunities to enable the machines to gain knowledge, creating a new paradigm toward the intelligence altificial. Do you believe that we are paving the way for the era of intelligent machines? More info about : Brain-like systems? "As for the human brain-like characteristics, memristor technology could one day lead to computer systems that can remember and associate patterns in a way similar to how people do. This could be used to substantially improve facial recognition technology or to provide more complex biometric recognition systems that could more effectively restrict access to personal information. These same pattern-matching capabilities could enable appliances that learn from experience and computers that can make decisions." [EDITED] The way is open. News on the subject Brain-Like Computer Closer to Realization

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  • System.Timers.Timer leaking due to "direct delegate roots"

    - by alimbada
    Apologies for the rather verbose and long-winded post, but this problem's been perplexing me for a few weeks now so I'm posting as much information as I can in order to get this resolved quickly. We have a WPF UserControl which is being loaded by a 3rd party app. The 3rd party app is a presentation application which loads and unloads controls on a schedule defined by an XML file which is downloaded from a server. Our control, when it is loaded into the application makes a web request to a web service and uses the data from the response to display some information. We're using an MVVM architecture for the control. The entry point of the control is a method that is implementing an interface exposed by the main app and this is where the control's configuration is set up. This is also where I set the DataContext of our control to our MainViewModel. The MainViewModel has two other view models as properties and the main UserControl has two child controls. Depending on the data received from the web service, the main UserControl decides which child control to display, e.g. if there is a HTTP error or the data received is not valid, then display child control A, otherwise display child control B. As you'd expect, these two child controls bind two separate view models each of which is a property of MainViewModel. Now child control B (which is displayed when the data is valid) has a RefreshService property/field. RefreshService is an object that is responsible for updating the model in a number of ways and contains 4 System.Timers.Timers; a _modelRefreshTimer a _viewRefreshTimer a _pageSwitchTimer a _retryFeedRetrievalOnErrorTimer (this is only enabled when something goes wrong with retrieving data). I should mention at this point that there are two types of data; the first changes every minute, the second changes every few hours. The controls' configuration decides which type we are using/displaying. If data is of the first type then we update the model quite frequently (every 30 seconds) using the _modelRefreshTimer's events. If the data is of the second type then we update the model after a longer interval. However, the view still needs to be refreshed every 30 seconds as stale data needs to be removed from the view (hence the _viewRefreshTimer). The control also paginates the data so we can see more than we can fit on the display area. This works by breaking the data up into Lists and switching the CurrentPage (which is a List) property of the view model to the right List. This is done by handling the _pageSwitchTimer's Elapsed event. Now the problem My problem is that the control, when removed from the visual tree doesn't dispose of it's timers. This was first noticed when we started getting an unusually high number of requests on the web server end very soon after deploying this control and found that requests were being made at least once a second! We found that the timers were living on and not stopping hours after the control had been removed from view and that the more timers there were the more requests piled up at the web server. My first solution was to implement IDisposable for the RefreshService and do some clean up when the control's UnLoaded event was fired. Within the RefreshServices Dispose method I've set Enabled to false for all the timers, then used the Stop() method on all of them. I've then called Dispose() too and set them to null. None of this worked. After some reading around I found that event handlers may hold references to Timers and prevent them from being disposed and collected. After some more reading and researching I found that the best way around this was to use the Weak Event Pattern. Using this blog and this blog I've managed to work around the shortcomings in the Weak Event pattern. However, none of this solves the problem. Timers are still not being disabled or stopped (let alone disposed) and web requests are continuing to build up. Mem Profiler tells me that "This type has N instances that are directly rooted by a delegate. This can indicate the delegate has not been properly removed" (where N is the number of instances). As far as I can tell though, all listeners of the Elapsed event for the timers are being removed during the cleanup so I can't understand why the timers continue to run. Thanks for reading. Eagerly awaiting your suggestions/comments/solutions (if you got this far :-p)

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  • what is the return value of BeautifulSoup.find ?

    - by prosseek
    I run to get some value as score. score = soup.find('div', attrs={'class' : 'summarycount'}) I run 'print score' to get as follows. <div class=\"summarycount\">524</div> I need to extract the number part. I used re module but failed. m = re.search("[^\d]+(\d+)", score) TypeError: expected string or buffer function search in re.py at line 142 return _compile(pattern, flags).search(string) What's the return type of the find function? How to get the number from the score variable? Is there any easy way to let BeautifulSoup to return the value(in this case 524) itself?

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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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  • Is ActiveMQ unreliable?

    - by user122991
    Hello, We have been using ActiveMQ 5.2 in our distributed enterprise application for about 3 months. During that time, we have experienced debilitating failures at least twice weekly. In particular, we see: 1) Topic publisher has its connection arbitrarily closed and experiences EOF on attempt to publish. Note well that this issue is not a function of some timeout. It does not correlate reliably with any inactivity. 2) Queue listeners never receive message. Message simply sits on Queue. 2) is much rarer (hardly ever) than 1). In both cases, the failures are highly intermittent-- they cannot be reliably reproduced through any testing usage pattern. Also, there are no errors or warning in the AMQ logs. Have others experienced similar problems? Is there an opinion that some other JMS provider is more reliable? thanks, Joe

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  • Django "Page not found" error page shows only one of two expected urls

    - by Frank V
    I'm working with Django, admittedly for the first time doing anything real. The URL config looks like the following: urlpatterns = patterns('my_site.core_prototype.views', (r'^newpost/$', 'newPost'), (r'^$', 'NewPostAndDisplayList'), # capture nothing... #more here... - perhaps the perma-links? ) This is in an app's url.py which is loaded from the project's url.py via: urlpatterns = patterns('', # only app for now. (r'^$', include('my_site.core_prototype.urls')), ) The problem is, when I receive a 404 attempting to utilize newpost, the error page only shows the ^$ -- it seems to ignore the newpost pattern... I'm sure the solution is probably stupid-simple but right now I'm missing it. Can someone help get me on the right track...

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  • Is it possible to use Dependency Injection/IoC on an ASP.NET MVC FilterAttribute ?

    - by Pure.Krome
    Hi folks, I've got a simple custom FilterAttribute which I use decorate various ActionMethods. eg. [AcceptVerbs(HttpVerbs.Get)] [MyCustomFilter] public ActionResult Bar(...) { ... } Now, I wish to add some logging to this CustomFilter Action .. so being a good boy, I'm using DI/IoC ... and as such wish to use this pattern for my custom FilterAttribute. So if i have the following... ILoggingService and wish to add this my custom FilterAttribute .. i'm not sure how. Like, it's easy for me to do the following... public class MyCustomFilterAttribute : FilterAttribute { public MyCustomFilterAttribute(ILoggingService loggingService) { ... } } But the compiler errors saying the attribute which decorates my ActionMethod (listed above...) requires 1 arg .. so i'm just not sure what to do :(

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  • Bitmap manipulation in C++ on Windows

    - by Oliver
    Hi, I have myself a handle to a bitmap, in C++, on Windows: HBITMAP hBitmap; On this image I want to do some Image Recognition, pattern analysis, that sort of thing. In my studies at University, I have done this in Matlab, it is quite easy to get at the individual pixels based on their position, but I have no idea how to do this in C++ under Windows - I haven't really been able to understand what I have read so far. I have seen some references to a nice looking Bitmap class that lets you setPixel() and getPixel() and that sort of thing, but I think this is with .net . How should I go about turning my HBITMAP into something I can play with easily? I need to be able to get at the RGBA information. Are there libraries that allow me to work with the data without having to learn about DCs and BitBlt and that sort of thing?

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  • A PHP object server for business logic

    - by Matthieu
    I wonder if such a thing is possible or even exist : In the MVC pattern, I would like to have the Model part to be persistant in memory, instead of reloading my instances at each execution. So I want only the Controller and View part to be executed. Is there any solution of server that would provide PHP objects (just like a Mysql server provides data records), and that keeps these objects in memory ? A problem would be also : how to have a constructed query to get objects ? Maybe PHP Linq ?

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  • How to tell when my batch of EAP calls are completed?

    - by codemonkie
    This is following my question: http://stackoverflow.com/questions/2607038/c-how-to-consume-web-service-adheres-to-the-event-based-asynchronous-pattern My program is calling the DoStuffAsync() x many times in a batch, hence the callback will get invoked the same number of times upon OnComplete(). Is there a way to find out when my batch is finished such that I can generate a report on the success/failed results? All I can think of is to have a static count variable for x and deduct 1 every time OnComplete() is called, but its kind of silly and error prone I'm afraid. TIA.

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  • Zend Framework Custom Validation Class Error Message

    - by remlabm
    The validation fails as it should but does not return the error message. $form->addElement('text', 'phone_number', array( 'required' => true, 'validators' => array( array('NotEmpty', true, array('messages' => 'Enter a valid Phone Number')), array('regex', false, array('pattern' => '/\([0-9]{3}\)\s[0-9]{3}-[0-9]{4}/', 'messages' => 'Enter a valid Phone Number' )), 'CheckPhoneNumber'), ), )); Custom Class: class Custom_Validators_CheckPhoneNumber extends Zend_Validate_Abstract{ const IN_USE = 'inUse'; protected $_messageTemplates = array( self::IN_USE => "'%value%' is currently in use" ); public function isValid($value) { $this->_setValue($value); $user_check = Users::getActive(preg_replace("/[^0-9]/", "", $value)); if($user_check->id){ $this->_error(self::IN_USE); return false; } return true; } } Just fails does not give the "IN_USE" error.

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  • Restrict violation of architecture - asp.net MVP

    - by Srikanth
    If we had a defined hierarchy in an application. For ex a 3 - tier architecture, how do we restrict subsequent developers from violating the norms? For ex, in case of MVP (not asp.net MVC) architecture, the presenter should always bind the model and view. This helps in writing proper unit test programs. However, we had instances where people directly imported the model in view and called the functions violating the norms and hence the test cases couldn't be written properly. Is there a way we can restrict which classes are allowed to inherit from a set of classes? I am looking at various possibilities, including adopting a different design pattern, however a new approach should be worth the code change involved.

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  • Efficient storage/retrieval method for replayable comet style applications (Google Wave, Etherpad)

    - by Gareth Simpson
    I am considering a web application that would have the same kind of multi user, automatic saving, infinite undo / replay capabilities that you see in Google Wave and Etherpad (albeit on a drastically smaller scale and userbase). Before I go away and reinvent the wheel, is this something that has already been addressed as either a piece of technology or library, or even just a design pattern. I know this isn't necessarily the best Stack Overflow question as there is probably not a "right" answer, but my Google-fu has failed me and I'd just like a reading list! Ordinarily I would be developing under python/django but this is not a firm requirement just a preference :)

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  • Zend Framework - Database Table Singleton

    - by Sonny
    I have found myself doing this in my code to 'cache' the work done when instantiating my Zend_Db_Table models: if (Zend_Registry::isRegistered('x_table')) { $x_table = Zend_Registry::get('x_table'); } else { $x_table = new Default_Model_DbTable_X; Zend_Registry::set('x_table', $x_table); } It bothered me that this method isn't very DRY and it dawned on me today that a singleton pattern would probably be a better way to do this. Problem is, I've never written a singleton class. When I did some web searches, I found some offhand comments about Zend_Db_Table singletons, but no real examples. I already have meta-data caching configured. How do I make my Zend_Db_Table models singletons? Are there pitfalls or downsides?

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  • Find inner arrays in nested arrays

    - by 50ndr33
    I have a nested array in PHP: array ( '0' => "+5x", '1' => array ( '0' => "+", '1' => "(", '2' => "+3", '3' => array ( '0' => "+", '1' => "(", '2' => array ( // I want to find this one. '0' => "+", '1' => "(", '2' => "+5", '3' => "-3", '4' => ")" ), '3' => "-3", '4' => ")" ), '4' => ")" ) ); I need to process the innermost arrays here, the one with the comment: "I want to find this one." Is there a function for that? I have thought about doing (written as an idea, not as correct PHP): foreach ($array as $id => $value) { if ($value is array) { $name = $id; foreach ($array[$id] as $id_2 => $value_2) { if ($value_2 is array) { $name .= "." . $id_2; foreach ($array[$id][$id_2] as $id_3 => $value_3) { if ($value_3 is array) { $name .= "." . $id_3; foreach ($array[$id][$id_2][$id_3] as $id_4 => $value_4) { if ($value_4 is array) { $name .= "." . $id_4; foreach [and so it goes on]; } else { $listOfInnerArrays[] = $name; break; } } } else { $listOfInnerArrays[] = $name; break; } } } else { $listOfInnerArrays[] = $name; break; } } } } So what it does is it makes $name the current key in the array. If the value is an array, it goes into it with foreach and adds "." and the id of the array. So we would in the example array end up with: array ( '0' => "1.3.2", ) Then I can process those values to access the innner arrays. The problem is that the array that I'm trying to find the inner arrays of is dynamic and made of a user input. (It splits an input string where it finds + or -, and puts it in a separate nested array if it contains brackets. So if the user types a lot of brackets, there will be a lot of nested arrays.) Therefore I need to make this pattern go for 20 times down, and still it will only catch 20 nested arrays no matter what. Is there a function for that, again? Or is there a way to make it do this without my long code? Maybe make a loop make the necessary number of the foreach pattern and run it through eval()? Long answer to J. Bruni: <?php $liste = array ( '0' => "+5x", '1' => array ( '0' => "+", '1' => "(", '2' => "+3", '3' => array ( '0' => "+", '1' => "(", '2' => array ( '0' => "+", '1' => "(", '2' => "+5", '3' => "-3", '4' => ")" ), '3' => "-3", '4' => ")" ), '4' => ")" ) ); function find_deepest( $item, $key ) { echo "0"; if ( !is_array( $item ) ) return false; foreach( $item as $sub_item ) { if ( is_array( $sub_item ) ) return false; } echo "1"; print_r( $item ); return true; } array_walk_recursive( $liste, 'find_deepest' ); echo "<pre>"; print_r($liste); ?> I wrote echo 0 and 1 to see what the script did, and here is the output: 00000000000000 Array ( [0] => +5x [1] => Array ( [0] => + [1] => ( [2] => +3 [3] => Array ( [0] => + [1] => ( [2] => Array ( [0] => + [1] => ( [2] => +5 [3] => -3 [4] => ) ) [3] => -3 [4] => ) ) [4] => ) ) )

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  • Where should I put zoomIn in my MapActivity?

    - by Johny
    I'm writing an Android app, and I'd like to zoomIn as soon as the map has been loaded. I get the following error: java.lang.IllegalArgumentException: width and height must be > 0 This MapActivity - width and height must be > 0 question suggests the problem is the zoomIn() method is in the onCreate() method. But I get same error when I put it in the onResume() method. I've been searching for hours and I can't find anything about it at http://developer.android.com or anywhere else... Also I can't find a way to get the time point the map has been loaded. A "MapLoadedListener" or something like that... EDIT Here is my code: public class AMap extends MapActivity{ private final String LOG_TAG = this.getClass().getSimpleName(); private Context mContext; private Chronometer timer; private TextView tvCountdown; private RelativeLayout rl; private MapView mapView; private MapController mapController; private List<Overlay> mapOverlays; private PlayersOverlay playersOverlay; private Drawable drawable; private Builder endDialog; private ContextThemeWrapper ctw; private Handler mHandler = new Handler(); private Player player = new Player(); private StartTask startTask; private EndTask endTask; private MyDBAdapter mdba; private Cursor playersCursor; private UpdateBroadcastReceiver r; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.map_view); mContext = AMap.this; // set map mapView = (MapView) findViewById(R.id.mapview); mapView.setBuiltInZoomControls(true); mapView.setFocusable(true); // find the relative layout rl = (RelativeLayout) findViewById(R.id.rl); // set the chronometer timer = (Chronometer) findViewById(R.id.tv_timer); timer.setBackgroundColor(Color.DKGRAY); // set the countdown textview tvCountdown = (TextView) findViewById(R.id.tv_countdown); // Open DB connection and get players Cursor mdba = new MyDBAdapter(mContext); mdba.open(); playersCursor = mdba.getGame(); // Get this player's id and location Intent starter = this.getIntent(); player.setId(starter.getIntExtra("id", 0)); player.setLatitude(starter.getDoubleExtra("lat", 0)); player.setLongitude(starter.getDoubleExtra("lon", 0)); // Set this player's location as map's center GeoPoint geoPoint = new GeoPoint((int) (player.getLatitude()*1E6), (int) (player.getLongitude()*1E6)); mapController = mapView.getController(); mapController.setCenter(geoPoint); mapController.setZoom(15); Log.d(LOG_TAG, "My playersCursor has "+playersCursor.getCount()+" rows"); // drawable is needed but not used drawable = this.getResources().getDrawable(R.drawable.ic_launcher); // set PlayersOverlay (locations and statuses) playersOverlay = new PlayersOverlay(player.getId(), playersCursor, drawable, this); mapOverlays = mapView.getOverlays(); mapOverlays.add(playersOverlay); mHandler.postDelayed(mUpdateTimeTask, 100); } private Runnable mUpdateTimeTask = new Runnable() { public void run() { int h = mapView.getLayoutParams().height; int w = mapView.getLayoutParams().width; Log.d(LOG_TAG, "w = "+w+" , h = "+h); mHandler.postAtTime(this, System.currentTimeMillis() + 1000); } }; @Override public void onAttachedToWindow(){ Log.d(LOG_TAG, "Attached to Window"); int h = mapView.getLayoutParams().height; int w = mapView.getLayoutParams().width; Log.d(LOG_TAG, " Attached to window: w = "+w+" , h = "+h); //mapController.zoomInFixing(screenPoint.x, screenPoint.y); } public void onWindowFocusChanged(boolean hasFocus){ Log.d(LOG_TAG, "Focus changed to: "+hasFocus); int h = mapView.getLayoutParams().height; int w = mapView.getLayoutParams().width; Log.d(LOG_TAG, " Window focus changed: w = "+w+" , h = "+h); //mapController.zoomInFixing(screenPoint.x, screenPoint.y); } @Override protected void onStart(){ super.onStart(); // Create and register the broadcast receiver for messages from service IntentFilter filter = new IntentFilter(AppConstants.iGAME_UPDATE); r = new UpdateBroadcastReceiver(); registerReceiver(r, filter); // Create the dialog for end of game ctw = new ContextThemeWrapper(mContext, android.R.style.Theme_Translucent_NoTitleBar_Fullscreen); endDialog = new AlertDialog.Builder(ctw); endDialog.setMessage("End of Game"); endDialog.setCancelable(false); endDialog.setNeutralButton("OK", new OnClickListener(){ @Override public void onClick(DialogInterface dialog, int which) { Intent highScores = new Intent(AMap.this, HighScores.class); startActivity(highScores); playersCursor.close(); finish(); } }); } @Override protected void onStop() { if(!playersCursor.isClosed()) playersCursor.close(); unregisterReceiver(r); mdba.close(); super.onStop(); } @Override protected boolean isRouteDisplayed() { return false; } // Receives signal from NetworkService that DB has been updated public class UpdateBroadcastReceiver extends BroadcastReceiver { boolean startSignal, update, endSignal; @Override public void onReceive(Context context, Intent intent) { endSignal = intent.getBooleanExtra("endSignal", false); if(endSignal){ Log.d(LOG_TAG, "Game Update BroadcastReceiver received End Signal"); endTask = new EndTask(); endTask.execute(); return; } update = intent.getBooleanExtra("update", false); if(update){ Log.d(LOG_TAG, "Game Update BroadcastReceiver received game update"); playersCursor.requery(); mapView.invalidate(); return; } startSignal = intent.getBooleanExtra("startSignal", false); if(startSignal){ Log.d(LOG_TAG, "Game Update BroadcastReceiver received Start Signal"); startTask = new StartTask(); startTask.execute(); return; } } } class StartTask extends AsyncTask<Void,Integer,Void>{ private final ToneGenerator tg = new ToneGenerator(AudioManager.STREAM_NOTIFICATION, 100); private final long DELAY = 1200; @Override protected Void doInBackground(Void... params) { int i = 3; while(i>=0){ publishProgress(i); try { Thread.sleep(DELAY); } catch (InterruptedException e) { e.printStackTrace(); } i--; } return null; } @Override protected void onProgressUpdate(Integer... progress){ tg.startTone(ToneGenerator.TONE_PROP_PROMPT); tvCountdown.setText(""+progress[0]); } @Override protected void onPostExecute(Void result) { rl.removeView(tvCountdown); timer.setBase(SystemClock.elapsedRealtime()); timer.start(); //enable screen touches playersOverlay.setGameStarted(true); } } class EndTask extends AsyncTask<Void,Void,Void>{ @Override protected void onPreExecute(){ //disable screen touches playersOverlay.setEndOfGame(true); timer.stop(); } @Override protected Void doInBackground(Void... params) { return null; } @Override protected void onPostExecute(Void result) { try{ endDialog.show(); }catch(Exception e){ Toast.makeText(mContext, "End of game", Toast.LENGTH_LONG); Intent highScores = new Intent(AMap.this, HighScores.class); startActivity(highScores); playersCursor.close(); finish(); } mHandler.removeCallbacks(mUpdateTimeTask); } } }

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  • string parsing help

    - by sprugman
    I've got a string like this: #################### Section One #################### Data A Data B #################### Section Two #################### Data C Data D etc. I want to parse it into something like: $arr( 'Section One' => array('Data A', 'Data B'), 'Section Two' => array('Data C', 'Data D') ) At first I tried this: $sections = preg_split("/(\r?\n)(\r?\n)#/", $file_content); The problem is, the file isn't perfectly clean: sometimes there are different numbers of blank lines between the sections, or blank spaces between data rows. The section head pattern itself seems to be relatively consistent: #################### Section Title #################### The number of #'s is probably consistent, but I don't want to count on it. The white space on the title line is pretty random. Once I have it split into sections, I think it'll be pretty straightforward, but any help writing a killer reg ex to get it there would be appreciated. (Or if there's a better approach than reg ex...)

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  • Different background colors for the top and bottom of a UITableView

    - by Aaron Brethorst
    If you look at your Inbox in iPhone OS 3.0's Mail app, you'll see that swiping down displays a grayish background color above the UISearchBar. Now, if you scroll down to the bottom of the table, you'll see that the background color at that end is white. I can think of a couple ways of solving this problem, but they're pretty hacky: Change the table view's background color depending on the current scrollOffset by overriding -scrollViewDidScroll: Give the UITableView a clear background color and then set its superview's backgroundColor to a gradient pattern image. Does anyone know what the "best practice" solution is for this problem? thanks.

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  • Type patterns in Haskell

    - by finnsson
    I'm trying to compile a simple example of generic classes / type patterns (see http://www.haskell.org/ghc/docs/latest/html/users_guide/generic-classes.html) in Haskell but it won't compile. Any ideas about what's wrong with the code would be helpful. According to the documentation there should be a module Generics with the data types Unit, :*:, and :+: but ghc (6.12.1) complaints about Not in scope: data constructor 'Unit' etc. It seems like there's a package instant-generics with the data types :*:, :+: and U but when I import that module (instead of Generics) I get the error Illegal type pattern in the generic bindings {myPrint _ = ""} The complete source code is import Generics.Instant class MyPrint a where myPrint :: a -> String myPrint {| U |} _ = "" myPrint {| a :*: b |} (x :*: y) = "" (show x) ++ ":*:" ++ (show y) myPrint {| a :+: b |} _ = "" data Foo = Foo String instance MyPrint a => MyPrint a main = myPrint $ Foo "hi" and I compile it using ghc --make Foo.hs -fglasgow-exts -XGenerics -XUndecidableInstances P.S. The module Generics export no data types, only the functions: canDoGenerics mkGenericRhs mkTyConGenericBinds validGenericInstanceType validGenericMethodType

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  • What can I use the Google App Engine for?

    - by Sergio Boombastic
    This question possibly doesn't belong here. We'll see how the answers pan out, if this doesn't belong here please move it to where it belongs. I'm following the getting started guide for Google App Engine, and I'm seeing what it can and can't do. Basically, I'm seeing it's very similar to an MVC pattern. You create your model, then create a View that uses that Model to display information. Not only that, but it uses a controller of some kind in this fashion: application = webapp.WSGIApplication( [('/', MainPage)], debug=True) My question is, why would you use this Google App Engine if it's the same as using a number of other MVC frameworks? Is the only benefit you gain the load balancing being handled by Google automagically? What is a good example of something you would need the App Engine for? I'm trying to learn, so thanks for the discussion.

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  • How should i build my GUI in Qt ?

    - by Apollo
    I am wondering which way is the best to start building a GUI+SOFT in Qt. I am trying to build a sound media player based on a MVC pattern. Until now i have found 3 ways to do so. 1- Should I use a .ui file thanks to Qt designer, is it flexible enough ? 2- Should I use QML to make the design than integrate it to a C++ development ? 3- Should I just start from scratch and do it by hand without Qt Designer and using Qt library ? Thank you very much for your answers.

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  • How can I create a qr// in Perl 5.12 from C?

    - by kristina
    This has been working for me in 5.8 and 5.10, but in 5.12 my code creates this weird non-qr object: # running "print Dumper($regex)" $VAR1 = bless( do{\(my $o = '')}, 'Regexp' ); Whereas printing a qr// not created by my code looks like this: # running "print Dumper(qr/foo/i)" $VAR1 = qr/(?i-xsm:foo)/; My code is basically: REGEXP *rx = re_compile(pattern, flags); SV *regex = sv_2mortal(newSVpv("",0)); sv_magic(regex, (SV*)rx, PERL_MAGIC_qr, 0, 0); stash = gv_stashpv("Regexp", 0); sv_bless(newRV((SV*)regex), stash); Anyone know how to correctly create a regex from a string in 5.12?

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  • creative way for implementing Data object with its corresponding business logic class in java

    - by ekeren
    I have a class that need to be serialized (for both persistentcy and client-server communication) for simplicity's sake let's call the classes Business a BusinessData and I prefix for their Interfaces. All the getter and setter are delegated from Business class to BusinessData class. I thought about implementing IBusinessData interface that will contain all the getter and setters and IBusiness interface that will extend it. I can either make Business extend BuisnessData so I will not need to implement all getter and setter delegates, or make some abstract class ForwardingBusinessData that will only delegate getter and setters. Any of the above option I lose my hierarchy freedom, do any of you have any creative solutions for this problem... I also reviewed DAO pattern: http://java.sun.com/blueprints/patterns/DAO.html

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  • how to start animation using MVVM?

    - by Kishore Kumar
    I am converting my exising Application using WPF using MVVM pattern. I have different storyboards in my view . eg. 1. showing splashscreen while loading the app 2. while clicking Menu Toggle button/Radio Button to show the slide in and Slide out animation effect 3. And different mouseover effect for different elements available in the View. How will i call the storyboard using MVVM and which is the best method?. To show the mouse over effect do we really have to use MVVM or code behind?

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