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  • UIImageView subclass with CGRectIntersectsRect - help!

    - by Flafla2
    The title of this question should be pretty self explanatory. I am making an app that involves multiple UIImageViews that serve the same purpose. They are merely different sizes. Anyway, I decided that the best solution was to make UIImageView subclasses, link the subcalsses in IB, and work from there. My code should explain this better - #define kPausedStatePaused 1 #define kPausedStatePlay 2 #import "Game.h" #import "ScoreSystem.h" @interface Doctor : UIImageView { } @end @interface Ground : UIImageView { } @end @interface Wall : UIImageView { } @end @interface Electric_Wire : UIImageView { } @end @implementation Game /* // The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { // Custom initialization } return self; } */ /* // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; } */ - (IBAction)pause { UIAlertView *pause = [[UIAlertView alloc] initWithTitle:@"Pause" message:nil delegate:self cancelButtonTitle:@"Quit" otherButtonTitles:@"Play", nil]; [pause show]; [pause release]; pauseint = kPausedStatePaused; } - (void)viewDidAppear { pauseint = kPausedStatePlay; } - (void)loop { Doctor *doctorview; Ground *groundview; if (CGRectIntersectsRect(doctorview, groundview)) { } } - (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex { if ([alertView.title isEqual:@"Pause"]) { if(buttonIndex == 0) [self dismissModalViewControllerAnimated:YES]; pauseint = kPausedStatePlay; } } // Override to allow orientations other than the default portrait orientation. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationLandscapeRight); } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } - (void)dealloc { [super dealloc]; } @end Unsurprisingly, Xcode gave me an "incompatible type for CGRectIntersectsRect" error.

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  • Giving another object a NSManagedObject

    - by Wayfarer
    Alright, so I'm running into an issue with my code. What I have done is subclassed UIButton so I can give it some more infomormation that pertain to my code. I have been able to create the buttons and they work great. Capiche. However, one of the things I want my subclass to hold is a reference to a NSMangedObject. I have this code in my header file: @interface ButtonSubclass : UIButton { NSManagedObjectContext *context; NSManagedObject *player; } @property (nonatomic, retain) NSManagedObject *player; @property (nonatomic, retain) NSManagedObjectContext *context; - (id)initWithFrame:(CGRect)frame andTitle:(NSString*)title; //- (void)setPlayer:(NSManagedObject *)aPlayer; @end As you can see, it has a instance variable to the NSMangedobject I want it to hold (as well as the Context). But for the life of me, I can't get it to hold that NSManagedObject. I run both the @synthesize methods in the Implementation file. @synthesize context; @synthesize player; So I'm not sure what I'm doing wrong. This is how I create my button: ButtonSubclass *playerButton = [[ButtonSubclass alloc] initWithFrame:frame andTitle:@"20"]; //works playerButton.context = self.context; //works playerButton.player = [players objectAtIndex:i]; //FAILS And I have initilaized the players array earlier, where I get the objects. Another weird thing is that when it gets to this spot in the code, the app crashes (woot) and the the console output stops. It doesn't give me any error, and notification at all that the app has crashed. It just... stops. So I don't even know what the error is that is crashing the code, besides it has to do with that line up there setting the "player" variable. Thoughts and ideas? I'd love your wisdom!

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  • Is there a practical benefit to casting a NULL pointer to an object and calling one of its member fu

    - by zdawg
    Ok, so I know that technically this is undefined behavior, but nonetheless, I've seen this more than once in production code. And please correct me if I'm wrong, but I've also heard that some people use this "feature" as a somewhat legitimate substitute of a lacking aspect of the current C++ standard, namely, the inability to obtain the address (well, offset really) of a member function. For example, this is out of a popular implementation of a PCRE (Perl-compatible Regular Expression) library: #ifndef offsetof #define offsetof(p_type,field) ((size_t)&(((p_type *)0)->field)) #endif One can debate whether the exploitation of such a language subtlety in a case like this is valid or not, or even necessary, but I've also seen it used like this: struct Result { void stat() { if(this) // do something... else // do something else... } }; // ...somewhere else in the code... ((Result*)0)->stat(); This works just fine! It avoids a null pointer dereference by testing for the existence of this, and it does not try to access class members in the else block. So long as these guards are in place, it's legitimate code, right? So the question remains: Is there a practical use case, where one would benefit from using such a construct? I'm especially concerned about the second case, since the first case is more of a workaround for a language limitation. Or is it? PS. Sorry about the C-style casts, unfortunately people still prefer to type less if they can.

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  • Using StructureMap to create classes by a name?

    - by Bevan
    How can I use StructureMap to resolve to an appropriate implementation of an interface based on a name stored in an attribute? In my project, I have many different kinds of widgets, each descending from IWidget, and each decorated with an attribute specifying the kind of associated element. To illustrate: [Configuration("header")] public class HeaderWidget : IWidget { } [Configuration("linegraph")] public class LineGraphWidget : IWidget { } When processing my (XML) configuration file, I want to obtain an instance of the appropriate concrete class based on the name of the element I'm processing. public IWidget CreateWidget(XElement definition) { var kind = definition.Name.LocalName; var widget = // What goes here? widget.Configure(definition); return widget; } Each definition should result in a different widget being created - I don't need or want the instances to be shared. In the past I've written plenty of code to do this kind of thing manually, including writing a custom "roll-your-own" IoC container for one project. However, one of my goals with this project is to become proficient with StructureMap instead of reinventing the wheel. I think I've already managed to set up automatic scanning of assemblies so that StructureMap knows about all my IWidget implementations: public class WidgetRegistration : Registry { public WidgetRegistration() { Scan( scanner => { scanner.AssembliesFromApplicationBaseDirectory(); scanner.AddAllTypesOf<IWidget>(); }); } } However, this isn't registering the names of my widgets with StructureMap. What do I need to add to make my scenario work? (While I am trying to use StructureMap in this project, an answer showing me how to solve this problem with a different DI/IoC tool would still be valuable.)

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  • c++ - strange problem with polymorphism - cellular automaton

    - by Green
    Hello, I am making "game of life" implementation that, when cell has: two live neighbours I make object of class CCellB two live neighbours I make object of class CCellA when has 3 or <2 I make object of class CCellX (dead) Class CCell is base of CCellA, CCellB, CCellX My problem is: That works fine, until I change new CCell(); to new CCellB();: CCell ***temp = allocateArray(); for(int i = 0; i < n; i++) { for(int j = 0; j < m; j++) { c = arr[i][j]->countAliveNeighbor(); if(c == 3) { temp[i][j] = new CCellA(); temp[i][j]->alive = 1; }else if(c == 2) { temp[i][j] = new CCell(); // HERE, WHEN I CHANGE IT TO CCELLB IT DON'T WORKS temp[i][j]->alive = tab[i][j]->alive; }else if((c >= 4)||(c < 2)) { temp[i][j] = new CCellX(); } } } Then it seems don't work properly... Seems like neighbours are not count properly, Cell with 4,5 neighbours still alive alive var is member of base class - CCell, all is public, please help!

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  • Nested Class member function can't access function of enclosing class. Why?

    - by Rahul
    Please see the example code below: class A { private: class B { public: foobar(); }; public: foo(); bar(); }; Within class A & B implementation: A::foo() { //do something } A::bar() { //some code foo(); //more code } A::B::foobar() { //some code foo(); //<<compiler doesn't like this } The compiler flags the call to foo() within the method foobar(). Earlier, I had foo() as private member function of class A but changed to public assuming that B's function can't see it. Of course, it didn't help. I am trying to re-use the functionality provided by A's method. Why doesn't the compiler allow this function call? As I see it, they are part of same enclosing class (A). I thought the accessibility issue for nested class meebers for enclosing class in C++ standards was resolved. How can I achieve what I am trying to do without re-writing the same method (foo()) for B, which keeping B nested within A? I am using VC++ compiler ver-9 (Visual Studio 2008). Thank you for your help.

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  • What to do when ServerSocket throws IOException and keeping server running

    - by s5804
    Basically I want to create a rock solid server. while (keepRunning.get()) { try { Socket clientSocket = serverSocket.accept(); ... spawn a new thread to handle the client ... } catch (IOException e) { e.printStackTrace(); // NOW WHAT? } } In the IOException block, what to do? Is the Server socket at fault so it need to be recreated? For example wait a few seconds and then serverSocket = ServerSocketFactory.getDefault().createServerSocket(MY_PORT); However if the server socket is still OK, then it is a pity to close it and kill all previously accepted connections that are still communicating. EDIT: After some answers, here my attempt to deal with the IOException. Would the implementation be guaranteeing keeping the server up and only re-create server socket when only necessary? while (keepRunning.get()) { try { Socket clientSocket = serverSocket.accept(); ... spawn a new thread to handle the client ... bindExceptionCounter = 0; } catch (IOException e) { e.printStackTrace(); recreateServerSocket(); } } private void recreateServerSocket() { while (keepRunning) { try { logger.info("Try to re-create Server Socket"); ServerSocket socket = ServerSocketFactory.getDefault().createServerSocket(RateTableServer.RATE_EVENT_SERVER_PORT); // No exception thrown, then use the new socket. serverSocket = socket; break; } catch (BindException e) { logger.info("BindException indicates that the server socket is still good.", e); bindExceptionCounter++; if (bindExceptionCounter < 5) { break; } } catch (IOException e) { logger.warn("Problem to re-create Server Socket", e); e.printStackTrace(); try { Thread.sleep(30000); } catch (InterruptedException ie) { logger.warn(ie); } } } }

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  • Does Android AsyncTaskQueue or similar exist?

    - by Ben L.
    I read somewhere (and have observed) that starting threads is slow. I always assumed that AsyncTask created and reused a single thread because it required being started inside the UI thread. The following (anonymized) code is called from a ListAdapter's getView method to load images asynchronously. It works well until the user moves the list quickly, and then it becomes "janky". final File imageFile = new File(getCacheDir().getPath() + "/img/" + p.image); image.setVisibility(View.GONE); view.findViewById(R.id.imageLoading).setVisibility(View.VISIBLE); (new AsyncTask<Void, Void, Bitmap>() { @Override protected Bitmap doInBackground(Void... params) { try { Bitmap image; if (!imageFile.exists() || imageFile.length() == 0) { image = BitmapFactory.decodeStream(new URL( "http://example.com/images/" + p.image).openStream()); image.compress(Bitmap.CompressFormat.JPEG, 85, new FileOutputStream(imageFile)); image.recycle(); } image = BitmapFactory.decodeFile(imageFile.getPath(), bitmapOptions); return image; } catch (MalformedURLException ex) { // TODO Auto-generated catch block ex.printStackTrace(); return null; } catch (IOException ex) { // TODO Auto-generated catch block ex.printStackTrace(); return null; } } @Override protected void onPostExecute(Bitmap image) { if (view.getTag() != p) // The view was recycled. return; view.findViewById(R.id.imageLoading).setVisibility( View.GONE); view.findViewById(R.id.image) .setVisibility(View.VISIBLE); ((ImageView) view.findViewById(R.id.image)) .setImageBitmap(image); } }).execute(); I'm thinking that a queue-based method would work better, but I'm wondering if there is one or if I should attempt to create my own implementation.

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  • Use LINQ to group a sequence by date with no gaps

    - by Codesleuth
    I'm trying to select a subgroup of a list where items have contiguous dates, e.g. ID StaffID Type Title ActivityDate -- ------- ---- ----------------- ------------ 1 41 1 Doctors 07/06/2010 2 41 0 Meeting with John 08/06/2010 3 41 0 Meeting Continues 09/06/2010 4 41 0 Meeting Continues 10/06/2010 5 41 3 Annual Leave 11/06/2010 6 41 0 Meeting Continues 14/06/2010 I'm using a pivot point each time, so take the example pivot item as 3, I'd like to get the following resulting contiguous events around the pivot: ID StaffID Type Title ActivityDate -- ------- ---- ----------------- ------------ 2 41 0 Meeting with John 08/06/2010 3 41 0 Meeting Continues 09/06/2010 4 41 0 Meeting Continues 10/06/2010 My current implementation is a laborious "walk" into the past, then into the future, to build the list: var orderedEvents = activities.OrderBy(a => a.ActivityDate).ToArray(); // Walk into the past until a gap is found var preceedingEvents = orderedEvents.TakeWhile(a => a.ID != activity.ID); DateTime dayBefore; var previousEvent = activity; while (previousEvent != null) { dayBefore = previousEvent.ActivityDate.AddDays(-1).Date; previousEvent = preceedingEvents.TakeWhile(a => a.ID != previousEvent.ID).LastOrDefault(); if (previousEvent != null) { if (previousEvent.ActivityDate.Date == dayBefore) relatedActivities.Insert(0, previousEvent); else previousEvent = null; } } // Walk into the future until a gap is found var followingEvents = orderedEvents.SkipWhile(a => a.ID != activity.ID); DateTime dayAfter; var nextEvent = activity; while (nextEvent != null) { dayAfter = nextEvent.ActivityDate.AddDays(1).Date; nextEvent = followingEvents.SkipWhile(a => a.ID != nextEvent.ID).Skip(1).FirstOrDefault(); if (nextEvent != null) { if (nextEvent.ActivityDate.Date == dayAfter) relatedActivities.Add(nextEvent); else nextEvent = null; } } The list relatedActivities should then contain the contiguous events, in order. Is there a better way (maybe using LINQ) for this? I had an idea of using .Aggregate() but couldn't think how to get the aggregate to break out when it finds a gap in the sequence.

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  • jQuery e.target bubbling best practice ?

    - by olouv
    In my heavy-ajax code, i always bind "click" the body tag & act depending on $(e.target) & using $.fn.hasClass(). However when i click on an anchor that has a </span> tag inside, my $(e.target) equals this node, and not the parent anchor as i would like it to. From now on, i have used this trick (var $t = $(e.target);) : /** bubbling **/ if($t.get(0).tagName !== "A" && $t.get(0).tagName !== "AREA") { $t = $t.parent("a"); if(empty($t)) return true; //else console.log("$t.bubble()", $t); } It feels wrong somehow... Do you have any better implementation ? $.fn.live() does not solve my issue as it still returns the span as the target. Moreover i'm looking for speed (running on atom-based touch devices) & live appeared to be way slower (twice) : http://jsperf.com/bind-vs-click/3 In fact, as @Guffa pointed, using $.fn.live() solves the span bubbling issue as i don't need the event.target anymore. I guess there is no other "right" answer here (using bind).

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  • Singleton EXC_BAD_ACCESS

    - by lclaud
    Hi, so I have a class that I decleare as a singleton and in that class I have a NSMutableArray that contains some NSDictionaries with some key/value pairs in them. The trouble is it doesn't work and I dont't know why... I mean it crashes with EXC_BAD_ACCESS but i don't know where. I followed the code and it did create a new array on first add, made it to the end of the funtion ..and crashed ... @interface dataBase : NSObject { NSMutableArray *inregistrari; } @property (nonatomic,retain) NSMutableArray *inregistrari; -(void)adaugaInregistrareCuData:(NSDate *)data siValoare:(NSNumber *)suma caVenit:(BOOL)venit cuDetaliu:(NSString *)detaliu; -(NSDictionary *)raportIntreData:(NSDate *)dataInitiala siData:(NSDate *)dataFinala; -(NSArray *)luniDisponibileIntreData:(NSDate *)dataInitiala siData:(NSDate *)dataFinala; -(NSArray *)aniDisponibiliIntreData:(NSDate *)dataInitiala siData:(NSDate *)dataFinala; -(NSArray *)vectorDateIntreData:(NSDate *)dataI siData:(NSDate *)dataF; -(void)salveazaInFisier; -(void)incarcaDinFisier; + (dataBase *)shareddataBase; @end And here is the .m file #import "dataBase.h" #import "SynthesizeSingleton.h" @implementation dataBase @synthesize inregistrari; SYNTHESIZE_SINGLETON_FOR_CLASS(dataBase); -(void)adaugaInregistrareCuData:(NSDate *)data siValoare:(NSNumber *)suma caVenit:(BOOL)venit cuDetaliu:(NSString *)detaliu{ NSNumber *v=[NSNumber numberWithBool:venit]; NSArray *input=[NSArray arrayWithObjects:data,suma,v,detaliu,nil]; NSArray *keys=[NSArray arrayWithObjects:@"data",@"suma",@"venit",@"detaliu",nil]; NSDictionary *inreg=[NSDictionary dictionaryWithObjects:input forKeys:keys]; if(inregistrari == nil) { inregistrari=[[NSMutableArray alloc ] initWithObjects:inreg,nil]; }else { [inregistrari addObject:inreg]; } [inreg release]; [input release]; [keys release]; } It made it to the end of that adaugaInregistrareCuData ... ok . said the array had one object ... and then crashed

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  • How to benchmark on multi-core processors

    - by Pascal Cuoq
    I am looking for ways to perform micro-benchmarks on multi-core processors. Context: At about the same time desktop processors introduced out-of-order execution that made performance hard to predict, they, perhaps not coincidentally, also introduced special instructions to get very precise timings. Example of these instructions are rdtsc on x86 and rftb on PowerPC. These instructions gave timings that were more precise than could ever be allowed by a system call, allowed programmers to micro-benchmark their hearts out, for better or for worse. On a yet more modern processor with several cores, some of which sleep some of the time, the counters are not synchronized between cores. We are told that rdtsc is no longer safe to use for benchmarking, but I must have been dozing off when we were explained the alternative solutions. Question: Some systems may save and restore the performance counter and provide an API call to read the proper sum. If you know what this call is for any operating system, please let us know in an answer. Some systems may allow to turn off cores, leaving only one running. I know Mac OS X Leopard does when the right Preference Pane is installed from the Developers Tools. Do you think that this make rdtsc safe to use again? More context: Please assume I know what I am doing when trying to do a micro-benchmark. If you are of the opinion that if an optimization's gains cannot be measured by timing the whole application, it's not worth optimizing, I agree with you, but I cannot time the whole application until the alternative data structure is finished, which will take a long time. In fact, if the micro-benchmark were not promising, I could decide to give up on the implementation now; I need figures to provide in a publication whose deadline I have no control over.

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  • django: control json serialization

    - by abolotnov
    Is there a way to control json serialization in django? Simple code below will return serialized object in json: co = Collection.objects.all() c = serializers.serialize('json',co) The json will look similar to this: [ { "pk": 1, "model": "picviewer.collection", "fields": { "urlName": "architecture", "name": "\u0413\u043e\u0440\u043e\u0434 \u0438 \u0430\u0440\u0445\u0438\u0442\u0435\u043a\u0442\u0443\u0440\u0430", "sortOrder": 0 } }, { "pk": 2, "model": "picviewer.collection", "fields": { "urlName": "nature", "name": "\u041f\u0440\u0438\u0440\u043e\u0434\u0430", "sortOrder": 1 } }, { "pk": 3, "model": "picviewer.collection", "fields": { "urlName": "objects", "name": "\u041e\u0431\u044a\u0435\u043a\u0442\u044b \u0438 \u043d\u0430\u0442\u044e\u0440\u043c\u043e\u0440\u0442", "sortOrder": 2 } } ] You can see it's serializing it in a way that you are able to re-create the whole model, shall you want to do this at some point - fair enough, but not very handy for simple JS ajax in my case: I want bring the traffic to minimum and make the whole thing little clearer. What I did is I created a view that passes the object to a .json template and the template will do something like this to generate "nicer" json output: [ {% if collections %} {% for c in collections %} {"id": {{c.id}},"sortOrder": {{c.sortOrder}},"name": "{{c.name}}","urlName": "{{c.urlName}}"}{% if not forloop.last %},{% endif %} {% endfor %} {% endif %} ] This does work and the output is much (?) nicer: [ { "id": 1, "sortOrder": 0, "name": "????? ? ???????????", "urlName": "architecture" }, { "id": 2, "sortOrder": 1, "name": "???????", "urlName": "nature" }, { "id": 3, "sortOrder": 2, "name": "??????? ? ?????????", "urlName": "objects" } ] However, I'm bothered by the fast that my solution uses templates (an extra step in processing and possible performance impact) and it will take manual work to maintain shall I update the model, for example. I'm thinking json generating should be part of the model (correct me if I'm wrong) and done with either native python-json and django implementation but can't figure how to make it strip the bits that I don't want. One more thing - even when I restrict it to a set of fields to serialize, it will keep the id always outside the element container and instead present it as "pk" outside of it.

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  • c# delegate and abstract class

    - by BeraCim
    Hi all: I currently have 2 concrete methods in 2 abstract classes. One class contains the current method, while the other contains the legacy method. E.g. // Class #1 public abstract class ClassCurrent<T> : BaseClass<T> where T : BaseNode, new() { public List<T> GetAllRootNodes(int i) { //some code } } // Class #2 public abstract class MyClassLegacy<T> : BaseClass<T> where T : BaseNode, new() { public List<T> GetAllLeafNodes(int j) { //some code } } I want the corresponding method to run in their relative scenarios in the app. I'm planning to write a delegate to handle this. The idea is that I can just call the delegate and write logic in it to handle which method to call depending on which class/project it is called from (at least thats what I think delegates are for and how they are used). However, I have some questions on that topic (after some googling): 1) Is it possible to have a delegate that knows the 2 (or more) methods that reside in different classes? 2) Is it possible to make a delegate that spawns off abstract classes (like from the above code)? (My guess is a no, since delegates create concrete implementation of the passed-in classes) 3) I tried to write a delegate for the above code. But I'm being technically challenged: public delegate List GetAllNodesDelegate(int k); GetAllNodesDelegate del = new GetAllNodesDelegate(ClassCurrent.GetAllRootNodes); I got the following error: An object reference is required for the non-static field, method, property ClassCurrent<BaseNode>.GetAllRootNodes(int) I might have misunderstood something... but if I have to manually declare a delegate at the calling class, AND to pass in the function manually as above, then I'm starting to question whether delegate is a good way to handle my problem. Thanks.

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  • finding ALL cycles in a huge sparse matrix

    - by Andy
    Hi there, First of all I'm quite a Java beginner, so I'm not sure if this is even possible! Basically I have a huge (3+million) data source of relational data (i.e. A is friends with B+C+D, B is friends with D+G+Z (but not A - i.e. unmutual) etc.) and I want to find every cycle within this (not necessarily connected) directed graph. I've found this thread (http://stackoverflow.com/questions/546655/finding-all-cycles-in-graph/549402#549402) which has pointed me to Donald Johnson's (elementary) cycle-finding algorithm which, superficially at least, looks like it'll do what I'm after (I'm going to try when I'm back at work on Tuesday - thought it wouldn't hurt to ask in the meanwhile!). I had a quick scan through the code of the Java implementation of Johnson's algorithm (in that thread) and it looks like a matrix of relations is the first step, so I guess my questions are: a) Is Java capable of handling a 3+million*3+million matrix? (was planning on representing A-friends-with-B by a binary sparse matrix) b) Do I need to find every connected subgraph as my first problem, or will cycle-finding algorithms handle disjoint data? c) Is this actually an appropriate solution for the problem? My understanding of "elementary" cycles is that in the graph below, rather than picking out A-B-C-D-E-F it'll pick out A-B-F, B-C-D etc. but that's not the end of the world given the task. E / \ D---F / \ / \ C---B---A d) If necessary, I can simplify the problem by enforcing mutuality in relations - i.e. A-friends-with-B <== B-friends-with-A, and if really necessary I can maybe cut down the data size, but realistically it is always going to be around the 1mil mark. z) Is this a P or NP task?! Am I biting off more than I can chew? Thanks all, any help appreciated! Andy

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  • Thread-safe data structure design

    - by Inso Reiges
    Hello, I have to design a data structure that is to be used in a multi-threaded environment. The basic API is simple: insert element, remove element, retrieve element, check that element exists. The structure's implementation uses implicit locking to guarantee the atomicity of a single API call. After i implemented this it became apparent, that what i really need is atomicity across several API calls. For example if a caller needs to check the existence of an element before trying to insert it he can't do that atomically even if each single API call is atomic: if(!data_structure.exists(element)) { data_structure.insert(element); } The example is somewhat awkward, but the basic point is that we can't trust the result of "exists" call anymore after we return from atomic context (the generated assembly clearly shows a minor chance of context switch between the two calls). What i currently have in mind to solve this is exposing the lock through the data structure's public API. This way clients will have to explicitly lock things, but at least they won't have to create their own locks. Is there a better commonly-known solution to these kinds of problems? And as long as we're at it, can you advise some good literature on thread-safe design? EDIT: I have a better example. Suppose that element retrieval returns either a reference or a pointer to the stored element and not it's copy. How can a caller be protected to safely use this pointer\reference after the call returns? If you think that not returning copies is a problem, then think about deep copies, i.e. objects that should also copy another objects they point to internally. Thank you.

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  • Can I add a portrait layout on top of a landscape Camera SurfaceView?

    - by Uwe Krass
    My application should hold a camera preview surface. The camera is fixed to landscape view via AndroidMainfest.xml <application android:icon="@drawable/icon" android:label="Camera"> <uses-library android:name="com.google.android.maps" /> <uses-feature android:name="android.hardware.camera" /> <uses-feature android:name="android.hardware.camera.autofocus" /> <activity android:name=".CameraPreview" android:label="Camera" android:screenOrientation="landscape"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> If there is another way to get the camera preview itself to behave correctly, please let me know. Now I need to have an overlay that holds a bunch of buttons. Due to usability, the user interface should be set to portrait view (or even better orientation aware). Is there a way to have a transparent layout (for buttons and other GUI elements) in portrait orientation? I tried to write a special rotated layout by extending a RelativeLayout, but the onDraw method isn't called at anytime. public class RotatedOverlay extends RelativeLayout { private static final String TAG = "RotatedOverlay"; public RotatedOverlay(Context context, AttributeSet attrs ) { super(context, attrs); } @Override protected void onDraw(Canvas canvas) { canvas.rotate(90); super.onDraw(canvas); } I am quite new to the Android plattform programming. Of course I dont know much about the programming tricks and workarounds yet. I did a lot of research over the last two weeks (even studied the native Camera implementation), but couldnt find a good solution so far. Maybe it works with two seperate Activities, but I dont think, that this can the right solution.

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  • How to receive Email in JEE application

    - by Hank
    Obviously it's not so difficult to send out emails from a JEE application via JavaMail. What I am interested in is the best pattern to receive emails (notification bounces, mostly)? I am not interested in IMAP/POP3-based approaches (polling the inbox) - my application shall react to inbound emails. One approach I could think of would be Keep existing MTA (postfix on linux in my case) - ops team already knows how to configure / operate it For every mail that arrives, spawn a Java app that receives the data and sends it off via JMS. I could do this via an entry in /etc/aliases like myuser: "|/path/to/javahelper" with javahelper calling the Java app, passing STDIN along. MDB (part of JEE application) receives JMS message, parses it, detects bounce message and acts accordingly. Another approach could be Open a listening network socket on port 25 on the JEE application container. Associate a SessionBean with the socket. Bean is part of JEE application and can parse/detect bounces/handle the messages directly. Keep existing MTA as inbound relay, do all its security/spam filtering, but forward emails to myuser (that pass the filter) to the JEE application container, port 25. The first approach I have done before (albeit in a different language/setup). From a performance and (perceived) cleanliness point of view, I think the second approach is better, but it would require me to provide a proper SMTP transport implementation. Also, I don't know if it's at all possible to connect a network socket with a bean... What is your recommendation? Do you have details about the second approach?

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  • Dynamically overriding an abstract method in c#

    - by ng
    I have the following abstract class public abstract class AbstractThing { public String GetDescription() { return "This is " + GetName(); } public abstract String GetName(); } Now I would like to implement some new dynamic types from this like so. AssemblyName assemblyName = new AssemblyName(); assemblyName.Name = "My.TempAssembly"; AssemblyBuilder assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run); ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule("DynamicThings"); TypeBuilder typeBuilder = moduleBuilder.DefineType(someName + "_Thing", TypeAttributes.Public | TypeAttributes.Class, typeof(AbstractThing)); MethodBuilder methodBuilder = typeBuilder.DefineMethod("GetName", MethodAttributes.Public | MethodAttributes.ReuseSlot | MethodAttributes.Virtual | MethodAttributes.HideBySig, null, Type.EmptyTypes); ILGenerator msil = methodBuilder.GetILGenerator(); msil.EmitWriteLine(selectionList); msil.Emit(OpCodes.Ret); However when I try to instantiate via typeBuilder.CreateType(); I get an exception saying that there is no implementation for GetName. Is there something I am doing wrong here. I can not see the problem. Also, what would be the restrictions on instantiating such a class by name? For instance if I tried to instantiate via "My.TempAssembly.x_Thing" would it be availble for instantiation without the Type generated?

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  • Why does Tex/Latex not speed up in subsequent runs?

    - by Debilski
    I really wonder, why even recent systems of Tex/Latex do not use any caching to speed up later runs. Every time that I fix a single comma*, calling Latex costs me about the same amount of time, because it needs to load and convert every single picture file. (* I know that even changing a tiny comma could affect the whole structure but of course, a well-written cache format could see the impact of that. Also, there might be situations where 100% correctness is not needed as long as it’s fast.) Is there something in the language of Tex which makes this complicated or impossible to accomplish or is it just that in the original implementation of Tex, there was no need for this (because it would have been slow anyway on those large computers)? But then on the other hand, why doesn’t this annoy other people so much that they’ve started a fork which has some sort of caching (or transparent conversion of Tex files to a format which is faster to parse)? Is there anything I can do to speed up subsequent runs of Latex? Except from putting all the stuff into chapterXX.tex files and then commenting them out?

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  • accessing a method from a button within a class?

    - by flo
    #import "GameObject.h" #import "Definitions.h" @implementation GameObject @synthesize owner; @synthesize state; @synthesize mirrored; @synthesize button; @synthesize switcher; - (id) init { if ( self = [super init] ) { [self setOwner: EmptyField]; button = [UIButton buttonWithType:UIButtonTypeCustom]; [self setSwitcher: FALSE]; } return self; } - (UIButton*) display{ button.frame = CGRectMake(0, 0, GO_Width, GO_Height); [button setBackgroundImage:[UIImage imageNamed:BlueStone] forState:UIControlStateNormal]; [button addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside]; return button; } -(void)buttonPressed:(id) sender { //... } } - (void) dealloc { [super dealloc]; } @end Hi! i would like to know if the above is possible somehow within a class (in my case it is called GameObject) or if i HAVE to have the button call a methode in the viewcontroller... the above results with the app crashing. i would call display within a loop on the viewcontroller and id like to change some of the GameObjects instance variables within buttonPressed. Also id like to change some other stuff by calling some other methods from within buttonPressed but i think that will be the lesser of my problems ;) also id like to know how i can pass some variables to the buttonPressed method... cant find it anywhere :( help on this one would be much appreciated ;) thanks flo

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  • Any info about book "Unix Internals: The New Frontiers" by Uresh Vahalia 2nd edition (Jan 2010)

    - by claws
    This summer I'm getting into UNIX (mostly *BSD) development. I've graduate level knowledge about operating systems. I can also understand the code & read from here and there but the thing is I want to make most of my time. Reading books are best for this. From my search I found that these two books The Design and Implementation of the 4.4 BSD Operating System "Unix Internals: The New Frontiers" by Uresh Vahalia are like established books on UNIX OS internals. But the thing is these books are pretty much outdated. yay!! Lucky me. "Unix Internals: The New Frontiers" by Uresh Vahalia 2 edition (Jan 2010) is released. I've been search for information on this book. Sadly, Amazon says "Out of Print--Limited Availability" & I couldn't find any info regarding this book. This is the information I'm looking for: Table of Contents Whats new in this edition? Where the hell can I buy soft-copy of this book? I really cannot afford buying a hardcopy. How can I contact the author? I've lot of hopes & expectations on this book. I've been waiting for its release for a long time. I've sent random mails to & & requesting to have a proper website for this book. I even contacted publisher for any further information but no replies from any one. If you have any other books that you think will help me. I again repeat, I want to get max possible out of these 2.5 months summer.

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  • iPhone: AppStore InAppPurchase Connects in Simulator but Not on Device

    - by riteshkumar1905
    I am having trouble connecting to the AppStore from within my application. Everything runs fine in the Simulator but when I run on device the app cannot connect to the Appstore. Here is the code that connects to the Appstore #import "BuyController.h"#import "InAppPurchaseManager.h" #import "SKProducts.h" #define kInAppPurchaseProUpgradeProductId @"com.vigyaapan.iWorkOut1" @implementation BuyController - (IBAction)buy:(id)sender{ /* get the product description (defined in early sections)*/ //[self requestProUpgradeProductData]; if ([SKPaymentQueue canMakePayments]) { InAppPurchaseManager *Observer = [[InAppPurchaseManager alloc] init]; [[SKPaymentQueue defaultQueue] addTransactionObserver:Observer]; //NSURL *sandboxStoreURL = [[NSURL alloc]initWithString:@"http://sandbox.itunes.apple.com/verifyReceipt"]; //[[UIApplication sharedApplication]openURL:[NSURL URLWithString:@"http://sandbox.itunes.apple.com"]]; [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"http://phobos.apple.com/WebObjects/ com.vigyaapan.iWorkOut1?id=9820091347&;amp;amp;amp;amp;mt=8"]]; //[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=301349397&;amp;amp;amp;amp;mt=8"]]; SKPayment *payment = [SKPayment paymentWithProductIdentifier:@"com.vigyaapan.iWorkOut1"]; [[SKPaymentQueue defaultQueue] addPayment:payment]; } else { UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"MyApp" message:@"You are not authorized to purchase from AppStore" delegate:self cancelButtonTitle:@"OK" otherButtonTitles: nil]; [alert show]; [alert release]; } //return [SKPaymentQueue canMakePayments];} SKPayment *payment = [SKPayment paymentWithProductIdentifier:kInAppPurchaseProUpgradeProductId]; [[SKPaymentQueue defaultQueue] addPayment:payment]; //[self requestProUpgradeProductData]; /* get the product description (defined in early sections)*/ } @end

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  • JUnit Test method with randomized nature

    - by Peter
    Hey, I'm working on a small project for myself at the moment and I'm using it as an opportunity to get acquainted with unit testing and maintaining proper documentation. I have a Deck class with represents a deck of cards (it's very simple and, to be honest, I can be sure that it works without a unit test, but like I said I'm getting used to using unit tests) and it has a shuffle() method which changes the order of the cards in the deck. The implementation is very simple and will certainly work: public void shuffle() { Collections.shuffle(this.cards); } But, how could I implement a unit test for this method. My first thought was to check if the top card of the deck was different after calling shuffle() but there is of course the possibility that it would be the same. My second thought was to check if the entire order of cards has changed, but again they could possibly be in the same order. So, how could I write a test that ensures this method works in all cases? And, in general, how can you unit test methods for which the outcome depends on some randomness? Cheers, Pete

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  • Algorithm for count-down timer that can add on time

    - by Person
    I'm making a general timer that has functionality to count up from 0 or count down from a certain number. I also want it to allow the user to add and subtract time. Everything is simple to implement except for the case in which the timer is counting down from some number, and the user adds or subtracts time from it. For example: (m_clock is an instance of SFML's Clock) float Timer::GetElapsedTime() { if ( m_forward ) { m_elapsedTime += m_clock.GetElapsedTime() - m_elapsedTime; } else { m_elapsedTime -= m_elapsedTime - m_startingTime + m_clock.GetElapsedTime(); } return m_elapsedTime; } To be a bit more clear, imagine that the timer starts at 100 counting down. After 10 seconds, the above function would look like 100 -= 100 - 100 + 10 which equals 90. If it was called after 20 more seconds it would look like 90 -= 90 - 100 + 30 which equals 70. This works for normal counting, but if the user calls AddTime() ( just m_elapsedTime += arg ) then the algorithm for backwards counting fails miserably. I know that I can do this using more members and keeping track of previous times, etc. but I'm wondering whether I'm missing some implementation that is extremely obvious. I'd prefer to keep it as simple as possible in that single operation.

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