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• Understanding REST: is GET fundamentally incompatible with any "number of views" counter?

  - by cocotwo

  I'm trying to understand REST. Under REST a GET must not trigger something transactional on the server (this is a definition everybody agrees upon, it is fundamental to REST). So imagine you've got a website like stackoverflow.com (I say like so if I got the underlying details of SO wrong it doesn't change anything to my question), where everytime someone reads a question, using a GET, there's also some display showing "This question has been read 256 times". Now someone else reads that question. The counter now is at 257. The GET is transactional because the number of views got incremented and is now incremented again. The "number of views" is incremented in the DB, there's no arguing about that (for example on SO the number of time any question has been viewed is always displayed). So, is a REST GET fundamentally incompatible with any kind of "number of views" like functionality in a website? So should it want to be "RESTFUL", should the SO main page either stop display plain HTML links that are accessed using GETs or stop displaying the "this question has been viewed x times"? Because incrementing a counter in a DB is transactional and hence "unrestful"? EDIT just so that people Googling this can get some pointers: From http://www.xfront.com/REST-Web-Services.html : 4. All resources accessible via HTTP GET should be side-effect free. That is, the request should just return a representation of the resource. Invoking the resource should not result in modifying the resource. Now to me if the representation contains the "number of views", it is part of the resource [and in SO the "number of views" a question has is a very important information] and accessing it definitely modifies the resource. This is in sharp contrast with, say, a true RESTFUL HTTP GET like the one you can make on an Amazon S3 resource, where your GET is guaranteed not to modify the resource you get back. But then I'm still very confused.

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• Building an 'Activation Key' Generator in JAVA

  - by jax

  I want to develop a Key generator for my phone applications. Currently I am using an external service to do the job but I am a little concerned that the service might go offline one day hence I will be in a bit of a pickle. How authentication works now. Public key stored on the phone. When the user requests a key the 'phone ID' is sent to the "Key Generation Service" and the encrypted key key is returned and stored inside a license file. On the phone I can check if the key is for the current phone by using a method getPhoneId() which I can check with the the current phone and grant or not grant access to features. I like this and it works well, however, I want to create my own "Key Generation Service" from my own website. Requirements: Public and Private Key Encryption:(Bouncy Castle) Written in JAVA Must support getApplicationId() (so that many applications can use the same key generator) and getPhoneId() (to get the phone id out of the encrypted license file) I want to be able to send the ApplicationId and PhoneId to the service for license key generation. Can someone give me some pointers on how to accomplish this? I have dabbled around with some java encryption but am definitely no expert and can't find anything that will help me. A list of the Java classes I would need to instantiate would be helpful.

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• Can I architect a web app so it can be deployed to either the cloud or a dedicated server / VPS ? Ho

  - by CAD bloke

  Is there are an architecture versatile enough that it may be deployed to either a cloud server or to a dedicated (or VPS) server with minimal change? Obviously there would be config changes but I'd rather leave the rest of the app consistent, keeping one maintainable codebase. The app would be ASP.NET &/or ASP.MVC. My dev environment is VS 2010. The cloud may, or may not be, Azure. Dedicated or VPS would be Win Server 2008. Probably. It is not a public-facing web site. The web app I have in mind would be a separate deployment for each client. Some clients would be small-scale, some will prefer the app to run on a local intranet rather than on the web. Other clients may prefer the cloud approach for a black-box solution. The app may run for a few hours or it may run indefinitely, it depends on the client and the project. Other than deployment scenarios the apps would be more or less identical. As you may see from the tags, I'm assuming a message-based architecture is probably the most versatile but I'm also used to being wrong about this stuff. All suggestions and pointers welcome regarding general architectures and also specific solutions.

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• C++ polymorphism, function calls

  - by moai

  Okay, I'm pretty inexperienced as a programmer, let alone in C++, so bear with me here. What I wanted to do was to have a container class hold a parent class pointer and then use polymorphism to store a child class object. The thing is that I want to call one of the child class's functions through the parent class pointer. Here's a sort of example of what I mean in code: class SuperClass { public: int x; } class SubClass : public SuperClass { public: void function1() { x += 1; } } class Container { public: SuperClass * alpha; Container(SuperClass& beta) { alpha = beta; } } int main() { Container cont = new Container(new SubClass); } (I'm not sure that's right, I'm still really shaky on pointers. I hope it gets the point across, at least.) So, I'm not entirely sure whether I can do this or not. I have a sneaking suspicion the answer is no, but I want to be sure. If someone has another way to accomplish this sort of thing, I'd be glad to hear it.

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• autorelease object not confirming protocol does not give any warning

  - by Sahil Wasan

  I have a class "ABC" and its method which returns non autoreleases object of that class. @interface ABC:NSObject +(ABC *)aClassMethodReturnsObjectWhichNotAutoreleased; @end @implementation ABC +(ABC *)aClassMethodReturnsObjectWhichNotAutoreleased{ ABC *a = [[ABC alloc]init]; return a; } @end If I have a protocol Foo. @Protocol Foo @required -(void)abc; @end My ABC class is "not" confirming Foo protocols. 1st call id<Foo> obj = [ABC aClassMethodReturnsObjectWhichNotAutoreleased]; //show warning It shows warning "Non Compatible pointers.." thats good.Abc did not confirm protocol Foo BUT 2nd call id<Foo> obj = [NSArray arrayWithObjects:@"abc",@"def",nil]; // It will "not" show warning as it will return autorelease object.NSArray don't confirm protocol Foo In first call compiler gives warning and in second call compiler is not giving any warning.I think that is because i am not returning autorelease object. Why is compiler not giving warning in 2nd call as NSArray is also not confirming FOO Thanks in advance

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• Does "delegate" mean a type or an object?

  - by Michal Czardybon

  Reading from MSDN: "A delegate is a type that references a method. Once a delegate is assigned a method, it behaves exactly like that method." Does then "delegate" mean a type or an object?! ...It cannot be both. It seems to me that the single word is used in two different meanings: a type containing a reference to a method of some specified signature, an object of that type, which can be actually called like a method. I would prefer a more precise vocabulary and use "delegate type" for the first case. I have been recently reading a lot about events and delegates and that ambiguity was making me confused many times. Some other uses of "delegate" word in MSDN in the first meaning: "Custom event delegates are needed only when an event generates event data" "A delegate declaration defines a class that is derived from the class System.Delegate" Some other uses of "delegate" word in MSDN in the second meaning: "specify a delegate that will be called upon the occurrence of some event" "Delegates are objects that refer to methods. They are sometimes described as type-safe function pointers" What do you think? Why did people from Microsoft introduced this ambiguity? Am I the only person to have conceptual problems with different notions being referenced with the same word.

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• Best way to implement game loop without freezing UI thread

  - by Matt H

  I'm trying to make a simple 2D game in Java. So far I have a JFrame, with a menubar, and a class which extends JPanel and overrides it's paint method. Now, I need to get a game loop going, where I will update the position of images and so on. However, I'm stuck at how best to achieve this. Should I use multi-threading, because surely, if you put an infinite loop on the main thread, the UI (and thus my menu bar) will freeze up? Here's my code so far: import java.awt.Color; import java.awt.Graphics; import javax.swing.JPanel; @SuppressWarnings("serial") public class GameCanvas extends JPanel { public void paint(Graphics g) { while (true) { g.setColor(Color.DARK_GRAY); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } } } import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; @SuppressWarnings("serial") public class Main extends JFrame { GameCanvas canvas = new GameCanvas(); final int FRAME_HEIGHT = 400; final int FRAME_WIDTH = 400; public static void main(String args[]) { new Main(); } public Main() { super("Game"); JMenuBar menuBar = new JMenuBar(); JMenu fileMenu = new JMenu("File"); JMenuItem startMenuItem = new JMenuItem("Pause"); menuBar.add(fileMenu); fileMenu.add(startMenuItem); super.add(canvas); super.setVisible(true); super.setSize(FRAME_WIDTH, FRAME_WIDTH); super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); super.setJMenuBar(menuBar); } } Any pointers/tips? Also, where should I put my loop? In my main class, or my GameCanvas class? Any help is appreciated, thanks.

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• Dereferencing the null pointer

  - by zilgo

  The standard says that dereferencing the null pointer leads to undefined behaviour. But what is "the null pointer"? In the following code, what we call "the null pointer": struct X { static X* get() { return reinterpret_cast<X*>(1); } void f() { } }; int main() { X* x = 0; (*x).f(); // the null pointer? (1) x = X::get(); (*x).f(); // the null pointer? (2) x = reinterpret_cast<X*>( X::get() - X::get() ); (*x).f(); // the null pointer? (3) (*(X*)0).f(); // I think that this the only null pointer here (4) } My thought is that dereferencing of the null pointer takes place only in the last case. Am I right? Is there difference between compile time null pointers and runtime according to C++ Standard?

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• JPA: persisting object, parent is ok but child not updated

  - by James.Elsey

  Hello, I have my domain object, Client, I've got a form on my JSP that is pre-populated with its data, I can take in amended values, and persist the object. Client has an abstract entity called MarketResearch, which is then extended by one of three more concrete sub-classes. I have a form to pre-populate some MarketResearch data, but when I make changes and try to persist the Client, it doesn't get saved, can someone give me some pointers on where I've gone wrong? My 3 domain classes are as follows (removed accessors etc) public class Client extends NamedEntity { @OneToOne @JoinColumn(name = "MARKET_RESEARCH_ID") private MarketResearch marketResearch; ... } @Inheritance(strategy = InheritanceType.JOINED) public abstract class MarketResearch extends AbstractEntity { ... } @Entity(name="MARKETRESEARCHLG") public class MarketResearchLocalGovernment extends MarketResearch { @Column(name = "CURRENT_HR_SYSTEM") private String currentHRSystem; ... } This is how I'm persisting public void persistClient(Client client) { if (client.getId() != null) { getJpaTemplate().merge(client); getJpaTemplate().flush(); } else { getJpaTemplate().persist(client); } } To summarize, if I change something on the parent object, it persists, but if I change something on the child object it doesn't. Have I missed something blatantly obvious? Thanks

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• Dictionaries with more than one key per value in Python

  - by nickname

  I am attempting to create a nice interface to access a data set where each value has several possible keys. For example, suppose that I have both a number and a name for each value in the data set. I want to be able to access each value using either the number OR the name. I have considered several possible implementations: Using two separate dictionaries, one for the data values organized by number, and one for the data values organized by name. Simply assigning two keys to the same value in a dictionary. Creating dictionaries mapping each name to the corresponding number, and vice versa Attempting to create a hash function that maps each name to a number, etc. (related to the above) Creating an object to encapsulate all three pieces of data, then using one key to map dictionary keys to the objects and simply searching the dictionary to map the other key to the object. None of these seem ideal. The first seems ugly and unmaintainable. The second also seems fragile. The third/fourth seem plausible, but seem to require either much manual specification or an overly complex implementation. Finally, the fifth loses constant-time performance for one of the lookups. In C/C++, I believe that I would use pointers to reference the same piece of data from different keys. I know that the problem is rather similar to a database lookup problem by a non-key column, however, I would like (if possible), to maintain the approximate O(1) performance of Python dictionaries. What is the most Pythonic way to achieve this data structure?

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• What are the default return values for operator< and operator[] in C++ (Visual Studio 6)?

  - by DustOff

  I've inherited a large Visual Studio 6 C++ project that needs to be translated for VS2005. Some of the classes defined operator< and operator[], but don't specify return types in the declarations. VS6 allows this, but not VS2005. I am aware that the C standard specifies that the default return type for normal functions is int, and I assumed VS6 might have been following that, but would this apply to C++ operators as well? Or could VS6 figure out the return type on its own? For example, the code defines a custom string class like this: class String { char arr[16]; public: operator<(const String& other) { return something1 < something2; } operator[](int index) { return arr[index]; } }; Would VS6 have simply put the return types for both as int, or would it have been smart enough to figure out that operator[] should return a char and operator< should return a bool (and not convert both results to int all the time)? Of course I have to add return types to make this code VS2005 C++ compliant, but I want to make sure to specify the same type as before, as to not immediately change program behavior (we're going for compatibility at the moment; we'll standardize things later).

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• Fastest way to perform subset test operation on a large collection of sets with same domain

  - by niktech

  Assume we have trillions of sets stored somewhere. The domain for each of these sets is the same. It is also finite and discrete. So each set may be stored as a bit field (eg: 0000100111...) of a relatively short length (eg: 1024). That is, bit X in the bitfield indicates whether item X (of 1024 possible items) is included in the given set or not. Now, I want to devise a storage structure and an algorithm to efficiently answer the query: what sets in the data store have set Y as a subset. Set Y itself is not present in the data store and is specified at run time. Now the simplest way to solve this would be to AND the bitfield for set Y with bit fields of every set in the data store one by one, picking the ones whose AND result matches Y's bitfield. How can I speed this up? Is there a tree structure (index) or some smart algorithm that would allow me to perform this query without having to AND every stored set's bitfield? Are there databases that already support such operations on large collections of sets?

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• Beginner Question on traversing a EF4 model

  - by user564577

  I have a basic EF4 model with two entities. I'm using Self Tracking Entities Client has ClientAddresses relationship on clientkey = clientkey. (1 to many) How do i get a list/collection of client entities (STE) and their addresses (STE) but only ones where they live in a particular state or some such filter on the address??? This seems to filter and bring back clients but doesnt bring back addresses. var j = from client in context.Clients where client.ClientAddresses.All(c => c.ZIP == "80923") select client; I cant get this to create the Addresses because ClientAddresses is IEnumerable and it needs a TrackableCollection var query = from t1 in context.Clients join t2 in context.ClientAddresses on t1.ClientKey equals t2.ClientKey where t2.ZIP == "80923" select new Client { FirstName = t1.FirstName, LastName = t1.LastName, IsEnabled = t1.IsEnabled, ClientKey = t1.ClientKey, ChangeUser = t1.ChangeUser, ChangeDate = t1.ChangeDate, ClientAddresses = from a in t1.ClientAddresses select new ClientAddress { AddressKey = a.AddressKey, AddressLine1 = a.AddressLine1, AddressLine2 = a.AddressLine2, AddressTypeCode = a.AddressTypeCode, City = a.City, ClientKey = a.ClientKey, State = a.State, ZIP = a.ZIP } }; Any pointers would be appreciated. Thanks Edit: This seems to work.... var j = from client in context.Clients.Include("ClientAddresses") where client.ClientAddresses.Any(c => c.ZIP == "80923") select client;

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• C++ design related question

  - by Kotti

  Hi! Here is the question's plot: suppose I have some abstract classes for objects, let's call it Object. It's definition would include 2D position and dimensions. Let it also have some virtual void Render(Backend& backend) const = 0 method used for rendering. Now I specialize my inheritance tree and add Rectangle and Ellipse class. Guess they won't have their own properties, but they will have their own virtual void Render method. Let's say I implemented these methods, so that Render for Rectangle actually draws some rectangle, and the same for ellipse. Now, I add some object called Plane, which is defined as class Plane : public Rectangle and has a private member of std::vector<Object*> plane_objects; Right after that I add a method to add some object to my plane. And here comes the question. If I design this method as void AddObject(Object& object) I would face trouble like I won't be able to call virtual functions, because I would have to do something like plane_objects.push_back(new Object(object)); and this should be push_back(new Rectangle(object)) for rectangles and new Circle(...) for circles. If I implement this method as void AddObject(Object* object), it looks good, but then somewhere else this means making call like plane.AddObject(new Rectangle(params)); and this is generally a mess because then it's not clear which part of my program should free the allocated memory. ["when destroying the plane? why? are we sure that calls to AddObject were only done as AddObject(new something).] I guess the problems caused by using the second approach could be solved using smart pointers, but I am sure there have to be something better. Any ideas?

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• Masonry js won't bunch images vertically

  - by user1449737

  The images are being aligned horizontally correctly but they are all spaced out vertically.. Take a look here http://brstudios.co.uk/testing to see what I mean properly.. My mark up is as followed (simplified): <html> <head> <script type="text/javascript" src="http://code.jquery.com/jquery-latest.js"></script> <script type="text/javascript" src="http://masonry.desandro.com/jquery.masonry.min.js"></script> <script type="text/javascript" src="https://raw.github.com/desandro/imagesloaded/master/jquery.imagesloaded.min.js"></script> <script type="text/javascript"> var $container = $('.portfolio-container'); $container.imagesLoaded(function(){ $container.masonry({ itemSelector : '.break', columnWidth : 429 }); }); </script> <style type="text/css"> .break { float: left; width: 429px; margin: 10px 20px; } </style> </head> <body> <div class="portfolio-container"> <?php do { ?> <div class="break"> // Contents taken from MySQL // </div> <?php } while ($row_displayPosts = mysql_fetch_assoc($displayPosts)); ?> </div> </body> </html> I think part of it is working but as you can see by the link provided it isn't moving the elements together vertically. Does anyone have any pointers?

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• Elegant code question: How to avoid creating unneeded object

  - by SeaDrive

  The root of my question is that the C# compiler is too smart. It detects a path via which an object could be undefined, so demands that I fill it. In the code, I look at the tables in a DataSet to see if there is one that I want. If not, I create a new one. I know that dtOut will always be assigned a value, but the the compiler is not happy unless it's assigned a value when declared. This is inelegant. How do I rewrite this in a more elegant way? System.Data.DataTable dtOut = new System.Data.DataTable(); . . // find table with tablename = grp // if none, create new table bool bTableFound = false; foreach (System.Data.DataTable d1 in dsOut.Tables) { string d1_name = d1.TableName; if (d1_name.Equals(grp)) { dtOut = d1; bTableFound = true; break; } } if (!bTableFound) dtOut = RptTable(grp);

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• S3 file Uploading from Mac app though PHP?

  - by Ilija Tovilo

  I have asked this question before, but it was deleted due too little information. I'll try to be more concrete this time. I have an Objective-C mac application, which should allow users to upload files to S3-storage. The s3 storage is mine, the users don't have an Amazon account. Until now, the files were uploaded directly to the amazon servers. After thinking some more about it, it wasn't really a great concept, regarding security and flexibility. I want to add a server in between. The user should authenticate with my server, the server would open a session if the authentication was successful, and the file-sharing could begin. Now my question. I want to upload the files to S3. One option would be to make a POST-request and wait until the server would receive the file. Problems here are, that there would be a delay, when the file is being uploaded from my server to the S3 servers, and it would double the uploading time. Best would be, if I could validate the request, and then redirecting it, so the client uploads it directly to the s3-storage. Not sure if this is possible somehow. Uploading directly to S3 doesn't seem to be very smart. After looking into other apps like Droplr and Dropmark, it looks like they don't do this. Btw. I did this using Little Snitch. They have their api on their own web-server, and that's it. Could someone clear things up for me? EDIT How should I transmit my files to S3? Is there a way to "forward" it, or do I have to upload it to my server and then upload it from there to S3? Like I said, other apps can do this efficiently and without the need of communicating with S3 directly.

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• jQuery indexOf select box manipulation

  - by kenny99

  Hi, I'm trying to figure out how to remove options from a select box when that option has been selected in an adjacent select box. Basically the user has the option to add multiple records here via select boxes, but I want to remove the list of options available to them so that, for example, they can't enter the same value in two select boxes. When an Add More button is clicked, I fade in the next select box container. A number of select boxes have been generated by PHP and I use JS to hide them. Each select box has a unique number appended to the ID, so i want to access those select boxes which contain the string "other_pet_types", then I want to iterate through the currently visible ones and build an array of the values which have been selected, which I will then remove from the list of options in the newly displayed select box. This is what I have so far, but it's definitely not right - I can't get the initial test on the ID to work. Any pointers greatly appreciated as i realise i'm pretty wide of the mark at the moment! var vals = new Array(); //build array with currently selected options $('p.mult_entries select').each(function(){ vals += $(this).val(); }); $("p.mult_entries:hidden:first").fadeIn("slow", function() { $(this).find(('select').attr('id').indexOf('other_pet_types') > 0).each(function(){ console.log($(this).val()); //as expected prints nothing - need to iterate through the options of the above select //once i extract the correct values, iterate through new select box and use inArray to remove options where that value already exists in one of previous select boxes }); });

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• wrap from last screen to first screen in android Launcher2

  - by poboy975

  hi, I'm learning java and android. and I've been looking at trying to wrap the last screen to the first screen in the android Launcher2. I've tried googleing, and searching here, but there really isnt much information about the launcher2 source...I've been modifying the workspace.java file, but there has been minimal effect. no wrap around so far...I have not been able to find a .xml file that also might control the hard stop when you reach the end of the screens. I'll give a small example of the code that i have been modifying. original code: public void scrollRight() { clearVacantCache(); if (mNextScreen == INVALID_SCREEN && mCurrentScreen < getChildCount() -1 && mScroller.isFinished()) { snapToScreen(mCurrentScreen + 1); } modified code: public void scrollRight() { clearVacantCache(); if (mNextScreen == INVALID_SCREEN && mCurrentScreen < getChildCount() -1 && mScroller.isFinished()) { snapToScreen(mCurrentScreen + 1); }if (mCurrentScreen == getChildCount() -1 && mScroller.isFinished()) { snapToScreen(0); I would appreciate any tips or pointers if anyone has an idea where i'm going wrong, or someplace i can search to get the answers. the code looks to me like it should work, but I'm probably missing something obvious.

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• PHP : How to get specific data from array

  - by Giffary

  Hello! I try to use amazon API using PHP. If I use print_r($parsed_xml->Items->Item->ItemAttributes) it show me some result like SimpleXMLElement Object ( [Binding] = Electronics [Brand] = Canon [DisplaySize] = 2.5 [EAN] = 0013803113662 [Feature] = Array ( [0] = High-powered 20x wide-angle optical zoom with Optical Image Stabilizer [1] = Capture 720p HD movies with stereo sound; HDMI output connector for easy playback on your HDTV [2] = 2.5-inch Vari-Angle System LCD; improved Smart AUTO intelligently selects from 22 predefined shooting situations [3] = DIGIC 4 Image Processor; 12.1-megapixel resolution for poster-size, photo-quality prints [4] = Powered by AA batteries (included); capture images to SD/SDHC memory cards (not included) ) [FloppyDiskDriveDescription] = None [FormFactor] = Rotating [HasRedEyeReduction] = 1 [IsAutographed] = 0 [IsMemorabilia] = 0 [ItemDimensions] = SimpleXMLElement Object ( [Height] = 340 [Length] = 490 [Weight] = 124 [Width] = 350 ) [Label] = Canon [LensType] = Zoom lens [ListPrice] = SimpleXMLElement Object ( [Amount] = 60103 [CurrencyCode] = USD [FormattedPrice] = $601.03 ) [Manufacturer] = Canon [MaximumFocalLength] = 100 [MaximumResolution] = 12.1 [MinimumFocalLength] = 5 [Model] = SX20IS [MPN] = SX20IS [OpticalSensorResolution] = 12.1 [OpticalZoom] = 20 [PackageDimensions] = SimpleXMLElement Object ( [Height] = 460 [Length] = 900 [Weight] = 242 [Width] = 630 ) [PackageQuantity] = 1 [ProductGroup] = Photography [ProductTypeName] = CAMERA_DIGITAL [ProductTypeSubcategory] = point-and-shoot [Publisher] = Canon [Studio] = Canon [Title] = Canon PowerShot SX20IS 12.1MP Digital Camera with 20x Wide Angle Optical Image Stabilized Zoom and 2.5-inch Articulating LCD [UPC] = 013803113662 ) my goal is to get only Feature infomation and I try to use $feature = $parsed_xml->Items->Item->ItemAttributes->Feature it does'not work for me because it just show me the first feature only. How do i get all feature information? please help

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• Who deletes the copied instance in + operator ? (c++)

  - by Dima

  Hello, I searched how to implement + operator properly all over the internet and all the results i found do the following steps : const MyClass MyClass::operator+(const MyClass &other) const { MyClass result = *this; // Make a copy of myself. Same as MyClass result(*this); result += other; // Use += to add other to the copy. return result; // All done! } I have few questions about this "process" : Isn't that stupid to implement + operator this way, it calls the assignment operator(which copies the class) in the first line and then the copy constructor in the return (which also copies the class , due to the fact that the return is by value, so it destroys the first copy and creates a new one.. which is frankly not really smart ... ) When i write a=b+c, the b+c part creates a new copy of the class, then the 'a=' part copies the copy to himself. who deletes the copy that b+c created ? Is there a better way to implement + operator without coping the class twice, and also without any memory issues ? thanks in advance

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• Timing related crash when unloading a DLL?

  - by fbrereto

  I know I'm reaching for straws here, but this one is a mystery... any pointers or help would be most welcome, so I'm appealing to those more intelligent than I: We have a crash exhibited in our release binaries only. The crash takes place as the binary is bringing itself down and terminating sub-libraries upon which it depends. Its ability to be reproduced is dependent on the machine- some are 100% reliable in reproducing the crash, some don't exhibit the issue at all, and some are in between. The crash is deep within one of the sublibraries, and there is a good likelihood the stack is corrupt by the time the rubble can be brought into a debugger (MSVC 2008 SP1) to be examined. Running the binary under the debugger prevents the bug from happening, as does remote debugging, as does (of all things) connecting to the machine via VNC. We have tried to install the Microsoft Driver Development Kit, and doing so also squelches the bug. What would be the next best place to look? What tools would be best in this circumstance? Does it sound like a race condition, or something else?

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• How does one force construction of a global object in a statically linked library? [MSVC9]

  - by Peter C O Johansson

  I have a global list of function pointers. This list should be populated at startup. Order is not important and there are no dependencies that would complicate static initialization. To facilitate this, I've written a class that adds a single entry to this list in its constructor, and scatter global instances of this class via a macro where necessary. One of the primary goals of this approach is to remove the need for explicitly referencing every instance of this class externally, instead allowing each file that needs to register something in the list to do it independently. Nice and clean. However, when placing these objects in a static library, the linker discards (or rather never links in) these units because no code in them is explicitly referenced. Explicitly referencing symbols in the compilation units would be counterproductive, directly contradicting one of the main goals of the approach. For the same reason, /INCLUDE is not an acceptable option, and /OPT:NOREF is not actually related to this problem. Metrowerks has a __declspec directive for it, GCC has -force_load, but I cannot find any equivalent for MSVC.

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• Listening UDP or switch to TCP in a MFC application

  - by Alexander.S

  I'm editing a legacy MFC application, and I have to add some basic network functionalities. The operating side has to receive a simple instruction (numbers 1,2,3,4...) and do something based on that. The clients wants the latency to be as fast as possible, so naturally I decided to use datagrams (UDP). But reading all sorts of resources left me bugged. I cannot listen to UDP sockets (CAsyncSocket) in MFC, it's only possible to call Receive which blocks and waits. Blocking the UI isn't really a smart. So I guess I could use some threading technique, but since I'm not all that experienced with MFC how should that be implemented? The other part of the question is should I do this, or revert to TCP, considering reliability and implementation issues. I know that UDP is unreliable, but just how unreliable is it really? I read that it is up to 50% faster, which is a lot for me. References I used: http://msdn.microsoft.com/en-us/library/09dd1ycd(v=vs.80).aspx

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• odp.net SQL query retrieve set of rows from two input arrays.

  - by Karl Trumstedt

  I have a table with a primary key consisting of two columns. I want to retrieve a set of rows based on two input arrays, each corresponding to one primary key column. select pkt1.id, pkt1.id2, ... from PrimaryKeyTable pkt1, table(:1) t1, table(:2) t2 where pkt1.id = t1.column_value and pkt1.id2 = t2.column_value I then bind the values with two int[] in odp.net. This returns all different combinations of my resulting rows. So if I am expecting 13 rows I receive 169 rows (13*13). The problem is that each value in t1 and t2 should be linked. Value t1[4] should be used with t2[4] and not all the different values in t2. Using distinct solves my problem, but I'm wondering if my approach is wrong. Anyone have any pointers on how to solve this the best way? One way might be to use a for-loop accessing each index in t1 and t2 sequentially, but I wonder what will be more efficient. Edit: actually distinct won't solve my problem, it just did it based on my input-values (all values in t2 = 0)

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