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  • How to use accessors within the same class in Objective C?

    - by Azeworai
    Hi, I have a few properties defined in my header file like so @property (assign) bool connectivity_N; @property (assign) bool isConnected_N; In my implementation file I have an init and the synthesized properties like so @implementation Map @synthesize connectivity_N; @synthesize isConnected_N; a init to set the initial values like so -(id) init { if( (self=[super init]) ) { //initialise default properties self.connectivity_N=NO; self.isConnected_N=NO; } return self; } I'm running into an error that states Error: accessing unknown 'connectivity_N' class method. In this public method within the class +(bool) isConnectable:(directions) theDirection{ bool isTheDirectionConnectable= NO; switch (theDirection) { case north: isTheDirectionConnectable= self.connectivity_N; break; I'm not sure why is this so as I'm trying to grab the value of the property. According to the apple developer documentation "The default names for the getter and setter methods associated with a property are propertyName and setPropertyName: respectively—for example, given a property “foo”, the accessors would be foo and setFoo:" That has given me a clue that I've done something wrong here, I'm fairly new to objective C so would appreciate anyone who spends the time to explain this to me. Thanks!

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  • Exemplars of large document-centric applications with COM/XPCOM/.NET interfaces.

    - by Warren P
    I am looking for exemplars (design examples) showing the use of interfaces (aka 'protocols' for you smalltalkers) to design a document management architecture in a large Word Processor, Spreadsheet, vector graphic or publishing package, or office-productivity (non-database) application with support for as many of the following as possible: any open source project, will be ideal, and language of implementation is unimportant since I am looking for design examples, however an object oriented language with support for "interfaces" is a must. I know at least a dozen languages, and I'm willing to study any application's source. use of "interface" could loosely be applied to either XPCOM or COM interfaces, or .NET interfaces, or even the use of pure-virtual (virtual+abstract) base-classes for OOP languages that lack the ability to declare an interface distinct from a class. I am mostly looking for a robust, thorough and flexible implementation for a document, IDocument, various document views (IDocumentView), and whatever operations make sense in that case. I am particular interested in cases where the product in question is a real-world product. For example, if anybody familiar with OpenOffice can tell me if the code contains a good sample design. I am looking for design documentation that outlines the design of the interfaces for such an application. So for example, if the openoffice spreadsheet has such an interface design, then that might be the best case, because it is a widely used real-world design, with millions of users, rather than a textbook example, which is minimal, and contrived. I know that the Mozilla platform uses XPCOM, and its design is heavily "interface" oriented, but I am looking more for a "word processor" or "spreadsheet" type of document design, rather than a web-browser. I am particularly interested in the interfaces used to access to data and meta-data such as markup (attributes like bold, and italics, and font size), and the ability to search and look up named entities within a document.

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  • How to detect a Socket disconnection?

    - by AngryHacker
    I've implemented a task using the async Sockets pattern in Silverlight 3. I started with Michael Schwarz's implementation and built on top of that. So basically, my Silverlight app establishes a persistent socket connection to a device and then data flows both ways as necessary between the device and the Silverlight app. One thing I am struggling with is how to detect disconnection. I could think of 2 approaches: Keep-Alive. I know this can be done at the Sockets level, but I am not sure how to do this in an async model. How would the Socket class let me know there has been a disconnection. Manual keep alive. Basically, I am having the Silverlight app send a dummy packet every 20 seconds or so. If it fails, I'd assume disconnection. However, incredibly, SocketAsyncEventArgs.SocketError always reports success, even if I simply unplug the device that the Silverlight app is connected to. I am not sure whether this is a bug or what or perhaps I need to upgrade to SL4. Any ideas, direction or implementation would be appreciated.

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  • Type-safe generic data structures in plain-old C?

    - by Bradford Larsen
    I have done far more C++ programming than "plain old C" programming. One thing I sorely miss when programming in plain C is type-safe generic data structures, which are provided in C++ via templates. For sake of concreteness, consider a generic singly linked list. In C++, it is a simple matter to define your own template class, and then instantiate it for the types you need. In C, I can think of a few ways of implementing a generic singly linked list: Write the linked list type(s) and supporting procedures once, using void pointers to go around the type system. Write preprocessor macros taking the necessary type names, etc, to generate a type-specific version of the data structure and supporting procedures. Use a more sophisticated, stand-alone tool to generate the code for the types you need. I don't like option 1, as it is subverts the type system, and would likely have worse performance than a specialized type-specific implementation. Using a uniform representation of the data structure for all types, and casting to/from void pointers, so far as I can see, necessitates an indirection that would be avoided by an implementation specialized for the element type. Option 2 doesn't require any extra tools, but it feels somewhat clunky, and could give bad compiler errors when used improperly. Option 3 could give better compiler error messages than option 2, as the specialized data structure code would reside in expanded form that could be opened in an editor and inspected by the programmer (as opposed to code generated by preprocessor macros). However, this option is the most heavyweight, a sort of "poor-man's templates". I have used this approach before, using a simple sed script to specialize a "templated" version of some C code. I would like to program my future "low-level" projects in C rather than C++, but have been frightened by the thought of rewriting common data structures for each specific type. What experience do people have with this issue? Are there good libraries of generic data structures and algorithms in C that do not go with Option 1 (i.e. casting to and from void pointers, which sacrifices type safety and adds a level of indirection)?

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  • How to replace auto-implemented c# get body at runtime or compile time?

    - by qstarin
    I've been trying to figure this out all night, but I guess my knowledge of the .Net Framework just isn't that deep and the problem doesn't exactly Google well, but if I can get a nod in the right direction I'm sure I can implement it, one way or another. I'd like to be able to declare a property decorated with a custom attribute as such: public MyClass { [ReplaceWithExpressionFrom(typeof(SomeOtherClass))] public virtual bool MyProperty { get; } } public SomeOtherClass : IExpressionHolder<MyClass, bool> { ... } public interface IExpressionHolder<TArg, TResult> { Expression<Func<TArg, TResult>> Expression { get; } } And then somehow - this is the part I'm having trouble figuring - replace the automatically generated implementation of that getter with a piece of custom code, something like: Type expressionHolderType = LookupAttributeCtorArgTypeInDeclarationOfPropertyWereReplacing(); return ReplaceWithExpressionFromAttribute.GetCompiledExpressionFrom(expressionHolderType)(this); The main thing I'm not sure how to do is replace the automatic implementation of the get. The first thing that came to mind was PostSharp, but that's a more complicated dependency than I care for. I'd much prefer a way to code it without using post-processing attached to the build (I think that's the jist of how PostSharp sinks its hooks in anyway). The other part of this I'm not so sure about is how to retrieve the type parameter passed to the particular instantiation of the ReplaceWithExpressionFrom attribute (where it decorates the property whose body I want to replace; in other words, how do I get typeof(SomeOtherClass) where I'm coding the get body replacement). I plan to cache compiled expressions from concrete instances of IExpressionHolder, as I don't want to do that every time the property gets retrieved. I figure this has just got to be possible. At the very least I figure I should be able to search an assembly for any method decorated with the attribute and somehow proxy the class or just replace the IL or .. something? And I'd like to make the integration as smooth as possible, so if this can be done without explicitly calling a registration or initialization method somewhere that'd be super great. Thanks!

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  • Free cross-platform library to convert numbers (money amounts) to words?

    - by bialix
    I'm looking for cross-platform library which I can use in my C application to convert money amounts (e.g. $123.50) to words (one hundred twenty three dollars and fifty cents). I need support for multiple currencies: dollars, euros, UK pounds etc. Although I understand this is not hard at all to write my own implementation, but I'd like to avoid reinventing wheel. I've tried to google it, but there is too much noise related to MS Word converters. Can anybody suggest something? UPDATE numerous comments suggest to write my own implementation because it's really easy task. And I agree. My point was about support of multiple currencies in the same time and different business rules to spell the amounts (should be fractional part written as text or numbers? etc.) As I understand serious business applications have such library inside, but I think there is nothing open-source available, maybe because it seems as very easy task. I'm going to write my own libary and then open-source it. Thanks to all.

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  • How can one make a 'passthru' function in C++ using macros or metaprogramming?

    - by Ryan
    So I have a series of global functions, say: foo_f1(int a, int b, char *c); foo_f2(int a); foo_f3(char *a); I want to make a C++ wrapper around these, something like: MyFoo::f1(int a, int b, char* c); MyFoo::f2(int a); MyFoo::f3(char* a); There's about 40 functions like this, 35 of them I just want to pass through to the global function, the other 5 I want to do something different with. Ideally the implementation of MyFoo.cpp would be something like: PASSTHRU( f1, (int a, int b, char *c) ); PASSTHRU( f2, (int a) ); MyFoo::f3(char *a) { //do my own thing here } But I'm having trouble figuring out an elegant way to make the above PASSTHRU macro. What I really need is something like the mythical X getArgs() below: MyFoo::f1(int a, int b, char *c) { X args = getArgs(); args++; //skip past implicit this.. ::f1(args); //pass args to global function } But short of dropping into assembly I can't find a good implementation of getArgs().

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  • Java: Inputting text from a file using split

    - by 00PS
    I am inputting an adjacency list for a graph. There are three columns of data (vertex, destination, edge) separated by a single space. Here is my implementation so far: FileStream in = new FileStream("input1.txt"); Scanner s = new Scanner(in); String buffer; String [] line = null; while (s.hasNext()) { buffer = s.nextLine(); line = buffer.split("\\s+"); g.add(line[0]); System.out.println("Added vertex " + line[0] + "."); g.addEdge(line[0], line[1], Integer.parseInt(line[2])); System.out.println("Added edge from " + line[0] + " to " + line[1] + " with a weight of " + Integer.parseInt(line[2]) + "."); } System.out.println("Size of graph = " + g.size()); Here is the output: Added vertex a. Added edge from a to b with a weight of 9. Exception in thread "main" java.lang.NullPointerException at structure5.GraphListDirected.addEdge(GraphListDirected.java:93) at Driver.main(Driver.java:28) I was under the impression that line = buffer.split("\\s+"); would return a 2 dimensional array of Strings to the variable line. It seemed to work the first time but not the second. Any thoughts? I would also like some feedback on my implementation of this problem. Is there a better way? Anything to help out a novice! :)

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  • VB6 Game Development : Don't ask me why :-)

    - by CVS-2600Hertz-wordpress-com
    Hi All, I am developing a game in VB6 (plz don't ask me why :) ). The storyboard is ready and a rough implementation is underway. I am following a "pure-software-rendering" approach. (i.e. no DirectX, no openGL etc.) Amongst many others, the following "serious" problems exist: 2D alpha transparency reqd. to implement overlays. Parallax implementation to give depth-of-field illusion. Capturing mouse-scroll events globally (as in FPS-es; mapping them to changing weapon). Async sound play with absolute "zero-lag". Any ideas anyone. Please suggest any well documented library/ocx or sample-code. Plz do provide solutions with max performance and with as little overhead as possible. Also, anyone who has developed any games, and would be open to sharing her/his code would be highly appreciated. (any well-acknowledged VB games whose source-code i can study??) Thank You

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  • Why is my view controllers view not quadratic?

    - by mystify
    I created an UIViewController subclass, and figured out that the default implementation of -loadView in UIViewController will ignore my frame size settings in a strange way. To simplify it and to make sure it's really not the fault of my code, I did a clean test with a plain instance of UIViewController directly, rather than making a subclass. The result is the same. I try to make an exactly quadratic view of 320 x 320, but the view appears like 320 x 200. iPhone OS 3.0, please check this out: UIViewController *ts = [[UIViewController alloc] initWithNibName:nil bundle:nil]; ts.view.frame = CGRectMake(0.0f, 0.0f, 320.0f, 320.0f); ts.view.backgroundColor = [UIColor cyanColor]; [self.view addSubview:ts.view]; like you can see, I do this: 1) Create a UIViewController instance 2) Set the frame of the view to a quadratic dimension of 320 x 320 3) Give it a color, so I can see it 4) Added it as a subview. Now the part, that's even more strange: When I make my own implementation of -loadView, i.e. if I put this code in there like this: - (void)loadView { UIView *v = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 320.0f, 320.0f)]; v.backgroundColor = [UIColor cyanColor]; self.view = v; [v release]; } then it looks right. Now lets think about that: In the first example, I do pretty much exactly the same, just that I let UIViewController create the view on it's own, and then take it over in order to change it's frame. Right? So why do I get this strange error? Right now I see no other way of messing around like that to correct this wrong behavior. I did not activate anything like clipsToBounds and there's no other code touching this.

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  • Is it a wise decision to go from dev to third line/Tier 3 dev support?

    - by dotnetdev
    Hi, I am an experienced, mid-level developer. However, I recently spotted a job for a company which is small but has a lot of emphasis on training(beyond the basic technical training, but also mentoring, leadership training, etc). The role is 3rd line so still very technical. It's in app support so it's post implementation development rather than pure out-and-out development like I do now (or don't, as the senior devs do all of the interesting work). However, and this is the question - is this sort of career move common? Also, wouldn't a tech support role be a big shock to the system because I've never dealt with customers? I therefore think it's a bad move? Working in dev, I am used to the lack of customer contact and it is all filtered through by my manager. But in tech support, contacting customers/rude customers could be scary. I don't mind fixing other people's mistakes (better than me making mistakes!) and doing post-implementation dev for production systems (will give me a lot of discipline), and I do get bored sitting in the same place looking/talking to the same people in suits (I work in a corporate environment). The company puts A LOT of emphasis on training and prospects, which I don't get in the current (big) company I work at. Any advice on how to handle tech support is appreciated! Thanks

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  • Is there a case for parameterising using Abstract classes rather than Interfaces?

    - by Chris
    I'm currently developing a component based API that is heavily stateful. The top level components implement around a dozen interfaces each. The stock top-level components therefore sit ontop of a stack of Abstract implementations which in turn contain multiple mixin implementations and implement multiple mixin interfaces. So far, so good (I hope). The problem is that the base functionality is extremely complex to implement (1,000s of lines in 5 layers of base classes) and therefore I do not wish for component writers to implement the interfaces themselves but rather to extend my base classes (where all the boiler plate code is already written). If the API therefore accepts interfaces rather than references to the Abstract implementation that I wish for component writers to extends, then I have a risk that the implementer will not perform the validation that is both required and assumed by other areas of code. Therefore, my question is, is it sometimes valid to paramerise API methods using an abstract implementation reference rather than a reference to the interface(s) that it implements? Do you have an example of a well-designed API that uses this technique or am I trying to talk myself into bad-practice?

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  • How to bind Assisted Injected class to interface?

    - by eric2323223
    Here is the problem I met: Class SimpleCommand implements Executable{ private final ConfigManager config; private String name; @Inject public SimpleCommand(ConfigManager config, @Assisted String name){ this.config = config; this.name = name; } } Class MyModule extends AbstractModule{ @Override protected void configure() { bind(CommandFactory.class).toProvider(FactoryProvider.newFactory(CommandFactory.class, SimpleCommand.class)); bind(Executable.class).to(SimpleCommand.class); } } When I try to get instance of SimpleCommand using: Guice.createInjector(new MyModule()).getInstance(CommandFactory.class).create("sample command"); I got this error: 1) No implementation for java.lang.String annotated with @com.google.inject.assistedinject.Assisted(value=) was bound. while locating java.lang.String annotated with @com.google.inject.assistedinject.Assisted(value=) for parameter 2 at model.Command.<init>(SimpleCommand.java:58) at module.MyModule.configure(MyModule.java:34) So my problem is how can I bind SimpleCommand to Executable when SimpleCommand has Assisted Injected parameter? Here is the CommandFactory and its implementation: public interface CommandFactory{ public Command create(String name); } public class GuiceCommandFactory implements CommandFactory{ private Provider<ConfigManager> configManager ; @Inject public GuiceCommandFactory(Provider<ConfigManager> configManager){ this.configManager = configManager; } public Command create(String cmd){ return new Command(configManager.get(), cmd); } }

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  • hibernate annotation bi-directional mapping

    - by smithystar
    I'm building a web application using Spring framework and Hibernate with annotation and get stuck with a simple mapping between two entities. I'm trying to create a many-to-many relationship between User and Course. I followed one of the Hibernate tutorials and my implementation is as follows: User class: @Entity @Table(name="USER") public class User { private Long id; private String email; private String password; private Set<Course> courses = new HashSet<Course>(0); @Id @GeneratedValue @Column(name="USER_ID") public Long getId() { return id; } public void setId(Long id) { this.id = id; } @Column(name="USER_EMAIL") public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } @Column(name="USER_PASSWORD") public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } @ManyToMany(cascade = CascadeType.ALL) @JoinTable(name = "USER_COURSE", joinColumns = { @JoinColumn(name = "USER_ID") }, inverseJoinColumns = { @JoinColumn(name = "COURSE_ID") }) public Set<Course> getCourses() { return courses; } public void setCourses(Set<Course> courses) { this.courses = courses; } } Course class: @Entity @Table(name="COURSE") public class Course { private Long id; private String name; @Id @GeneratedValue @Column(name="COURSE_ID") public Long getId() { return id; } public void setId(Long id) { this.id = id; } @Column(name="NAME") public String getName() { return name; } public void setName(String name) { this.name = name; } } The problem is that this implementation only allows me to go one way user.getCourses() What do I need to change, so I can go in both directions? user.getCourses() course.getUsers() Any help would be appreciated.

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  • How can I determine whether or not to add project items using IWizard?

    - by taarskog
    Hi, I am generating entity wrappers in VS2010 based on dynamic objects in a CRM system. In addition to the entity code, I want to add an EntityBase of which all entities inherit from. If the file exists in the project from before, it should not be added. I am using an IWizard implementation to give the generator the object names etc. Is it possible in the IWizard implementation to determine whether or not to add an item if it exists in the project from before? How do I get a hold of the project handle and its items in or before the ShouldAddProjectItem method? My code so far (not completed): public class EntityWizardImplementation : IWizard { public void BeforeOpeningFile(ProjectItem projectItem) { //Note: Nothing here. } public void ProjectFinishedGenerating(Project project) { //Note: Nothing here. } public void ProjectItemFinishedGenerating(ProjectItem projectItem) { //Note: Nothing here. } public void RunFinished() { //Note: Nothing here. } public void RunStarted(object automationObject, Dictionary<string, string> replacementsDictionary, WizardRunKind runKind, object[] customParams) { try { var window = new WizardWindow(); // Replace parameters gathered from the wizard replacementsDictionary.Add("$crmEntity$", window.CrmEntity); replacementsDictionary.Add("$crmOrganization$", window.CrmOrganization); replacementsDictionary.Add("$crmMetadataServiceUrl$", window.CrmMetadataUrl); window.Close(); } catch (SoapException se) { MessageBox.Show(se.ToString()); } catch (Exception e) { MessageBox.Show(e.ToString()); } } public bool ShouldAddProjectItem(string filePath) { // This is where I assume it is correct to handle the preexisting file. return true; } }

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  • Ways to make (relatively) safe assumptions about the type of concrete subclasses?

    - by Kylotan
    I have an interface (defined as a abstract base class) that looks like this: class AbstractInterface { public: bool IsRelatedTo(const AbstractInterface& other) const = 0; } And I have an implementation of this (constructors etc omitted): class ConcreteThing { public: bool IsRelatedTo(const AbstractInterface& other) const { return m_ImplObject.has_relationship_to(other.m_ImplObject); } private: ImplementationObject m_ImplObject; } The AbstractInterface forms an interface in Project A, and the ConcreteThing lives in Project B as an implementation of that interface. This is so that code in Project A can access data from Project B without having a direct dependency on it - Project B just has to implement the correct interface. Obviously the line in the body of the IsRelatedTo function cannot compile - that instance of ConcreteThing has an m_ImplObject member, but it can't assume that all AbstractInterfaces do, including the other argument. In my system, I can actually assume that all implementations of AbstractInterface are instances of ConcreteThing (or subclasses thereof), but I'd prefer not to be casting the object to the concrete type in order to get at the private member, or encoding that assumption in a way that will crash without a diagnostic later if this assumption ceases to hold true. I cannot modify ImplementationObject, but I can modify AbstractInterface and ConcreteThing. I also cannot use the standard RTTI mechanism for checking a type prior to casting, or use dynamic_cast for a similar purpose. I have a feeling that I might be able to overload IsRelatedTo with a ConcreteThing argument, but I'm not sure how to call it via the base IsRelatedTo(AbstractInterface) method. It wouldn't get called automatically as it's not a strict reimplementation of that method. Is there a pattern for doing what I want here, allowing me to implement the IsRelatedTo function via ImplementationObject::has_relationship_to(ImplementationObject), without risky casts? (Also, I couldn't think of a good question title - please change it if you have a better one.)

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  • UIViewController maintains state after being nilled

    - by Eric
    In my app, I made a BookViewController class that displays and animates the pages of a book and a MainMenuViewController class that displays a set of books the user can read. In the latter class, when the user taps on one of the books, a function is called that should create a completely new instance of BookViewController, but for some reason the instance maintains its state (i.e. it resumes from the page the user left off). How can this be if I set it to nil? What am I missing here? (Note that I'm using ARC). MainMenuViewController.m @interface MainMenuViewController () @property (strong) BookViewController *bookViewController; @end @implementation MainMenuViewController @synthesize bookViewController; -(void)bookTapped:(UIButton *)sender{ NSString *bookTitle; if(sender == book1button) bookTitle = @"book1"; else if(sender == book2button) bookTitle = @"book2"; bookViewController = nil; bookViewController = [[BookViewController alloc] initWithBookTitle:bookTitle]; [self presentViewController:bookViewController animated:YES completion:nil]; } BookViewController.h @interface BookViewController : UIViewController -(id)initWithBookTitle:(NSString *)bookTitle; @end BookViewController.m @implementation BookViewController -(id)initWithBookTitle:(NSString *)theBookTitle{ self = [super init]; if(self){ bookTitle = [NSString stringWithFormat:@"%@", theBookTitle]; [self setModalTransitionStyle:UIModalTransitionStyleCrossDissolve]; NSLog(@"init a BookViewController with bookTitle: %@", bookTitle); } return self; } Every time a book is tapped, bookTapped: is called, and thee console always prints: 2012-08-31 16:29:51.750 AppName[25713:c07] init a BookViewController with bookTitle: book1 So if a new instance of BookViewController is being created, how come it seems to be returning the old one?

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  • Extensions methods and forward compatibilty of source code.

    - by TcKs
    Hi, I would like solve the problem (now hypothetical but propably real in future) of using extension methods and maginification of class interface in future development. Example: /* the code written in 17. March 2010 */ public class MySpecialList : IList<MySpecialClass> { // ... implementation } // ... somewhere elsewhere ... MySpecialList list = GetMySpecialList(); // returns list of special classes var reversedList = list.Reverse().ToList(); // .Reverse() is extension method /* now the "list" is unchanged and "reveresedList" has same items in reversed order */ /* --- in future the interface of MySpecialList will be changed because of reason XYZ*/ /* the code written in some future */ public class MySpecialList : IList<MySpecialClass> { // ... implementation public MySpecialList Reverse() { // reverse order of items in this collection return this; } } // ... somewhere elsewhere ... MySpecialList list = GetMySpecialList(); // returns list of special classes var reversedList = list.Reverse().ToList(); // .Reverse() was extension method but now is instance method and do something else ! /* now the "list" is reversed order of items and "reveresedList" has same items lake in "list" */ My question is: Is there some way how to prevent this case (I didn't find them)? If is now way how to prevent it, is there some way how to find possible issues like this? If is now way how to find possible issues, should I forbid usage of extension methods? Thanks.

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  • Obj-C Sending Messages Between Classes

    - by user544359
    I'm a newbie in iPhone Programming. I'm trying to send a message from one view controller to another. The idea is that viewControllerA takes information from the user and sends it to viewControllerB. viewControllerB is then supposed to display the information in a label. viewControllerA.h #import <UIKit/UIKit.h> @interface viewControllerA : UIViewController { int num; } -(IBAction)do; @end viewControllerA.m #import "viewControllerA.h" #import "viewControllerB.h" @implementation viewControllerA - (IBAction)do { //initializing int for example num = 2; viewControllerB *viewB = [[viewControllerB alloc] init]; [viewB display:num]; [viewB release]; //viewA is presented as a ModalViewController, so it dismisses itself to return to the //original view, i know it is not efficient [self dismissModalViewControllerAnimated:YES]; } - (void)dealloc { [super dealloc]; } @end viewControllerB.h #import <UIKit/UIKit.h> @interface viewControllerB : UIViewController { IBOutlet UILabel *label; } - (IBAction)openA; - (void)display:(NSInteger)myNum; @end viewControllerB.m #import "viewControllerB.h" #import "viewControllerA.h" @implementation viewControllerB - (IBAction)openA { //presents viewControllerA when a button is pressed viewControllerA *viewA = [[viewControllerA alloc] init]; [self presentModalViewController:viewA animated:YES]; } - (void)display:(NSInteger)myNum { NSLog(@"YES"); [label setText:[NSString stringWithFormat:@"%d", myNum]]; } @end YES is logged successfully, but the label's text does not change. I have made sure that all of my connections in Interface Builder are correct, in fact there are other (IBAction) methods in my program that change the text of this very label, and all of those other methods work perfectly... Any ideas, guys? You don't need to give me a full solution, any bits of information will help. Thanks.

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  • is there a simple timed lock algorithm avoiding deadlock on multiple mutexes?

    - by Vicente Botet Escriba
    C++0x thread library or Boost.thread define a non-member variadic template function that locks all mutex at once that helps to avoid deadlock. template <class L1, class L2, class... L3> void lock(L1&, L2&, L3&...); The same can be applied to a non-member variadic template function try_lock_until, which locks all the mutex until a given time is reached that helps to avoid deadlock like lock(...). template <class Clock, class Duration, class L1, class L2, class... L3> void try_lock_until( const chrono::time_point<Clock,Duration>& abs_time, L1&, L2&, L3&...); I have an implementation that follows the same design as the Boost function boost::lock(...). But this is quite complex. As I can be missing something evident I wanted to know if: is there a simple timed lock algorithm avoiding deadlock on multiple mutexes? If no simple implementation exists, can this justify a proposal to Boost? P.S. Please avoid posting complex solutions.

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  • License For (Mostly) Open Source Website / Service

    - by Ryan Sullivan
    I have an interesting setup and am not sure how to license a website. I know this is not legal advice, and I am not asking for any. There are so many different Open Source Licenses and I do not have the time to read every last one to see which best fits my situation. Really, I am looking for suggestions and a nudge in the right direction. My setup is: I give away for free version of my web service with a clean website interface. The implementation I use in the actual web site is (almost) identical to what I give away. The main service works the exactly the same way, but the website interface to manage features in the service is fairly different. Really the web interfaces have the same exact backend, and the front ends accomplish the same tasks, but the service I offer on my site is very rich and uses a good deal of javascript, where I kept the interface in the version I give away as simple and javascript-less as possible. Mostly so it is easy to understand and integrate into other sites. I am not entirely sure how I should license this. It is more like I develop an open source service but have a separate site built upon it. I like the GPLv3 but I am not sure if I can use it in this case especially since I am making some money off of google ad's on the site and plan on using amazon affiliates as well. Any help would be greatly appreciated. I do want to open it up as much as possible. But I still want to be able to continue with my own implementation. Thanks in advance for any information or help anyone can provide.

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  • Java: multi-threaded maps: how do the implementations compare?

    - by user346629
    I'm looking for a good hash map implementation. Specifically, one that's good for creating a large number of maps, most of them small. So memory is an issue. It should be thread-safe (though losing the odd put might be an OK compromise in return for better performance), and fast for both get and put. And I'd also like the moon on a stick, please, with a side-order of justice. The options I know are: HashMap. Disastrously un-thread safe. ConcurrentHashMap. My first choice, but this has a hefty memory footprint - about 2k per instance. Collections.sychronizedMap(HashMap). That's working OK for me, but I'm sure there must be faster alternatives. Trove or Colt - I think neither of these are thread-safe, but perhaps the code could be adapted to be thread safe. Any others? Any advice on what beats what when? Any really good new hash map algorithms that Java could use an implementation of? Thanks in advance for your input!

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  • Python "callable" attribute (pseudo-property)

    - by mgilson
    In python, I can alter the state of an instance by directly assigning to attributes, or by making method calls which alter the state of the attributes: foo.thing = 'baz' or: foo.thing('baz') Is there a nice way to create a class which would accept both of the above forms which scales to large numbers of attributes that behave this way? (Shortly, I'll show an example of an implementation that I don't particularly like.) If you're thinking that this is a stupid API, let me know, but perhaps a more concrete example is in order. Say I have a Document class. Document could have an attribute title. However, title may want to have some state as well (font,fontsize,justification,...), but the average user might be happy enough just setting the title to a string and being done with it ... One way to accomplish this would be to: class Title(object): def __init__(self,text,font='times',size=12): self.text = text self.font = font self.size = size def __call__(self,*text,**kwargs): if(text): self.text = text[0] for k,v in kwargs.items(): setattr(self,k,v) def __str__(self): return '<title font={font}, size={size}>{text}</title>'.format(text=self.text,size=self.size,font=self.font) class Document(object): _special_attr = set(['title']) def __setattr__(self,k,v): if k in self._special_attr and hasattr(self,k): getattr(self,k)(v) else: object.__setattr__(self,k,v) def __init__(self,text="",title=""): self.title = Title(title) self.text = text def __str__(self): return str(self.title)+'<body>'+self.text+'</body>' Now I can use this as follows: doc = Document() doc.title = "Hello World" print (str(doc)) doc.title("Goodbye World",font="Helvetica") print (str(doc)) This implementation seems a little messy though (with __special_attr). Maybe that's because this is a messed up API. I'm not sure. Is there a better way to do this? Or did I leave the beaten path a little too far on this one? I realize I could use @property for this as well, but that wouldn't scale well at all if I had more than just one attribute which is to behave this way -- I'd need to write a getter and setter for each, yuck.

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  • two view controllers and reusability with delegate

    - by netcharmer
    Newbie question about design patterns in objC. I'm writing a functionality for my iphone app which I plan to use in other apps too. The functionality is written over two classes - Viewcontroller1 and Viewcontroller2. Viewcontroller1 is the root view of a navigation controller and it can push Viewcontroller2. Rest of the app will use only ViewController1 and will never access Viewcontroller2 directly. However, triggered by user events, Viewcontroller2 has to send a message to the rest of the app. My question is what is the best way of achieving it? Currently, I use two level of delegation to send the message out from Viewcontroller2. First send it to Viewcontroller1 and then let Viewcontroller1 send it to rest of the app or the application delegate. So my code looks like - //Viewcontroller1.h @protocol bellDelegate -(int)bellRang:(int)size; @end @interface Viewcontroller1 : UITableViewController <dummydelegate> { id <bellDelegate> delegate; @end //Viewcontroller1.m @implementation Viewcontroller1 -(void)viewDidLoad { //some stuff here Viewcontroller2 *vc2 = [[Viewcontroller2 alloc] init]; vc2.delegate = self; [self.navigationController pushViewController:vc2 animated:YES]; } -(int)dummyBell:(int)size { return([self.delegate bellRang:size]); } //Viewcontroller2.h @protocol dummyDelegate -(int)dummyBell:(int)size; @end @interface Viewcontroller2 : UITableViewController { id <dummyDelegate> delegate; @end //Viewcontroller2.m @implementation Viewcontroller2 -(int)eventFoo:(int)size { rval = [self.delegate dummyBell:size]; } @end

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  • OSX: Programmatically added subviews not responding to mouse down events

    - by BigCola
    I have 3 subclasses: a Block class, a Row class and a Table class. All are subclasses of NSView. I have a Table added with IB which programmatically displays 8 rows, each of which displays 8 blocks. I overrode the mouseDown: method in Block to change the background color to red, but it doesn't work. Still if I add a block directly on top of the Table with IB it does work so I can't understand why it won't work in the first case. Here's the implementation code for Block and Row (Table's implementation works the same way as Row's): //block.m - (void)drawRect:(NSRect)dirtyRect { [color set]; [NSBezierPath fillRect:dirtyRect]; } -(void)mouseDown:(NSEvent *)theEvent { color = [NSColor redColor]; checked = YES; [self setNeedsDisplay:YES]; } //row.m - (void)drawRect:(NSRect)dirtyRect { [[NSColor blueColor] set]; [NSBezierPath fillRect:dirtyRect]; int x; for(x=0; x<8; x++){ int margin = x*2; NSRect rect = NSMakeRect(0, 50*x+margin, 50, 50); Block *block = [[Block alloc] initWithFrame:rect]; [self addSubview:block]; } }

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