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  • Displaying indexed png- files out of NSArray on the iphone screen

    - by Thomas Hülsmann
    Hi, i like to create an artwork counter- display on an iphone, diplaying 0 to 9. The 10 digits are 10 png- files with the numbers 0 to 9 as their artwork content. The 10 png- files are implemented by using NSArray. Following you'll find the implementation- code: zahlenArray = [NSArray arrayWithObjects: [UIImage imageNamed:@"ziffer-0.png"], [UIImage imageNamed:@"ziffer-1.png"], [UIImage imageNamed:@"ziffer-2.png"], [UIImage imageNamed:@"ziffer-3.png"], [UIImage imageNamed:@"ziffer-4.png"], [UIImage imageNamed:@"ziffer-5.png"], [UIImage imageNamed:@"ziffer-6.png"], [UIImage imageNamed:@"ziffer-7.png"], [UIImage imageNamed:@"ziffer-8.png"], [UIImage imageNamed:@"ziffer-9.png"], nil]; As an index for the 10 digitis I use an integer variable, initializing with 0: int counter = 0; Furthermore I declare an UIImageview programmaticaly: UIImageView *zahlenEinsBisNeun; The implementation code for the UIImageview is: zahlenEinsBisNeun = [UIImage alloc] initWithFrame:CGRectMake(240, 50, 200, 200)]; ???????????????????????????????????????? [self.view addSubview:zahlenEinsBisNeun]; [zahlenEinsBisNeun release]; There, where you see the questionmarks, I don't know how to write the code, to retrieve my content artworks 0 to 9 from NSArray with the index "counter" and make it visible on my iphone screen by using .... addSubview:zahlenEinsBisNeun ... Can anybody help??? My thanks for your support in advance Thomas Hülsmann

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  • When can a == b be false and a.Equals(b) true?

    - by alastairs
    I ran into this situation today. I have an object which I'm testing for equality; the Create() method returns a subclass implementation of MyObject. MyObject a = MyObject.Create(); MyObject b = MyObject.Create(); a == b; // is false a.Equals(b); // is true Note I have also over-ridden Equals() in the subclass implementation, which does a very basic check to see whether or not the passed-in object is null and is of the subclass's type. If both those conditions are met, the objects are deemed to be equal. The other slightly odd thing is that my unit test suite does some tests similar to Assert.AreEqual(MyObject.Create(), MyObject.Create()); // Green bar and the expected result is observed. Therefore I guess that NUnit uses a.Equals(b) under the covers, rather than a == b as I had assumed. Side note: I program in a mixture of .NET and Java, so I might be mixing up my expectations/assumptions here. I thought, however, that a == b worked more consistently in .NET than it did in Java where you often have to use equals() to test equality.

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  • How to keep only duplicates efficiently?

    - by Marc Eaddy
    Given an STL vector, I'd like an algorithm that outputs only the duplicates in sorted order, e.g., INPUT : { 4, 4, 1, 2, 3, 2, 3 } OUTPUT: { 2, 3, 4 } The algorithm is trivial, but the goal is to make it as efficient as std::unique(). My naive implementation modifies the container in-place: My naive implementation: void keep_duplicates(vector<int>* pv) { // Sort (in-place) so we can find duplicates in linear time sort(pv->begin(), pv->end()); vector<int>::iterator it_start = pv->begin(); while (it_start != pv->end()) { size_t nKeep = 0; // Find the next different element vector<int>::iterator it_stop = it_start + 1; while (it_stop != pv->end() && *it_start == *it_stop) { nKeep = 1; // This gets set redundantly ++it_stop; } // If the element is a duplicate, keep only the first one (nKeep=1). // Otherwise, the element is not duplicated so erase it (nKeep=0). it_start = pv->erase(it_start + nKeep, it_stop); } } If you can make this more efficient, elegant, or general, please let me know. For example, a custom sorting algorithm, or copy elements in the 2nd loop to eliminate the erase() call.

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  • WCF Callback Faulted - what happens to the session?

    - by RemotecUk
    Just trying to get my head around what can happen when things go wrong with WCF. I have an implementation of my service contract declared with an InstanceContextMode of PerSession... [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession, ConcurrencyMode = ConcurrencyMode.Multiple)] The calls happen as follows: My client calls the server and calls GetServerUTC() to return the current UTC time of the server. This is a one way call and the server will call the client back when its ready (trivial in this instance to simply return the current time!) The server calls back to the client and for test purposes in the callback implementation on the client I throw an exception. This goes unhandled in the client (for test purposes) and the client crashes and closes down. On the server I handle the faulted event handler on the ICommunicationObject... obj.Faulted += new EventHandler(EventService_Faulted); Questions... Will this kill off the session for the current connection on the server. I presume I am free to do what I want in this method e.g. logging or something, but should I do anything specific here to terminate the session or will WCF handle this? From a best practise view point what should I do when the callback is faulted? Does it mean "something has happened in your client" and thats the end of that or is there something I a missing here? Additionally, are there any other faulted handlers I should be handling. Ive done a lot of reading on WCF and it seems sort of vague on what to do when something goes wrong. At present I am implementing a State Machine on my client which will manage the connection and determine if a user action can happen dependant on if a connection exists to the server - or is this overkill. Any tips would be really appreciated ;)

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  • Synchronization of Nested Data Structures between Threads in Java

    - by Dominik
    I have a cache implementation like this: class X { private final Map<String, ConcurrentMap<String, String>> structure = new HashMap...(); public String getValue(String context, String id) { // just assume for this example that there will be always an innner map final ConcurrentMap<String, String> innerStructure = structure.get(context); String value = innerStructure.get(id); if(value == null) { synchronized(structure) { // can I be sure, that this inner map will represent the last updated // state from any thread? value = innerStructure.get(id); if(value == null) { value = getValueFromSomeSlowSource(id); innerStructure.put(id, value); } } } return value; } } Is this implementation thread-safe? Can I be sure to get the last updated state from any thread inside the synchronized block? Would this behaviour change if I use a java.util.concurrent.ReentrantLock instead of a synchronized block, like this: ... if(lock.tryLock(3, SECONDS)) { try { value = innerStructure.get(id); if(value == null) { value = getValueFromSomeSlowSource(id); innerStructure.put(id, value); } } finally { lock.unlock(); } } ... I know that final instance members are synchronized between threads, but is this also true for the objects held by these members? Maybe this is a dumb question, but I don't know how to test it to be sure, that it works on every OS and every architecture.

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  • How can I effectively test against the Windows API?

    - by Billy ONeal
    I'm still having issues justifying TDD to myself. As I have mentioned in other questions, 90% of the code I write does absolutely nothing but Call some Windows API functions and Print out the data returned from said functions. The time spent coming up with the fake data that the code needs to process under TDD is incredible -- I literally spend 5 times as much time coming up with the example data as I would spend just writing application code. Part of this problem is that often I'm programming against APIs with which I have little experience, which forces me to write small applications that show me how the real API behaves so that I can write effective fakes/mocks on top of that API. Writing implementation first is the opposite of TDD, but in this case it is unavoidable: I do not know how the real API behaves, so how on earth am I going to be able to create a fake implementation of the API without playing with it? I have read several books on the subject, including Kent Beck's Test Driven Development, By Example, and Michael Feathers' Working Effectively with Legacy Code, which seem to be gospel for TDD fanatics. Feathers' book comes close in the way it describes breaking out dependencies, but even then, the examples provided have one thing in common: The program under test obtains input from other parts of the program under test. My programs do not follow that pattern. Instead, the only input to the program itself is the system upon which it runs. How can one effectively employ TDD on such a project?

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  • dotnetopenauth with asp.net mvc proving too frustrating to use.

    - by Stacey
    I've been trying excessively hard to implement a good open id solution into asp.net mvc - and everywhere I turn is absolute dead ends. DotNetOpenAuth is just too big and I have been thusfar unable to get even the most simplistic, basic, absolute cut and dry implementation of it to work. NerdDinner had a promising implementation, but it is impossible to track down all of the dependant files and scripts. The DotNetOpenAuth website has virtually no information that helps, either, unfortunately. Does ANYONE know of a simple approach to just implementing this that actually explains and details how it is working with some kind of selector? It is talked about so much, but everything I find for it is so difficult to work with that it is really putting my whole team off from even considering it. We want to implement it similar to how stack overflow already does - using a selector that'll popup a login page if it needs to. I realize there is a lot of code that needs to be done for this, but everything just hails and praises dotnetopenauth, and nothing really teaches it. Even the sample projects do not open or compile. It looks like a wonderful library - but it really just isn't clicking for me.

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  • How to serialize object containing NSData?

    - by AO
    I'm trying to serialize an object containing a number of data fields...where one of the fields is of datatype NSData which won't serialize. I've followed instructions at http://www.isolated.se but my code (see below) results in the error "[NSConcreteData data]: unrecognized selector sent to instance...". How do I serialize my object? Header file: @interface Donkey : NSObject<NSCoding> { NSString* s; NSData* d; } @property (nonatomic, retain) NSString* s; @property (nonatomic, retain) NSData* d; - (NSData*) serialize; @end Implementation file: @implementation Donkey @synthesize s, d; static NSString* const KEY_S = @"string"; static NSString* const KEY_D = @"data"; - (void) encodeWithCoder:(NSCoder*)coder { [coder encodeObject:self.s forKey:KEY_S]; [coder encodeObject:self.d forKey:KEY_D]; } - (id) initWithCoder:(NSCoder*)coder; { if(self = [super init]) { self.s = [coder decodeObjectForKey:KEY_STRING]; self.d [coder decodeObjectForKey:KEY_DATA]; } return self; } - (NSData*) serialize { return [NSKeyedArchiver archivedDataWithRootObject:self]; } @end

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  • Suggestions on how build an HTML Diff tool?

    - by Danimal
    In this post I asked if there were any tools that compare the structure (not actual content) of 2 HTML pages. I ask because I receive HTML templates from our designers, and frequently miss minor formatting changes in my implementation. I then waste a few hours of designer time sifting through my pages to find my mistakes. The thread offered some good suggestions, but there was nothing that fit the bill. "Fine, then", thought I, "I'll just crank one out myself. I'm a halfway-decent developer, right?". Well, once I started to think about it, I couldn't quite figure out how to go about it. I can crank out a data-driven website easily enough, or do a CMS implementation, or throw documents in and out of BizTalk all day. Can't begin to figure out how to compare HTML docs. Well, sure, I have to read the DOM, and iterate through the nodes. I have to map the structure to some data structure (how??), and then compare them (how??). It's a development task like none I've ever attempted. So now that I've identified a weakness in my knowledge, I'm even more challenged to figure this out. Any suggestions on how to get started? clarification: the actual content isn't what I want to compare -- the creative guys fill their pages with lorem ipsum, and I use real content. Instead, I want to compare structure: <div class="foo">lorem ipsum<div> is different that <div class="foo"><p>lorem ipsum<p><div>

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  • Error While Linking Multiple C Object files in Delphi 2007

    - by Ramnish
    Hello Everyone. I am new to delphi. I was trying to add C Object files in my Delphi project and link them directly since Delphi Supports C Object Linking. I got it working when i link a single Object file. But when i try to link multiple object files, i am getting error 'Unsatisfied forward or external declaration'. I have tried this in Delphi 2007 as well as XE.So what am i doing wrong here? Working Code: function a_function():Integer;cdecl; implementation {$Link 'a.obj'} function a_function():Integer;cdecl;external; end. Error Code: function a_function():Integer;cdecl; function b_function();Integer;cdecl; function c_function();Integer;cdecl; implementation {$LINK 'a.obj'} {$LINK 'b.obj'} {$LINK 'c.obj'} function a_function():Integer;cdecl;external; function b_function();Integer;cdecl;external; function c_function();Integer;cdecl;external; end.

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  • Delphi Mock Wizard

    - by Todd
    Let me preface this by saying I'm fairly new to Unit Testing, Mocks, Stubs, Etc... I've installed Delphi-Mock-Wizard. When I select a unit and "Generate Mock", a new unit is created but it's very basic and not anything what I understand Mocks to be. unit Unit1; (** WARNING - AUTO-GENERATED MOCK! Change this unit if you want to, but be aware that any changes you make will be lost if you regenerate the mock object (for instance, if the interface changes). My advice is to create a descendent class of your auto-generated mock - in a different unit - and override things there. That way you get to keep them. Also, the auto-generate code is not yet smart enough to generate stubs for inherited interfaces. In that case, change your mock declaration to inherit from a mock implementation that implements the missing interface. This, unfortunately, is a violation of the directive above. I'm working on it. You may also need to manually change the unit name, above. Another thing I am working on. **) interface uses PascalMock, TestInterfaces; type IThingy = interface; implementation end. Looking at the source there seems to be quite a bit commented out. I'm wondering, has anyone gotten this to work? My IDE is D2010. Thanks.

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  • Pitfalls and practical Use-Cases: Toplink, Hibernate, Eclipse Link, Ibatis ...

    - by Martin K.
    I worked a lot with Hibernate as my JPA implementation. In most cases it works fine! But I have also seen a lot of pitfalls: Remoting with persisted Objects is difficult, because Hibernate replaces the Java collections with its own collection implementation. So the every client must have the Hibernate .jar libraries. You have to take care on LazyLoading exceptions etc. One way to get around this problem is the use of webservices. Dirty checking is done against the Database without any lock. "Delayed SQL", causes that the data access isn't ACID compliant. (Lost data...) Implict Updates So we don't know if an object is modified or not (commit causes updates). Are there similar issues with Toplink, Eclipse Link and Ibatis? When should I use them? Have they a similar performance? Are there reasons to choose Eclipse Link/Toplink... over Hibernate?

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  • Practical Scheme Programming

    - by Ixmatus
    It's been a few months since I've touched Scheme and decided to implement a command line income partitioner using Scheme. My initial implementation used plain recursion over the continuation, but I figured a continuation would be more appropriate to this type of program. I would appreciate it if anyone (more skilled with Scheme than I) could take a look at this and suggest improvements. I'm that the multiple (display... lines is an ideal opportunity to use a macro as well (I just haven't gotten to macros yet). (define (ab-income) (call/cc (lambda (cc) (let ((out (display "Income: ")) (income (string->number (read-line)))) (cond ((<= income 600) (display (format "Please enter an amount greater than $600.00~n~n")) (cc (ab-income))) (else (let ((bills (* (/ 30 100) income)) (taxes (* (/ 20 100) income)) (savings (* (/ 10 100) income)) (checking (* (/ 40 100) income))) (display (format "~nDeduct for bills:---------------------- $~a~n" (real->decimal-string bills 2))) (display (format "Deduct for taxes:---------------------- $~a~n" (real->decimal-string taxes 2))) (display (format "Deduct for savings:-------------------- $~a~n" (real->decimal-string savings 2))) (display (format "Remainder for checking:---------------- $~a~n" (real->decimal-string checking 2)))))))))) Invoking (ab-income) asks for input and if anything below 600 is provided it (from my understanding) returns (ab-income) at the current-continuation. My first implementation (as I said earlier) used plain-jane recursion. It wasn't bad at all either but I figured every return call to (ab-income) if the value was below 600 kept expanding the function. (please correct me if that apprehension is incorrect!)

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  • Graph drawing for the Web 2.0

    - by tokel
    Hi. There are a lot of chart drawing libraries out there, but what I am looking for is an interactive(!) graph (nodes and edges) drawing library. At best some kind of AJAX, but I am also open for other technologies (Java, Flash). However I would really prefer an AJAX implementation. Also only Open Source framework suggestions please (I already know about yFiles). The thing I have in mind is a bit like GWTUML. That is quite nice already, but misses an API for their graph drawing. It seems that it is an custom implementation for their product. Also some layout algorithms would be nice. Is there really no library around for that task? I wonder a bit as there are so many chart libraries available. Let me emphasize again (seems to be necessary cause of the first two comments): I am NOT looking for another chart library! Regards, Kai P.S. Things I know about already: JUNG (Java), Prefuse (Java), GINY (Java), yFiles (AJAX, but not Open Source). Just another graph library I found (Javascript, not sure if it is still maintained): Graph Gear

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  • trying to make a simple grid-class, non-lvalue in assignment

    - by Tyrfing
    I'm implementing a simple C++ grid class. One Function it should support is accessed through round brackets, so that I can access the elements by writing mygrid(0,0). I overloaded the () operator and i am getting the error message: "non-lvalue in assignment". what I want to be able to do: //main cGrid<cA*> grid(5, 5); grid(0,0) = new cA(); excerpt of my implementation of the grid class: template class cGrid { private: T* data; int mWidth; int mHeight; public: cGrid(int width, int height) : mWidth(width), mHeight(height) { data = new T[width*height]; } ~cGrid() { delete data; } T operator ()(int x, int y) { if (x >= 0 && x <= mWidth) { if (y >= 0 && y <= mHeight) { return data[x + y * mWidth]; } } } const T &operator ()(int x, int y) const { if (x >= 0 && x <= mWidth) { if (y >= 0 && y <= mHeight) { return data[x + y * mWidth]; } } } The rest of the code deals with the implementation of an iterator and should not be releveant.

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  • Custom Cocoa Framework and a problem using it

    - by happyCoding25
    Hello, I made a custom cocoa framework just to experiment and find the best way to make one but ran in to a problem using it. The framework project builds and compiles just fine, but when I use it in an xcode project I get the error, 'LogTest' undeclared. The name of the framework is LogTest Heres the code to my app that uses the framework: AppDelegate.h: #import <Cocoa/Cocoa.h> #import <LogTest/LogTest.h> @interface TestAppDelegate : NSObject <NSApplicationDelegate> { NSWindow *window; } @property (assign) IBOutlet NSWindow *window; @end AppDelegate.m: #import "TestAppDelegate.h" @implementation TestAppDelegate @synthesize window; - (void)awakeFromNib { [LogTest logStart:@"testing 123":@"testing 1234"]; //This is the line where the error occurs } @end Framework Code........ LogTest.h: #import <Cocoa/Cocoa.h> #import "Method.h" @protocol LogTest //Not sure if this is needed I just wanted a blank header @end Method.h: #import <Cocoa/Cocoa.h> @interface Method : NSObject { } + (void)logStart:(NSString *)test:(NSString *)test2; @end Method.m: #import "Method.h" @implementation Method + (void)logStart:(NSString *)test:(NSString *)test2 { NSLog(test); NSLog(test2); } @end If anyone knows why I am getting this error please reply. Thanks for any help

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  • How to get around the jslint error 'Don't make functions within a loop.'

    - by Ernelli
    I am working on making all of our JS code pass through jslint, sometimes with a lot of tweaking with the options to get legacy code pass for now on with the intention to fix it properly later. There is one thing that jslint complains about that I do not have a workround for. That is when using constructs like this, we get the error 'Don't make functions within a loop.' for (prop in newObject) { // Check if we're overwriting an existing function if (typeof newObject[prop] === "function" && typeof _super[prop] === "function" && fnTest.test(newObject[prop])) { prototype[prop] = (function (name, func) { return function () { var result, old_super; old_super = this._super; this._super = _super[name]; result = func.apply(this, arguments); this._super = old_super; return result; }; })(prop, newObject[prop]); } This loop is part of a JS implementation of classical inheritance where classes that extend existing classes retain the super property of the extended class when invoking a member of the extended class. Just to clarify, the implementation above is inspired by this blog post by John Resig. But we also have other instances of functions created within a loop. The only workaround so far is to exclude these JS files from jslint, but we would like to use jslint for code validation and syntax checking as part of our continuous integration and build workflow. Is there a better way to implement functionality like this or is there a way to tweak code like this through jslint?

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  • Libraries for developing NCPDP SCRIPT based systems (a standard for e-prescribing)

    - by Kaveh Shahbazian
    What are (based on experiences) best (commercial or open source) libraries for developing NCPDP-based systems? Background: NCPDP (National Council for Prescription Drug Programs) is a not-for-profit, ANSI-accredited, standards development organization. One of it's standards is the SCRIPT Standard for Electronic Prescribing, which allows PHARMACY, PRESCRIBER (i.e. Physician) and PAYERS (patient or more often insurer) communicate. So the SCRIPT standard is about data transmission. Problem: One step in implementing such systems is to develop models for data based on SCRIPT standard. These models should have utilities for serializing/deserializing to/from SCRIPT binary format and SCRIPT XML format (there are two distinct formats here; both must be supported). Here rises the problem (for me at least). To develop this subsystem for handling the model, implementing serializing and deserializing facilities and keep it uptodate with the SCRIPT standard specifications is a lot of work; it needs it's own team and team management issues (to support a standard implementation). So I am looking for a solution to this problem; to keep standard implementation out of the way and focusing on main problems. Thanks to all (Thankyou Freiheit for your hints!) Edit 2: Thanks to all for help! NCPDP (National Council for Prescription Drug Programs) is an standard for e-prescribing. It defines two formats for message transmission: binary and XML. Implementing XML is somehow easier because it is a standard format which in turn gives us more tooling options. The binary format has a very big specification and time-consuming to implement. I did not find an open source solution to work with. So I am looking for commercial alternatives. Edit 1: Please guide me; what's wrong with this question?

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  • Does JAXWS client make difference between an empty collection and a null collection value as returne

    - by snowflake
    Since JAX-WS rely on JAXB, and since I observed the code that unpack the XML bean in JAX-B Reference Implementation, I guess the difference is not made and that a JAXWS client always return an empty collection, even the webservice result was a null element: public T startPacking(BeanT bean, Accessor<BeanT, T> acc) throws AccessorException { T collection = acc.get(bean); if(collection==null) { collection = ClassFactory.create(implClass); if(!acc.isAdapted()) acc.set(bean,collection); } collection.clear(); return collection; } I agree that for best interoperability service contracts should be non ambiguous and avoid such differences, but it seems that the JAX-WS service I'm invoking (hosted on a Jboss server with Jbossws implementation) is returning as expected either null either empty collection (tested with SoapUI). I used for my test code generated by wsimport. Return element is defined as: @XmlElement(name = "return", nillable = true) protected List<String> _return; I even tested to change the Response class getReturn method from : public List<String> getReturn() { if (_return == null) { _return = new ArrayList<String>(); } return this._return; } to public List<String> getReturn() { return this._return; } but without success. Any helpful information/comment regarding this problem is welcome !

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  • Why can't I initialize a class through a setter?

    - by Rob emenaker
    If I have a custom class called Tires: #import <Foundation/Foundation.h> @interface Tires : NSObject { @private NSString *brand; int size; } @property (nonatomic,copy) NSString *brand; @property int size; - (id)init; - (void)dealloc; @end ============================================= #import "Tires.h" @implementation Tires @synthesize brand, size; - (id)init { if (self = [super init]) { [self setBrand:[[NSString alloc] initWithString:@""]]; [self setSize:0]; } return self; } - (void)dealloc { [super dealloc]; [brand release]; } @end And I synthesize a setter and getter in my View Controller: #import <UIKit/UIKit.h> #import "Tires.h" @interface testViewController : UIViewController { Tires *frontLeft, *frontRight, *backleft, *backRight; } @property (nonatomic,copy) Tires *frontLeft, *frontRight, *backleft, *backRight; @end ==================================== #import "testViewController.h" @implementation testViewController @synthesize frontLeft, frontRight, backleft, backRight; - (void)viewDidLoad { [super viewDidLoad]; [self setFrontLeft:[[Tires alloc] init]]; } - (void)dealloc { [super dealloc]; } @end It dies after [self setFrontLeft:[[Tires alloc] init]] comes back. It compiles just fine and when I run the debugger it actually gets all the way through the init method on Tires, but once it comes back it just dies and the view never appears. However if I change the viewDidLoad method to: - (void)viewDidLoad { [super viewDidLoad]; frontLeft = [[Tires alloc] init]; } It works just fine. I could just ditch the setter and access the frontLeft variable directly, but I was under the impression I should use setters and getters as much as possible and logically it seems like the setFrontLeft method should work. This brings up an additional question that my coworkers keep asking in these regards (we are all new to Objective-C); why use a setter and getter at all if you are in the same class as those setters and getters.

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  • Is this a good way to expose generic base class methods through an interface?

    - by Nate Heinrich
    I am trying to provide an interface to an abstract generic base class. I want to have a method exposed on the interface that consumes the generic type, but whose implementation is ultimately handled by the classes that inherit from my abstract generic base. However I don't want the subclasses to have to downcast to work with the generic type (as they already know what the type should be). Here is a simple version of the only way I can see to get it to work at the moment. public interface IFoo { void Process(Bar_base bar); } public abstract class FooBase<T> : IFoo where T : Bar_base { abstract void Process(T bar); // Explicit IFoo Implementation void IFoo.Process(Bar_base bar) { if (bar == null) throw new ArgumentNullException(); // Downcast here in base class (less for subclasses to worry about) T downcasted_bar = bar as T; if (downcasted_bar == null) { throw new InvalidOperationException( string.Format("Expected type '{0}', not type '{1}'", T.ToString(), bar.GetType().ToString()); } //Process downcasted object. Process(downcasted_bar); } } Then subclasses of FooBase would look like this... public class Foo_impl1 : FooBase<Bar_impl1> { void override Process(Bar_impl1 bar) { //No need to downcast here! } } Obviously this won't provide me compile time Type Checking, but I think it will get the job done... Questions: 1. Will this function as I think it will? 2. Is this the best way to do this? 3. What are the issues with doing it this way? 4. Can you suggest a different approach? Thanks!

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  • How do I correctly use Unity to pass a ConnectionString to my repository classes?

    - by GenericTypeTea
    I've literally just started using the Unity Application Blocks Dependency Injection library from Microsoft, and I've come unstuck. This is my IoC class that'll handle the instantiation of my concrete classes to their interface types (so I don't have to keep called Resolve on the IoC container each time I want a repository in my controller): public class IoC { public static void Intialise(UnityConfigurationSection section, string connectionString) { _connectionString = connectionString; _container = new UnityContainer(); section.Configure(_container); } private static IUnityContainer _container; private static string _connectionString; public static IMovementRepository MovementRepository { get { return _container.Resolve<IMovementRepository>(); } } } So, the idea is that from my Controller, I can just do the following: _repository = IoC.MovementRepository; I am currently getting the error: Exception is: InvalidOperationException - The type String cannot be constructed. You must configure the container to supply this value. Now, I'm assuming this is because my mapped concrete implementation requires a single string parameter for its constructor. The concrete class is as follows: public sealed class MovementRepository : Repository, IMovementRepository { public MovementRepository(string connectionString) : base(connectionString) { } } Which inherits from: public abstract class Repository { public Repository(string connectionString) { _connectionString = connectionString; } public virtual string ConnectionString { get { return _connectionString; } } private readonly string _connectionString; } Now, am I doing this the correct way? Should I not have a constructor in my concrete implementation of a loosely coupled type? I.e. should I remove the constructor and just make the ConnectionString property a Get/Set so I can do the following: public static IMovementRepository MovementRepository { get { return _container.Resolve<IMovementRepository>( new ParameterOverrides { { "ConnectionString", _connectionString } }.OnType<IMovementRepository>() ); } } So, I basically wish to know how to get my connection string to my concrete type in the correct way that matches the IoC rules and keeps my Controller and concrete repositories loosely coupled so I can easily change the DataSource at a later date.

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  • Catching a nested-in-template exception [C++]

    - by Karol
    Hello, I have a problem with writing a catch clause for an exception that is a class nested in a template. To be more specific, I have a following definition of the template and exception: /** Generic stack implementation. Accepts std::list, std::deque and std::vector as inner container. */ template < typename T, template < typename Element, typename = std::allocator<Element> > class Container = std::deque > class stack { public: class StackEmptyException { }; ... /** Returns value from the top of the stack. Throws StackEmptyException when the stack is empty. */ T top() const; ... } I have a following template method that I want exception to catch: template <typename Stack> void testTopThrowsStackEmptyExceptionOnEmptyStack() { Stack stack; std::cout << "Testing top throws StackEmptyException on empty stack..."; try { stack.top(); } catch (Stack::StackEmptyException) { // as expected. } std::cout << "success." << std::endl; } When I compile it (-Wall, -pedantic) I get the following error: In function ‘void testTopThrowsStackEmptyExceptionOnEmptyStack()’: error: expected type-specifier error: expected unqualified-id before ‘)’ token === Build finished: 2 errors, 0 warnings === Thanks in advance for any help! What is interesting, if the stack implementation was not a template, then the compiler would accept the code as it is.

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  • Is this a good KVO-compliant way to model a mutable to-many relationship?

    - by andyvn22
    Say I'd like a mutable, unordered to-many relationship. For internal optimization reasons, it'd be best to store this in an NSMutableDictionary rather than an NSMutableSet. But I'd like to keep that implementation detail private. I'd also like to provide some KVO-compliant accessors, so: - (NSSet*)things; - (NSUInteger)countOfThings; - (void)addThings:(NSSet*)someThings; - (void)removeThings:(NSSet*)someThings; Now, it'd be convenient and less evil to provide accessors (private ones, of course, in my implementation file) for the dictionary as well, so: @interface MYClassWithThings () @property (retain) NSMutableDictionary* keyedThings; @end This seems good to me! I can use accessors to mess with my keyedThings within the class, but other objects think they're dealing with a mutable, unordered (, unkeyed!) to-many relationship. I'm concerned that several things I'm doing may be "evil" though, according to good style and Apple approval and whatnot. Have I done anything evil here? (For example, is it wrong not to provide setThings, since the things property is supposedly mutable?)

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  • Newtonsoft JSON Interface Serialization error

    - by Ben
    I am using C# .NET 4.0, Newtonsoft JSON 4.5.0. public class Recipe { [JsonProperty(TypeNameHandling = TypeNameHandling.All)] public List<IFood> Foods{ get; set; } ... } I want to serialize and deserialize this Recipe object. If I serialize and deserialize the object during application lifetime this succeeds, but if I serialize the object, exit application and then deserialize it then it throws an exception, that it cannot instantiate IFood (since it is an interface). The problem is that it does not serialize the implementation of interface. "$type": "System.Collections.Generic.List`1[[NSM.Shared.Models.IFood, NSMShared]], mscorlib" I tried using TypeNameHandling.Object and Array and Auto, but it didn't help. Is there any way to serialize it properly? Or at least to define the class mapping before deserializing? EDIT: I am using JSON coupled with Hammock ( http://code.google.com/p/relax-net/ ), C# driver for CouchDB, which internally serializes and deserializes objects. As mentioned the problem is that it does not serialize the interface implementation.

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