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• is there something equivalent to 'Address of' or offset operator in .net?

  - by Gio

  We have nested stuctures as such, used as an interface for some device drivers. On occasion we have to update individual elements. An 'address of' operator would be helpful, but an 'offset' function or operator is what I'm really looking for, but not sure how to go about it. In other words, how far is structureN.elementX away from the start of the structure in bytes? [StructLayout(LayoutKind.Sequential)] public struct s1 { UInt16 elem1; UInt16 elem2; UInt16 elem3; } [StructLayout(LayoutKind.Sequential)] public struct s2 { UInt16 elem1; UInt16 elem2; UInt16 elem3; } [StructLayout(LayoutKind.Sequential)] public struct driver { public S1 s1; public S2 s2; } For instance we need to send the device driver some data to update driver.s1.elem3, by way of providing an offset address, data block and length. We would update our local copy, then call the device api with the afore mentioned data. Not sure I have to do this with 'unsafe' method calls. Any help?

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• Which is the correct design pattern for my PHP application?

  - by user1487141

  I've been struggling to find good way to implement my system which essentially matches the season and episode number of a show from a string, you can see the current working code here: https://github.com/huddy/tvfilename I'm currently rewriting this library and want a nicer way to implement how the the match happens, currently essentially the way it works is: There's a folder with classes in it (called handlers), every handler is a class that implements an interface to ensure a method called match(); exists, this match method uses the regex stored in a property of that handler class (of which there are many) to try and match a season and episode. The class loads all of these handlers by instantiating each one into a array stored in a property, when I want to try and match some strings the method iterates over these objects calling match(); and the first one that returns true is then returned in a result set with the season and episode it matched. I don't really like this way of doing it, it's kind of hacky to me, and I'm hoping a design pattern can help, my ultimate goal is to do this using best practices and I wondered which one I should use? The other problems that exist are: More than one handler could match a string, so they have to be in an order to prevent the more greedy ones matching first, not sure if this is solvable as some of the regex patterns have to be greedy, but possibly a score system, something that shows a percentage of how likely the match is correct, i'd have no idea how to actually implement this though. I'm not if instantiating all those handlers is a good way of doing it, speed is important, but using best practices and sticking to design patterns to create good, extensible and maintainable code is my ultimate priority. It's worth noting the handler classes sometimes do other things than just regex matching, they sometimes prep the string to be matched by removing common words etc. Cheers for any help Billy

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• Closing Windows Forms on a Touchscreen

  - by drharris

  Our clients have fat fingers, and so do we. We take touchscreen netbooks apart to insert them into our custom hardware, and I write a software interface that shows up on the touchscreen. The problem is that it has about a 3/4" bezel over the screen, which means hitting that little red "X" becomes a challenge, especially considering reduced capacitive ability on the edges and corners. Is there a way to make this standard close button larger? Of course in the application I can always make really nice 80x80 buttons that are perfectly usable, but there seems to be no way to override the default frame of the form. We have tried enabling Large Fonts and all the built-in accessibility features, but nothing seems to make it large enough to hit successfully. Simply adding a toolbar button is also not much of an option. We prefer to utilize the standard look and feel of a normal Windows application. Alternatively, should we be looking at making some sort of "kiosk mode" where we simply go fullscreen and do nothing involving the taskbar or title bar? How difficult is this to accomplish, if so?

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• Looking for Simplified Overview of EJB3

  - by sdoca

  Hi I'm looking for a simplified overview of EJB3 components. I seem to understand most of the pieces of the puzzle, but can't quite get them to fit together in my brain as a full picture. I've developed numerous web applications (wars) that have been deployed on Tomcat before, but not a full-fledged EE application (ear). I would like the overview to be as generic as possible. I'm not looking for a tutorial on how to set up EJB3 on Glassfish built in NetBeans or some other vendor specific tutorial that's more about the IDE than the technology. I keep reading about Java, ejb-jar, web and ear modules but am not clear on what these different modules contain and how to use them to put together my app. In my case, I want to write a simple database CRUD web application. The first step is simple; create entity classes that model the database tables my app will be using. I plan on using annotations. Should I create a jar that contains just these enity classes? Is this the ejb-jar module (sometimes referred to as the Java module)? Next, I'll need some business logic classes that make use of the entity classes. These are the session beans (stateless or stateful) correct? Should these be packaged in the same jar as the entity classes or a separate jar? Finally, I'll need some sort of web interface (I'll be creating a JSF portlet) application that makes use of the both the session and entity beans. Together with the above jar(s), this will be my war? Assuming the above to be correct, what is involved in creating an ear? Forgive me if this post is vague, but I'm having a hard time defining what it is I don't understand. Thanks for any help!

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• J2EE and alternatives

  - by Ilya K

  Hello, I am J2SE developer but I have rich web-background (php, perl/cgi and so on) and now I am starting new project. It will have web interface, spaghetti business logic, relational database as storage and connections to other services. I do it from the scratch. My colleagues told me to use spring, spring security and struts. I look briefly at J2EE spec and found that it covers almost all aspects of enterprise application. I asked my colleagues why do they need spring and struts, but looks like they use technologies simply because they are familiar with them and not familiar with classic J2EE stack. So, my question is: what is bad about J2EE? Why do I need spring if there are JNDI lookups? It will take a day or two to create fake InitialContext for unit-tests. And that is all: I stand with out of external tools like spring. Why do I need spring-security if there is a security built in Servlets spec? I can map any request to any servlet using web.xml, no struts.xml is needed. I can use servlet-filters instead of struts interceptors. There is RMI, so I do not need spring-remote. And so on.. Why should I bother my self with all that fancy stuff if there is J2EE? I really want to find situation when J2EE is not enough. Do you have any? Thanks!

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• Move to php in windows? Concern, hints, "please don't do!"?

  - by Daniel

  I am considering to move frome Microsoft languages to PHP (just for web dev) which has quite an interesting syntax, a perlish look (but a wider programmer base) and it allows me to reuse the web without reinventing it. I have some concerns too. I would be more than happy to gather some wisdom from stackoverflow community, (challenge to my opinions warmly welcome). Here are my doubts. Efficiency. Cgi are slow, what I am supposed to use? Fastcgi? Or what else? Efficiency + stability. Is PHP on windows really stable and a good choice in terms of performances? Database. I use very often MSSQL (I regret, i like it). Could I widely and efficiently interface PHP with MSSQL (using smartly stored pro, for example). XSLT + XML performance. I work quite a lot with XML and XSLT and I really find the MS xml parser a great software component. Are parser used in PHP fast, reliable and efficient (I am interested mainly in DOM, not SAX)? Objects. Is the PHP object programming model valid end efficient? 6 Regex. How efficient is PHP processing regexp? Many thanks for your advices.

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• Why do I have to specify pure virtual functions in the declaration of a derived class in Visual C++?

  - by neuviemeporte

  Given the base class A and the derived class B: class A { public: virtual void f() = 0; }; class B : public A { public: void g(); }; void B::g() { cout << "Yay!"; } void B::f() { cout << "Argh!"; } I get errors saying that f() is not declared in B while trying do define void B::f(). Do I have to declare f() explicitly in B? I think that if the interface changes I shouldn't have to correct the declarations in every single class deriving from it. Is there no way for B to get all the virtual functions' declarations from A automatically? EDIT: I found an article that says the inheritance of pure virtual functions is dependent on the compiler: http://www.objectmentor.com/resources/articles/abcpvf.pdf I'm using VC++2008, wonder if there's an option for this.

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• How to manage large amounts of delegates and usercallbacks in C# async http library

  - by Tyler

  I'm coding a .NET library in C# for communicating with XBMC via its JSON RPC interface using HTTP. I coded and released a preliminary version but everything is done synchronously. I then recoded the library to be asynchronous for my own purposes as I was/am building an XBMC remote for WP7. I now want to release the new async library but want to make sure it's nice and tidy before I do. Due to the async nature a user initiates a request, supplies a callback method that matches my delegate and then handles the response once it's been received. The problem I have is that within the library I track a RequestState object for the lifetime of the request, it contains the http request/response as well as the user callback etc. as member variables, this would be fine if only one type of object was coming back but depending on what the user calls they may be returned a list of songs or a list of movies etc. My implementation at the moment uses a single delegate ResponseDataRecieved which has a single parameter which is a simple Object - As this has only be used by me I know which methods return what and when I handle the response I cast said object to the type I know it really is - List, List etc. A third party shouldn't have to do this though - The delegate signature should contain the correct type of object. So then I need a delegate for every type of response data that can be returned to the third party - The specific problem is, how do I handle this gracefully internally - Do I have a bunch of different RequestState objects that each have a different member variable for the different delegates? That doesn't "feel" right. I just don't know how to do this gracefully and cleanly.

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• GetIpAddrTable() leaks memory. How to resolve that?

  - by Stabledog

  On my Windows 7 box, this simple program causes the memory use of the application to creep up continuously, with no upper bound. I've stripped out everything non-essential, and it seems clear that the culprit is the Microsoft Iphlpapi function "GetIpAddrTable()". On each call, it leaks some memory. In a loop (e.g. checking for changes to the network interface list), it is unsustainable. There seems to be no async notification API which could do this job, so now I'm faced with possibly having to isolate this logic into a separate process and recycle the process periodically -- an ugly solution. Any ideas? // IphlpLeak.cpp - demonstrates that GetIpAddrTable leaks memory internally: run this and watch // the memory use of the app climb up continuously with no upper bound. #include <stdio.h> #include <windows.h> #include <assert.h> #include <Iphlpapi.h> #pragma comment(lib,"Iphlpapi.lib") void testLeak() { static unsigned char buf[16384]; DWORD dwSize(sizeof(buf)); if (GetIpAddrTable((PMIB_IPADDRTABLE)buf, &dwSize, false) == ERROR_INSUFFICIENT_BUFFER) { assert(0); // we never hit this branch. return; } } int main(int argc, char* argv[]) { for ( int i = 0; true; i++ ) { testLeak(); printf("i=%d\n",i); Sleep(1000); } return 0; }

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• Approach for caching data from data logger

  - by filip-fku

  Greetings, I've been working on a C#.NET app that interacts with a data logger. The user can query and obtain logs for a specified time period, and view plots of the data. Typically a new data log is created every minute and stores a measurement for a few parameters. To get meaningful information out of the logger, a reasonable number of logs need to be acquired - data for at least a few days. The hardware interface is a UART to USB module on the device, which restricts transfers to a maximum of about 30 logs/second. This becomes quite slow when reading in the data acquired over a number of days/weeks. What I would like to do is improve the perceived performance for the user. I realize that with the hardware speed limitation the user will have to wait for the full download cycle at least the first time they acquire a larger set of data. My goal is to cache all data seen by the app, so that it can be obtained faster if ever requested again. The approach I have been considering is to use a light database, like SqlServerCe, that can store the data logs as they are received. I am then hoping to first search the cache prior to querying a device for logs. The cache would be updated with any logs obtained by the request that were not already cached. Finally my question - would you consider this to be a good approach? Are there any better alternatives you can think of? I've tried to search SO and Google for reinforcement of the idea, but I mostly run into discussions of web request/content caching. Thanks for any feedback!

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• "Detecting" and loading of "plugins" in GAE

  - by Patrick Cornelissen

  Hi! I have a "plugin like" architecture and I want to create one instance of each class that implements a dedicated interface and put these in a cache. (To have a singleton-ish effect). The plugins will be provided as jars and put into the app engine war file before the app is uploaded. I have tried to use the ClassPathScanningCandidateComponentProvider as I'm using spring anyway, but this didn't work. The provider complained that it was not able to find the HttpServletResponse class file while scanning the classpath. I can't get around this, when I add the servlet jar, then I'll get of course problems, because the same jar is also provided by the GAE. If I don't, I'm getting the error above... So I tried to add a static initialization code, but of course this doesn't work, because the class is initialized when it's instantiated for the first time. (Well I knew that but it was worth a try) The last chance I currently see is that I create a properties file with all plugin classes when the package is created, but this requires writing of a maven plugin etc. and I'd like to avoid that. Is there something that I am missing?

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• Basic SWIG C++ use for Java

  - by duckworthd

  I've programmed a couple years in both C++ and Java, but I've finally come to a point where I need to bring a little unification between the two -- ideally, using SWIG. I've written a tiny and fairly pointless little class called Example: #include <stdio.h> class Example { public: Example(); ~Example(); int test(); }; #include "example.h" Example::Example() { printf("Example constructor called\n"); } Example::~Example() { printf("Example destructor called\n"); } int Example::test() { printf("Holy sh*t, I work!\n"); return 42; } And a corresponding interface file: /* File: example.i */ %module test %{ #include "example.h" %} %include "example.h" Now I have questions. Firstly, when I want to actually run SWIG initially, am I supposed to use the example_wrap.c (from swig -java example.i) or example_wrap.cxx (from swig -c++ example.i) file when recompiling with my original example.cpp? Or perhaps both? I tried both and the latter seemed most likely, but when I recompile as so: g++ example.cpp example_wrap.cxx -I/usr/lib/jvm/java-6-sun-.../include/ I get a host of errors regarding TcL of all things, asking me for the tcl.h header. I can't even wrap my mind around why it wants that much less needs it, and as such have found myself where I don't even know how to begin using SWIG.

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• Compile for mixed platform (32, 64) and reference a 32 or 64 bit DLL resolved at runtime

  - by Nigel Aston

  Using VS2010 under windows 32 or 64 bit. Our C# app calls a 3rd party DLL (managed) that interfaces to an unmanaged DLL. The 3rd party DLL API appears identical in 32 or 64 bit although underneath it links to a 32 or 64 bit unmanaged DLL. We want our C# app to run on either 32 or 64 bit OS, ideally it will auto detect the OS and load the appropriate 32rd party DLL - via a simple factory class which tests the Enviroment. So the neatest solution would be a runtime folder containing: OurApp.exe 3rdParty32.DLL 3rdPartyUnmanaged32.DLL 3rdParty64.DLL 3rdPartyUnmanaged64.DLL However, the interface for the managed 3rdParty 32 and 64 dll is identical so both cannot be referenced within the same VS2010 project: when adding the second the warning triangle is shown and it does not get referenced. Is my only answer to create two extra library DLL projects to reference the 3rdParty 32 and 64 Dlls? So I would end up with this project arrangement: Project 1: Builds OurApp.exe, dynamically creates an object for project2 or project3. Project 2: Builds OurApp32.DLL which references 3rdParty32.dll Project 3: Builds OurApp64.DLL which references 3rdParty64.dll

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• Why are controls (null) in awakeFromNib?

  - by fuzzygoat

  This is a follow on from another question regarding why I could not set UIControls in awakeFromNib. The answer to that is that as you can see below the controls are nil in the awakeFromNib, although they are initialised to the correct objects by the time we get to viewDidLoad. I setup the view the same as I always do, should I be doing something different to access them here, the xib(nib) was designed and saved with the current version of Image Builder. CODE: @interface iPhone_TEST_AwakeFromNibViewController : UIViewController { UILabel *myLabel; UIImageView *myView; } @property(nonatomic, retain)IBOutlet UILabel *myLabel; @property(nonatomic, retain)IBOutlet UIImageView *myView; @end . @synthesize myLabel; @synthesize myView; -(void)awakeFromNib { NSLog(@"awakeFromNib ..."); NSLog(@"myLabel: %@", [myLabel class]); NSLog(@"myView : %@", [myView class]); //[myLabel setText:@"AWAKE"]; [super awakeFromNib]; } -(void)viewDidLoad { NSLog(@"viewDidLoad ..."); NSLog(@"myLabel: %@", [myLabel class]); NSLog(@"myView : %@", [myView class]); //[myLabel setText:@"VIEW"]; [super viewDidLoad]; } OUTPUT: awakeFromNib ... myLabel: (null) myView : (null) viewDidLoad ... myLabel: UILabel myLabel: UIImageView Much appreciated ... gary

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• "|" pipe operator not working in command line in C++

  - by user332024

  I am having a windows application interacting with DB2 database. In my application i have code to execute some DB2 commands through command line interface. I have used windowsAPI "ShellExecuteEx()" to execute those DB2 commands through command line. Following is the code written to execute DB2 command through command line. string command = "/c /w /i DB2 UNCATALOG NODE DB_DATABASE "" test.log | echo %date% %time% test.log SHELLEXECUTEINFO shellInfo; ZeroMemory(&shellInfo, sizeof(shellInfo)); shellInfo.cbSize = sizeof(shellInfo); shellInfo.fMask = SEE_MASK_FLAG_NO_UI | SEE_MASK_NOCLOSEPROCESS; //shellInfo.lpFile = "db2cmd"; shellInfo.lpFile = "db2cmd"; shellInfo.lpParameters = command.c_str(); The code is executed successfully , however if test.log is observered i only get result of DB2 command and not date and time. If you see the above command there is "|" pipe operator and echo command to log date and time in test.log Please note that if I execute above DB2 command through separately command line i.e. not through code. I am able to view date and time log along with DB2 command result in test.log. Following is the full command which i executed through command line. DB2CMD /c /i /w DB2 UNCATALOG NODE DB_DATABASE "" test.log | echo %date% %time% test.log According to me since DB2 command is executed successfully through code, there is problem with only usage of "|" pipe operator or echo command.

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• OrderBy Linq.Expression as parameter = (Of Func(Of T,IComparable)) to perform LinqToEntity is not working

  - by NicoJuicy

  I'd like to get this working: Call: (Count & Page are used for pagination, so Count = 20 and Page = 1 for example, for the first 20 values). Sorting should be by name LeverancierService.GetLeveranciers(Function(el) el.Name, Count, Page) Equivalent in c#: LeverancierService.GetLeveranciers(el= el.Name, Count, Page) Method that gives an error (parameters shown above): Public Overridable Function GetAllPaged(orderby As Expression(Of Func(Of T, IComparable)), ByVal Count As Integer, ByVal Page As Integer) As IEnumerable(Of T) Return dbset.OrderBy(orderby).Skip((Page - 1) * Count).Take(Count).ToList() End Function Already tried changing it to this, but it gives the same error: Public Overridable Function GetAllPaged(Of TOrderBy)(orderby As Expression(Of Func(Of T, TOrderBy)), ByVal Count As Integer, ByVal Page As Integer) As IEnumerable(Of T) Return dbset.OrderBy(orderby).Skip((Page - 1) * Count).Take(Count).ToList() End Function Error: Unable to cast the type 'System.String' to type 'System.IComparable'. LINQ to Entities only supports casting Entity Data Model primitive types. Any idea how to do this? Extra info: I'm in a DDD-layered application, so the parameter should stay the same as the called method is an overridden interface (eg. if i change this, i have to do this for 200 times or so, because it's in VB.Net and not in C# (= 1 change) ) I know there is a way to change the expression to a string and then use DLinq (= Dynamic Linq), but that's not how it should be.

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• TFS2010 API - Which server event fires when checkin notes are changed?

  - by user3708981

  I've written a TFS plugin that impliments the ISubscribe interface, and creates an external ticket base off of the contents of a check-in note. What I would like to do, if when I go back through older TFS check-ins in VS and edit a check-in note, the plugin would process that event and create an external ticket retroactively. What event / SubscribedType do I need to subscribe to in order for ProcessEvents to fire? My stubbed out code - using Microsoft.TeamFoundation.Client; using Microsoft.TeamFoundation.Common; using Microsoft.TeamFoundation.VersionControl.Client; // From C:\Program Files\Microsoft Team Foundation Server 2010\Tools\ using Microsoft.TeamFoundation.Framework.Server; using Microsoft.TeamFoundation.VersionControl.Server; using Changeset = Microsoft.TeamFoundation.VersionControl.Server.Changeset; public class EmbeddedWorkItemEventHandler : ISubscriber { const string EVENT_NAME = "TicketEvent"; const string APP_LOG = "Application"; public Type[] SubscribedTypes() { return new Type[1] { typeof(CheckinNotification) }; // What else do I need here? } public string Name { get { return EVENT_NAME; } } public SubscriberPriority Priority { get { return SubscriberPriority.Normal; } } public EventNotificationStatus ProcessEvent(TeamFoundationRequestContext requestContext, NotificationType notificationType, object notificationEventArgs, out int statusCode, out string statusMessage, out ExceptionPropertyCollection properties) { // Create the event source, if it doesn't exist if (!System.Diagnostics.EventLog.SourceExists(EVENT_NAME)) { System.Diagnostics.EventLog.CreateEventSource(EVENT_NAME, APP_LOG); } statusCode = 0; properties = null; statusMessage = String.Empty; string ErrorLine = ""; try { // Here we'll validate the Ticket name if (notificationType == NotificationType.DecisionPoint && notificationEventArgs is CheckinNotification) { //Check-in blocking logic here. } else if (notificationType == NotificationType.Notification && notificationEventArgs is CheckinNotification) { // Tickets on check-in here. } } Catch { // Error checking } return EventNotificationStatus.ActionPermitted; }

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• JPA returning null for deleted items from a set

  - by Jon

  This may be related to my question from a few days ago, but I'm not even sure how to explain this part. (It's an entirely different parent-child relationship.) In my interface, I have a set of attributes (Attribute) and valid values (ValidValue) for each one in a one-to-many relationship. In the Spring MVC frontend, I have a page for an administrator to edit these values. Once it's submitted, if any of these fields (as <input> tags) are blank, I remove the ValidValue object like so: Set<ValidValue> existingValues = new HashSet<ValidValue>(attribute.getValidValues()); Set<ValidValue> finalValues = new HashSet<ValidValue>(); for(ValidValue validValue : attribute.getValidValues()) { if(!validValue.getValue().isEmpty()) { finalValues.add(validValue); } } existingValues.removeAll(finalValues); for(ValidValue removedValue : existingValues) { getApplicationDataService().removeValidValue(removedValue); } attribute.setValidValues(finalValues); getApplicationDataService().modifyAttribute(attribute); The problem is that while the database is updated appropriately, the next time I query for the Attribute objects, they're returned with an extra entry in their ValidValue set -- a null, and thus, the next time I iterate through the values to display, it shows an extra blank value in the middle. I've confirmed that this happens at the point of a merge or find, at the point of "Execute query ReadObjectQuery(entity.Attribute). Here's the code I'm using to modify the database (in the ApplicationDataService): public void modifyAttribute(Attribute attribute) { getJpaTemplate().merge(attribute); } public void removeValidValue(ValidValue removedValue) { ValidValue merged = getJpaTemplate().merge(removedValue); getJpaTemplate().remove(merged); } Here are the relevant parts of the entity classes: Entity @Table(name = "attribute") public class Attribute { @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "attribute") private Set<ValidValue> validValues = new HashSet<ValidValue>(0); } @Entity @Table(name = "valid_value") public class ValidValue { @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "attr_id", nullable = false) private Attribute attribute; }

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• How do I call +class methods in Objective C without referencing the class?

  - by TimM

  I have a series of "policy" objects which I thought would be convenient to implement as class methods on a set of policy classes. I have specified a protocol for this, and created classes to conform to (just one shown below) @protocol Counter +(NSInteger) countFor: (Model *)model; @end @interface CurrentListCounter : NSObject <Counter> +(NSInteger) countFor: (Model *)model; @end I then have an array of the classes that conform to this protocol (like CurrentListCounter does) +(NSArray *) availableCounters { return [[[NSArray alloc] initWithObjects: [CurrentListCounter class],[AllListsCounter class], nil] autorelease]; } Notice how I am using the classes like objects (and this might be my problem - in Smalltalk classes are objects like everything else - I'm not sure if they are in Objective-C?) My exact problem is when I want to call the method when I take one of the policy objects out of the array: id<Counter> counter = [[MyModel availableCounters] objectAtIndex: self.index]; return [counter countFor: self]; I get a warning on the return statement - it says -countFor: not found in protocol (so its assuming its an instance method where I want to call a class method). However as the objects in my array are instances of class, they are now like instance methods (or conceptually they should be). Is there a magic way to call class methods? Or is this just a bad idea and I should just create instances of my policy objects (and not use class methods)?

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• Efficient database access when dealing with multiple abstracted repositories

  - by Nathan Ridley

  I want to know how most people are dealing with the repository pattern when it involves hitting the same database multiple times (sometimes transactionally) and trying to do so efficiently while maintaining database agnosticism and using multiple repositories together. Let's say we have repositories for three different entities; Widget, Thing and Whatsit. Each repository is abstracted via a base interface as per normal decoupling design processes. The base interfaces would then be IWidgetRepository, IThingRepository and IWhatsitRepository. Now we have our business layer or equivalent (whatever you want to call it). In this layer we have classes that access the various repositories. Often the methods in these classes need to do batch/combined operations where multiple repositories are involved. Sometimes one method may make use of another method internally, while that method can still be called independently. What about, in this scenario, when the operation needs to be transactional? Example: class Bob { private IWidgetRepository _widgetRepo; private IThingRepository _thingRepo; private IWhatsitRepository _whatsitRepo; public Bob(IWidgetRepository widgetRepo, IThingRepository thingRepo, IWhatsitRepository whatsitRepo) { _widgetRepo = widgetRepo; _thingRepo= thingRepo; _whatsitRepo= whatsitRepo; } public void DoStuff() { _widgetRepo.StoreSomeStuff(); _thingRepo.ReadSomeStuff(); _whatsitRepo.SaveSomething(); } public void DoOtherThing() { _widgetRepo.UpdateSomething(); DoStuff(); } } How do I keep my access to that database efficient and not have a constant stream of open-close-open-close on connections and inadvertent invocation of MSDTS and whatnot? If my database is something like SQLite, standard mechanisms like creating nested transactions are going to inherently fail, yet the business layer should not have to be concerning itself with such things. How do you handle such issues? Does ADO.Net provide simple mechanisms to handle this or do most people end up wrapping their own custom bits of code around ADO.Net to solve these types of problems?

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• C# threading solution for long queries

  - by Eddie

  Senerio We have an application that records incidents. An external database needs to be queried when an incident is approved by a supervisor. The queries to this external database are sometimes taking a while to run. This lag is experienced through the browser. Possible Solution I want to use threading to eliminate the simulated hang to the browser. I have used the Thread class before and heard about ThreadPool. But, I just found BackgroundWorker in this post. MSDN states: The BackgroundWorker class allows you to run an operation on a separate, dedicated thread. Time-consuming operations like downloads and database transactions can cause your user interface (UI) to seem as though it has stopped responding while they are running. When you want a responsive UI and you are faced with long delays associated with such operations, the BackgroundWorker class provides a convenient solution. Is BackgroundWorker the way to go when handling long running queries? What happens when 2 or more BackgroundWorker processes are ran simultaneously? Is it handled like a pool?

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• How do you unit test new code that uses a bunch of classes that cannot be instantiated in a test har

  - by trendl

  I'm writing a messaging layer that should handle communication with a third party API. The API has a bunch of classes that cannot be easily (if at all) instantiated in a test harness. I decided to wrap each class that I need in my unit tests with an adapter/wrapper and expose the members I need through this adapter class. Often I need to expose the wrapped type as well which I do by exposing it as an object. I have also provided an interface for for each or the adapter classes to be able to use them with a mocking framework. This way I can substitute the classes in test for whatever I need. The downside is that I have a bunch of adapter classes that so far server no other reason but testing. For me this is a good reason by itself but others may find this not enough. Possibly, when I write an implementation for another third party vendor's API, I may be able to reuse much of my code and only provide the adapters specific to the vendor's API. However, this is a bit of a long shot and I'm not actually sure it will work. What do you think? Is this approach viable or am I writing unnecessary code that serves no real purpose? Let me say that I do want to write unit tests for my messaging layer and I do now know how to do it otherwise.

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• How to efficiently implement a strategy pattern with spring ?

  - by Anth0

  I have a web application developped in J2EE 1.5 with Spring framework. Application contains "dashboards" which are simple pages where a bunch of information are regrouped and where user can modify some status. Managers want me to add a logging system in database for three of theses dashboards. Each dashboard has different information but the log should be traced by date and user's login. What I'd like to do is to implement the Strategy pattern kind of like this : interface DashboardLog { void createLog(String login, Date now); } // Implementation for one dashboard class PrintDashboardLog implements DashboardLog { Integer docId; String status; void createLog(String login, Date now){ // Some code } } class DashboardsManager { DashboardLog logger; String login; Date now; void createLog(){ logger.log(login,now); } } class UpdateDocAction{ DashboardsManager dbManager; void updateSomeField(){ // Some action // Now it's time to log dbManagers.setLogger = new PrintDashboardLog(docId, status); dbManagers.createLog(); } } Is it "correct" (good practice, performance, ...) to do it this way ? Is there a better way ? Note :I did not write basic stuff like constructors and getter/setter.

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• "'Objects' may not respond to 'functions'" warnings.

  - by Andrew

  Hello all, for the last couple of weeks I've finally gotten into Obj-C from regular C and have started my first app. I've watched tutorials and read through a book along with a lot of webpages, but I know I've only just begun. Anyway, for most of the night and this morning, I've been trying to get this code to work, and now that it will compile, I have a few warnings. I've searched and found similar problems with solutions, but still no dice. What I'm trying to do is put an array made from a txt document into the popup list in a combo box. AwesomeBoxList.h: #import <Cocoa/Cocoa.h> @interface AwesomeBoxList : NSObject { IBOutlet NSComboBox *ComboBoz; } -(NSArray *) getStringzFromTxtz; - (void) awesomeBoxList; @end AwesomeBoxList.m: #import "AwesomeBoxList.h" @implementation AwesomeBoxList -(NSArray *)getStringzFromTxtz { ... return combind; } - (void) awesomeBoxList { [ComboBoz setUsesDataSource:YES]; [ComboBoz setDataSource: [ComboBoz getStringzFromTxtz]: //'NSComboBox' may not respond to 'getStringzFromTxtz' [ComboBoz comboBox:(NSComboBox *)ComboBoz objectValueForItemAtIndex: [ComboBoz numberOfItemsInComboBox:(NSComboBox *)ComboBoz]]]; /*'NSComboBox' may not respond to '-numberOfItemsInComboBox:' 'NSComboBox' may not respond to '-comboBox:objectValueForItemAtIndex:' 'NSComboBox' may not respond to '-setDataSource:' */ } @end So, with all of these errors and my still shallow knowledge of Obj-C, I must be making some sort of n00b mistake. Thanks for the help.

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• TabBar as rootController flip animation.

  - by user558076

  Hi there, I'm using a TabBarController as the root controller for my app. I have all the views I use (5 tabs) all hooked together through it in interface builder. What I'm trying to do is trigger a slide or flip animation when moving between tabs. However, I only want this to occur when I change tabs programmatically (ie the animation is triggered when someone does a swipe gesture in the one of the views, but not when they just select one of the tabs). The way I'm currently handling this is by calling: [appDelegate.myTab setSelectedIndex:0]; when the iphone detects a swipe. I've been searching the internet for 5 straight hours and can't seem to find a way to add an animation here. It'd be really cool if there were something like: [appDelegate.myTab setSelectedIndex:0 animated:(YES)]; However, there isn't... I can't imagine no one's ever tried this before, but for the life of me, I can't find anything online that explains how this can be done. Thank you in advance for your help.

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