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  • C++ game designing & polymorphism question

    - by Kotti
    Hi! I'm trying to implement some sort of 'just-for-me' game engine and the problem's plot goes the following way: Suppose I have some abstract interface for a renderable entity, e.g. IRenderable. And it's declared the following way: interface IRenderable { // (...) // Suppose that Backend is some abstract backend used // for rendering, and it's implementation is not important virtual void Render(Backend& backend) = 0; }; What I'm doing right now is something like declaring different classes like class Ball : public IRenderable { virtual void Render(Backend& backend) { // Rendering implementation, that is specific for // the Ball object // (...) } }; And then everything looks fine. I can easily do something like std::vector<IRenderable*> items, push some items like new Ball() in this vector and then make a call similiar to foreach (IRenderable* in items) { item->Render(backend); } Ok, I guess it is the 'polymorphic' way, but what if I want to have different types of objects in my game and an ability to manipulate their state, where every object can be manipulated via it's own interface? I could do something like struct GameState { Ball ball; Bonus bonus; // (...) }; and then easily change objects state via their own methods, like ball.Move(...) or bonus.Activate(...), where Move(...) is specific for only Ball and Activate(...) - for only Bonus instances. But in this case I lose the opportunity to write foreach IRenderable* simply because I store these balls and bonuses as instances of their derived, not base classes. And in this case the rendering procedure turns into a mess like ball.Render(backend); bonus.Render(backend); // (...) and it is bad because we actually lose our polymorphism this way (no actual need for making Render function virtual, etc. The other approach means invoking downcasting via dynamic_cast or something with typeid to determine the type of object you want to manipulate and this looks even worse to me and this also breaks this 'polymorphic' idea. So, my question is - is there some kind of (probably) alternative approach to what I want to do or can my current pattern be somehow modified so that I would actually store IRenderable* for my game objects (so that I can invoke virtual Render method on each of them) while preserving the ability to easily change the state of these objects? Maybe I'm doing something absolutely wrong from the beginning, if so, please point it out :) Thanks in advance!

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  • 3-Tier architecture-layering and the term-mishmash

    - by Rookian
    Hi! I am confused about the different possibilities to express a 3-Tier architecture. Data-Access-Layer Business-Layer Presentation Layer (User Interface) or Database (aka Backend) Business-Layer Presentation Layer (User Interface) Why can you skip the database in the 1st approach? Both use a database! Does the database belong to the layering or not?! What is wrong and what is right? Can someone of you clarify this :)? Thanks in advance!

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  • JAXB doesn't unmarshal list of interfaces

    - by Joker_vD
    It seems JAXB can't read what it writes. Consider the following code: interface IFoo { void jump(); } @XmlRootElement class Bar implements IFoo { @XmlElement public String y; public Bar() { y = ""; } public Bar(String y) { this.y = y; } @Override public void jump() { System.out.println(y); } } @XmlRootElement class Baz implements IFoo { @XmlElement public int x; public Baz() { x = 0; } public Baz(int x) { this.x = x; } @Override public void jump() { System.out.println(x); } } @XmlRootElement public class Holder { private List<IFoo> things; public Holder() { things = new ArrayList<>(); } @XmlElementWrapper @XmlAnyElement public List<IFoo> getThings() { return things; } public void addThing(IFoo thing) { things.add(thing); } } // ... try { JAXBContext context = JAXBContext.newInstance(Holder.class, Bar.class, Baz.class); Holder holder = new Holder(); holder.addThing(new Bar("1")); holder.addThing(new Baz(2)); holder.addThing(new Baz(3)); for (IFoo thing : holder.getThings()) { thing.jump(); } StringWriter s = new StringWriter(); context.createMarshaller().marshal(holder, s); String data = s.toString(); System.out.println(data); StringReader t = new StringReader(data); Holder holder2 = (Holder)context.createUnmarshaller().unmarshal(t); for (IFoo thing : holder2.getThings()) { thing.jump(); } } catch (Exception e) { System.err.println(e.getMessage()); } It's a simplified example, of course. The point is that I have to store two very differently implemented classes, Bar and Baz, in one collection. Well, I observed that they have pretty similar public interface, so I created an interface IFoo and made them two to implement it. Now, I want to have tools to save and load this collection to/from XML. Unfortunately, this code doesn't quite work: the collection is saved, but then it cannot be loaded! The intended output is 1 2 3 some xml 1 2 3 But unfortunately, the actual output is 1 2 3 some xml com.sun.org.apache.xerces.internal.dom.ElementNSImpl cannot be cast to testapplication1.IFoo Apparently, I need to use the annotations in a different way? Or to give up on JAXB and look for something else? I, well, can write "XMLNode toXML()" method for all classes I wan't to (de)marshal, but...

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  • What's the best software analogy you've heard?

    - by Mantorok
    Hi Quite frequently I have to explain things to Project Managers who sometimes want to know a little bit more about something, and sometimes I try and come up with some analogy that best explains it. Now, I can't really kick this off with a good analagy because mine usually suck, but I would be interested in yours, or some you've heard that have been used to simplify explanations. One analogy that does come up often is when explaining Interfaces (i.e. .Net) to which I usually explain in terms of a vehicle has a driver interface, and all vehicles must implement that interface so that anyone who can drive a vehicle will be able to utilise it. Any more? Would like to hear some, both serious and humourous. Please close if a duplicate.

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  • Accidentally deletion of classes from XCode 3.2.5

    - by Alok Srivastava
    Accidentally my classes folder is deleted with reference from xcode(project). i try to recover them from trash but it was not present in trash. how ever i used svn for backup. but after check out the whole project when i try to run the project then it gives ann error 2012-06-05 09:46:59.651 Lisnx[527:207] Unknown class LisnxAppDelegate in Interface Builder file. 2012-06-05 09:46:59.652 Lisnx[527:207] Unknown class LisnxViewController in Interface Builder file. 2012-06-05 09:46:59.656 Lisnx[527:207] * Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key viewController.'

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  • Need help with developing a class for my JUnit test

    - by alpdog14
    I have this JUnit test that I need help developing a Interface and Class for, here is the test: Box b1 = new DefaultBox( "abc" ); Box b2 = new DefaultBox( "def" ); Box b3 = new DefaultBox( "" ); assertEquals("abc", b1.contents()); assertEquals("[abc]", b1.toString()); assertTrue(b1.equals(b1)); assertFalse(b1.equals(b2)); assertFalse(b1.equals(null)); assertEquals("cba", b1.flip().contents()); assertEquals("", b3.flip().contents()); can anyone help me in developing a Default box class and a box interface to make these test pass? Any help would be most appreciated.

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  • How do I determine inactivity in a MVVM application?

    - by Jordan
    I have an MVVM kiosk application that I need to restart when it has been inactive for a set amount of time. I'm using Prism and Unity to facilitate the MVVM pattern. I've got the restarting down and I even know how to handle the timer. What I want to know is how to know when activity, that is any mouse event, has taken occurred. The only way I know how to do that is by subscribing to the preview mouse events of the main window. That breaks MVVM thought, doesn't it? I've thought about exposing my window as an interface that exposes those events to my application, but that would require that the window implement that interface which also seems to break MVVM.

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  • Is a Multi-DAL Approach the way to go here?

    - by Krisc
    Working on the data access / model layer in this little MVC2 project and trying to think things out to future projects. I have a database with some basic tables and I have classes in the model layer that represent them. I obviously need something to connect the two. The easiest is to provide some sort of 'provider' that can run operations on the database and return objects. But this is for a website that would potentially be used "a lot" (I know, very general) so I want to cache results from the data layer and keep the cache updated as new data is generated. This question deals with how best to approach this problem of dual DALS. One that returns cached data when possible and goes to the data layer when there is a cache miss. But more importantly, how to integrate the core provider (thing that goes into database) with the caching layer so that it too can rely on cached objects rather than creating new ones. Right now I have the following interfaces: IDataProvider is used to reach the database. It doesn't concern itself with the meaning of the objects it produces, but simply the way to produce them. interface IDataProvider{ // Select, Update, Create, et cetera access IEnumerable<Entry> GetEntries(); Entry GetEntryById(int id); } IDataManager is a layer that sits on top of the IDataProvider layer and manages the cache interface IDataManager : IDataProvider{ void ClearCache(); } Note that in practice the IDataManager implementation will have useful helper functions to add objects to their related cache stores. (In the future I may define other functions on the interface) I guess what I am looking for is the best way to approach a loop back from the IDataProvider implementations so that they can access the cache. Or a different approach entirely may be in order? I am not very interested in 3rd party products at the moment as I am interested in the design of these things much more than this specific implementation. Edit: I realize the title may be a bit misleading. I apologize for that... not sure what to call this question.

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  • Starting new transaction in Spring bean

    - by Marcus
    We have: @Transactional(propagation = Propagation.REQUIRED) public class MyClass implementes MyInterface { ... MyInterface has a single method: go(). When go() executes we start a new transaction which commits/rollbacks when the method is complete - this is fine. Now let's say in go() we call a private method in MyClass that has @Transactional(propagation = Propagation.REQUIRES_NEW. It seems that Spring "ignores" the REQUIRES_NEW annotation and does not start a new transaction. I believe this is because Spring AOP operates on the interface level (MyInterface) and does not intercept any calls to MyClass methods. Is this correct? Is there any way to start a new transaction within the go() transaction? Is the only way to call another Spring managed bean that has transactions configured as REQUIRES_NEW? Update: Adding that when clients execute go() they do so via a reference to the interface, not the class: @Autowired MyInterface impl; impl.go();

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  • What's going on with "expected specifier-qualifier-list" error

    - by Tattat
    It is my GameEngine.h: #import <Foundation/Foundation.h> #import "GameArray.h"; @interface GameEngine : NSObject { GameArray *gameButtonsArray; } @property (nonatomic, retain) GameArray *gameButtonsArray; And this is my GameArray.h: #import <Foundation/Foundation.h> #import "MyAppDelegate.h" @interface GameArray : NSObject { NSMutableArray *gameButtonsArray; } @property (nonatomic, retain) NSMutableArray *gameButtonsArray; It keep prompt my "expected specifier-qualifier-list" error i my GameEngine.h, and error said that "expected specifier-qualifier-list before 'GameArray'", what's going on?

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  • How can I require an attribute on a class definition?

    - by spoulson
    Is there a way to enforce a compile requirement for certain attributes on a class or interface implementation? For example, let's say my application uses a series of static classes that contain const int resource values. I'd like to decorate the class in a Description attribute to describe its contents. In concept, I'd like to apply this attribute requirement to an interface, then each static class would implement it with its required Description. I could write a run-time check or a unit test to check compliance. But really a compile-time check would be best. Is there such a thing?

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  • c# Generic overloaded method dispatching ambiguous

    - by sebgod
    Hello, I just hit a situation where a method dispatch was ambiguous and wondered if anyone could explain on what basis the compiler (.NET 4.0.30319) chooses what overload to call interface IfaceA { } interface IfaceB<T> { void Add(IfaceA a); T Add(T t); } class ConcreteA : IfaceA { } class abstract BaseClassB<T> : IfaceB<T> { public virtual T Add(T t) { ... } public virtual void Add(IfaceA a) { ... } } class ConcreteB : BaseClassB<IfaceA> { // does not override one of the relevant methods } void code() { var concreteB = new ConcreteB(); // it will call void Add(IfaceA a) concreteB.Add(new ConcreteA()); } In any case, why does the compiler not warn me or even why does it compile? Thank you very much for any answers.

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  • ASP.NET UpdatePanel PostBacks

    - by Matthew
    I created a marker interface: public interface ISupportAJAXPostsBacks{} I added it to my Page.. public partial class MyWebForm : PageBase, ISupportAJAXPostsBacks I have this check in my PageBase class... if(this is ISupportAJAXPostsBacks) { ... do some stuff ... } If I step through via the debugger, "this is ISupportAJAXPostsBacks" evaluates to true for the initial page load, but evaluates to false when an UpdatePanel posts back on that same page. (scratches head) What is happening under the covers to cause this and what can I do about it?

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  • Low overhead Java Web Services container?

    - by trojanfoe
    I want to provide a Java-based Web Service, but I don't require the features of a full-blown J2EE Application Server. I would like it to start as quickly as possible, though that's not a hard requirement. The Web Service will handle multiple connections and require access to an Oracle database so it will at least require a thread pool and database connection pool. I may want to put a JSP interface onto it later to provide an internal maintainence interface. I have looked at Jetty with an Apache CXF stack, but it looks like I'll have to do a fair amount configuration before even coding the web service - Will it be worth it? Will it even work? Should I forget about the complexity and simply go with JBoss/Weblogic/etc and put up with the bloat and extra start-up time?

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  • What is your favorite way to read XML files?

    - by stacker
    Let's take this xml structure as example: <?xml version="1.0" encoding="utf-8"?> <Configuration-content> <XFile Name="file name 1" /> <XFile Name="name2" /> <XFile Name="name3" /> <XFile Name="name4" /> </Configuration-content> C# interface to implement: public class Configuration { public XFile[] Files { get; set; } } public interface IConfigurationRipository { Configuration Get(); void Save(Configuration entity); } I wonder what's the best way to do that. The task is to implement IConfigurationRipository using your favorite approach.

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  • Are Objective-C initializers allowed to share the same name?

    - by NattKatt
    I'm running into an odd issue in Objective-C when I have two classes using initializers of the same name, but differently-typed arguments. For example, let's say I create classes A and B: A.h: #import <Cocoa/Cocoa.h> @interface A : NSObject { } - (id)initWithNum:(float)theNum; @end A.m: #import "A.h" @implementation A - (id)initWithNum:(float)theNum { self = [super init]; if (self != nil) { NSLog(@"A: %f", theNum); } return self; } @end B.h: #import <Cocoa/Cocoa.h> @interface B : NSObject { } - (id)initWithNum:(int)theNum; @end B.m: #import "B.h" @implementation B - (id)initWithNum:(int)theNum { self = [super init]; if (self != nil) { NSLog(@"B: %d", theNum); } return self; } @end main.m: #import <Foundation/Foundation.h> #import "A.h" #import "B.h" int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; A *a = [[A alloc] initWithNum:20.0f]; B *b = [[B alloc] initWithNum:10]; [a release]; [b release]; [pool drain]; return 0; } When I run this, I get the following output: 2010-04-26 20:44:06.820 FnTest[14617:a0f] A: 20.000000 2010-04-26 20:44:06.823 FnTest[14617:a0f] B: 1 If I reverse the order of the imports so it imports B.h first, I get: 2010-04-26 20:45:03.034 FnTest[14635:a0f] A: 0.000000 2010-04-26 20:45:03.038 FnTest[14635:a0f] B: 10 For some reason, it seems like it's using the data type defined in whichever @interface gets included first for both classes. I did some stepping through the debugger and found that the isa pointer for both a and b objects ends up the same. I also found out that if I no longer make the alloc and init calls inline, both initializations seem to work properly, e.g.: A *a = [A alloc]; [a initWithNum:20.0f]; If I use this convention when I create both a and b, I get the right output and the isa pointers seem to be different for each object. Am I doing something wrong? I would have thought multiple classes could have the same initializer names, but perhaps that is not the case.

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  • Why are the default UI controls in my iPhone app blurred?

    - by Tom H
    Why would the default iPhone interface elements, specifically the UISwitch (unmodified) and a UISegmentedControl appear slightly blurred? I have not changed them or called any private APIs. This blurring occurs when I run it both in the simulator and when I load it on my iPod Touch, so I don't think it's a one off drawing glitch. These elements were created via some code (initWithFrame:) not in interface builder. Here is a screenshot of the blurring in the simulator: http://drp.ly/14rS6a It looks similar on the actual device. Thanks for your help

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  • Why do I get a WCF timeout even though my service call and callback are successful?

    - by KallDrexx
    I'm playing around with hooking up an in-game console to a WCF interface, so an external application can send console commands and receive console output. To accomplish this I created the following service contracts: public interface IConsoleNetworkCallbacks { [OperationContract(IsOneWay = true)] void NewOutput(IEnumerable<string> text, string category); } [ServiceContract(SessionMode = SessionMode.Required, CallbackContract = typeof(IConsoleNetworkCallbacks))] public interface IConsoleInterface { [OperationContract] void ProcessInput(string input); [OperationContract] void ChangeCategory(string category); } On the server I implemented it with: public class ConsoleNetworkInterface : IConsoleInterface, IDisposable { public ConsoleNetworkInterface() { ConsoleManager.Instance.RegisterOutputUpdateHandler(OutputHandler); } public void Dispose() { ConsoleManager.Instance.UnregisterOutputHandler(OutputHandler); } public void ProcessInput(string input) { ConsoleManager.Instance.ProcessInput(input); } public void ChangeCategory(string category) { ConsoleManager.Instance.UnregisterOutputHandler(OutputHandler); ConsoleManager.Instance.RegisterOutputUpdateHandler(OutputHandler, category); } protected void OutputHandler(IEnumerable<string> text, string category) { var callbacks = OperationContext.Current.GetCallbackChannel<IConsoleNetworkCallbacks>(); callbacks.NewOutput(text, category); } } On the client I implemented the callback with: public class Callbacks : IConsoleNetworkCallbacks { public void NewOutput(IEnumerable<string> text, string category) { MessageBox.Show(string.Format("{0} lines received for '{1}' category", text.Count(), category)); } } Finally, I establish the service host with the following class: public class ConsoleServiceHost : IDisposable { protected ServiceHost _host; public ConsoleServiceHost() { _host = new ServiceHost(typeof(ConsoleNetworkInterface), new Uri[] { new Uri("net.pipe://localhost") }); _host.AddServiceEndpoint(typeof(IConsoleInterface), new NetNamedPipeBinding(), "FrbConsolePipe"); _host.Open(); } public void Dispose() { _host.Close(); } } and use the following code on my client to establish the connection: protected Callbacks _callbacks; protected IConsoleInterface _proxy; protected void ConnectToConsoleServer() { _callbacks = new Callbacks(); var factory = new DuplexChannelFactory<IConsoleInterface>(_callbacks, new NetNamedPipeBinding(), new EndpointAddress("net.pipe://localhost/FrbConsolePipe")); _proxy = factory.CreateChannel(); _proxy.ProcessInput("Connected"); } So what happens is that my ConnectToConsoleServer() is called and then it gets all the way to _proxy.ProcessInput("Connected");. In my game (on the server) I immediately see the output caused by the ProcessInput call, but the client is still stalled on the _proxy.ProcessInput() call. After a minute my client gets a JIT TimeoutException however at the same time my MessageBox message appears. So obviously not only is my command being sent immediately, my callback is being correctly called. So why am I getting a timeout exception? Note: Even removing the MessageBox call, I still have this issue, so it's not an issue of the GUI blocking the callback response.

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  • Accessing "Mapi32.dll" with C#. [not solved]

    - by Code Smack
    Hello, I am using VS 2008 C# Windows Application. I have this DLL Import I am trying to use. [DllImport("Mapi32.dll", PreserveSig = true)] private static extern void WrapCompressedRTFStream( [MarshalAs(UnmanagedType.Interface)] UCOMIStream lpCompressedRTFStream, uint ulflags, [MarshalAs(UnmanagedType.Interface)] out UCOMIStream lpUncompressedRTFStream ); public const uint MAPI_MODIFY = 0x00000001; public const uint STORE_UNCOMPRESSED_RTF = 0x00008000; I have a compressed string that is in CompressedRFTFormat. How do I pass the string into the WrapCompressedRTFStream? I do not understand what the method is expecting. I am trying to use it on a button. RichText1.text = WrapCompressedRTFStream(_CompressedRichText.ToString(),something,somethingelse); The first error I get is "cannot convert from 'string' to 'System.Runtime.InteropServices.UCOMIStream" I hope someone who understands this posts an answer that helps!

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  • Calling C# from ColdFusion

    - by stomcavage
    I've written a .dll in C# to change the permissions on a folder. I also wrote an .exe to test the .dll and it successfully changes the permissions. Now I'm trying to call the .dll from ColdFusion, but I'm getting an error about System/Security/IPermission not being found. I'm assuming this is an interface in C# that ColdFusion can't find in any of the available assemblies on my system. I've added the System.Security assembly to my References in the C# project. Is there something else I need to do to make sure ColdFusion can find the interface? Here's how I'm using the .dll: <cfobject type="dotnet" name="permObj" assembly="#pathToDLLs#CoursePortal.dll" class="CoursePortal.Permissions"> <cfset permObj.revokePermissions(dir, username)>

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  • iPhone app - Terminating DUE TO UNCAUGHT EXCEPTION

    - by Kenneth
    Hi Guys, im trying to switch views between view controllers but it crashed. so basically im switching from mainScreen to test i get an error in the Debugger 0x01d6a000 <+0000 push %ebp 0x01d6a001 <+0001 mov %esp,%ebp 0x01d6a003 <+0003 int3 0x01d6a004 <+0004 leave (HIGHLIGHTED) 0x01d6a005 <+0005 ret 0x01d6a006 <+0006 nopw %cs:0x0(%eax,%eax,1) mainscreen.h import @interface MainScreen : UIViewController { } -(IBAction)btnFirstPage:(id)sender; @end mainscreen.m import "MainScreen.h" import "test.h" @implementation MainScreen -(IBAction)btnFirstPage:(id)sender{ test1 = [[test1 alloc] initWithNibName:@"test" (test may not respond to -alloc) bundle:nil]; [self.view addSubview:test1.view]; .................etc test.h import @interface test : UIViewController { } @end test.m etc (did not edit)

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  • FindBugs and CheckForNull on classes vs. interfaces

    - by ndn
    Is there any way to let FindBugs check and warn me if a CheckForNull annotation is present on the implementation of a method in a class, but not on the declaration of the method in the interface? import javax.annotation.CheckForNull; interface Foo { public String getBar(); } class FooImpl implements Foo { @CheckForNull @Override public String getBar() { return null; } } public class FindBugsDemo { public static void main(String[] args) { Foo foo = new FooImpl(); System.out.println(foo.getBar().length()); } } I just discovered a bug in my application due to a missing null check that was not spotted by FindBugs because CheckForNull was only present on FooImpl, but not on Foo, and I don't want to spot all other locations of this problem manually.

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  • PHP/Apache Deny folder access to user but not to script

    - by Piero
    Hey all, So I have this php web app, and one of my folder contains some files that can be downloaded. I have a download script that modifies the headers, in order to always offer a download link. (instead of showing a picture for example, when you click on a link, a download box pops out) Right now, if you enter a url like: http://www.mywebsite.com/content/ You get the listing of all the downloadable files, and of course, you can just download them all, without going through the website interface. Personally, I don't think it's a problem, since I often use downthemall or other downloading tool, and this type of access is a great time saver.... But of course my company does not think so :-p They want people to use the interface in order to view the Ads... Would they be a way, maybe with a protected .htaccess, to leave the folder access to my download script, but deny access to the users...? I hope I am making sense and you know what I mean :) All help/remarks appreciated!

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