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• Gartner PCC: A Shovel & Some Ah-Ha's

  - by kellsey.ruppel

  When Gartner Vice President and leading analyst Whit Andrews kicked off the Gartner Portals, Content & Collaboration Summit on Monday, March 12 at the Gaylord Palms in Orlando, FL by bringing a shovel to the stage, eyebrows raised and a few thoughts went through my head. Either this guy plans to go help the construction workers outside construct that new pool at the Gaylord or he took a wrong turn and is at the wrong conference. Oh and how did he get that shovel through airport security? As Whit explained more his objective became more clear…take everything anyone has ever told you about portals and throw it out the window, as portals have evolved and times they are most certainly changing. The future Web is here, available not only on browsers but also via a broad spectrum of access points, including automobiles, consumer electronics and more and more mobile devices. Not merely prevalent, the future Web is also multimedia-driven and operates in real time, driven by mobility, social media, streaming video and other dynamic services. Applications and user experiences are in the midst of an evolution — from the early, simple mobile Web models to today’s Web 2.0 mobile apps and, ultimately, to a world of predominantly Web apps. Additionally, cloud services will forever change how portals and user experience are designed, built, delivered, sourced and managed. So what does this mean for you? Today’s organizations need software that will enable them to not just do their jobs, but to do it in a way that is familiar and easy for them.  What does this mean for IT? Use software and technology as an enabler, not as a roadblock. Overall, we had a great week in Orlando learning about how to improve the user experience, manage content explosion, launch social initiatives, transition to mobile environments and understand cloud and SaaS options.  We had some great conversations throughout the conference and at the Oracle booth. Lots of demonstrations were given of Oracle WebCenter Sites and Oracle Social Network. And as Christie mentioned earlier this week, our Vice President of Product Management and Strategy for WebCenter Loren Weinberg presented on the topic of customer engagement and talked about how organization’s relationships with their customers have fundamentally changed today and the resulting impact that has on their priorities.  Loren also talked about the importance of customer engagement, why that matters now more than ever, and what you can do to help your company or organization succeed in this new world. The question asked in every keynote and session was a simple one: What is your “ah-ha” moment? I personally had quite a few, some of which I’ve captured below. 70% of internal social initiatives eventually fail. By 2014, refusing to communicate with consumers via social media will be as harmful as ignoring emails/phone calls is today. Customer engagement = multi-channel + social & interactive + personal & relevant + optimized. If people choose to talk about your product/company/service, it's because it's remarkable. -- Seth Godin's keynote (one of the highlights of the conference!) The Web will become the primary method used for delivering content and applications to mobile devices. By 2015, 20% of smart phone users worldwide will conduct commerce using context-enriched services on a weekly basis.  86% of customers will pay more for a better customer experience. 6 P's of Quality User Experience. Product. Enabled by: People, Patterns, Process, Profit, Priorities. Did you attend the Gartner Summit? What were your ah-ha moments?

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• Question on the implementation of my Entity System

  - by miguel.martin

  I am currently creating an Entity System, in C++, it is almost completed (I have all the code there, I just have to add a few things and test it). The only thing is, I can't figure out how to implement some features. This Entity System is based off a bit from the Artemis framework, however it is different. I'm not sure if I'll be able to type this out the way my head processing it. I'm going to basically ask whether I should do something over something else. Okay, now I'll give a little detail on my Entity System itself. Here are the basic classes that my Entity System uses to actually work: Entity - An Id (and some methods to add/remove/get/etc Components) Component - An empty abstract class ComponentManager - Manages ALL components for ALL entities within a Scene EntitySystem - Processes entities with specific components Aspect - The class that is used to help determine what Components an Entity must contain so a specific EntitySystem can process it EntitySystemManager - Manages all EntitySystems within a Scene EntityManager - Manages entities (i.e. holds all Entities, used to determine whether an Entity has been changed, enables/disables them, etc.) EntityFactory - Creates (and destroys) entities and assigns an ID to them Scene - Contains an EntityManager, EntityFactory, EntitySystemManager and ComponentManager. Has functions to update and initialise the scene. Now in order for an EntitySystem to efficiently know when to check if an Entity is valid for processing (so I can add it to a specific EntitySystem), it must recieve a message from the EntityManager (after a call of activate(Entity& e)). Similarly the EntityManager must know when an Entity is destroyed from the EntityFactory in the Scene, and also the ComponentManager must know when an Entity is created AND destroyed. I do have a Listener/Observer pattern implemented at the moment, but with this pattern I may remove a Listener (which is this case is dependent on the method being called). I mainly have this implemented for specific things related to a game, i.e. Teams, Tagging of entities, etc. So... I was thinking maybe I should call a private method (using friend classes) to send out when an Entity has been activated, deleted, etc. i.e. taken from my EntityFactory void EntityFactory::killEntity(Entity& e) { // if the entity doesn't exsist in the entity manager within the scene if(!getScene()->getEntityManager().doesExsist(e)) { return; // go back to the caller! (should throw an exception or something..) } // tell the ComponentManager and the EntityManager that we killed an Entity getScene()->getComponentManager().doOnEntityWillDie(e); getScene()->getEntityManager().doOnEntityWillDie(e); // notify the listners for(Mouth::iterator i = getMouth().begin(); i != getMouth().end(); ++i) { (*i)->onEntityWillDie(*this, e); } _idPool.addId(e.getId()); // add the ID to the pool delete &e; // delete the entity } As you can see on the lines where I am telling the ComponentManager and the EntityManager that an Entity will die, I am calling a method to make sure it handles it appropriately. Now I realise I could do this without calling it explicitly, with the help of that for loop notifying all listener objects connected to the EntityFactory's Mouth (an object used to tell listeners that there's an event), however is this a good idea (good design, or what)? I've gone over the PROS and CONS, I just can't decide what I want to do. Calling Explicitly: PROS Faster? Since these functions are explicitly called, they can't be "removed" CONS Not flexible Bad design? (friend functions) Calling through Listener objects (i.e. ComponentManager/EntityManager inherits from a EntityFactoryListener) PROS More Flexible? Better Design? CONS Slower? (virtual functions) Listeners can be removed, i.e. may be removed and not get called again during the program, which could cause in a crash. P.S. If you wish to view my current source code, I am hosting it on BitBucket.

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• More Free Apps Bound for the Marketplace

  - by Scott Kuhl

  Microsoft has announced they are raising the limit of free applications a developer can submit from 5 to 100.  But what does that really mean? First, lets look at the reason for the limitation.  The iTunes Store and the Android Market both have a lot more applications available than the Windows Phone Marketplace.  But that says nothing about the quality of those applications.  I attended a couple of pre-launch events and Microsoft representatives were clearly told to send a message. We don’t want a bunch of junky applications that do nothing but spam the marketplace.  That was the reason for the 5 free application limit. Okay, so now what has the result been?  Well, there are still fart apps, but there is no sign of a developer flooding the marking with 1500 wallpaper applications or 1000 of the same application all pointed at different RSS feeds.   On the other hand there are developers who want to release real free apps but are constrained by the 5 app limit. So why did Microsoft change it’s mind?  Is it to get the count of applications up, or is to make developers happy?  Windows Phone Marketplace is growing fast but it’s a long way behind the other guys.   I don’t think Microsoft wants to have 100,000 apps show up in the next 3 months if they are loaded with copy cat apps.  Those numbers will get picked apart quickly and the press will start complaining about  the same problems the Android Market has.  I do think the bump was at developer request.  Microsoft is usually good about listening to developer feedback, but has been pretty slow about it at times.  And from a financial perspective, there will me more apps that Microsoft has to review that they will see no profit on.  At least not until they bake in a advertising model connected to Bing. Ultimately, what does this mean for the future? Well, there are developers out there looking to release more than 5 simple free apps, so I think we will see more hobby apps.  And there are developers out there trying to make money from advertising instead of sales, so I think we will see more of those also.  But the category that I think will grow the fastest is free versions of paid applications that are the same as the trial version of the application.  While technically that makes no sense, its purely a marketing move.  Free apps get downloaded a lot more than paid apps, even with a trial mode.  It always surprises me how little consumers are willing to spend on mobile apps.  How many reviews of applications have you seen that says something like “a bit pricey at $1.99”.  Really?  Have you looked at how much you spend on your phone and plan?  I always thought the trial mode baked into Windows Marketplace was a good idea.  So I’m not sure how the more open free market will play out. In the long run though, I won’t be surprised to see a Bing ad mobile ad model show up so Microsoft can capitalize on the more open and free Windows Marketplace. Bonus: The Oatmeal on How I Feel About Buying Apps

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• Games development with a game loop that's abstracted away

  - by Davy8

  Most game development happens with a main game loop. Are there any good articles/blog posts/discussions about games without a game loop? I imagine they'd mostly be web games, but I'd be interested in hearing otherwise. (As a side note, I think it's really interesting that the concept is almost exclusively used in gaming as far as I'm aware, perhaps that may be another question.) Edit: I realize there's probably a redraw loop somewhere. I guess what I really mean is a loop that is hidden to you. Frames are something you as the developer are not concerned with as you're working on a higher level of abstraction. E.g. someLootItem.moveTo(inventory, someAnimatationType) and that will move from the loot box to your inventory using the specified animation type without the game developer having to worry about the implementation details of that animation. Maybe that's how "real" games end up working, but from reading most tutorials they seem to imply a much more granular level of control is used, but that might just be an artifact of being a tutorial. Edit2: I think most people are misunderstanding what I'm trying to ask, likely because I'm having trouble describing exactly what I'm trying to ask. After some more thinking perhaps what I'm referring to is more along the lines of what I believe is referred to as "scripting" where you're working at a very high level and having some game engine take care of the low level details. For example, take custom maps in Starcraft II or Warcraft III. Many of the "maps" have gameplay that deviates enough from the primary game that they could be considered a separate game written on the same engine. What I'm referring to then is along those lines. I may be wrong because I only dabbed in the Warcraft III editor, but as far as I remember no where in the map editor do you control the game loop, and yet you can create many different games out of it. In my mind, these are games in their own right. If you're playing DotA you don't say you're playing Warcraft III, you say you're playing DotA because that's the actual game you're playing. Such a system may impose limitations that don't exist if you're creating a game from scratch, but it greatly reduces development time because much of the "hard" work has already been done for you. Hopefully that clarifies what I'm asking. Another example of what is I mean, is when you write a web app, of course it communicates through sockets and TCP. But does the average web developer doesn't explicitly write code for connecting sockets. They just need to know about receiving a request and sending a response. There are unique scenarios where you do occasionally need to use raw sockets, but it's generally rare in web development. In a similar fashion, it's very possible to write a game without directly using the game loop, even though one is used behind the scenes. Probably not a AAA title, but there must be hundreds of smaller scale games that can and possibly are written this way. Are there any good resources on writing these "simpler" games?

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• How to use DI and DI containers

  - by Pinetree

  I am building a small PHP mvc framework (yes, yet another one), mostly for learning purposes, and I am trying to do it the right way, so I'd like to use a DI container, but I am not asking which one to use but rather how to use one. Without going into too much detail, the mvc is divided into modules which have controllers which render views for actions. This is how a request is processed: a Main object instantiates a Request object, and a Router, and injects the Request into the Router to figure out which module was called. then it instantiates the Module object and sends the Request to that the Module creates a ModuleRouter and sends the Request to figure out the controller and action it then creates the Controller and the ViewRenderer, and injects the ViewRenderer into the Controller (so that the controller can send data to the view) the ViewRenderer needs to know which module, controller and action were called to figure out the path to the view scripts, so the Module has to figure out this and inject it to the ViewRenderer the Module then calls the action method on the controller and calls the render method on the ViewRenderer For now, I do not have any DI container set up, but what I do have are a bunch of initX() methods that create the required component if it is not already there. For instance, the Module has the initViewRenderer() method. These init methods get called right before that component is needed, not before, and if the component was already set it will not initialize it. This allows for the components to be switched, but it does not require manually setting them if they are not there. Now, I'd like to do this by implementing a DI container, but still keep the manual configuration to a bare minimum, so if the directory structure and naming convention is followed, everything should work, without even touching the config. If I use the DI container, do I then inject it into everything (the container would inject itself when creating a component), so that other components can use it? When do I register components with the DI? Can a component register other components with the DI during run-time? Do I create a 'common' config and use that? How do I then figure out on the fly which components I need and how they need to be set up? If Main uses Router which uses Request, Main then needs to use the container to get Module (or does the module need to be found and set beforehand? How?) Module uses Router but needs to figure out the settings for the ViewRenderer and the Controller on the fly, not in advance, so my DI container can't be setting those on the Module before the module figures out the controller and action... What if the controller needs some other service? Do I inject the container into every controller? If I start doing that, I might just inject it into everything... Basically I am looking for the best practices when dealing with stuff like this. I know what DI is and what DI containers do, but I am looking for guidance to using them in real life, and not some isolated examples on the net. Sorry for the lengthy post and many thanks in advance.

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• How would I handle input with a Game Component?

  - by Aufziehvogel

  I am currently having problems from finding my way into the component-oriented XNA design. I read an overview over the general design pattern and googled a lot of XNA examples. However, they seem to be right on the opposite site. In the general design pattern, an object (my current player) is passed to InputComponent::update(Player). This means the class will know what to do and how this will affect the game (e.g. move person vs. scroll text in a menu). Yet, in XNA GameComponent::update(GameTime) is called automatically without a reference to the current player. The only XNA examples I found built some sort of higher-level Keyboard engine into the game component like this: class InputComponent: GameComponent { public void keyReleased(Keys); public void keyPressed(Keys); public bool keyDown(Keys); public void override update(GameTime gameTime) { // compare previous state with current state and // determine if released, pressed, down or nothing } } Some others went a bit further making it possible to use a Service Locator by a design like this: interface IInputComponent { public void downwardsMovement(Keys); public void upwardsMovement(Keys); public bool pausedGame(Keys); // determine which keys pressed and what that means // can be done for different inputs in different implementations public void override update(GameTime); } Yet, then I am wondering if it is possible to design an input class to resolve all possible situations. Like in a menu a mouse click can mean "click that button", but in game play it can mean "shoot that weapon". So if I am using such a modular design with game components for input, how much logic is to be put into the InputComponent / KeyboardComponent / GamepadComponent and where is the rest handled? What I had in mind, when I heard about Game Components and Service Locator in XNA was something like this: use Game Components to run the InputHandler automatically in the loop use Service Locator to be able to switch input at runtime (i.e. let player choose if he wants to use a gamepad or a keyboard; or which shall be player 1 and which player 2). However, now I cannot see how this can be done. First code example does not seem flexible enough, as on a game pad you could require some combination of buttons for something that is possible on keyboard with only one button or with the mouse) The second code example seems really hard to implement, because the InputComponent has to know in which context we are currently. Moreover, you could imagine your application to be multi-layered and let the key-stroke go through all layers to the bottom-layer which requires a different behaviour than the InputComponent would have guessed from the top-layer. The general design pattern with passing the Player to update() does not have a representation in XNA and I also cannot see how and where to decide which class should be passed to update(). At most time of course the player, but sometimes there could be menu items you have to or can click I see that the question in general is already dealt with here, but probably from a more elobate point-of-view. At least, I am not smart enough in game development to understand it. I am searching for a rather code-based example directly for XNA. And the answer there leaves (a noob like) me still alone in how the object that should receive the detected event is chosen. Like if I have a key-up event, should it go to the text box or to the player?

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• Synchronous Actions

  - by Dan Krasinski-Oracle

  Since the introduction of SMF, svcadm(1M) has had the ability to enable or disable a service instance and wait for that service instance to reach a final state.  With Oracle Solaris 11.2, we’ve expanded the set of administrative actions which can be invoked synchronously. Now all subcommands of svcadm(1M) have synchronous behavior. Let’s take a look at the new usage: Usage: svcadm [-v] [cmd [args ... ]] svcadm enable [-rt] [-s [-T timeout]] <service> ... enable and online service(s) svcadm disable [-t] [-s [-T timeout]] <service> ... disable and offline service(s) svcadm restart [-s [-T timeout]] <service> ... restart specified service(s) svcadm refresh [-s [-T timeout]] <service> ... re-read service configuration svcadm mark [-It] [-s [-T timeout]] <state> <service> ... set maintenance state svcadm clear [-s [-T timeout]] <service> ... clear maintenance state svcadm milestone [-d] [-s [-T timeout]] <milestone> advance to a service milestone svcadm delegate [-s] <restarter> <svc> ... delegate service to a restarter As you can see, each subcommand now has a ‘-s’ flag. That flag tells svcadm(1M) to wait for the subcommand to complete before returning. For enables, that means waiting until the instance is either ‘online’ or in the ‘maintenance’ state. For disable, the instance must reach the ‘disabled’ state. Other subcommands complete when: restart A restart is considered complete once the instance has gone offline after running the ‘stop’ method, and then has either returned to the ‘online’ state or has entered the ‘maintenance’ state. refresh If an instance is in the ‘online’ state, a refresh is considered complete once the ‘refresh’ method for the instance has finished. mark maintenance Marking an instance for maintenance completes when the instance has reached the ‘maintenance’ state. mark degraded Marking an instance as degraded completes when the instance has reached the ‘degraded’ state from the ‘online’ state. milestone A milestone transition can occur in one of two directions. Either the transition moves from a lower milestone to a higher one, or from a higher one to a lower one. When moving to a higher milestone, the transition is considered complete when the instance representing that milestone reaches the ‘online’ state. The transition to a lower milestone, on the other hand, completes only when all instances which are part of higher milestones have reached the ‘disabled’ state. That’s not the whole story. svcadm(1M) will also try to determine if the actions initiated by a particular subcommand cannot complete. Trying to enable an instance which does not have its dependencies satisfied, for example, will cause svcadm(1M) to terminate before that instance reaches the ‘online’ state. You’ll also notice the optional ‘-T’ flag which can be used in conjunction with the ‘-s’ flag. This flag sets a timeout, in seconds, after which svcadm gives up on waiting for the subcommand to complete and terminates. This is useful in many cases, but in particular when the start method for an instance has an infinite timeout but might get stuck waiting for some resource that may never become available. For the C-oriented, each of these administrative actions has a corresponding function in libscf(3SCF), with names like smf_enable_instance_synchronous(3SCF) and smf_restart_instance_synchronous(3SCF).  Take a look at smf_enable_instance_synchronous(3SCF) for details.

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• Problems with moving 2D circle/box collision detection

  - by dario3004

  This is my first game ever and I'm a newbie in computer physics. I've got this code for the collision detection and it works fine for BOTTOM and TOP collision.It miss the collision detection with the paddle's edge and angles so I've (roughly) tried to implement it. Main method that is called for bouncing, it checks if it bounce with wall, or with top (+ right/left side) or with bottom (+ right/left side): protected void handleBounces(float px, float py) { handleWallBounce(px, py); if(mBall.y < getHeight()/4){ if (handleRedFastBounce(mRed, px, py)) return; if (handleRightSideBounce(mRed,px,py)) return; if (handleLeftSideBounce(mRed,px,py)) return; } if(mBall.y > getHeight()/4 * 3){ if (handleBlueFastBounce(mBlue, px, py)) return; if (handleRightSideBounce(mBlue,px,py)) return; if (handleLeftSideBounce(mBlue,px,py)) return; } } This is the code for the BOTTOM bounce: protected boolean handleRedFastBounce(Paddle paddle, float px, float py) { if (mBall.goingUp() == false) return false; // next position tx = mBall.x; ty = mBall.y - mBall.getRadius(); // actual position ptx = px; pty = py - mBall.getRadius(); dyp = ty - paddle.getBottom(); xc = tx + (tx - ptx) * dyp / (ty - pty); if ((ty < paddle.getBottom() && pty > paddle.getBottom() && xc > paddle.getLeft() && xc < paddle.getRight())) { mBall.x = xc; mBall.y = paddle.getBottom() + mBall.getRadius(); mBall.bouncePaddle(paddle); playSound(mPaddleSFX); increaseDifficulty(); return true; } else return false; } As long as I understood it should be something like this: So I tried to make the "left side" and "right side" bounce method: protected boolean handleLeftSideBounce(Paddle paddle, float px, float py){ // next position tx = mBall.x + mBall.getRadius(); ty = mBall.y; // actual position ptx = px + mBall.getRadius(); pty = py; dyp = tx - paddle.getLeft(); yc = ty + (pty - ty) * dyp / (ptx - tx); if (ptx < paddle.getLeft() && tx > paddle.getLeft()){ System.out.println("left side bounce1"); System.out.println("yc: " + yc + "top: " + paddle.getTop() + " bottom: " + paddle.getBottom()); if (yc > paddle.getTop() && yc < paddle.getBottom()){ System.out.println("left side bounce2"); mBall.y = yc; mBall.x = paddle.getLeft() - mBall.getRadius(); mBall.bouncePaddle(paddle); playSound(mPaddleSFX); increaseDifficulty(); return true; } } return false; } I think I'm quite near to the solution but I'm having big troubles with the new "yc" formula. I tried so many versions of it but since I don't know the theory behind it I can't adjust for the Y axis. Since the Y axis is inverted I even tried this: yc = ty - (pty - ty) * dyp / (ptx - tx); I tried Googling it but I can't seem to find a solution for it. Also this method fails when ball touches the angle and I don't think is a nice way because it just test "one" point of the ball and probably there will be many cases in which the ball won't bounce.

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• RemoveHandler Issues with Custom Events

  - by Jeff Certain

  This is a case of things being more complicated that I thought they should be. Since it took a while to figure this one out, I thought it was worth explaining and putting all of the pieces to the answer in one spot. Let me set the stage. Architecturally, I have the notion of generic producers and consumers. These put items onto, and remove items from, a queue. This provides a generic, thread-safe mechanism to load balance the creation and processing of work items in our application. Part of the IProducer(Of T) interface is: 1: Public Interface IProducer(Of T) 2: Event ItemProduced(ByVal sender As IProducer(Of T), ByVal item As T) 3: Event ProductionComplete(ByVal sender As IProducer(Of T)) 4: End Interface Nothing sinister there, is there? In order to simplify our developers’ lives, I wrapped the queue with some functionality to manage the produces and consumers. Since the developer can specify the number of producers and consumers that are spun up, the queue code manages adding event handlers as the producers and consumers are instantiated. Now, we’ve been having some memory leaks and, in order to eliminate the possibility that this was caused by weak references to event handles, I wanted to remove them. This is where it got dicey. My first attempt looked like this: 1: For Each producer As P In Producers 2: RemoveHandler producer.ItemProduced, AddressOf ItemProducedHandler 3: RemoveHandler producer.ProductionComplete, AddressOf ProductionCompleteHandler 4: producer.Dispose() 5: Next What you can’t see in my posted code are the warnings this caused. The 'AddressOf' expression has no effect in this context because the method argument to 'AddressOf' requires a relaxed conversion to the delegate type of the event. Assign the 'AddressOf' expression to a variable, and use the variable to add or remove the method as the handler.  Now, what on earth does that mean? Well, a quick Bing search uncovered a whole bunch of talk about delegates. The first solution I found just changed all parameters in the event handler to Object. Sorry, but no. I used generics precisely because I wanted type safety, not because I wanted to use Object. More searching. Eventually, I found this forum post, where Jeff Shan revealed a missing piece of the puzzle. The other revelation came from Lian_ZA in this post. However, these two only hinted at the solution. Trying some of what they suggested led to finally getting an invalid cast exception that revealed the existence of ItemProducedEventHandler. Hold on a minute! I didn’t create that delegate. There’s nothing even close to that name in my code… except the ItemProduced event in the interface. Could it be? Naaaaah. Hmmm…. Well, as it turns out, there is a delegate created by the compiler for each event. By explicitly creating a delegate that refers to the method in question, implicitly cast to the generated delegate type, I was able to remove the handlers: 1: For Each producer As P In Producers 2: Dim _itemProducedHandler As IProducer(Of T).ItemProducedEventHandler = AddressOf ItemProducedHandler 3: RemoveHandler producer.ItemProduced, _itemProducedHandler 4:  5: Dim _productionCompleteHandler As IProducer(Of T).ProductionCompleteEventHandler = AddressOf ProductionCompleteHandler 6: RemoveHandler producer.ProductionComplete, _productionCompleteHandler 7: producer.Dispose() 8: Next That’s “all” it took to finally be able to remove the event handlers and maintain type-safe code. Hopefully, this will save you the same challenges I had in trying to figure out how to fix this issue!

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• Dont Throw Duplicate Exceptions

  In your code, youll sometimes have write code that validates input using a variety of checks.  Assuming you havent embraced AOP and done everything with attributes, its likely that your defensive coding is going to look something like this: public void Foo(SomeClass someArgument) { if(someArgument == null) { throw new InvalidArgumentException("someArgument"); } if(!someArgument.IsValid()) { throw new InvalidArgumentException("someArgument"); }   // Do Real Work } Do you see a problem here?  Heres the deal Exceptions should be meaningful.  They have value at a number of levels: In the code, throwing an exception lets the develop know that there is an unsupported condition here In calling code, different types of exceptions may be handled differently At runtime, logging of exceptions provides a valuable diagnostic tool Its this last reason I want to focus on.  If you find yourself literally throwing the exact exception in more than one location within a given method, stop.  The stack trace for such an exception is likely going to be identical regardless of which path of execution led to the exception being thrown.  When that happens, you or whomever is debugging the problem will have to guess which exception was thrown.  Guessing is a great way to introduce additional problems and/or greatly increase the amount of time require to properly diagnose and correct any bugs related to this behavior. Dont Guess Be Specific When throwing an exception from multiple code paths within the code, be specific.  Virtually ever exception allows a custom message use it and ensure each case is unique.  If the exception might be handled differently by the caller, than consider implementing a new custom exception type.  Also, dont automatically think that you can improve the code by collapsing the if-then logic into a single call with short-circuiting (e.g. if(x == null || !x.IsValid()) ) that will guarantee that you cant easily throw different information into the message as easily as constructing the exception separately in each case. The code above might be refactored like so:   public void Foo(SomeClass someArgument) { if(someArgument == null) { throw new ArgumentNullException("someArgument"); } if(!someArgument.IsValid()) { throw new InvalidArgumentException("someArgument"); }   // Do Real Work } In this case its taking advantage of the fact that there is already an ArgumentNullException in the framework, but if you didnt have an IsValid() method and were doing validation on your own, it might look like this: public void Foo(SomeClass someArgument) { if(someArgument.Quantity < 0) { throw new InvalidArgumentException("someArgument", "Quantity cannot be less than 0. Quantity: " + someArgument.Quantity); } if(someArgument.Quantity > 100) { throw new InvalidArgumentException("someArgument", "SomeArgument.Quantity cannot exceed 100. Quantity: " + someArgument.Quantity); }   // Do Real Work }   Note that in this last example, Im throwing the same exception type in each case, but with different Message values.  Im also making sure to include the value that resulted in the exception, as this can be extremely useful for debugging.  (How many times have you wished NullReferenceException would tell you the name of the variable it was trying to reference?) Dont add work to those who will follow after you to maintain your application (especially since its likely to be you).  Be specific with your exception messages follow DRY when throwing exceptions within a given method by throwing unique exceptions for each interesting case of invalid state. Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Refactoring existing PHP Project. I need some advices

  - by b0x

  i have a small SAS ERP that was written some years ago using PHP. At that time, it didn't used any framework, but the code isn't a mess as i will explain more detailed in the following lines. Nowadays, the project grow and I’m now working with 3 more programmers. Often, they ask to me why we don’t migrate to a framework such Laravel. Although I'd love trying Laravel, I’m a small business and i don't have time/money to stop and spend a whole year building everything from scratch. I need to live and pay the bills. So, I've read a lot about this matter, and I decided that doing a refactoring is the best way to do it. Also, I'm not so sure that a framework will make things easy. Business goals are: Make the code easier to new hired programmers I must separate the "view", because: I want to release different versions of this product (using the same code), but under different brands and websites at the minimum cost (just changing view) Release different versions to fit mobile/tablet. Make different types of this product, seeling packages as if it were plugins. Develop custom packages for some costumers (like plugins/addon's that they can buy to put on the main application). Code goals: Introduce best pratices, standards for everyone Try to build my own MVC structure Improve validation of data/forms (today they are mixed in both ajax and classes) Create automated testing rotines, to quality assurance. My actual structure project: class\ extra\ hd\ logs\ public_html\ public_html\includes\ public_html\css|js|images\ class\ There are three types of classes. They are all “autoloaded” with something similar with PSR-0, but I don’t use namespaces. 1. class.Something.php Connects to Database using specific methods. I.e: Costumer-list(); It uses “class.Db.php”, that it’s an abstraction of mysqli on every method. 2. class.SomethingProc.php Do things that “join” things that come from “class.Something.php”. Like IF/ELSE, math operations. 3. class.SomethingHTML.php The classes with “HTML” suffix implements only static methods and HTML code only. A real life example: All the programmers need to use $cSomething ($c to class) and $arrSomething (to array). Costumer.php (view) <?php $cCosumter = new Costumer(); $arrCostumer = $cCostumer->list(); echo CostumerHTML::table($arrCostumer); ?> Extra\ Store 3rdparty projects/classes from others, such MPDF, PHPMailer, etc. Hd\ Store user’s fies outsite wwwroot dir. Logs\ Store phplogs and the system itself logs (We have a static Log::error() method, that we put in every method of every class) Public_html\ Stores the files that people use. Public_html\includes\ Store the main “config.php” file and all files that do “ajax things” ajax.Costumer.php, for example. Help is needed ;) So, as you can see we have some standards, and also for database things. But i want to write a manual of our rules. Something that i can give to any new programmer at my companie and he can go on. This is not totally a mess, but It could be better seeing the new practices. What could I do to separate this as MVC, to have multiple VIEW’s. Could you gimme some tips considering my goals? Keep im mind the different products/custom things for specific costumers without breaking the main application. URL for tutorials, books, etc. It would be nice. Thanks!

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• Advice on refactoring PHP Project

  - by b0x

  I have a small SAS ERP that was written some years ago using PHP. At that time, it didn't use any framework, but the code isn't a mess. Nowadays, the project grows and I’m now working with 3 more programmers. Often, they ask to me why we don’t migrate to a framework such as Laravel. Although I'd love trying Laravel, I’m a small business and I don't have time nor money to stop and spend a whole year building everything from scratch. I need to live and pay the bills. So, I've read a lot about this matter, and I decided that doing a refactoring is the best way to do it. Also, I'm not so sure that a framework will make things easy. Business goals are: Make the code easier to new hired programmers Separate the "view", in order to: release different versions of this product (using the same code), but under different brands and websites at the minimum cost (just changing view) release different versions to fit mobile/tablet. Make different types of this product, selling packages as if they were plugins. Develop custom packages for some costumers (like plugins/addon's that they can buy to put on the main application). Code goals: Introduce best pratices, standards for everyone Try to build my own MVC structure Improve validation of data/forms (today they are mixed in both ajax and classes) Create automated testing routines for quality assurance. My current structure project: class\ extra\ hd\ logs\ public_html\ public_html\includes\ public_html\css|js|images\ class\ There are three types of classes. They are all “autoloaded” with something similar with PSR-0, but I don’t use namespaces. 1. class.Something.php Connects to Database using specific methods. I.e: Costumer-list(); It uses “class.Db.php”, that it’s an abstraction of mysql on every method. 2. class.SomethingProc.php Do things that “join” things that come from “class.Something.php”. Like IF/ELSE, math operations. 3. class.SomethingHTML.php The classes with “HTML” suffix implements only static methods and HTML code only. A real life example: All the programmers need to use $cSomething ($c to class) and $arrSomething (to array). Costumer.php (view) <?php $cCosumter = new Costumer(); $arrCostumer = $cCostumer->list(); echo CostumerHTML::table($arrCostumer); ?> Extra\ Store 3rdparty projects/classes from others, such MPDF, PHPMailer, etc. Hd\ Store user’s files outsite wwwroot dir. Logs\ Store phplogs and the system itself logs (We have a static Log::error() method, that we put in every method of every class) Public_html\ Stores the files that people use. Public_html\includes\ Store the main “config.php” file and all files that do “ajax things” ajax.Costumer.php, for example. Help is needed ;) So, as you can see we have some standards, and also for database things. But I want to write a manual of our rules. Something that I can give to any new programmer at my company and he can go on. This is not totally a mess, but it could be better seeing the new practices. What could I do to separate this as MVC, to have multiple views. Could you give me some tips considering my goals? Keep im mind the different products/custom things for specific costumers without breaking the main application. URL for tutorials, books, etc, would be nice.

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• How to safely copy an object?

  - by Prog

  This question is going to be a little long. Please bear with me. Something that happened in a project of mine made me think about how to safely copy objects. I'll present the situation I had and then ask a question. There was a class SomeClass: class SomeClass{ Thing[] things; public SomeClass(Thing[] things){ this.things = things; } // irrelevant stuff omitted public SomeClass copy(){ return new SomeClass(things); } } There was another class Processor that takes SomeClass objects, copies them (via someClassInstance.copy()), manipulates the copy's state, and returns the copy. Here it is: class Processor{ public SomeClass processObject(SomeClass object){ SomeClass copy = object.copy(); manipulateTheCopy(copy); return copy; } // irrelevant stuff omitted } I ran this, and it had bugs. I looked into these bugs, and it turned out that the manipulations Processor does on copy actually affect not only the copy, but also the original SomeClass object that was passed into processObject. I found out that it was because the original and the copy shared state - because the original passed it's field things into the copy when creating it. This made me realize that copying objects is harder than simply instantiating them with the same fields as the original. For the two objects to be completely disconnected, without any shared state, each of the fields passed to the copy also has to be copied. And if that object contains other objects - they have to be copied too. And so on. So basically, in order to be able to actually copy an object, each class in the system must have a copy() method, that also invokes copy() on all of it's fields, and so on. So for example, for copy() in SomeClass to work, it needs to look like this: public SomeClass copy(){ Thing[] copyThings = new Thing[things.length]; for(int i=0; i<things.length; i++) copyThings[i] = things[i].copy(); return new SomeClass(copyThings); } And if Thing has object fields of it's own, than it's own copy() method must be appropriate: class Thing{ Apple apple; Pencil pencil; int number; public Thing(Apple apple, Pencil pencil, int number){ this.apple = apple; this.pencil = pencil; this.number = number; } public Thing copy(){ // 'number' is a primitve. return new Thing(apple.getCopy(), pencil.getCopy(), number); } } And so on. Of course, instead of all classes having a copy() method, the copying mechanism can happen in all of the getters and the constructors of classes (unless places where it isn't suitable, for example when the field points to an external object, not to an object that 'is part' of this object). Still, that means that in order to be able to safely copy an object - most classes would have to have copying mechanisms in their getters. My question is divided into two parts: How frequently do you need to get a copy of an object? Is this a regular issue? Is the technique described common and/or reasonable? Or is there a better way to make safe copies of objects? Or is there an easier way to safely copy objects, without them sharing any state?

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• Color Picking Troubles - LWJGL/OpenGL

  - by Tom Johnson

  I'm attempting to check which object the user is hovering over. While everything seems to be just how I'd think it should be, I'm not able to get the correct color due to the second time I draw (without picking colors). Here is my rendering code: public void render() { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); camera.applyTranslations(); scene.pick(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); camera.applyTranslations(); scene.render(); } And here is what gets called on each block/tile on "scene.pick()": public void pick() { glColor3ub((byte) pickingColor.x, (byte) pickingColor.y, (byte) pickingColor.z); draw(); glReadBuffer(GL_FRONT); ByteBuffer buffer = BufferUtils.createByteBuffer(4); glReadPixels(Mouse.getX(), Mouse.getY(), 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, buffer); int r = buffer.get(0) & 0xFF; int g = buffer.get(1) & 0xFF; int b = buffer.get(2) & 0xFF; if(r == pickingColor.x && g == pickingColor.y && b == pickingColor.z) { hovered = true; } else { hovered = false; } } I believe the problem is that in the method of each tile/block called by scene.pick(), it is reading the color from the regular drawing state, after that method is called somehow. I believe this because when I remove the "glReadBuffer(GL_FRONT)" line from the pick method, it seems to almost fix it, but then it will also select blocks behind the one you are hovering as it is not only looking at the front. If you have any ideas of what to do, please be sure to reply!/ EDIT: Adding scene.render(), tile.render(), and tile.draw() scene.render: public void render() { for(int x = 0; x < tiles.length; x++) { for(int z = 0; z < tiles.length; z++) { tiles[x][z].render(); } } } tile.render: public void render() { glColor3f(color.x, color.y, color.z); draw(); if(hovered) { glColor3f(1, 1, 1); glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); draw(); glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); } } tile.draw: public void draw() { float x = position.x, y = position.y, z = position.z; //Top glBegin(GL_QUADS); glVertex3f(x, y + size, z); glVertex3f(x + size, y + size, z); glVertex3f(x + size, y + size, z + size); glVertex3f(x, y + size, z + size); glEnd(); //Left glBegin(GL_QUADS); glVertex3f(x, y, z); glVertex3f(x + size, y, z); glVertex3f(x + size, y + size, z); glVertex3f(x, y + size, z); glEnd(); //Right glBegin(GL_QUADS); glVertex3f(x + size, y, z); glVertex3f(x + size, y + size, z); glVertex3f(x + size, y + size, z + size); glVertex3f(x + size, y, z + size); glEnd(); } (The game is like an isometric game. That's why I only draw 3 faces.)

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• PHP code works on Chrome, but not on Firefox or IE (send email via HTML form) [on hold]

  - by Cachirro

  My brother has this form: <form id="lista" action="lista2.php" method="post"> <input name="cf_name" type="text" size="50" hidden="yes" class="obscure"> <input name="cf_email" type="text" size="50" hidden="yes" class="obscure"> <textarea name="cf_message" cols="45" rows="10" hidden="yes" class="obscure"> </textarea> <input type="image" name="submit" value="Enviar Lista por Email" src="imagens/lista_email.png" width="40" height="40" onclick="this.form.elements['cf_message'].value = lista_mail;this.form.elements['cf_name'].value = prompt('Escreva o seu nome:', '');this.form.elements['cf_email'].value = prompt('Escreva o seu email:', '');"> <input name="submit2" type="submit" value="Enviar" hidden="yes" class="obscure"> </form> That calls this PHP file: <?php if ( isset($_POST['submit']) ) { // Dados de autenticacao SMTP $smtpinfo['host'] = 'localhost'; $smtpinfo['port'] = '25'; $smtpinfo['auth'] = true; $smtpinfo['username'] = 'xxx'; $smtpinfo['password'] = 'xxx'; // Dados recebidos do formulario $nome = $_POST['cf_name']; $email = $_POST['cf_email']; $mensagem = $_POST['cf_message']; // Inclusão de ficheiro PEAR. Certifique-se que o PEAR está activado no seu alojamento require_once "Mail.php"; // Corpo da mensagem $body = "Nome: ".$nome; $body.= "\n\n"; $body.= nl2br($mensagem); $headers = array ('From' => $email, 'To' => $smtpinfo["username"], 'Subject' => 'Encomenda Website'); $mail_object = Mail::factory('smtp', $smtpinfo); $mail = $mail_object->send($smtpinfo["username"], $headers, $body); if ( PEAR::isError($mail) ) { echo ("<p>" . $mail->getMessage() . "</p>"); } else { echo ('<b><font color="FFFF00">Mensagem enviada com sucesso.<br><br></b>Seu email: ' . $email . '<br><br></font>'); }} ?> This basically sends an email with some selected products, name and email. The problem is that it works perfectly on Chrome, but not on FF or IE. When the submit image is pressed, the URL changes to the PHP file, but it displays a blank page. After display errors activated: ini_set('display_errors',1); ini_set('display_startup_errors',1); error_reporting(-1) FF/IE display blank page and email isn't sent, Chrome sends the email and displays this: Strict Standards: Non-static method Mail::factory() should not be called statically in /var/www/vhosts/[site url]/httpdocs/lista2.php on line 33 Strict Standards: Non-static method PEAR::isError() should not be called statically, assuming $this from incompatible context in /usr/share/php/Mail/smtp.php , dont know if it helps So, what is causing the email to be sent on chrome and not on FF or IE? Thank you.

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• Multithreading 2D gravity calculations

  - by Postman

  I'm building a space exploration game and I've currently started working on gravity ( In C# with XNA). The gravity still needs tweaking, but before I can do that, I need to address some performance issues with my physics calculations. This is using 100 objects, normally rendering 1000 of them with no physics calculations gets well over 300 FPS (which is my FPS cap), but any more than 10 or so objects brings the game (and the single thread it runs on) to its knees when doing physics calculations. I checked my thread usage and the first thread was killing itself from all the work, so I figured I just needed to do the physics calculation on another thread. However when I try to run the Gravity.cs class's Update method on another thread, even if Gravity's Update method has nothing in it, the game is still down to 2 FPS. Gravity.cs public void Update() { foreach (KeyValuePair<string, Entity> e in entityEngine.Entities) { Vector2 Force = new Vector2(); foreach (KeyValuePair<string, Entity> e2 in entityEngine.Entities) { if (e2.Key != e.Key) { float distance = Vector2.Distance(entityEngine.Entities[e.Key].Position, entityEngine.Entities[e2.Key].Position); if (distance > (entityEngine.Entities[e.Key].Texture.Width / 2 + entityEngine.Entities[e2.Key].Texture.Width / 2)) { double angle = Math.Atan2(entityEngine.Entities[e2.Key].Position.Y - entityEngine.Entities[e.Key].Position.Y, entityEngine.Entities[e2.Key].Position.X - entityEngine.Entities[e.Key].Position.X); float mult = 0.1f * (entityEngine.Entities[e.Key].Mass * entityEngine.Entities[e2.Key].Mass) / distance * distance; Vector2 VecForce = new Vector2((float)Math.Cos(angle), (float)Math.Sin(angle)); VecForce.Normalize(); Force = Vector2.Add(Force, VecForce * mult); } } } entityEngine.Entities[e.Key].Position += Force; } } Yeah, I know. It's a nested foreach loop, but I don't know how else to do the gravity calculation, and this seems to work, it's just so intensive that it needs its own thread. (Even if someone knows a super efficient way to do these calculations, I'd still like to know how I COULD do it on multiple threads instead) EntityEngine.cs (manages an instance of Gravity.cs) public class EntityEngine { public Dictionary<string, Entity> Entities = new Dictionary<string, Entity>(); public Gravity gravity; private Thread T; public EntityEngine() { gravity = new Gravity(this); } public void Update() { foreach (KeyValuePair<string, Entity> e in Entities) { Entities[e.Key].Update(); } T = new Thread(new ThreadStart(gravity.Update)); T.IsBackground = true; T.Start(); } } EntityEngine is created in Game1.cs, and its Update() method is called within Game1.cs. I need my physics calculation in Gravity.cs to run every time the game updates, in a separate thread so that the calculation doesn't slow the game down to horribly low (0-2) FPS. How would I go about making this threading work? (any suggestions for an improved Planetary Gravity system are welcome if anyone has them) I'm also not looking for a lesson in why I shouldn't use threading or the dangers of using it incorrectly, I'm looking for a straight answer on how to do it. I've already spent an hour googling this very question with little results that I understood or were helpful. I don't mean to come off rude, but it always seems hard as a programming noob to get a straight meaningful answer, I usually rather get an answer so complex I'd easily be able to solve my issue if I understood it, or someone saying why I shouldn't do what I want to do and offering no alternatives (that are helpful). Thank you for the help!

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• If the model is validating the data, shouldn't it throw exceptions on bad input?

  - by Carlos Campderrós

  Reading this SO question it seems that throwing exceptions for validating user input is frowned upon. But who should validate this data? In my applications, all validations are done in the business layer, because only the class itself really knows which values are valid for each one of its properties. If I were to copy the rules for validating a property to the controller, it is possible that the validation rules change and now there are two places where the modification should be made. Is my premise that validation should be done on the business layer wrong? What I do So my code usually ends up like this: <?php class Person { private $name; private $age; public function setName($n) { $n = trim($n); if (mb_strlen($n) == 0) { throw new ValidationException("Name cannot be empty"); } $this->name = $n; } public function setAge($a) { if (!is_int($a)) { if (!ctype_digit(trim($a))) { throw new ValidationException("Age $a is not valid"); } $a = (int)$a; } if ($a < 0 || $a > 150) { throw new ValidationException("Age $a is out of bounds"); } $this->age = $a; } // other getters, setters and methods } In the controller, I just pass the input data to the model, and catch thrown exceptions to show the error(s) to the user: <?php $person = new Person(); $errors = array(); // global try for all exceptions other than ValidationException try { // validation and process (if everything ok) try { $person->setAge($_POST['age']); } catch (ValidationException $e) { $errors['age'] = $e->getMessage(); } try { $person->setName($_POST['name']); } catch (ValidationException $e) { $errors['name'] = $e->getMessage(); } ... } catch (Exception $e) { // log the error, send 500 internal server error to the client // and finish the request } if (count($errors) == 0) { // process } else { showErrorsToUser($errors); } Is this a bad methodology? Alternate method Should maybe I create methods for isValidAge($a) that return true/false and then call them from the controller? <?php class Person { private $name; private $age; public function setName($n) { $n = trim($n); if ($this->isValidName($n)) { $this->name = $n; } else { throw new Exception("Invalid name"); } } public function setAge($a) { if ($this->isValidAge($a)) { $this->age = $a; } else { throw new Exception("Invalid age"); } } public function isValidName($n) { $n = trim($n); if (mb_strlen($n) == 0) { return false; } return true; } public function isValidAge($a) { if (!is_int($a)) { if (!ctype_digit(trim($a))) { return false; } $a = (int)$a; } if ($a < 0 || $a > 150) { return false; } return true; } // other getters, setters and methods } And the controller will be basically the same, just instead of try/catch there are now if/else: <?php $person = new Person(); $errors = array(); if ($person->isValidAge($age)) { $person->setAge($age); } catch (Exception $e) { $errors['age'] = "Invalid age"; } if ($person->isValidName($name)) { $person->setName($name); } catch (Exception $e) { $errors['name'] = "Invalid name"; } ... if (count($errors) == 0) { // process } else { showErrorsToUser($errors); } So, what should I do? I'm pretty happy with my original method, and my colleagues to whom I have showed it in general have liked it. Despite this, should I change to the alternate method? Or am I doing this terribly wrong and I should look for another way?

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• MVC Communication Pattern

  - by Kedu

  This is kind of a follow up question to this http://stackoverflow.com/questions/23743285/model-view-controller-and-callbacks, but I wanted to post it separately, because its kind of a different topic. I'm working on a multiplayer cardgame for the Android platform. I split the project into MVC which fits the needs pretty good, but I'm currently stuck because I can't figure out a good way to communicate between the different parts. I have everything setup and working with the controller being a big state machine, which is called over and over from the gameloop, and calls getter methods from the GUI and the android/network part to get the input. The input itself in the GUI and network is set by inputlisteners that set a local variable which I read in the getter method. So far so good, this is working. But my problem is, the controller has to check every input separately,so if I want to add an input I have to check in which states its valid and call the getter method from all these states. This is not good, and lets the code look pretty ugly, makes additions uncomfortable and adds redundance. So what I've got from the question I mentioned above is that some kind of command or event pattern will fit my needs. What I want to do is to create a shared and threadsafe queue in the controller and instead of calling all these getter methods, I just check the queue for new input and proceed it. On the other side, the GUI and network don't have all these getters, but instead create an event or command and send it to the controller through, for example, observer/observable. Now my problem: I can't figure out a way, for these commands/events to fit a common interface (which the queue can store) and still transport different kind of data (button clicks, cards that are played, the player id the command comes from, synchronization data etc.). If I design the communication as command pattern, I have to stick all the information that is needed to execute the command into it when its created, that's impossible because the GUI or network has no knowledge of all the things the controller needs to execute stuff that needs to be done when for example a card is played. I thought about getting this stuff into the command when executing it. But over all the different commands I have, I would need all the information the controller has, and thus give the command a reference to the controller which would make everything in it public, which is real bad design I guess. So, I could try some kind of event pattern. I have to transport data in the event. So, like the command, I would have an interface, which all events have in common, and can be stored in the shared queue. I could create a big enum with all the different events that a are possible, save one of these enums in the actual event, and build a big switch case for the events, to proceed different stuff for different events. The problem here: I have different data for all the events. But I need a common interface, to store the events in a queue. How do I get the specific data, if I can only access the event through the interface? Even if that wouldn't be a problem, I'm creating another big switch case, which looks ugly, and when i want to add a new event, I have to create the event itself, the case, the enum, and the method that's called with the data. I could of course check the event with the enum and cast it to its type, so I can call event type specific methods that give me the data I need, but that looks like bad design too.

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• What's new in Servlet 3.1 ? - Java EE 7 moving forward

  - by arungupta

  Servlet 3.0 was released as part of Java EE 6 and made huge changes focused at ease-of-use. The idea was to leverage the latest language features such as annotations and generics and modernize how Servlets can be written. The web.xml was made as optional as possible. Servet 3.1 (JSR 340), scheduled to be part of Java EE 7, is an incremental release focusing on couple of key features and some clarifications in the specification. The main features of Servlet 3.1 are explained below: Non-blocking I/O - Servlet 3.0 allowed asynchronous request processing but only traditional I/O was permitted. This can restrict scalability of your applications. Non-blocking I/O allow to build scalable applications. TOTD #188 provide more details about how non-blocking I/O can be done using Servlet 3.1. HTTP protocol upgrade mechanism - Section 14.42 in the HTTP 1.1 specification (RFC 2616) defines an upgrade mechanism that allows to transition from HTTP 1.1 to some other, incompatible protocol. The capabilities and nature of the application-layer communication after the protocol change is entirely dependent upon the new protocol chosen. After an upgrade is negotiated between the client and the server, the subsequent requests use the new chosen protocol for message exchanges. A typical example is how WebSocket protocol is upgraded from HTTP as described in Opening Handshake section of RFC 6455. The decision to upgrade is made in Servlet.service method. This is achieved by adding a new method: HttpServletRequest.upgrade and two new interfaces: javax.servlet.http.HttpUpgradeHandler and javax.servlet.http.WebConnection. TyrusHttpUpgradeHandler shows how WebSocket protocol upgrade is done in Tyrus (Reference Implementation for Java API for WebSocket). Security enhancements Applying run-as security roles to #init and #destroy methods Session fixation attack by adding HttpServletRequest.changeSessionId and a new interface HttpSessionIdListener. You can listen for any session id changes using these methods. Default security semantic for non-specified HTTP method in <security-constraint> Clarifying the semantics if a parameter is specified in the URI and payload Miscellaneous ServletResponse.reset clears any data that exists in the buffer as well as the status code, headers. In addition, Servlet 3.1 will also clears the state of calling getServletOutputStream or getWriter. ServletResponse.setCharacterEncoding: Sets the character encoding (MIME charset) of the response being sent to the client, for example, to UTF-8. Relative protocol URL can be specified in HttpServletResponse.sendRedirect. This will allow a URL to be specified without a scheme. That means instead of specifying "http://anotherhost.com/foo/bar.jsp" as a redirect address, "//anotherhost.com/foo/bar.jsp" can be specified. In this case the scheme of the corresponding request will be used. Clarification in HttpServletRequest.getPart and .getParts without multipart configuration. Clarification that ServletContainerInitializer is independent of metadata-complete and is instantiated per web application. A complete replay of What's New in Servlet 3.1: An Overview from JavaOne 2012 can be seen here (click on CON6793_mp4_6793_001 in Media). Each feature will be added to the JSR subject to EG approval. You can share your feedback to [email protected]. Here are some more references for you: Servlet 3.1 Public Review Candidate Downloads Servlet 3.1 PR Candidate Spec Servlet 3.1 PR Candidate Javadocs Servlet Specification Project JSR Expert Group Discussion Archive Java EE 7 Specification Status Several features have already been integrated in GlassFish 4 Promoted Builds. Have you tried any of them ? Here are some other Java EE 7 primers published so far: Concurrency Utilities for Java EE (JSR 236) Collaborative Whiteboard using WebSocket in GlassFish 4 (TOTD #189) Non-blocking I/O using Servlet 3.1 (TOTD #188) What's New in EJB 3.2 ? JPA 2.1 Schema Generation (TOTD #187) WebSocket Applications using Java (JSR 356) Jersey 2 in GlassFish 4 (TOTD #182) WebSocket and Java EE 7 (TOTD #181) Java API for JSON Processing (JSR 353) JMS 2.0 Early Draft (JSR 343) And of course, more on their way! Do you want to see any particular one first ?

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• Cannot get ATI Drivers installed

  - by bittoast67

  I am trying to install the Catalyst driver. The best I can get is a strange resolution problem and firefox acts all wonkt. The worst I have gotten is low graphics mode in which I just reinstall Ubuntu. I have a HP Pavilion Dv7 laptop. With Radeon 3200 HD. I plan to try again with a fresh install of Ubuntu 12.4.3 as I have heard its the most compatible. This is what I have done: I have tried just the easy way of going to synaptic and installing the drivers that way. the fglrx package (not the fglrx update). And if memory serves I think that boots me into low graphics mode. So, fresh install of Ubuntu and tried again. I have done everything a couple times from this site (http://wiki.cchtml.com/index.php/Ubuntu_Precise_Installation_Guide) following every instruction to a T. That gets me something, such as a lowered fan speed and a much cooler computer, but I also lose most of my resolution. And displays says its the best resolution I can get. I also have a very screwy firefox. Using this method I can see AMD Catalyst Control Center in my dash (two of them really one administrator and one not) but when I try to open it it says no amd driver detected. So again, ubuntu reinstall. I have tried the GUI method from the Legacy driver I got from AMD's site. It runs through smoothly and at the very end after I exit the installer it gives me an error. I have also tried various other methods using terminal, as well as various different drivers (the one from the amd's site and the one suggested in the above link for my graphics card) both to no avail. When I try the method in the link on number 2, and I get the super low res and screwy fire fox. I type in, fglrxinfo ,and get a badrequest error. I have yet to type in fglrxinfo and get anything like what I am supposed to. UPDATE: I am now currently reinstalling Ubuntu 12.4. I tried the above mentioned link - thank you very much!- just to see on the previously failed driver attempt by following the purge commands. And to no avail when typing fglrxinfo I still get the badrequest thing. I will update again after a try with a true fresh install. Thanks again!! UPDATE: Alright everyone. Still no go. I have done everything word per word in the provided tutorial. I have rebooted my computer again to a fucked up resolution and this is what I get when typing fglrxinfo: $ fglrxinfo X Error of failed request: BadRequest (invalid request code or no such operation) Major opcode of failed request: 153 (GLX) Minor opcode of failed request: 19 (X_GLXQueryServerString) Serial number of failed request: 12 Current serial number in output stream: 12 I would like to add that when installing this file: fglrx_8.970-0ubuntu1_amd64.deb I got this: Building initial module for 3.8.0-29-generic Error! Bad return status for module build on kernel: 3.8.0-29-generic (x86_64) Consult /var/lib/dkms/fglrx/8.970/build/make.log for more information. update-initramfs: deferring update (trigger activated) Processing triggers for ureadahead ... Processing triggers for bamfdaemon ... Rebuilding /usr/share/applications/bamf.index... Processing triggers for initramfs-tools ... update-initramfs: Generating /boot/initrd.img-3.8.0-29-generic Processing triggers for libc-bin ... ldconfig deferred processing now taking place Any ideas? Anyone? I cant for the life of me figure out what I am doing wrong.

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• Can you/should you develop components for ASP.NET MVC?

  - by Vilx-

  Following from the previous question I've started to wonder - is it possible to implement "Components" in ASP.NET MVC (latest version)? And should you? Let's clarify what I mean with a "component". With that I mean a "control" (aka "widget"), similar to those that ASP.NET webforms is built upon. A gridview might be a good example. In webforms I can place on my form a datasource component (one line of code), a gridview component (another line of code) and bind them together (specify an attribute on the gridview). In the codebehind file I fill the datasource with data (a few lines of DB-querying code), and I'm all set. At this point the gridview is a fully functional standalone component. I can open the form, and I'll see all the data. I can sort it by clicking on the column headers; it is split into several pages; I can drag the column headers around and rearrange columns; I can turn on "grouping" mode; etc. And I don't need to write another line of code for any of it. The gridview, as a component, already has all the code tucked away in its classes and assemblies. I just place it on the form, initialize it, and it Just Works. At some times (like sorting or navigation to a different page) it will also perform ajax callbacks to the server, but those too will be handled internally, with my code having no knowledge at all about it. And then there are also events that I can attach if I want to get notified when something happens. In MVC I cannot see a way of doing this cleanly. Sure, there are the partial views, but those only handle half of the problem - they render the initial HTML. Some more can be achieved with client-side Javascript (like column re-arranging), but when the grid needs to do an ajax callback (say, to fetch the next page of data), my code will have to get involved and process that request. At best I guess I can provide some helper methods to process it, but I'll have to write the code that calls them, and also provide a controller method with signature matching the arguments of that callback. I guess that I could make some hacks with global events or special routes or something, but that just seems... hackish. Unelegant. Perhaps this is not the MVC way? Although I've completed one project in it, I'm still far from being an MVC expert. But then what is? In the intranet application that we're building there are dozens upon dozens of such grids. Naturally I want them all to have a unified look & behavior, and I don't want to repeat the same code all over the place. So what's the "MVC" approach to this problem?

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• Delegates: A Practical Understanding

  - by samerpaul

  It's been a while since I have written on this blog, and I'm planning on reviving it this summer, since I have more time to do so again.I've also recently started working on the iPhone platform, so I haven't been as busy in .NET as before.In either case, today's blog post applies to both C# and Objective-C, because it's more about a practical understanding of delegates than it is about code. When I was learning coding, I felt like delegates was one of the hardest things to conceptually understand, and a lot of books don't really do a good job (in my opinion) of explaining it. So here's my stab at it.A Real Life Example of DelegatesLet's say there are three of you. You, your friend, and your brother. You're each in a different room in your house so you can't hear each other, even if you shout. 1)You are playing a computer game2) Friend is building a puzzle3) Brother is nappingNow, you three are going to stay in your room but you want to be informed if anything interesting is happening to the one of you. Let's say you (playing the computer game) want to know when your brother wakes up.You could keep walking to the room, checking to see if he's napping, and then walking back to your room. But that would waste a lot of time / resources, and what if you miss when he's awake before he goes back to sleep? That would be bad.Instead, you hand him a 2-way radio that works between your room and his room. And you inform him that when he wakes up, he should press a button on the radio and say "I'm awake". You are going to be listening to that radio, waiting for him to say he's awake. This, in essence, is how a delegate works.You're creating an "object" (the radio) that allows you to listen in on an event you specify. You don't want him to send any other messages to you right now, except when he wakes up. And you want to know immediately when he does, so you can go over to his room and say hi. (the methods that are called when a delegate event fires). You're also currently specifying that only you are listening on his radio.Let's say you want your friend to come into the room at the same time as you, and do something else entirely, like fluff your brother's pillow. You will then give him an identical radio, that also hooks into your brother's radio, and inform him to wait and listen for the "i'm awake" signal.Then, when your brother wakes up, he says "I'm awake!" and both you and your friend walk into the room. You say hi, and your friend fluffs the pillow, then you both exit.Later, if you decide you don't care to say hi anymore, you turn off your radio. Now, you have no idea when your brother is awake or not, because you aren't listening anymore.So again, you are each classes in this example, and each of you have your own methods. You're playing a computer game (PlayComputerGame()), your friend is building a puzzle (BuildPuzzle()) and your brother is napping (Napping()). You create a delegate (ImAwake) that you set your brother to do, when he wakes up. You listen in on that delegate (giving yourself a radio and turning it on), and when you receive the message, you fire a new method called SayHi()). Your friend is also wired up to the same delegate (using an identical radio) and fires the method FluffPillow().Hopefully this makes sense, and helps shed some light on how delegates operate. Let me know! Feel free to drop me a line at Twitter (preferred method of contact) here: samerabousalbi

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• Is the Leptonica implementation of 'Modified Median Cut' not using the median at all?

  - by TheCodeJunkie

  I'm playing around a bit with image processing and decided to read up on how color quantization worked and after a bit of reading I found the Modified Median Cut Quantization algorithm. I've been reading the code of the C implementation in Leptonica library and came across something I thought was a bit odd. Now I want to stress that I am far from an expert in this area, not am I a math-head, so I am predicting that this all comes down to me not understanding all of it and not that the implementation of the algorithm is wrong at all. The algorithm states that the vbox should be split along the lagest axis and that it should be split using the following logic The largest axis is divided by locating the bin with the median pixel (by population), selecting the longer side, and dividing in the center of that side. We could have simply put the bin with the median pixel in the shorter side, but in the early stages of subdivision, this tends to put low density clusters (that are not considered in the subdivision) in the same vbox as part of a high density cluster that will outvote it in median vbox color, even with future median-based subdivisions. The algorithm used here is particularly important in early subdivisions, and 3is useful for giving visible but low population color clusters their own vbox. This has little effect on the subdivision of high density clusters, which ultimately will have roughly equal population in their vboxes. For the sake of the argument, let's assume that we have a vbox that we are in the process of splitting and that the red axis is the largest. In the Leptonica algorithm, on line 01297, the code appears to do the following Iterate over all the possible green and blue variations of the red color For each iteration it adds to the total number of pixels (population) it's found along the red axis For each red color it sum up the population of the current red and the previous ones, thus storing an accumulated value, for each red note: when I say 'red' I mean each point along the axis that is covered by the iteration, the actual color may not be red but contains a certain amount of red So for the sake of illustration, assume we have 9 "bins" along the red axis and that they have the following populations 4 8 20 16 1 9 12 8 8 After the iteration of all red bins, the partialsum array will contain the following count for the bins mentioned above 4 12 32 48 49 58 70 78 86 And total would have a value of 86 Once that's done it's time to perform the actual median cut and for the red axis this is performed on line 01346 It iterates over bins and check they accumulated sum. And here's the part that throws me of from the description of the algorithm. It looks for the first bin that has a value that is greater than total/2 Wouldn't total/2 mean that it is looking for a bin that has a value that is greater than the average value and not the median ? The median for the above bins would be 49 The use of 43 or 49 could potentially have a huge impact on how the boxes are split, even though the algorithm then proceeds by moving to the center of the larger side of where the matched value was.. Another thing that puzzles me a bit is that the paper specified that the bin with the median value should be located, but does not mention how to proceed if there are an even number of bins.. the median would be the result of (a+b)/2 and it's not guaranteed that any of the bins contains that population count. So this is what makes me thing that there are some approximations going on that are negligible because of how the split actually takes part at the center of the larger side of the selected bin. Sorry if it got a bit long winded, but I wanted to be as thoroughas I could because it's been driving me nuts for a couple of days now ;)

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• How to introduce a computer illiterate 50-year old to programming [closed]

  - by sunday

  The other day my dad asked me a question that I would have never expected from him. "How can I learn C++?" My dad is turning 56 this year and computers are a distant concept for him. He doesn't know how to use a phone very well besides calling numbers (no speed dial or contacts); though he has started to learn computers a little better - to the point that he knows how to open the internet (in Windows) and browse around (and has successfully completed several job applications entirely on his own online, of which he was offered positions too). But still, these are too narrow-windowed experiences to mean much, really. While he may not have the background, my dad knows how to read. And I mean reading as a skill, not just an ability. He has little to no college education (financial problems, family, etc.) and was fortunate enough to finish high school, but still taught himself to become a master electrician and has been one for almost 30 years now. He did the same with guitar, learning to play at a very professional level and has been praised for his skill. In high school, he picked up a weight lifting book - and was the only person in his high school at the time to qualify officially as an "athlete" by national standards. In all cases, he just needed something to read. Something to teach him. He absorbs information like a sponge. I have no doubt in my dad's motivation or capability of doing this, so my general goal is simply: Get my dad into the world of computers, and get him on the road to programming. I strongly believe that once I get him through the fundamentals, his drive and reading skill will keep him going on this own. So I'm asking you all: where should I start with all this? And what are the best resources out there? Should I get him to start Linux instead of Windows? Is C++ a bad idea? Remember, he needs to (IMO) learn computers first, and then get that first grasp (the "Hello world" experience) of programming. For money's sake and at top preference, I'd like free online resources that he can read, but by all means any good suggestions in print or paid-for-online are welcome (that I could possibly look into later to purchase). And also, I intend to start him off with C++ (no Python, Java, etc.), because I know it the best and will be able to help him along the way with code. (I have minimal knowledge right now in other languages). Edit: I'm getting a lot of persistent suggestions to use Python. The only reason I wanted to do C++ is that I KNOW it and can be THERE when my dad needs help. My VERY FIRST exposure to programming ever was Java. I learned Java, and I got good at it. I open to other suggestions, but please provide an effective application of your suggestions. EDIT #2: I understand my approach/thinking/knowledge could be lacking here. I'm a sophomore level undergraduate CS major. If you don't agree with anything in my post, tell me why - give me ideas, information - that's why I'm asking in the first place. To narrow down my general goal to specific reachable goals.

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• Selenium &ndash; Use Data Driven tests to run in multiple browsers and sizes

  - by Aligned

  Originally posted on: http://geekswithblogs.net/Aligned/archive/2013/11/04/selenium-ndash-use-data-driven-tests-to-run-in-multiple.aspxSelenium uses WebDriver (or is it the same? I’m still learning how it is connected) to run Automated UI tests in many different browsers. For example, you can run the same test in Chrome and Firefox and in a smaller sized Chrome browser. The permutations can grow quickly. One way to get them to run in MStest is to create  a test method for each test (ie ChromeDeleteItem_Small, ChromeDeleteItem_Large, FFDeleteItem_Small, FFDeleteItem_Large) that each call  the same base method, passing in the browser and size you’d like. This approach was causing a lot of duplicate code, so I decided to use the data driven approach, common to Coded UI or Unit test methods. 1. Create a class with a test method. 2. Create a csv with two columns: BrowserType, BrowserSize 3. Add rows for each permutation: Chrome, Large | Chrome, Small | Firefox, Large | Firefox, Small | IE, Large | IE, Small | *** 4. Add the csv to the Visual Studio Project. 5. Set the Copy to output directory to Copy always 6. Add the attribute: [DataSource("Microsoft.VisualStudio.TestTools.DataSource.CSV", "|DataDirectory|\\TestMatrix.csv", "TestMatrix#csv", DataAccessMethod.Sequential), DeploymentItem("TestMatrix.csv")] 7. Run the test in the test explorer Example:[CodedUITest] public class AllTasksTests : TasksTestBase { [TestMethod] [TestCategory("Tasks")] [DataSource("Microsoft.VisualStudio.TestTools.DataSource.CSV", "|DataDirectory|\\TestMatrix.csv", "TestMatrix#csv", DataAccessMethod.Sequential), DeploymentItem("TestMatrix.csv")] public void CreateTask() { this.PrepForDataDrivenTest(); base.CreateTaskTest("New Task"); } } protected void PrepForDataDrivenTest() { var browserType = this.ParseBrowserType(Context.DataRow["BrowserType"].ToString()); var browserSize = this.ParseBrowserSize(Context.DataRow["BrowserSize"].ToString()); this.BrowserType = browserType; this.BrowserSize = browserSize; Trace.WriteLine("browser: " + browserType.ToString()); Trace.WriteLine("browser size: " + browserSize.ToString()); } /// <summary> /// Get the enum value from the string /// </summary> /// <param name="browserType">Chrome, Firefox, or IE</param> /// <returns>The browser type.</returns> private BrowserType ParseBrowserType(string browserType) { return (UITestFramework.BrowserType)Enum.Parse(typeof(UITestFramework.BrowserType), browserType, true); } /// <summary> /// Get the browser size enum value from the string /// </summary> /// <param name="browserSize">Small, Medium, Large</param> /// <returns>the browser size</returns> private BrowserSizeEnum ParseBrowserSize(string browserSize) { return (BrowserSizeEnum)Enum.Parse(typeof(BrowserSizeEnum), browserSize, true); }/// <summary> /// Change the browser to the size based on the enum. /// </summary> /// <param name="browserSize">The BrowserSizeEnum value to resize the window to.</param> private void ResizeBrowser(BrowserSizeEnum browserSize) { switch (browserSize) { case BrowserSizeEnum.Large: this.driver.Manage().Window.Maximize(); break; case BrowserSizeEnum.Medium: this.driver.Manage().Window.Size = new Size(800, this.driver.Manage().Window.Size.Height); break; case BrowserSizeEnum.Small: this.driver.Manage().Window.Size = new Size(500, this.driver.Manage().Window.Size.Height); break; default: break; } }/// <summary> /// Browser sizes for automation testing /// </summary> public enum BrowserSizeEnum { /// <summary> /// Large size, Maximized to the desktop /// </summary> Large, /// <summary> /// Similar to tablets /// </summary> Medium, /// <summary> /// Phone sizes... 610px and smaller /// </summary> Small } Hope it helps!

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