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• Perl - can't flush STDOUT or STDERR

  - by Jim Salter

  Perl 5.14 from stock Ubuntu Precise repos. Trying to write a simple wrapper to monitor progress on copying from one stream to another: use IO::Handle; while ($bufsize = read (SOURCE, $buffer, 1048576)) { STDERR->printflush ("Transferred $xferred of $sendsize bytes\n"); $xferred += $bufsize; print TARGET $buffer; } This does not perform as expected (writing a line each time the 1M buffer is read). I end up seeing the first line (with a blank value of $xferred), and then the 7th and 8th lines (on an 8MB transfer). Been pounding my brains out on this for hours - I've read the perldocs, I've read the classic "Suffering from Buffering" article, I've tried everything from select and $|++ to IO::Handle to binmode (STDERR, "::unix") to you name it. I've also tried flushing TARGET with each line using IO::Handle (TARGET-flush). No dice. Has anybody else ever encountered this? I don't have any ideas left. Sleeping one second "fixes" the problem, but obviously I don't want to sleep a second every time I read a buffer just so my progress will output on the screen! FWIW, the problem is exactly the same whether I'm outputting to STDERR or STDOUT.

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• Windows 8 Camp&ndash;Ways to Prepare

  - by Lori Lalonde

  When Windows 8 was announced at the BUILD conference back in September, it created quite a buzz among the developer community. By the spring of 2012,  Windows 8 Developer Camps started popping up everywhere imaginable. I received a lot of questions from CTTDNUG members about whether or not we would be hosting one locally. If you recall my post about the Windows Phone/Azure Developer Workshop that CTTDNUG hosted back in March, you’ll remember that the biggest hurdle to overcome when planning this type of event was finding the right venue. It took some time, but I finally found a venue that was available and provided the prerequisites needed to ensure this camp is a success. I am very excited that CTTDNUG will be hosting a Windows 8 Camp this summer in the Kitchener/Waterloo area. In fact, it’s coming up in less than 2 weeks. Clearly other developers are excited as well, because our registration numbers show that the event is already 70% full! On top of that, I was fortunate enough to also book two well-known evangelists to present and teach at this full day developer camp: Andrei Marukovich and Atley Hunter. This was the icing on the cake. With the content provided by Microsoft, and two local experts that live and breathe Windows 8 development, I know that I, along with other developers that attend this event, will have the opportunity to maximize our learning potential and hit the ground running. If you plan on attending a Windows 8 Developer Camp soon, and want to ensure you get the most “bang for your buck” (figuratively speaking, since these camps are free), there are some things you can do to prepare before the big day: 1) Install the prerequisites on your own device before the big day I can’t stress this enough. Otherwise, you will be spending valuable time during the hands-on period downloading and installing what is needed, rather than digging into the development and using that time to ask the experts on-hand about programming challenges, issues, questions you may have with respect to your development. Prerequisites: Windows 8 Release Preview Visual Studio 2012 RC Download the Windows 8 SDK Samples 2) Purchase, download, and read Charles Petzold’s newest book:  Programming Windows 6th Edition This is a great introduction to the type of content you will be learning about during the camp. Doing some light reading beforehand might raise some questions about the concepts discussed in the book, which will give you the opportunity to write them down and bring them with you to the camp. The experts on hand will be able to answer them for you. 3) Make use of the freebies that are available Telerik has recently released a preview of their RadControls for Metro. You can sign up to receive a license code to give you access to install the preview for free and start playing around with it. Syncfusion also offers a free download of their Metro Studio package, which is a collection of metro style icons that you can customize and use in your own applications. Last but not least, once you’ve installed the Windows 8 Release Preview on your own device, go to the Windows 8 Store and download a handful of the free apps that are available. Testing out other Metro apps may give you ideas of what you can do in your own apps and analyze what features you like: application flow, type of animations used, concepts that were leveraged, how live tiles were used, etc. I hope you found these tips to be useful as you embark on a new development journey! Although this post focused on how to prepare for a Windows 8 camp, the same ideas are there whichever developer camp/workshop/event you attend. Learning does not begin and end on the day of the event. Attending a developer camp is just one step of many to master whatever technology you are interested in. It is a continuous process, which is fully maximized when you do your homework beforehand, actively participate during,  and follow up by putting what you learned to practice afterwards. Happy coding!

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• C#: Handling Notifications: inheritance, events, or delegates?

  - by James Michael Hare

  Often times as developers we have to design a class where we get notification when certain things happen. In older object-oriented code this would often be implemented by overriding methods -- with events, delegates, and interfaces, however, we have far more elegant options. So, when should you use each of these methods and what are their strengths and weaknesses? Now, for the purposes of this article when I say notification, I'm just talking about ways for a class to let a user know that something has occurred. This can be through any programmatic means such as inheritance, events, delegates, etc. So let's build some context. I'm sitting here thinking about a provider neutral messaging layer for the place I work, and I got to the point where I needed to design the message subscriber which will receive messages from the message bus. Basically, what we want is to be able to create a message listener and have it be called whenever a new message arrives. Now, back before the flood we would have done this via inheritance and an abstract class: 1:  2: // using inheritance - omitting argument null checks and halt logic 3: public abstract class MessageListener 4: { 5: private ISubscriber _subscriber; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber) 11: { 12: _subscriber = subscriber; 13: _messageThread = new Thread(MessageLoop); 14: _messageThread.Start(); 15: } 16:  17: // user will override this to process their messages 18: protected abstract void OnMessageReceived(Message msg); 19:  20: // handle the looping in the thread 21: private void MessageLoop() 22: { 23: while(!_isHalted) 24: { 25: // as long as processing, wait 1 second for message 26: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 27: if(msg != null) 28: { 29: OnMessageReceived(msg); 30: } 31: } 32: } 33: ... 34: } It seems so odd to write this kind of code now. Does it feel odd to you? Maybe it's just because I've gotten so used to delegation that I really don't like the feel of this. To me it is akin to saying that if I want to drive my car I need to derive a new instance of it just to put myself in the driver's seat. And yet, unquestionably, five years ago I would have probably written the code as you see above. To me, inheritance is a flawed approach for notifications due to several reasons: Inheritance is one of the HIGHEST forms of coupling. You can't seal the listener class because it depends on sub-classing to work. Because C# does not allow multiple-inheritance, I've spent my one inheritance implementing this class. Every time you need to listen to a bus, you have to derive a class which leads to lots of trivial sub-classes. The act of consuming a message should be a separate responsibility than the act of listening for a message (SRP). Inheritance is such a strong statement (this IS-A that) that it should only be used in building type hierarchies and not for overriding use-specific behaviors and notifications. Chances are, if a class needs to be inherited to be used, it most likely is not designed as well as it could be in today's modern programming languages. So lets look at the other tools available to us for getting notified instead. Here's a few other choices to consider. Have the listener expose a MessageReceived event. Have the listener accept a new IMessageHandler interface instance. Have the listener accept an Action<Message> delegate. Really, all of these are different forms of delegation. Now, .NET events are a bit heavier than the other types of delegates in terms of run-time execution, but they are a great way to allow others using your class to subscribe to your events: 1: // using event - ommiting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private bool _isHalted = false; 6: private Thread _messageThread; 7:  8: // assign the subscriber and start the messaging loop 9: public MessageListener(ISubscriber subscriber) 10: { 11: _subscriber = subscriber; 12: _messageThread = new Thread(MessageLoop); 13: _messageThread.Start(); 14: } 15:  16: // user will override this to process their messages 17: public event Action<Message> MessageReceived; 18:  19: // handle the looping in the thread 20: private void MessageLoop() 21: { 22: while(!_isHalted) 23: { 24: // as long as processing, wait 1 second for message 25: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 26: if(msg != null && MessageReceived != null) 27: { 28: MessageReceived(msg); 29: } 30: } 31: } 32: } Note, now we can seal the class to avoid changes and the user just needs to provide a message handling method: 1: theListener.MessageReceived += CustomReceiveMethod; However, personally I don't think events hold up as well in this case because events are largely optional. To me, what is the point of a listener if you create one with no event listeners? So in my mind, use events when handling the notification is optional. So how about the delegation via interface? I personally like this method quite a bit. Basically what it does is similar to inheritance method mentioned first, but better because it makes it easy to split the part of the class that doesn't change (the base listener behavior) from the part that does change (the user-specified action after receiving a message). So assuming we had an interface like: 1: public interface IMessageHandler 2: { 3: void OnMessageReceived(Message receivedMessage); 4: } Our listener would look like this: 1: // using delegation via interface - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private IMessageHandler _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler.OnMessageReceived(msg); 28: } 29: } 30: } 31: } And they would call it by creating a class that implements IMessageHandler and pass that instance into the constructor of the listener. I like that this alleviates the issues of inheritance and essentially forces you to provide a handler (as opposed to events) on construction. Well, this is good, but personally I think we could go one step further. While I like this better than events or inheritance, it still forces you to implement a specific method name. What if that name collides? Furthermore if you have lots of these you end up either with large classes inheriting multiple interfaces to implement one method, or lots of small classes. Also, if you had one class that wanted to manage messages from two different subscribers differently, it wouldn't be able to because the interface can't be overloaded. This brings me to using delegates directly. In general, every time I think about creating an interface for something, and if that interface contains only one method, I start thinking a delegate is a better approach. Now, that said delegates don't accomplish everything an interface can. Obviously having the interface allows you to refer to the classes that implement the interface which can be very handy. In this case, though, really all you want is a method to handle the messages. So let's look at a method delegate: 1: // using delegation via delegate - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler(msg); 28: } 29: } 30: } 31: } Here the MessageListener now takes an Action<Message>.  For those of you unfamiliar with the pre-defined delegate types in .NET, that is a method with the signature: void SomeMethodName(Message). The great thing about delegates is it gives you a lot of power. You could create an anonymous delegate, a lambda, or specify any other method as long as it satisfies the Action<Message> signature. This way, you don't need to define an arbitrary helper class or name the method a specific thing. Incidentally, we could combine both the interface and delegate approach to allow maximum flexibility. Doing this, the user could either pass in a delegate, or specify a delegate interface: 1: // using delegation - give users choice of interface or delegate 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // passes the interface method as a delegate using method group 19: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 20: : this(subscriber, handler.OnMessageReceived) 21: { 22: } 23:  24: // handle the looping in the thread 25: private void MessageLoop() 26: { 27: while(!_isHalted) 28: { 29: // as long as processing, wait 1 second for message 30: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 31: if(msg != null) 32: { 33: _handler(msg); 34: } 35: } 36: } 37: } } This is the method I tend to prefer because it allows the user of the class to choose which method works best for them. You may be curious about the actual performance of these different methods. 1: Enter iterations: 2: 1000000 3:  4: Inheritance took 4 ms. 5: Events took 7 ms. 6: Interface delegation took 4 ms. 7: Lambda delegate took 5 ms. Before you get too caught up in the numbers, however, keep in mind that this is performance over over 1,000,000 iterations. Since they are all < 10 ms which boils down to fractions of a micro-second per iteration so really any of them are a fine choice performance wise. As such, I think the choice of what to do really boils down to what you're trying to do. Here's my guidelines: Inheritance should be used only when defining a collection of related types with implementation specific behaviors, it should not be used as a hook for users to add their own functionality. Events should be used when subscription is optional or multi-cast is desired. Interface delegation should be used when you wish to refer to implementing classes by the interface type or if the type requires several methods to be implemented. Delegate method delegation should be used when you only need to provide one method and do not need to refer to implementers by the interface name.

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• C# 5 Async, Part 2: Asynchrony Today

  - by Reed

  The .NET Framework has always supported asynchronous operations.  However, different mechanisms for supporting exist throughout the framework.  While there are at least three separate asynchronous patterns used through the framework, only the latest is directly usable with the new Visual Studio Async CTP.  Before delving into details on the new features, I will talk about existing asynchronous code, and demonstrate how to adapt it for use with the new pattern. The first asynchronous pattern used in the .NET framework was the Asynchronous Programming Model (APM).  This pattern was based around callbacks.  A method is used to start the operation.  It typically is named as BeginSomeOperation.  This method is passed a callback defined as an AsyncCallback, and returns an object that implements IAsyncResult.  Later, the IAsyncResult is used in a call to a method named EndSomeOperation, which blocks until completion and returns the value normally directly returned from the synchronous version of the operation.  Often, the EndSomeOperation call would be called from the callback function passed, which allows you to write code that never blocks. While this pattern works perfectly to prevent blocking, it can make quite confusing code, and be difficult to implement.  For example, the sample code provided for FileStream’s BeginRead/EndRead methods is not simple to understand.  In addition, implementing your own asynchronous methods requires creating an entire class just to implement the IAsyncResult. Given the complexity of the APM, other options have been introduced in later versions of the framework.  The next major pattern introduced was the Event-based Asynchronous Pattern (EAP).  This provides a simpler pattern for asynchronous operations.  It works by providing a method typically named SomeOperationAsync, which signals its completion via an event typically named SomeOperationCompleted. The EAP provides a simpler model for asynchronous programming.  It is much easier to understand and use, and far simpler to implement.  Instead of requiring a custom class and callbacks, the standard event mechanism in C# is used directly.  For example, the WebClient class uses this extensively.  A method is used, such as DownloadDataAsync, and the results are returned via the DownloadDataCompleted event. While the EAP is far simpler to understand and use than the APM, it is still not ideal.  By separating your code into method calls and event handlers, the logic of your program gets more complex.  It also typically loses the ability to block until the result is received, which is often useful.  Blocking often requires writing the code to block by hand, which is error prone and adds complexity. As a result, .NET 4 introduced a third major pattern for asynchronous programming.  The Task<T> class introduced a new, simpler concept for asynchrony.  Task and Task<T> effectively represent an operation that will complete at some point in the future.  This is a perfect model for thinking about asynchronous code, and is the preferred model for all new code going forward.  Task and Task<T> provide all of the advantages of both the APM and the EAP models – you have the ability to block on results (via Task.Wait() or Task<T>.Result), and you can stay completely asynchronous via the use of Task Continuations.  In addition, the Task class provides a new model for task composition and error and cancelation handling.  This is a far superior option to the previous asynchronous patterns. The Visual Studio Async CTP extends the Task based asynchronous model, allowing it to be used in a much simpler manner.  However, it requires the use of Task and Task<T> for all operations.

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• Is there an application that converts a PC into a video game kiosk/arcade machine?

  - by Rahil627

  Sorry to make the question so vague. What I ultimately want is software that allows people to play independent video games on a PC and not have to worry about maintaining it. Imagine a game that was made in a few hours that does not have a restart button and crashes often. It should be able to handle these kinds of things and do more! The software should: allow the game to be restarted manually handle game crashes (likely by restarting the game) restrict the user from doing anything crazy later... offer a UI to select the game from a list handle pre-configured key bindings cross-platform (start with windows) I just want to know if this exists already before I start creating one. As of now AutoHotKey is being used to do this sloppily. If such software does not exist then perhaps someone could recommend a general open source Kiosk software? Open Kiosk? I'll take anything. (I also could not find a related tag. Not even sure if this question should be here rather than stackoverflow)

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• 101 Ways to Participate...and make the future Java

  - by heathervc

   In case you missed it earlier today, and as promised in BOF6283, here are the 101 Ways to Improve (and Make the Future) Java...thanks to Bruno Souza of SouJava and Martijn Verburg of the London Java Community for their contributions! Join or create a JUG Come to the meetings Help promoting your JUG: twitter, facebook, etc Find someone that can give a talk Get your company to sponsor (a meeting, an event) Organize an activity (meetings, hackathons, dojos, etc) Answer questions on a mailing list (or simply join!) Volunteer for a small, one time tasks (creating a web page, helping with an activity) Come early to an event, and help to carry the piano Moderate a list or add things to the wiki Participate in the organization meetings or mailing lists Take pictures of an event or meeting and publish them online Write a blog about an event or meeting, to help promote the group Help record and post a session online Present your JavaOne experience when you get back Repeat the best talk you saw at JavaOne at a JUG meeting Send this list of ideas to other Java developers in your area so they can help out too! Present a step-by-step tutorial Present GreenFoot and Alice to school students Present BlueJ and Alice to university students Teach those tools to teachers and professors Write a step-by-step tutorial on your blog or to a magazine Create a page that lists resources Give a talk about your favorite Java feature or technology Learn a new Java API and present to your co-workers Then, present in a JUG meeting, and then, present it in an event in your area, and submit it to JavaOne! Create a study group to get certified or to learn some new Java technology Teach a non-Java developer how to download the basic tools and where to find more information Download and use an open source project Improve the documentation Write an article or a blog post about the project Write an FAQ Join and participate on the mailing list Describe a bug in detail and submit a bug report Fix a bug and submit it to the project Give a talk about it at a JUG meeting Teach your co-workers how to use the project Sign up to Adopt a JSR Test regular builds of the Reference Implementation (RI) Report bugs in the RI Submit Feature Requests to the spec Triage issues on the issue tracker Run a hack day to discuss the API Moderate mailing lists and forums Create an FAQ or Wiki Evangelize a specification on Twitter, G+, Hacker News, etc Give a lightning talk Help build the RI Help build the Technical Compatibility Kit (TCK) Create a Podcast Learn Latin - e.g. legal language, translate to English Sign up to Adopt OpenJDK Run a Bugathon Fix javac compiler warnings Build virtual images Add tests to Java Submit Javadoc patches Give a webbing Teach someone to build OpenJDK Hold a brown bag session at work Fix the oldest known bug Overhaul Javadoc to use HTML Load the OpenJDK into different IDEs Run a build farm node Test your code on a nightly build Learn how to read Java byte code Visit JCP.org Follow jcp_org on Twitter Friend JCP on Facebook Read JCP Blog Register for JCP.org site Create a JSR Watch List Review JSRs in progress Comment on JSRs in progress, write and track bug reports, use cases, etc Review JSRs in Maintenance Comment on JSRs in Maintenance Implement Final JSRs Review the Transparency of JSRs in progress and provide feedback to the PMO and Spec Lead/community Become a JCP Member or associate with a current JCP member Nominate to serve on an Expert Group (EG) Serve on an EG Submit a JSR proposal and become Spec Lead Take a Spec Lead role in an Inactive or Dormant JSR Nominate for an Executive Committee (EC) seat Vote in the EC elections Vote in EC Special Elections Review EC Meeting Summaries Attend Spec Lead calls Write blogs, articles on your experiences Join the EC project on java.net Join JCP.Next on java.net/JSR 358 Participate on the JCP forums and join JSR projects on java.net Suggest agenda items for open EC meetings Attend public EC teleconference (2x per year) Attend open EC meetings at JavaOne Nominate for JCP Annual Awards Attend annual JavaOne and JCP Annual Awards Ceremony Attend JCP related BOF sessions and give your feedback to Program Office Invite JCP program office members to your JUG  or meetup Invite JSR Spec Leads to your JUG or meetup And always - hold a party!

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• Thoughts on type aliases/synonyms?

  - by Rei Miyasaka

  I'm going to try my best to frame this question in a way that doesn't result in a language war or list, because I think there could be a good, technical answer to this question. Different languages support type aliases to varying degrees. C# allows type aliases to be declared at the beginning of each code file, and they're valid only throughout that file. Languages like ML/Haskell use type aliases probably as much as they use type definitions. C/C++ are sort of a Wild West, with typedef and #define often being used seemingly interchangeably to alias types. The upsides of type aliasing don't invoke too much dispute: It makes it convenient to define composite types that are described naturally by the language, e.g. type Coordinate = float * float or type String = [Char]. Long names can be shortened: using DSBA = System.Diagnostics.DebuggerStepBoundaryAttribute. In languages like ML or Haskell, where function parameters often don't have names, type aliases provide a semblance of self-documentation. The downside is a bit more iffy: aliases can proliferate, making it difficult to read and understand code or to learn a platform. The Win32 API is a good example, with its DWORD = int and its HINSTANCE = HANDLE = void* and its LPHANDLE = HANDLE FAR* and such. In all of these cases it hardly makes any sense to distinguish between a HANDLE and a void pointer or a DWORD and an integer etc.. Setting aside the philosophical debate of whether a king should give complete freedom to their subjects and let them be responsible for themselves or whether they should have all of their questionable actions intervened, could there be a happy medium that would allow the benefits of type aliasing while mitigating the risk of its abuse? As an example, the issue of long names can be solved by good autocomplete features. Visual Studio 2010 for instance will alllow you to type DSBA in order to refer Intellisense to System.Diagnostics.DebuggerStepBoundaryAttribute. Could there be other features that would provide the other benefits of type aliasing more safely?

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• Object oriented wrapper around a dll

  - by Tom Davies

  So, I'm writing a C# managed wrapper around a native dll. The dll contains several hundred functions. In most cases, the first argument to each function is an opaque handle to a type internal to the dll. So, an obvious starting point for defining some classes in the wrapper would be to define classes corresponding to each of these opaque types, with each instance holding and managing the opaque handle (passed to its constructor) Things are a little awkward when dealing with callbacks from the dll. Naturally, the callback handlers in my wrapper have to be static, but the callbacks arguments invariable contain an opaque handle. In order to get from the static callback back to an object instance, I've created a static dictionary in each class, associating handles with class instances. In the constructor of each class, an entry is put into the dictionary, and this entry is then removed in the Destructors. When I receive a callback, I can then consult the dictionary to retrieve the class instance corresponding to the opaque reference. Are there any obvious flaws to this? Something that seems to be a problem is that the existence static dictionary means that the garbage collector will not act on my class instances that are otherwise unreachable. As they are never garbage collected, they never get removed from the dictionary, so the dictionary grows. It seems I might have to manually dispose of my objects, which is something absolutely would like to avoid. Can anyone suggest a good design that allows me to avoid having to do this?

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• Pure functional programming and game state

  - by Fu86

  Is there a common technique to handle state (in general) in a functional programming language? There are solutions in every (functional) programming language to handle global state, but I want to avoid this as far as I could. All state in a pure functional manner are function parameters. So I need to put the whole game state (a gigantic hashmap with the world, players, positions, score, assets, enemies, ...)) as a parameter to all functions which wants to manipulate the world on a given input or trigger. The function itself picks the relevant information from the gamestate blob, do something with it, manipulate the gamestate and return the gamestate. But this looks like a poor mans solution for the problem. If I put the whole gamestate into all functions, there is no benefit for me in contrast to global variables or the imperative approach. I could put just the relevant information into the functions and return the actions which will be taken for the given input. And one single function apply all the actions to the gamestate. But most functions need a lot of "relevant" information. move() need the object position, the velocity, the map for collision, position of all enemys, current health, ... So this approach does not seem to work either. So my question is how do I handle the massive amount of state in a functional programming language -- especially for game development?

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• Should I expose IObservable<T> on my interfaces?

  - by Alex

  My colleague and I have dispute. We are writing a .NET application that processes massive amounts of data. It receives data elements, groups subsets of them into blocks according to some criterion and processes those blocks. Let's say we have data items of type Foo arriving some source (from the network, for example) one by one. We wish to gather subsets of related objects of type Foo, construct an object of type Bar from each such subset and process objects of type Bar. One of us suggested the following design. Its main theme is exposing IObservable objects directly from the interfaces of our components. // ********* Interfaces ********** interface IFooSource { // this is the event-stream of objects of type Foo IObservable<Foo> FooArrivals { get; } } interface IBarSource { // this is the event-stream of objects of type Bar IObservable<Bar> BarArrivals { get; } } / ********* Implementations ********* class FooSource : IFooSource { // Here we put logic that receives Foo objects from the network and publishes them to the FooArrivals event stream. } class FooSubsetsToBarConverter : IBarSource { IFooSource fooSource; IObservable<Bar> BarArrivals { get { // Do some fancy Rx operators on fooSource.FooArrivals, like Buffer, Window, Join and others and return IObservable<Bar> } } } // this class will subscribe to the bar source and do processing class BarsProcessor { BarsProcessor(IBarSource barSource); void Subscribe(); } // ******************* Main ************************ class Program { public static void Main(string[] args) { var fooSource = FooSourceFactory.Create(); var barsProcessor = BarsProcessorFactory.Create(fooSource) // this will create FooSubsetToBarConverter and BarsProcessor barsProcessor.Subscribe(); fooSource.Run(); // this enters a loop of listening for Foo objects from the network and notifying about their arrival. } } The other suggested another design that its main theme is using our own publisher/subscriber interfaces and using Rx inside the implementations only when needed. //********** interfaces ********* interface IPublisher<T> { void Subscribe(ISubscriber<T> subscriber); } interface ISubscriber<T> { Action<T> Callback { get; } } //********** implementations ********* class FooSource : IPublisher<Foo> { public void Subscribe(ISubscriber<Foo> subscriber) { /* ... */ } // here we put logic that receives Foo objects from some source (the network?) publishes them to the registered subscribers } class FooSubsetsToBarConverter : ISubscriber<Foo>, IPublisher<Bar> { void Callback(Foo foo) { // here we put logic that aggregates Foo objects and publishes Bars when we have received a subset of Foos that match our criteria // maybe we use Rx here internally. } public void Subscribe(ISubscriber<Bar> subscriber) { /* ... */ } } class BarsProcessor : ISubscriber<Bar> { void Callback(Bar bar) { // here we put code that processes Bar objects } } //********** program ********* class Program { public static void Main(string[] args) { var fooSource = fooSourceFactory.Create(); var barsProcessor = barsProcessorFactory.Create(fooSource) // this will create BarsProcessor and perform all the necessary subscriptions fooSource.Run(); // this enters a loop of listening for Foo objects from the network and notifying about their arrival. } } Which one do you think is better? Exposing IObservable and making our components create new event streams from Rx operators, or defining our own publisher/subscriber interfaces and using Rx internally if needed? Here are some things to consider about the designs: In the first design the consumer of our interfaces has the whole power of Rx at his/her fingertips and can perform any Rx operators. One of us claims this is an advantage and the other claims that this is a drawback. The second design allows us to use any publisher/subscriber architecture under the hood. The first design ties us to Rx. If we wish to use the power of Rx, it requires more work in the second design because we need to translate the custom publisher/subscriber implementation to Rx and back. It requires writing glue code for every class that wishes to do some event processing.

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• handling multiple interviews / offers [closed]

  - by farble1670

  What's the best way to handle a situation where you have, or expect to have multiple offers? The ideal situation is that your several offers come in about the same time, and you make a choice. this is not how it happens though. You may have an offer, and several near-final interviews lined up for the following days or weeks. One way to handle it would be to ask for a longer time to decide on the first offers you receive. 2 weeks? This gives time to rush the rest of the things you have going through to an end. i question whether asking for 2 weeks to decide is reasonable though. My guess is that an employer would see through that and force your hand. Another way to handle it would be to accept the first offer, and ask for a reasonable period before your start date, then simply "quit" the first position before you ever start if something better comes along. On one hand, employment is at-will, and employers exercise this fact regularly. On the other hand, it seems morally the wrong thing, and has the potential to burn some bridges. And of course the last option is to simply evaluate each offer in isolation, and accept or reject within the given time frame. any thoughts?

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• Unzipping in Java and FileUtil.copy

  - by Geertjan

  Via NetBeans File Systems API, which provides FileUtil.copy below, which means a dependency on NetBeans Utilities API: private void unzipEpubFile(String folder, File file) throws IOException { final AtomicBoolean canceled = new AtomicBoolean(); //define and start progress bar here... // ProgressHandle handle = // ProgressHandleFactory.createHandle( // Bundle.MSG_unpacking(zip.getName()), // new Cancellable() { // @Override // public boolean cancel() { // return canceled.compareAndSet(false, true); // } // }); //then unzip 'file' into 'root": try { List folders = new ArrayList<>(); try (InputStream is = new FileInputStream(file)) { ZipInputStream zis = new ZipInputStream(is); ZipEntry entry; while ((entry = zis.getNextEntry()) != null) { if (canceled.get()) { return; } String n = entry.getName(); File f = new File(folder, n); if (n.endsWith("/")) { if (!f.isDirectory()) { if (!f.mkdirs()) { throw new IOException("could not make " + f); } if (entry.getTime() > 0) { if (!f.setLastModified(entry.getTime())) { // oh well } } } folders.add(f); } else { //handle.progress(Bundle.MSG_creating(n)); File p = f.getParentFile(); if (!p.isDirectory() && !p.mkdirs()) { throw new IOException("could not make " + p); } try (OutputStream os = new FileOutputStream(f)) { FileUtil.copy(zis, os); } if (entry.getTime() > 0) { if (!f.setLastModified(entry.getTime())) { // oh well } } } } } //handle.switchToDeterminate(folders.size()); if (canceled.get()) { } } finally { //stop progress bar } } Mostly from NetBeans IDE sources for working with projects and ZIP files.

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• multi-thread in mmorpg server

  - by jean

  For MMORPG, there is a tick function to update every object's state in a map. The function was triggered by a timer in fixed interval. So each map's update can be dispatch to different thread. At other side, server handle player incoming package have its own threads also: I/O threads. Generally, the handler of the corresponding incoming package run in I/O threads. So there is a problem: thread synchronization. I have consider two methods: Synchronize with mutex. I/O thread lock a mutex before execute handler function and map thread lock same mutex before it execute map's update. Execute all handler functions in map's thread, I/O thread only queue the incoming handler and let map thread to pop the queue then call handler function. These two have a disadvantage: delay. For method 1, if the map's tick function is running, then all clients' request need to waiting the lock release. For method 2, if map's tick function is running, all clients' request need to waiting for next tick to be handle. Of course, there is another method: add lock to functions that use data which will be accessed both in I/O thread & map thread. But this is hard to maintain and easy to goes incorrect. It needs carefully check all variables whether or not accessed by both two kinds thread. My problem is: is there better way to do this? Notice that I said map is logic concept means no interactions can happen between two map except transport. I/O thread means thread in 3rd part network lib which used to handle client request.

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• How to build an API on top of an existing Rails app with NodeJs and what architecture to use?

  - by javiayala

  The explanation I was recently hired by a company that has an old RoR 2.3 application with more than 100k users, a strong SEO strategy with more than 170k indexed urls, native android and ios applications and other custom-made mobile and web applications that rely on a not so good API from the same RoR app. They recently merged with a company from another country as an strategy to grow the business and the profit. They have almost the same stats, a similar strategy and mobile apps. We have just decided that we need to merge the data from both companies and to start a new app from scratch since the RoR app is to old and heavily patched and the app from the other company was built with a custom PHP framework without any documentation. The only good news is that both databases are in MySQL and have a similar structure. The challenge I need to build a new version that: can handle a lot of traffic, preserves the SEO strategies of both companies, serve 2 different domains, and have a strong API that can support legacy mobile apps from both companies and be ready for a new set of native apps. I want to use RoR 3.2 for the main web apps and NodeJs with a Restful API. I know that I need to be very careful with the mobile apps and handle multiple versions of the API. I also think that I need to create a service that can handle a lot IO request since the apps is heavily used to create orders for restaurants at a certain time of the day. The questions With all this in mind: What type of architecture do you recommend me to follow? What gems or node packages do you think will work the best? How do I build a new rails app and keep using the same database structure? Should I use NodeJS to build an API or just build a new service with Ruby? I know that I'm asking to much from you guys, but please help me by answering any topic that you can or by pointing me on the right direction. All your comments and feedback will be extremely appreciated! Thanks!

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• PDF to Image Conversion in Java

  - by Geertjan

  In the past, I created a NetBeans plugin for loading images as slides into NetBeans IDE. That means you had to manually create an image from each slide first. So, this time, I took it a step further. You can choose a PDF file, which is then automatically converted to an image for each page, each of which is presented as a node that can be clicked to open the slide in the main window. As you can see, the remaining problem is font rendering. Currently I'm using PDFBox. Any alternatives that render font better? This is the createKeys method of the child factory, ideally it would be replaced by code from some other library that handles font rendering better: @Override protected boolean createKeys(List<ImageObject> list) { mylist = new ArrayList<ImageObject>(); try { if (file != null) { ProgressHandle handle = ProgressHandleFactory.createHandle( "Creating images from " + file.getPath()); handle.start(); PDDocument document = PDDocument.load(file); List<PDPage> pages = document.getDocumentCatalog().getAllPages(); for (int i = 0; i < pages.size(); i++) { PDPage pDPage = pages.get(i); mylist.add(new ImageObject(pDPage.convertToImage(), i)); } handle.finish(); } list.addAll(mylist); } catch (IOException ex) { Exceptions.printStackTrace(ex); } return true; } The import statements from PDFBox are as follows: import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.PDPage;

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• Task scheduler ran a task twice

  - by Ross Buggins

  Update: This has now happened two days in a row. Update: XML of scheduled tasks and images now included. Two servers located in London, both Windows 2012, have a scheduled task set to run at 3pm Monday to Friday. This has been set up for the last 5 months without a problem. However, on Monday the 28th of August they both ran the scheduled task at 3pm and then again at 4pm. When it was first reported, I thought it was too much of a coincidence to be the day after the clocks had gone back an hour. However, I’m failing in being able to explain why it has happened and if it is related to the clock change at all. The relevant logs from one server (the logs for the other follow this pattern as well): Event 129 15:00:20 Task Scheduler launch task "\3pm", instance "C:\Program Files (x86)\PHP\v5.4\php.exe" with process ID 2388. Event 100 15:00:20 Task Scheduler started "{75a3590f-dec1-4dee-bd27-73d63a50a9d7}" instance of the "\3pm" task for user "x\y". Event 200 15:00:20 Task Scheduler launched action "C:\Program Files (x86)\PHP\v5.4\php.exe" in instance "{75a3590f-dec1-4dee-bd27-73d63a50a9d7}" of task "\3pm". Event 201 15:00:23 Task Scheduler successfully completed task "\3pm" , instance "{75a3590f-dec1-4dee-bd27-73d63a50a9d7}" , action "C:\Program Files (x86)\PHP\v5.4\php.exe" with return code 0. Event 129 16:00:20 Task Scheduler launch task "\3pm", instance "C:\Program Files (x86)\PHP\v5.4\php.exe" with process ID 1224. Event 100 16:00:20 Task Scheduler started "{3dd46ca9-c525-4796-86b5-5e513fd45f26}" instance of the "\3pm" task for user "x\y". Event 200 16:00:20 Task Scheduler launched action "C:\Program Files (x86)\PHP\v5.4\php.exe" in instance "{3dd46ca9-c525-4796-86b5-5e513fd45f26}" of task "\3pm". Event 201 16:00:23 Task Scheduler successfully completed task "\3pm" , instance "{3dd46ca9-c525-4796-86b5-5e513fd45f26}" , action "C:\Program Files (x86)\PHP\v5.4\php.exe" with return code 0. I've seen this question Scheduled task running twice from time to time which points to a bug at http://support.microsoft.com/kb/2461249 being the cause. However, this doesn't include Server 2012 in it's list of problem operating systems. I’m struggling to explain this, can anyone else? The XML export for the scheduled task is: <?xml version="1.0" encoding="UTF-16"?> <Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task"> <RegistrationInfo> <Date>2013-04-16T14:04:17.4897806</Date> <Author>x\y</Author> </RegistrationInfo> <Triggers> <CalendarTrigger> <StartBoundary>2013-04-17T15:00:20</StartBoundary> <Enabled>true</Enabled> <ScheduleByWeek> <DaysOfWeek> <Monday /> <Tuesday /> <Wednesday /> <Thursday /> <Friday /> </DaysOfWeek> <WeeksInterval>1</WeeksInterval> </ScheduleByWeek> </CalendarTrigger> </Triggers> <Principals> <Principal id="Author"> <UserId>x\y</UserId> <LogonType>Password</LogonType> <RunLevel>LeastPrivilege</RunLevel> </Principal> </Principals> <Settings> <MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy> <DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries> <StopIfGoingOnBatteries>true</StopIfGoingOnBatteries> <AllowHardTerminate>true</AllowHardTerminate> <StartWhenAvailable>false</StartWhenAvailable> <RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable> <IdleSettings> <StopOnIdleEnd>true</StopOnIdleEnd> <RestartOnIdle>false</RestartOnIdle> </IdleSettings> <AllowStartOnDemand>true</AllowStartOnDemand> <Enabled>true</Enabled> <Hidden>false</Hidden> <RunOnlyIfIdle>false</RunOnlyIfIdle> <WakeToRun>false</WakeToRun> <ExecutionTimeLimit>P3D</ExecutionTimeLimit> <Priority>7</Priority> </Settings> <Actions Context="Author"> <Exec> <Command>"C:\Program Files (x86)\PHP\v5.4\php.exe"</Command> <Arguments>-f "c:\a.php"</Arguments> </Exec> </Actions> </Task> 29 October 17:00 - Update - Both servers have again run the scheduled task at 15:00 and 16:00. I've now updated the php file that is run by the scheduler to not actually do anything whilst I'm going through trying to solve this. I'm planning on restarting one server to see if this changes anything tomorrow. 30 October 08:25 - Update - When exporting the task XML I remembered that I hadn't included the fact that the scheduled task on second server was created by importing the XML of the task created on the first. The only difference between the two tasks is the path of the php file they are executing and the user account that they are running as.

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• WiX 3 Tutorial: Custom EULA License and MSI localization

  - by Mladen Prajdic

  In this part of the ongoing Wix tutorial series we’ll take a look at how to localize your MSI into different languages. We’re still the mighty SuperForm: Program that takes care of all your label color needs. :) Localizing the MSI With WiX 3.0 localizing an MSI is pretty much a simple and straightforward process. First let look at the WiX project Properties->Build. There you can see "Cultures to build" textbox. Put specific cultures to build into the testbox or leave it empty to build all of them. Cultures have to be in correct culture format like en-US, en-GB or de-DE. Next we have to tell WiX which cultures we actually have in our project. Take a look at the first post in the series about Solution/Project structure and look at the Lang directory in the project structure picture. There we have de-de and en-us subfolders each with its own localized stuff. In the subfolders pay attention to the WXL files Loc_de-de.wxl and Loc_en-us.wxl. Each one has a <String Id="LANG"> under the WixLocalization root node. By including the string with id LANG we tell WiX we want that culture built. For English we have <String Id="LANG">1033</String>, for German <String Id="LANG">1031</String> in Loc_de-de.wxl and for French we’d have to create another file Loc_fr-FR.wxl and put <String Id="LANG">1036</String>. WXL files are localization files. Any string we want to localize we have to put in there. To reference it we use loc keyword like this: !(loc.IdOfTheVariable) => !(loc.MustCloseSuperForm) This is our Loc_en-us.wxl. Note that German wxl has an identical structure but values are in German. <?xml version="1.0" encoding="utf-8"?><WixLocalization Culture="en-us" xmlns="http://schemas.microsoft.com/wix/2006/localization" Codepage="1252"> <String Id="LANG">1033</String> <String Id="ProductName">SuperForm</String> <String Id="LicenseRtf" Overridable="yes">\Lang\en-us\EULA_en-us.rtf</String> <String Id="ManufacturerName">My Company Name</String> <String Id="AppNotSupported">This application is is not supported on your current OS. Minimal OS supported is Windows XP SP2</String> <String Id="DotNetFrameworkNeeded">.NET Framework 3.5 is required. Please install the .NET Framework then run this installer again.</String> <String Id="MustCloseSuperForm">Must close SuperForm!</String> <String Id="SuperFormNewerVersionInstalled">A newer version of !(loc.ProductName) is already installed.</String> <String Id="ProductKeyCheckDialog_Title">!(loc.ProductName) setup</String> <String Id="ProductKeyCheckDialogControls_Title">!(loc.ProductName) Product check</String> <String Id="ProductKeyCheckDialogControls_Description">Plese Enter following information to perform the licence check.</String> <String Id="ProductKeyCheckDialogControls_FullName">Full Name:</String> <String Id="ProductKeyCheckDialogControls_Organization">Organization:</String> <String Id="ProductKeyCheckDialogControls_ProductKey">Product Key:</String> <String Id="ProductKeyCheckDialogControls_InvalidProductKey">The product key you entered is invalid. Please call user support.</String> </WixLocalization>   As you can see from the file we can use localization variables in other variables like we do for SuperFormNewerVersionInstalled string. ProductKeyCheckDialog* strings are to localize a custom dialog for Product key check which we’ll look at in the next post. Built in dialog text localization Under the de-de folder there’s also the WixUI_de-de.wxl file. This files contains German translations of all texts that are in WiX built in dialogs. It can be downloaded from WiX 3.0.5419.0 Source Forge site. Download the wix3-sources.zip and go to \src\ext\UIExtension\wixlib. There you’ll find already translated all WiX texts in 12 Languages. Localizing the custom EULA license Here it gets ugly. We can override the default EULA license easily by overriding WixUILicenseRtf WiX variable like this: <WixVariable Id="WixUILicenseRtf" Value="License.rtf" /> where License.rtf is the name of your custom EULA license file. The downside of this method is that you can only have one license file which means no localization for it. That’s why we need to make a workaround. License is checked on a dialog name LicenseAgreementDialog. What we have to do is overwrite that dialog and insert the functionality for localization. This is a code for LicenseAgreementDialogOverwritten.wxs, an overwritten LicenseAgreementDialog that supports localization. LicenseAcceptedOverwritten replaces the LicenseAccepted built in variable. <?xml version="1.0" encoding="UTF-8" ?><Wix xmlns="http://schemas.microsoft.com/wix/2006/wi"> <Fragment> <UI> <Dialog Id="LicenseAgreementDialogOverwritten" Width="370" Height="270" Title="!(loc.LicenseAgreementDlg_Title)"> <Control Id="LicenseAcceptedOverwrittenCheckBox" Type="CheckBox" X="20" Y="207" Width="330" Height="18" CheckBoxValue="1" Property="LicenseAcceptedOverwritten" Text="!(loc.LicenseAgreementDlgLicenseAcceptedCheckBox)" /> <Control Id="Back" Type="PushButton" X="180" Y="243" Width="56" Height="17" Text="!(loc.WixUIBack)" /> <Control Id="Next" Type="PushButton" X="236" Y="243" Width="56" Height="17" Default="yes" Text="!(loc.WixUINext)"> <Publish Event="SpawnWaitDialog" Value="WaitForCostingDlg">CostingComplete = 1</Publish> <Condition Action="disable"> <![CDATA[ LicenseAcceptedOverwritten <> "1" ]]> </Condition> <Condition Action="enable">LicenseAcceptedOverwritten = "1"</Condition> </Control> <Control Id="Cancel" Type="PushButton" X="304" Y="243" Width="56" Height="17" Cancel="yes" Text="!(loc.WixUICancel)"> <Publish Event="SpawnDialog" Value="CancelDlg">1</Publish> </Control> <Control Id="BannerBitmap" Type="Bitmap" X="0" Y="0" Width="370" Height="44" TabSkip="no" Text="!(loc.LicenseAgreementDlgBannerBitmap)" /> <Control Id="LicenseText" Type="ScrollableText" X="20" Y="60" Width="330" Height="140" Sunken="yes" TabSkip="no"> <!-- This is original line --> <!--<Text SourceFile="!(wix.WixUILicenseRtf=$(var.LicenseRtf))" />--> <!-- To enable EULA localization we change it to this --> <Text SourceFile="$(var.ProjectDir)\!(loc.LicenseRtf)" /> <!-- In each of localization files (wxl) put line like this: <String Id="LicenseRtf" Overridable="yes">\Lang\en-us\EULA_en-us.rtf</String>--> </Control> <Control Id="Print" Type="PushButton" X="112" Y="243" Width="56" Height="17" Text="!(loc.WixUIPrint)"> <Publish Event="DoAction" Value="WixUIPrintEula">1</Publish> </Control> <Control Id="BannerLine" Type="Line" X="0" Y="44" Width="370" Height="0" /> <Control Id="BottomLine" Type="Line" X="0" Y="234" Width="370" Height="0" /> <Control Id="Description" Type="Text" X="25" Y="23" Width="340" Height="15" Transparent="yes" NoPrefix="yes" Text="!(loc.LicenseAgreementDlgDescription)" /> <Control Id="Title" Type="Text" X="15" Y="6" Width="200" Height="15" Transparent="yes" NoPrefix="yes" Text="!(loc.LicenseAgreementDlgTitle)" /> </Dialog> </UI> </Fragment></Wix>   Look at the Control with Id "LicenseText” and read the comments. We’ve changed the original license text source to "$(var.ProjectDir)\!(loc.LicenseRtf)". var.ProjectDir is the directory of the project file. The !(loc.LicenseRtf) is where the magic happens. Scroll up and take a look at the wxl localization file example. We have the LicenseRtf declared there and it’s been made overridable so developers can change it if they want. The value of the LicenseRtf is the path to our localized EULA relative to the WiX project directory. With little hacking we’ve achieved a fully localizable installer package.   The final step is to insert the extended LicenseAgreementDialogOverwritten license dialog into the installer GUI chain. This is how it’s done under the <UI> node of course.   <UI> <!-- code to be discussed in later posts –> <!-- BEGIN UI LOGIC FOR CLEAN INSTALLER --> <Publish Dialog="WelcomeDlg" Control="Next" Event="NewDialog" Value="LicenseAgreementDialogOverwritten">1</Publish> <Publish Dialog="LicenseAgreementDialogOverwritten" Control="Back" Event="NewDialog" Value="WelcomeDlg">1</Publish> <Publish Dialog="LicenseAgreementDialogOverwritten" Control="Next" Event="NewDialog" Value="ProductKeyCheckDialog">LicenseAcceptedOverwritten = "1" AND NOT OLDER_VERSION_FOUND</Publish> <Publish Dialog="InstallDirDlg" Control="Back" Event="NewDialog" Value="ProductKeyCheckDialog">1</Publish> <!-- END UI LOGIC FOR CLEAN INSTALLER –> <!-- code to be discussed in later posts --></UI> For a thing that should be simple for the end developer to do, localization can be a bit advanced for the novice WiXer. Hope this post makes the journey easier and that next versions of WiX improve this process. WiX 3 tutorial by Mladen Prajdic navigation WiX 3 Tutorial: Solution/Project structure and Dev resources WiX 3 Tutorial: Understanding main wxs and wxi file WiX 3 Tutorial: Generating file/directory fragments with Heat.exe  WiX 3 Tutorial: Custom EULA License and MSI localization WiX 3 Tutorial: Product Key Check custom action WiX 3 Tutorial: Building an updater WiX 3 Tutorial: Icons and installer pictures WiX 3 Tutorial: Creating a Bootstrapper

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• GWT Javascript Exception in Hosted Mode: Result of expression 'doc.getBoxObjectFor' [undefined] is

  - by holmes

  Anyone ever seen this exception? I'm running in hosted mode on GWT 1.6.4 on a mac. I'm using the AutoSuggest and it's throwing this exception trying to show the popup. It works fine in compiled mode, but obviously hosted mode is rather important. [ERROR] Uncaught exception escaped com.google.gwt.core.client.JavaScriptException: (TypeError): Result of expression 'doc.getBoxObjectFor' [undefined] is not a function. line: 71 sourceId: 1152617088 sourceURL: jar:file:/Users/holmes/.m2/repository/com/google/gwt/gwt-user/1.6.4/gwt-user-1.6.4.jar!/com/google/gwt/dom/client/DOMImplMozillaOld.java expressionBeginOffset: 288 expressionCaretOffset: 307 expressionEndOffset: 313 at com.google.gwt.dom.client.DOMImplMozillaOld.getAbsoluteLeftImpl(Native Method) at com.google.gwt.dom.client.DOMImplMozillaOld.getAbsoluteLeft(DOMImplMozillaOld.java:29) at com.google.gwt.dom.client.Element$.getAbsoluteLeft$(Element.java:86) at com.google.gwt.user.client.DOM.getAbsoluteLeft(DOM.java:646) at com.google.gwt.user.client.ui.UIObject.getAbsoluteLeft(UIObject.java:487) at com.google.gwt.user.client.ui.PopupPanel.position(PopupPanel.java:1015) at com.google.gwt.user.client.ui.PopupPanel.access$5(PopupPanel.java:958) at com.google.gwt.user.client.ui.PopupPanel$1.setPosition(PopupPanel.java:811) at com.google.gwt.user.client.ui.PopupPanel.setPopupPositionAndShow(PopupPanel.java:700) at com.google.gwt.user.client.ui.PopupPanel.showRelativeTo(PopupPanel.java:809) at com.google.gwt.user.client.ui.SuggestBox.showSuggestions(SuggestBox.java:768) at com.google.gwt.user.client.ui.SuggestBox.access$3(SuggestBox.java:738) at com.google.gwt.user.client.ui.SuggestBox$1.onSuggestionsReady(SuggestBox.java:281) at com.google.gwt.user.client.ui.MultiWordSuggestOracle.requestSuggestions(MultiWordSuggestOracle.java:225) at com.google.gwt.user.client.ui.SuggestBox.showSuggestions(SuggestBox.java:640) at com.google.gwt.user.client.ui.SuggestBox.refreshSuggestions(SuggestBox.java:713) at com.google.gwt.user.client.ui.SuggestBox.access$6(SuggestBox.java:705) at com.google.gwt.user.client.ui.SuggestBox$1TextBoxEvents.onKeyUp(SuggestBox.java:678) at com.google.gwt.event.dom.client.KeyUpEvent.dispatch(KeyUpEvent.java:54) at com.google.gwt.event.dom.client.KeyUpEvent.dispatch(KeyUpEvent.java:1) at com.google.gwt.event.shared.HandlerManager$HandlerRegistry.fireEvent(HandlerManager.java:65) at com.google.gwt.event.shared.HandlerManager$HandlerRegistry.access$1(HandlerManager.java:53) at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:178) at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:52) at com.google.gwt.event.dom.client.DomEvent.fireNativeEvent(DomEvent.java:116) at com.google.gwt.user.client.ui.Widget.onBrowserEvent(Widget.java:90) at com.google.gwt.user.client.ui.TextBoxBase.onBrowserEvent(TextBoxBase.java:193) at com.google.gwt.user.client.ui.Composite.onBrowserEvent(Composite.java:54) at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1320) at com.google.gwt.user.client.DOM.dispatchEventAndCatch(DOM.java:1299) at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1262)

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• Combining mousedown and mousemove events together with Javascript (JQUERY?)

  - by webzide

  Dear experts, I would like to combine a the mousedown and mousemove and mouseup events together. Basically the application of this would be making a UI for selecting elements. Like selecting icons in windows when the mouse is clicked down and as you move it, a dotted border dynamically moves with it. I know this is possible with the predefined UI of Jquery. But I am building a web application that requires the integration of this and would like to know the technique. I spend hours on this and it just doesn't work. here's is the code i have so far and the logic behind it: $(document).bind('mousedown', function (evt) { evt = (evt) ? evt : event; startX = evt.clientX; startY = evt.clientY; div = document.createElement("div"); div.style.position = "absolute"; div.style.left = startX + "px"; div.style.top = startY + "px"; div.style.border = "1px dotted #DDDDDD"; $(document).bind('mousemove', function(evt){ evt=(evt) ? evt: event; alert("TESTING OF THIS WORKS"); }); }); $(document).bind('mouseup',function(evt) { var evt = (evt) ? evt : event; var endX = evt.clientX; var endY = evt.clientY; difX = (endX - startX); difY = (endY - startY) if ((difX || difY) > 0) { div.style.width = difX + "px"; div.style.height = difY + "px"; document.body.appendChild(div); } $(this).unbind('mousemove'); }); As you can see I have placed an event binding of mousemove into the event function of mousedown so that it can only be invoked when the mouse is down. but the problem is, once that event is binded, it does not come off. The borders does not move dynamically as expected. Maybe my logic is entirely messed up. If anyone could point me the the right direction that would be great. THanks in advance.

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• Databinding a multiselect ListBox in a FormView control

  - by drs9222

  I have a multiselect ListBox within a FormView. I can't figure out how to setup the databinding for it. I can populate the listbox fine. If the listbox was a single select I could use say SelectValue='<%#Bind("col")%>' and that works fine. Is there something that I can bind to for a multiselect listbox? I've tried manually DataBinding by handling the DataBinding event of the listbox and setting the selected property on the appropriate items. Unfortunately, there are no items in the listbox during the DataBinding event. The closest thing I've found is to save the value that determines what items should be selecting during DataBinding and then use that value in the FormViews DataBinding event to select the right items which seems like a hack to me. Is there a better way? EDIT: To clarify what I am currently doing... I am using the FormViews's ItemCreated event to save the FormView's DataItem. Then in the FormView's DataBound event I find the listbox and manually set the selected items. It doesn't seem right that I have to save the value like this and I assume there is a more correct way to do this that I just can't see.

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• ESB Toolkit.exceptionHandling Error - The application does not exist - Any ideas?

  - by Andrew Cripps

  Hello I am getting following error while attempting to run the Management Portal for ESB Toolkit 2.0: Event Type: Warning Event Source: ENTSSO Event Category: Enterprise Single Sign-On Event ID: 10536 Description: SSO AUDIT Function: GetConfigInfo (SSOProperties) Application Name: ESB Toolkit.exceptionHandling Error Code: 0xC0002A04, The application does not exist I am using SSO config store for the ESB Config. However, looking in the esb.config file, there is no section, like there is for the other esb SSO applications. Why might this section (and therefore the SSO app) be missing? How can I set it up? Thanks for any help with this Andrew

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• Android: onKeyDown() problem

  - by niko

  Hi, I would like to create a photo/video capture application. I have created a CaptureView class which extends SurfaceView and placed it in the main form. The main form's activity has onCreateOptionsMenu() method which creates a menu. The menu worked fine but then I tried to implement a method onKeyDown: @Override public boolean onKeyDown(int keyCode, KeyEvent event) { if(event.getAction() == KeyEvent.ACTION_DOWN) { switch(keyCode) { case KeyEvent.KEYCODE_CAMERA: videoPreview.TakePicture(); return true; } } return super.onKeyDown(keyCode, event); } The menu doesn't appear anymore and the method doesn't catch onKeyDown event. Does anyone know what could be the reason for this issue? Thanks!

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• Submitting from from Colorbox iframe to parent window

  - by user281867

  I'm pretty new to colorbox and lovin-it. I've been trying to submit a form from Colorbox iframe to parent window but haven't had any luck. Any suggestions would be greatly appreciated! Here's my code. $('#CustomizeBuy').click(function(event){ event.preventDefault(); $(this).attr('action','customize-order.cfm'); parent.location.submit(); parent.$.fn.colorbox.close(); }); or $('#CustomizeBuy').click(function(event){ event.preventDefault(); document.QuickOrderForm.action ="customize-order.cfm"; $('#QuickOrderForm').submit(); parent.$.fn.colorbox.close(); });

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• Ho can I tell when the background is touched on a UICollectionView?

  - by Mason Cloud

  I've tried subclassing UICollectionView and overriding touchesBegan:withEvent: and hitTest:WithEvent:, and both of those methods trigger when I touch a cell. However, if I touch the space between the cells, nothing happens at all. Here's what I've created: @interface WSImageGalleryCollectionView : UICollectionView @end ..and.. @implementation WSImageGalleryCollectionView - (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { NSLog(@"Touches began"); [super touchesBegan:touches withEvent:event]; } - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event { NSLog(@"Hit test reached"); return [super hitTest:point withEvent:event]; } @end

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• Issue with TurnBased Multiplayer Game in Game-kit

  - by Nirav

  I am working with cocos2d game in which i am implementing Game-kit. My game supports multiplayer option. Actually as given example Raywenderlich link. I am GKTurnBasedMultiplayer class from Game-kit. But now the issue when first player connected to game center and will select option of "Play Now" it automatches for another player. but issue is it directly connects and starts the match, and doesn't wait for another player. I am using [[GCTurnBasedMatchHelper sharedInstance] findMatchWithMinPlayers:2 maxPlayers:4 viewController:viewConroller]; for connecting and playing with other players but directly connects the match. I want to wait for another player. That is the issue. I am also using GCTurnBasedMatchHelper Class.

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