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• Why do VMs need to be "stack machines" or "register machines" etc.?

  - by Prog

  (This is an extremely newbie-ish question). I've been studying a little about Virtual Machines. Turns out a lot of them are designed very similarly to physical or theoretical computers. I read that the JVM for example, is a 'stack machine'. What that means (and correct me if I'm wrong) is that it stores all of it's 'temporary memory' on a stack, and makes operations on this stack for all of it's opcodes. For example, the source code 2 + 3 will be translated to bytecode similar to: push 2 push 3 add My question is this: JVMs are probably written using C/C++ and such. If so, why doesn't the JVM execute the following C code: 2 + 3..? I mean, why does it need a stack, or in other VMs 'registers' - like in a physical computer? The underlying physical CPU takes care of all of this. Why don't VM writers simply execute the interpreted bytecode with 'usual' instructions in the language the VM is programmed with? Why do VMs need to emulate hardware, when the actual hardware already does this for us? Again, very newbie-ish questions. Thanks for your help

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• How do I find the correct Modeline to connect my computer to my Televsion

  - by Mikelane

  I've been trying to hook up a Ubuntu computer with my Panasonic TH-42PA60A Plasma television for weeks now. My original question was asked here, which includes all the specifications about the Television in detail and how I've connected the computer to the televsion. So far, I've tried hooking up three other computers; 2 Ubuntu computers with fairly new graphic cards, and a Windows XP computer. None of them have been able to display an image on the television. The closest I've come to getting a picture up is with my small laptop running Ubuntu, however the image came out all purple and distorted. I had gotten the image by adding extra modes via the xrandr command, using a process similar to described here. I realize it might be possible to get this working if I had the correct modeline. I've checked the Modeline database, but the Panasonic TH-42PA60A is not listed. How can I find the correct modeline for my television. What commands can I use? I've read that there may be a danger of damaging my TV when doing things like this. What things should I avoid to prevent damaging my television?

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• Using foldr to append two lists together (Haskell)

  - by Luke Murphy

  I have been given the following question as part of a college assignment. Due to the module being very short, we are using only a subset of Haskell, without any of the syntactic sugar or idiomatic shortcuts....I must write: append xs ys : The list formed by joining the lists xs and ys, in that order append (5:8:3:[]) (4:7:[]) => 5:8:3:4:7:[] I understand the concept of how foldr works, but I am only starting off in Functional programming. I managed to write the following working solution (hidden for the benefit of others in my class...) : However, I just can't for the life of me, explain what the hell is going on!? I wrote it by just fiddling around in the interpreter, for example, the following line : foldr (\x -> \y -> x:y) [] (2:3:4:[]) which returned [2:3:4] , which led me to try, foldr (\x -> \y -> x:y) (2:3:4:[]) (5:6:7:[]) which returned [5,6,7,2,3,4] so I worked it out from there. I came to the correct solution through guess work and a bit of luck... I am working from the following definition of foldr: foldr = \f -> \s -> \xs -> if null xs then s else f (head xs) (foldr f s (tail xs) ) Can someone baby step me through my correct solution? I can't seem to get it....I already have scoured the web, and also read a bunch of SE threads, such as How foldr works

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• CLR Profiler Allocated Bytes and XNA ContentManager

  - by Vackup

  I've been fighting with XNA ContentManager and memory allocations for some weeks because I'm trying to port my game from XNA (Windows) to ExEn / Monotouch (iphone). The problem is that after playing a few levels, my game exits unexpectedly on a real iPhone device (not simulator). Profiling memory usage on Windows with CLRProfile, I found some useful stuff but I also found something I dont understand. If I use 2 ContentManagers (1 for shared assets and 1 for level assets), when profiling, "Allocated Bytes" grows and grows after level through level but Memory consumption measured by Windows Task Manager stays constant (down when I unload the content manager and up again when I load content). Obviously, I contentManager.Unload() when level ends. After a few levels my game exits unexpectedly on an iPhone device. If I use 1 content manager, "CRLProfiler Allocated Bytes" stays constant on Windows and on the iPhone; I can play the game normally and it doesnt exit unexpectedly. I use the same assets level through level. It seems like in ios (iPhone) when loading and unloading the same assets, it allocates memory and consumes all device memory, so the ios kill it. Can anybody explain me how this really works? I've read quite a bit, but I still don't understand what's going on.

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• State Changes in a Component Based Architecture [closed]

  - by Maxem

  I'm currently working on a game and using the naive component based architecture thingie (Entities are a bag of components, entity.Update() calls Update on each updateable component), while the addition of new features is really simple, it makes a few things really difficult: a) multithreading / currency b) networking c) unit testing. Multithreading / Concurrency is difficult because I basically have to do poor mans concurrency (running the entity updates in separate threads while locking only stuff that crashes (like lists) and ignoring the staleness of read state (some states are already updated, others aren't)) Networking: There are no explicit state changes that I could efficiently push over the net. Unit testing: All updates may or may not conflict, so automated testing is at least awkward. I was thinking about these issues a bit and would like your input on these changes / idea: Switch from the naive cba to a cba with sub systems that work on lists of components Make all state changes explicit Combine 1 and 2 :p Example world update: statePostProcessing.Wait() // ensure that post processing has finished Apply(postProcessedState) state = new StateBag() Concurrently( () => LifeCycleSubSystem.Update(state), // populates the state bag () => MovementSubSystem.Update(state), // populates the state bag .... }) statePostProcessing = Future(() => PostProcess(state)) statePostProcessing.Start() // Tick is finished, the post processing happens in the background So basically the changes are (consistently) based on the data for the last tick; the post processing can a) generate network packages and b) fix conflicts / remove useless changes (example: entity has been destroyed - ignore movement etc.). EDIT: To clarify the granularity of the state changes: If I save these post processed state bags and apply them to an empty world, I see exactly what has happened in the game these state bags originated from - "Free" replay capability. EDIT2: I guess I should have used the term Event instead of State Change and point out that I kind of want to use the Event Sourcing pattern

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• Dell Powerdge840 2.4GHz 64 bit quad core

  - by newb64bit

  I am having an issue, where I have changed the boot order to cdrom and turned off hd boot all together and still my system is unable to detect ubuntu and claims, no boot device found. Some additional information: When this same cd is inserted and dell is booted into win 2003 server (which is what is installed on this machine), it detects the cd drive but not the cd at all (keeps asking me to insert disc) I have also created a bootable flash drive using LinuxLive USB creator and when this is selected in boot order again am told no boot device detected. I was speaking to dell and they suggested perhaps there are no drivers on the actual ubuntu installation for the hardware on this Dell and hence the failure of this dell to detect the ubuntu cd. Now, I don't know too much about computers, but this last bit confused me a bit. If the system detects the hardware (when it is booting it sees the cd rom and in bios it sees when the flash drive is connected), then shouldn't it be able to read what is on those drives? However, if there is some firmware or software install that needs to happen, could someone please tell me where to find the correct drivers for ubuntu and dell poweredge to work together? Shall I be installing the desktop version or the server edition, also, 32 bit or 63 bit? Thank you in advance.

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• PHP I am pulling my hair out trying to find the best! [closed]

  - by darga33

  PULLING MY HAIR OUT I have heard of Martin Fowler's book PoEAA and the other book Head First OOA OOD but those are not in PHP. I DESPERATELY WANT TO READ THEM, but ONLY in PHP utilizing SOLID principles! Does anyone know of the absolute best, most recent PHP book that utilizes the SOLID principles and GRASP, and all the other best practices? I want to learn from the best possible source! Not beginner books! I already understand OOP. This seems like an almost impossible question to find the answer to and so I thought, hey, might as well post on stackexchange!! Surely someone out there must know!!!!!!!!!! Or if noone knows Maybe they know of an open source application that utilizes these principles that is relatively small that is not a framework. Something that I can go through every single class, and spend time understanding the insides and outs of how the program was developed. Thanks so much in advance! I really really really really appreciate it!

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• Smart Phones Shockingly Energy Efficient; Lead to Decreased Household Power Consumption

  - by Jason Fitzpatrick

  Given how often our smart phones and tablets spend plugged in and topping off their battery reserves, it’s easy to assume they’re sucking down a lot of power. Analysis shows the lilliputian but powerful devices are surprisingly efficient and may be decreasing our overall power consumption. Courtesy of energy-centric blog Outlier, we’re treated to a look at the power sipping habits of popular smart phones and mobile devices. The simple take away? They use shockingly little electricity over the course of the year–you can charge your new iPhone for a year of regular usage for under a buck. The more complex analysis? The proliferation of tiny and energy efficient devices is displacing heavier energy consumers (large televisions, desktop computers, etc.) and driving a more efficient gadget-to-consumption ratio is many households. Hit up the link below to read the full post. How Much Does It Take to Charge an iPhone [via Mashable] 7 Ways To Free Up Hard Disk Space On Windows HTG Explains: How System Restore Works in Windows HTG Explains: How Antivirus Software Works

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• Can I set up samba so it automatically allows all the local usernames and passwords?

  - by dialer

  I have set up samba like this (this is the complete smb.conf): [global] log file = /var/log/samba/log log level = 2 security = user [homes] browsable = false read only = no valid users = %S I'd like to enable every user on server to access their home directories, but for some unknown reason only my 'administrator' account can do so. (I have done that with ftp before, but now smb is also needed). When I try to smbclient -L localhost -U [user], I get NT_STATUS_LOGON_FAILURE, except with the administrator (which is the user created during the ubuntu installation, not root). The samba log file says NT_STATUS_NO_SUCH_USER: [2012/04/04 20:26:02.081454, 2] smbd/reply.c:554(reply_special) netbios connect: name1=LOCALHOST 0x20 name2=DIALER-X 0x0 [2012/04/04 20:26:02.081733, 2] smbd/reply.c:565(reply_special) netbios connect: local=localhost remote=dialer-x, name type = 0 [2012/04/04 20:26:02.087200, 2] auth/auth.c:314(check_ntlm_password) check_ntlm_password: Authentication for user [public] - [public] FAILED with error NT_STATUS_NO_SUCH_USER I suspect that I have to manually create samba users, but the man pages state that If the client has passed a username/password pair and that username/password pair is validated by the UNIX system's password programs, the connection is made as that username. To me that sounds like as long as the provided username/password is a valid login on the server, it should work. Am I missing something totally obvious? I don't want / can't afford to manually update the samba users and passwords to match the server's. 11.10

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• ADF - Now with Robots!

  - by Duncan Mills

  I mentioned this briefly in a tweet the other day, just before the full rush of OOW really kicked off, so I though it was worth re-visiting. Check out this video, and then read on: So why so interesting? Well - you probably guessed from the title, ADF is involved. Indeed this is as about as far from the traditional ADF data entry application as you can get. Instead of a database at the back-end there's basically a robot. That's right, this remarkable tape drive is controlled through an ADF using all your usual friends of ADF Faces, Controller and Binding (but no ADFBC for obvious reasons). ADF is used both on the touch screen you see on the front of the device in the video, and also for the remote management console which provides a visual representation of the slots and drives. The latter uses ADF's Active Data Framework to provide a real-time view of what's going on the rack. . What's even more interesting (for the techno-geeks) is the fact that all of this is running out of flash storage on a ridiculously small form factor with tiny processor - I probably shouldn't reveal the actual specs but take my word for it, don't complain about the capabilities of your laptop ever again! This is a project that I've been personally involved in and I'm pumped to see such a good result and,  I have to say, those hardware guys are great to work with (and have way better toys on their desks than we do). More info in the SL150 (should you feel the urge to own one) is here. 

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• HTML Manifest for Content Folios

  - by Kyle Hatlestad

  I recently worked on a project to create a custom content folio renderer in WebCenter Content. It needed to output the native files in the folio along with a manifest file in HTML format which would list the contents of the folio along with any designated metadata and a relative link to the file within the download.  This way a person could hand someone the folio download and it would be a self-contained package with all of the content and a single file to display the information on the contents.  The default Zip rendition of the folio will output the web-viewable version of the file with an HDA formatted file for each one. And unless you are fluent in HDA or have a tool to read them, they are difficult to consume. I thought this might be useful for others, so I'm posting a copy of the component here. Beyond the standard instructions for installing a component, there is an environment configuration file (folionativezipwithmanifestrenderer_environment.cfg) which has a couple of options. FolioMetadataManifestList - This is a comma separated list of metadata fields (system or custom) that should be included in the manifest file. FolioMetadataManifestUseOriginalFilename - (True or False) If set to True, the filenames in the zip file will be based on the original filename as it was checked into WebCenter Content.  If False, it will use the 'Name' of the item as defined within the Folio.  This is usually the Title of the item. The component also includes the source code, so feel free to use this as a reference for creating other interesting folios. 

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• How to setup users for desktop app with SQL Azure as backend?

  - by Manuel

  I'm considering SQL Azure as DB for a new application I'm developing. The reason I want to go with Azure is because I don't want to have to maintain yet another database(s) and I want my users to be able to access the data from anywhere. The problem is that I'm not clear regarding how to users will connect. The application is a basic CRUD type of windows app. I've read that you need to add your IP to SQL Azure's firewall to connect to it, but I don't know if it's only for administration purposes only. Can anyone clarify if anyone (anywhere) can access the data with the proper credentials? Which of the following scenarios would work best (if at all)? A) Add each user to SQL Azure and have the app connect directly to Azure as if it was connecting to SQL Server B) Add an anonymous user SQL Azure and pass the real user's password/hash with every call so the Azure database can service the requests accordingly. C) Put a WCF service in between so that it handles the authentication stuff. The service will only serve the appropriate information to the user given his/her authentication and SQL Azure would be open to the service exclusively. D) - ideas are welcomed - This is confusing because all Azure examples I see are for websites. I have a hard time believing SQL Azure wouldn't handle the case of desktop apps connecting to it. So what's the best practice?

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• Java and .NET cost of use [on hold]

  - by 1110

  I work with .NET technology stack for about 4 years. I am learning and enjoy working with ASP MVC framework and I never did anything serious in other languages. This is not the question like what is better (I read all similar questions). What interest me is the cost of switching. For example: If you are about to start a start-up company today and you are in my situation not too much money, some good idea that you think others will use and have a knowledge of .NET. In my head I have a few questions that I can't answer and I know that somebody with experience can: 1) Java & .NET hosting. Suppose shared hosting is not good enough anymore, your site has grown and you need more resources. How much Java services is cheaper compared to .NET? 2) I didn't follow hype about ORACLE will kill java long time. Does oracle show interest in investing in java. I mean is is safe to bet on java as a technology when starting start-up (basically did oracle show some will to destroy java platform)? 3) I am not sure what I am asking here. When you use Java you can use JEEE stack or Java with third party stack (spring, hibernate, maven etc.). I saw a lot of project that work with second option if web application is not enterprise level but social networking site for example which stack is best pick? Summary of this question is is it safe to jump in to Java learn it and build product based on it. It's not too hard for me to learn it. But how much can I get from it.

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• Quaternions, Axis Angles and Rotation Matrices. Which of these should I use for FP Camera?

  - by Afonso Lage

  After 2 weeks of reading many math formulas and such I know what is a Quaternion, an Axis Angles and Matrices. I have made my own math libary (Java) to use on my game (LWJGL). But I'm really confused about all this. I want to have a 3D first person camera. The move (translation) is working fine but the rotation isnt working like I need. I need a camera to rotate arround world Axis and not about its own axis. But even using Quaternions, this doesnt work and no matter how much I read about Euler Angles, everybody says to me dont touch on it! This is a little piece of code that i'm using to make the rotation: Quaternion qPitch = Quaternion.createFromAxis(cameraRotate.x, 1.0f, 0.0f, 0.0f); Quaternion qYaw = Quaternion.createFromAxis(cameraRotate.y, 0.0f, 1.0f, 0.0f); this.multiplicate(qPitch.toMatrix4f().toArray()); this.multiplicate(qYaw.toMatrix4f().toArray()); Where this is a Matrix4f view matrix and cameraRotate is a Vector3f that just handle the angles to rotate obtained from mouse move. So I think I'm doing everything right: Translate the view Matrix Rotate the Move Matrix So, after reading all this, I just want to know: To obtain a correct first person camera rotate, I must need to use Quaternios to make the rotations, but how to rotate around world axis? Thanks for reading it. Best regards, Afonso Lage

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• Sound not working with Ubuntu 12.10 clean install

  - by ZooRocket

  Did a clean install of Ubuntu 12.10 from 12.04 and the sound is not working now. In 12.04 it worked out of the box. I ran hwinfo --sound > hal.1: read hal dataprocess 4222: arguments to dbus_move_error() were incorrect, assertion "(dest) == NULL || !dbus_error_is_set ((dest))" failed in file ../../dbus/dbus-errors.c line 282. This is normally a bug in some application using the D-Bus library. libhal.c 3483 : Error unsubscribing to signals, error=The name org.freedesktop.Hal was not provided by any .service files 10: PCI 1b.0: 0403 Audio device [Created at pci.318] Unique ID: u1Nb.ekgK5auW5RA SysFS ID: /devices/pci0000:00/0000:00:1b.0 SysFS BusID: 0000:00:1b.0 Hardware Class: sound Model: "Intel 82801G (ICH7 Family) High Definition Audio Controller" Vendor: pci 0x8086 "Intel Corporation" Device: pci 0x27d8 "82801G (ICH7 Family) High Definition Audio Controller" SubVendor: pci 0x1028 "Dell" SubDevice: pci 0x01de Revision: 0x01 Memory Range: 0xfdffc000-0xfdffffff (rw,non-prefetchable) IRQ: 11 (no events) Module Alias: "pci:v00008086d000027D8sv00001028sd000001DEbc04sc03i00" Driver Info #0: Driver Status: snd_hda_intel is active Driver Activation Cmd: "modprobe snd_hda_intel" Config Status: cfg=new, avail=yes, need=no, active=unknown Not sure how to proceed to fix this. Has also worked prior to this version.

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• How to avoid the GameManager god object?

  - by lorancou

  I just read an answer to a question about structuring game code. It made me wonder about the ubiquitous GameManager class, and how it often becomes an issue in a production environment. Let me describe this. First, there's prototyping. Nobody cares about writing great code, we just try to get something running to see if the gameplay adds up. Then there's a greenlight, and in an effort to clean things up, somebody writes a GameManager. Probably to hold a bunch of GameStates, maybe to store a few GameObjects, nothing big, really. A cute, little, manager. In the peaceful realm of pre-production, the game is shaping up nicely. Coders have proper nights of sleep and plenty of ideas to architecture the thing with Great Design Patterns. Then production starts and soon, of course, there is crunch time. Balanced diet is long gone, the bug tracker is cracking with issues, people are stressed and the game has to be released yesterday. At that point, usually, the GameManager is a real big mess (to stay polite). The reason for that is simple. After all, when writing a game, well... all the source code is actually here to manage the game. It's easy to just add this little extra feature or bugfix in the GameManager, where everything else is already stored anyway. When time becomes an issue, no way to write a separate class, or to split this giant manager into sub-managers. Of course this is a classical anti-pattern: the god object. It's a bad thing, a pain to merge, a pain to maintain, a pain to understand, a pain to transform. What would you suggest to prevent this from happening?

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• what to learn & practice to be a programmer (not for Job) [closed]

  - by Hanan N.

  I want to be able to write programs (tools) for my own needs, and I want to tell the computer what to do, not to be strict to what other's told it to do. I have a good knowledge of Linux & Windows, I am also have a bit of Python in my head, but I think that I need some guidance on what languages or practices to invest my time into in order to be able to tell the computer what to do. I know there is a lot of posts similar to what I am asking here, but there is a big difference and so I have opened this thread. My goal isn't to work at a company, so I don't need to learn how to work as a team, I don't need to learn as much how to maintain my code nor how to write it nice for others to understand (I know it is important but not for me). I don't want to learn it as a profession, but as a serious hobby (you can call it hacking as long as you know what cracking means), my end goal is to be able to understand other's people code, and to write my own code with a lot of deep knowledge of the ins and outs of the computer system in order to gain from it as much as I can. So in essence my questions are: How can I understand, in depth, computers, in order to exploit them as much as I can? What should I learn? Are there any books that I should read? Is it possible to do this, or do I have to learn every aspect of programming?

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• Deepest sense of programming [closed]

  - by xralf

  I suffer on depression for a few months. Programming was one of my big passions (as a hobby). I had a motivation to achieve my goals (projects), to read books and articles about it to have interest in algorithms and data structures, compilers etc. Then, my mind started to think that it has no sense, that the result is useless. I realized, that I loved programming because of an illusion that it has deep sense, that I love playing with code every day as nothing else with feeling that it leads somewhere. Could I rationalize that it has sense to work on some programming project? That there is a deep sense to do it and enjoy this activity? I have no idea what else should I do in the free time, the mornings without motivation are very depressing. It was nice time when I had an illusion that programming is enjoyable. Could you help me to figure out the deepest sense of programming in this world? Why to love it again? What everything could be achieved and realized? (things like higher salary and ego are not what I'm looking for)

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• Fast, accurate 2d collision

  - by Neophyte

  I'm working on a 2d topdown shooter, and now need to go beyond my basic rectangle bounding box collision system. I have large levels with many different sprites, all of which are different shapes and sizes. The textures for the sprites are all square png files with transparent backgrounds, so I also need a way to only have a collision when the player walks into the coloured part of the texture, and not the transparent background. I plan to handle collision as follows: Check if any sprites are in range of the player Do a rect bounding box collision test Do an accurate collision (Where I need help) I don't mind advanced techniques, as I want to get this right with all my requirements in mind, but I'm not sure how to approach this. What techniques or even libraries to try. I know that I will probably need to create and store some kind of shape that accurately represents each sprite minus the transparent background. I've read that per pixel is slow, so given my large levels and number of objects I don't think that would be suitable. I've also looked at Box2d, but haven't been able to find much documentation, or any examples of how to get it up and running with SFML.

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• What is the correct way to implement Auth/ACL in MVC?

  - by WiseStrawberry

  I am looking into making a correctly laid out MVC Auth/ACL system. I think I want the authentication of a user (and the session handling) to be separate from the ACL system. (I don't know why but this seems a good idea from the things I've read.) What does MVC have to do with this question you ask? Because I wish for the application to be well integrated with my ACL. An example of a controller (CodeIgniter): <?php class forums extends MX_Controller { $allowed = array('users', 'admin'); $need_login = true; function __construct() { //example of checking if logged in. if($this->auth->logged_in() && $this->auth->is_admin()) { echo "you're logged in!"; } } public function add_topic() { if($this->auth->allowed('add_topic') { //some add topic things. } else { echo 'not allowed to add topic'; } } } ?> My thoughts $this->auth would be autoloaded in the system. I would like to check the $allowed array against the user currently (not) logged in and react accordingly. Is this a good way of doing things? I haven't seen much literature on MVC integration and Auth. I want to make things as easy as possible.

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• What would be the fastest way of storing or calculating legal move sets for chess pieces?

  - by ioSamurai

  For example if a move is attempted I could just loop through a list of legal moves and compare the x,y but I have to write logic to calculate those at least every time the piece is moved. Or, I can store in an array [,] and then check if x and y are not 0 then it is a legal move and then I save the data like this [0][1][0][0] etc etc for each row where 1 is a legal move, but I still have to populate it. I wonder what the fastest way to store and read a legal move on a piece object for calculation. I could use matrix math as well I suppose but I don't know. Basically I want to persist the rules for a given piece so I can assign a piece object a little template of all it's possible moves considering it is starting from it's current location, which should be just one table of data. But is it faster to loop or write LINQ queries or store arrays and matrices? public class Move { public int x; public int y; } public class ChessPiece : Move { private List<Move> possibleMoves { get; set; } public bool LegalMove(int x, int y){ foreach(var p in possibleMoves) { if(p.x == x && p.y == y) { return true; } } } } Anyone know?

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• Is it reasonable to null guard every single dereferenced pointer?

  - by evadeflow

  At a new job, I've been getting flagged in code reviews for code like this: PowerManager::PowerManager(IMsgSender* msgSender) : msgSender_(msgSender) { } void PowerManager::SignalShutdown() { msgSender_->sendMsg("shutdown()"); } I'm told that last method should read: void PowerManager::SignalShutdown() { if (msgSender_) { msgSender_->sendMsg("shutdown()"); } } i.e., I must put a NULL guard around the msgSender_ variable, even though it is a private data member. It's difficult for me to restrain myself from using expletives to describe how I feel about this piece of 'wisdom'. When I ask for an explanation, I get a litany of horror stories about how some junior programmer, some-year, got confused about how a class was supposed to work and accidentally deleted a member he shouldn't have (and set it to NULL afterwards, apparently), and things blew up in the field right after a product release, and we've "learned the hard way, trust us" that it's better to just NULL check everything. To me, this feels like cargo cult programming, plain and simple. A few well-meaning colleagues are earnestly trying to help me 'get it' and see how this will help me write more robust code, but... I can't help feeling like they're the ones who don't get it. Is it reasonable for a coding standard to require that every single pointer dereferenced in a function be checked for NULL first—even private data members? (Note: To give some context, we make a consumer electronics device, not an air traffic control system or some other 'failure-equals-people-die' product.) EDIT: In the above example, the msgSender_ collaborator isn't optional. If it's ever NULL, it indicates a bug. The only reason it is passed into the constructor is so PowerManager can be tested with a mock IMsgSender subclass.

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• HTML5 - Does it have the power to handle a large 2D game with a huge world?

  - by user15858

  I have been using XNA game studio, but due to private reasons (as well as the ability to publish anywhere & my heavy interest in isogenic engine), I would like to switch to HTML5. However, I have very high 2D graphic demands for my game. The game itself will have a HDD size of anywhere between 6GB (min) to 12GB (max) which would be a full game deployed offline. The size of the images aren't significantly large, so streaming would be entirely possible if only those assets required were streamed as needed. The game has a massive file size because of the sheer amount of content. For some images or spritesheets, they would be quite massive. (ex. a very large Dragon, which if animated in a spritesheet would be split into two 4096x4096 sheets or one 8192x8192 sheet). Most assets would be very small, and about 7MB for a full character with 15 animations in every direction (all animations not required immediately) so in the size of a few hundred KB to download before the game loads. My question, however, is if the graphical power of HTML5 is enough to animate several characters on screen at once, when it flips through frames quite rapidly. All my sprites have about 25 frames per animation, 5 directions (a spritesheet for each direction & animation), and run at 30fps. Upon changing direction, animation, or a new character entering, spritesheets would change and be constantly loading/unloading. If I pack all directions in a single sheet, it would be about 2048x2048 per sheet. Most frameworks have no problem with this, but I am afraid from what I read that HTML5's graphical capabilities will limit me. Since it takes significant time simply to animate characters in any language, I'd like a quick answer.

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• How to automatically mount a folder and change ownership from root in virtualbox

  - by Fiztban

  It is my first time using virtualbox and ubuntu (14.04), I am on a host Windows 7 OS. I am trying to mount a shared folder that has files I need to access both in the virtualbox and on the windows OS. I have successfully mounted them using the vboxsf from the Guest Additions installed. To mount I used the command sudo mount -t vboxsf <dir name in vbox> <directory in linux for example I used sudo mount -t vboxsf Test /home/user/Test I found several ways of mounting the directories automatically upon startup using for example the /etc/rc.local method (here) where you modify said file appending the command to it (without sudo). Or by using the fstab method (here). I prefer the rc.local method personally. Once mounted it has permissions dr-xr-xr-x however once mounted the directory is of root ownership and chown user /home/user/Test has no effect. This means I cannot make or change files in it as a normal user. In the VirtualBox the directory to be shared is not set as read-only. Is there a way to automatically mount the shared folder and assign ownership to my non root user?

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• What online games would let me practice AI development?

  - by Myn

  I am working on a project experimenting with Artificial Intelligence design methodologies for online world avatars. Online world here is quite open to interpretation; Second Life is just as applicable as Counter Strike, for example. To carry out these experiments, I must first develop an intelligent agent for the world in question. However, I am honestly quite stuck as to which game I could use for this. My preference was to develop an intelligent "bot" to play an MMORPG, but the legal restrictions of such games prevent me. Likewise with most FPS games the use of an intelligent agent in place of a human player is considered cheating. The alternative, of course, is to create an NPC bot; an intelligent agent that populates the world alongside the player(s) rather than replacing a particular player. However, I'm struggling to find a game that would enable me to create an intelligent opponent either. I suppose the main requirements would be a game allows a third party program to use the function calls usually utilised by players and read feedback on the state of the world. Quake III and Unreal Tournament have been suggested before, but they have already been the subject of work on this research project. Short of writing my own online game from scratch, what games would allow me, through middleware, an API, or otherwise, to create either an artificially intelligent player or a bot?

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