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  • Adding Debian Sid as Package Repository?

    - by user1131467
    I am running 12.04 Precise beta (upgraded from 11.10 Oneiric) and I added the following line to my /etc/apt/source.list: deb http://http.us.debian.org/debian unstable main contrib non-free In order to get a newer version of a package (octave 3.6) that I needed but was not available in the precise repository. This worked fine, but now when I want to upgrade there is a large number of packages that need to get updated. I assume this is because sid has newer versions of many of the packages than precise. I've temporarily disabled the sid repository, and this works fine - however I am curious to know what would happen if I allowed all those upgrades to go through? Would it break my system? Are the structures of Ubuntu Precise and Debian Sid repositories fundamentally different somehow?

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  • WIn API Basic Paint program

    - by Tom Burman
    Just trying to learn a bit of Win API. Im trying to make a basic drawing app, a bit like MS Paint. For the time being im trying to get one function to work which is, when you left click and drag the mouse around the screen a line is drawn behind the mouse. Heres what i have so far, but for some reason: 1) the line starts drawing straight away rather then waiting for the left click 2) the line isn't solid its very dotty. case WM_MOUSEMOVE: { if(MK_LBUTTON){ hdc = GetDC(hwnd); hPen = CreatePen(PS_SOLID,5,RGB(0, 0, 255)); SelectObject(hdc, hPen); int x = LOWORD(lParam); int y = HIWORD(lParam); MoveToEx(hdc,x,y,NULL); LineTo(hdc, LOWORD(lParam), HIWORD(lParam)); ReleaseDC(hwnd,hdc); } else break; } } Thanks for any help!

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  • 24 Hours of PASS – first reflections

    - by Rob Farley
    A few days after the end of 24HOP, I find myself reflecting on it. I’m still waiting on most of the information. I want to be able to discover things like where the countries represented on each of the sessions, and things like that. So far, I have the feedback scores and the numbers of attendees. The data was provided in a PDF, so while I wait for it to appear in a more flexible format, I’ve pushed the 24 attendee numbers into Excel. This chart shows the numbers by time. Remember that we started at midnight GMT, which was 10:30am in my part of the world and 8pm in New York. It’s probably no surprise that numbers drooped a bit at the start, stayed comparatively low, and then grew as the larger populations of the English-speaking world woke up. I remember last time 24HOP ran for 24 hours straight, there were quite a few sessions with less than 100 attendees. None this time though. We got close, but even when it was 4am in New York, 8am in London and 7pm in Sydney (which would have to be the worst slot for attracting people), we still had over 100 people tuning in. As expected numbers grew as the UK woke up, and even more so as the US did, with numbers peaking at 755 for the “3pm in New York” session on SQL Server Data Tools. Kendra Little almost reached those numbers too, and certainly contributed the biggest ‘spike’ on the chart with her session five hours earlier. Of all the sessions, Kendra had the highest proportion of ‘Excellent’s for the “Overall Evaluation of the session” question, and those of you who saw her probably won’t be surprised by that. Kendra had one of the best ranked sessions from the 24HOP event this time last year (narrowly missing out on being top 3), and she has produced a lot of good video content since then. The reports indicate that there were nearly 8.5 thousand attendees across the 24 sessions, averaging over 350 at each one. I’m looking forward to seeing how many different people that was, although I do know that Wil Sisney managed to attend every single one (if you did too, please let me know). Wil even moderated one of the sessions, which made his feat even greater. Thanks Wil. I also want to send massive thanks to Dave Dustin. Dave probably would have attended all of the sessions, if it weren’t for a power outage that forced him to take a break. He was also a moderator, and it was during this session that he earned special praise. Part way into the session he was moderating, the speaker lost connectivity and couldn’t get back for about fifteen minutes. That’s an incredibly long time when you’re in a live presentation. There were over 200 people tuned in at the time, and I’m sure Dave was as stressed as I was to have a speaker disappear. I started chasing down a phone number for the speaker, while Dave spoke to the audience. And he did brilliantly. He started answering questions, and kept doing that until the speaker came back. Bear in mind that Dave hadn’t expected to give a presentation on that topic (or any other), and was simply drawing on his SQL expertise to get him through. Also consider that this was between midnight at 1am in Dave’s part of the world (Auckland, NZ). I would’ve been expecting just to welcome people, monitor questions, probably read some out, and in general, help make things run smoothly. He went far beyond the call of duty, and if I had a medal to give him, he’d definitely be getting one. On the whole, I think this 24HOP was a success. We tried a different platform, and I think for the most part it was a popular move. We didn’t ask the question “Was this better than LiveMeeting?”, but we did get a number of people telling us that they thought the platform was very good. Some people have told me I get a chance to put my feet up now that this is over. As I’m also co-ordinating a tour of SQLSaturday events across the Australia/New Zealand region, I don’t quite get to take that much of a break (plus, there’s the little thing of squeezing in seven SQL 2012 exams over the next 2.5 weeks). But I am pleased to be reflecting on this event rather than anticipating it. There were a number of factors that could have gone badly, but on the whole I’m pleased about how it went. A massive thanks to everyone involved. If you’re reading this and thinking you wish you could’ve tuned in more, don’t worry – they were all recorded and you’ll be able to watch them on demand very soon. But as well as that, PASS has a stream of content produced by the Virtual Chapters, so you can keep learning from the comfort of your desk all year round. More info on them at sqlpass.org, of course.

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  • Do you believe it's a good idea for Software Engineers to have to work as Quality Assurance Engineers for some period of time?

    - by Macy Abbey
    I believe it is. Why? I've encountered many Software Engineers who believe they are somehow superior to QA engineers. I think it may help quench this belief if they do the job of a QA engineer for some time, and realize that it is a unique and valuable skill-set of its own. The better a Software Engineer is at testing their own programs, the less cost in time their code incurs when making its way through the rest of the software development life-cycle. The more time a Software Engineer spends thinking about how a program can break, the more often they are to consider these cases as they are developing them, thus reducing bugs in the end product. A Software Engineer's definition of "complete" is always interesting...if they have spent time as a QA engineer maybe this definition will more closely match the designer of the software's. What do you all think?

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  • SEO URL structure for tag search on site

    - by Theo G
    I am looking to add tags to each product on my site e.g. brown, x products under £x, second hand x, refurbished x etc. Once you click these tags it will then search for other tags that are similar. I was thinking of using a url structure of www.site.com/tags/this%is%the%tag%name and then simply have a page that shows the results of all the products with that tag. I heard a while back that google generally ignores or downgrades anything with ‘search’ in the url and was wondering if anyone had any experience with this? Also, would you say /tags/ is a pretty valid destination or is it best to break it down and add more levels e.g. /product-type/product%variation Thanks in advance!

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  • Google Webmasters tools crawl error caused by URL split into two lines

    - by Shiro
    I am looking in to Google Webmaster Tools - Crawl Error section. How should I handle for those URL due their system / application showed invalid URL. e.g http://www.example/images/products/s_=enlarge_16gb.jpg but, I dunno what happen to yahoo groups, it break the link into http://www.example/images/products/s_= enlarge_16gb.jpg and I only make the top part become hyperlink, which is http://www.example/images/products/s_= Because of the URL, Google show crawl error, I got few error because of this kind of result or because other people typo error. How do I prevent this. I am sure I don't have the right go and change other people post. What is the solution for this. Thanks!

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  • still getting 403 on apt-get install: no proxy, urls seems valid

    - by Berry Tsakala
    i'm trying to install libreoffice (or openoffice) on Ubuntu server 12.10, the packages exist - verified with "apt-cache search", the file /etc/apt/apt.conf.d/30proxy doesn't exist on my system the text 'proxy' isn't mention in grep proxy /etc/apt/apt.conf.d/ other packages that i tried to apt-get-install -- are installed OK. the only thing i haven't done is to replace the respository servers; i'm afraid it can break the dpkg system! related questions http://askubuntu.com/questions/304340/apt-get-403-forbidden?rq=1 http://askubuntu.com/questions/303150/apt-get-403-forbidden-but-accessible-in-the-browser http://askubuntu.com/questions/409998/proxy-blocking-apt-get-allowing-wget-curl http://askubuntu.com/questions/367737/apt-get-upgrade-gives-403-forbidden-error?rq=1 What else can I do to solve this 403 error and install liber/open-office using apt?

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  • How to use short breaks at work effectively for self-development?

    - by Alaudo
    At the moment my daily work as a developer requires me to have short 10-20 min breaks after every 2-3 hours. It would be nice if I could use those effectively to improve my expertise in programming or CS in general. I tried several things: Reading jokes online gets boring very soon. Trying to solve some (even the most simple) tasks from different code contests requires more time, as long as I have some idea of an algorithm the time is over. Reading a randomly picked Wikipedia-article about Computer Science: depending upon the article sometimes it requires more time and is not an easy reading for a break. So, I ended up reading StackOverflow questions and answers with most votes: that is entertaining and educative. Do you have any other suggestions?

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  • How to fix the copy/paste-pattern?

    - by Lenny222
    Where i work, people (consultants) feel pressed to release features as fast as possible. So instead of spending too much time on thinking about how to do things the right way or because they don't want to break anything, code gets copied from different modules and modified. It's not easy to prevent this, since the code base is open to the whole company. Lots of people work on this. Now that the mess is there already, what is the best way to remove those redundancies without breaking too much?

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  • Can this word search algorithm be made faster?

    - by Ashwin Singh
    Problem: Find a match of word S in text T Given: S and T are part of spoken and written English. Example: Match 'Math' in 'I love Mathematics' NOTE: Ignore CASES. My algorithm: STEP 1) Convert S, T to char[] STEP 2) for i=0, i < T.length , i++ STEP 3) for j=S.length-1, j>0 , j-- STEP 3 is the magic, instead of going about matching M,A,T,H, this matches M, H, T and finally A. This helps in eliminating a lot of possible partial matches. For example, if I go sequentially like M A as in Boyer Moore's method ... it can match Matter, Mass, Matchstick etc. using M _ _ H will bring down size of partial matches. STEP 4) if S[j]!=T[i] -> break; else if j==i -> PRINT MATCH

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  • Netgear WNA1100 stopped working

    - by NOLFXceptMe
    I'm facing a rather strange issue with the USB wireless adapter WNA1100. I was able to connect to wireless using this yesterday. However, today am not. lsmod shows ath9k_htc, ath9k_common, ath9k_hw, ath and ndiswrapper. I'm not sure if this is relevant to the above problem, but between yesterday and today, the only change was an upgrade to Ubuntu 2.6.38 kernel, which caused the NVIDIA driver to break (I have a 7300GT), so I had to ignore that kernel, reboot into 2.6.35, and rebuild NVIDIA module from NVIDIA-Installer-270.run. Help?

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  • In the context of semantic versioning, does a change in the default configuration warrant a new major version?

    - by michielvoo
    My module is enabled by default (i.e. when you add the module). There's also a configuration you can optionally use, which supports an enabled="true|false" setting. This way the module can be disabled after it's been added, without the need to remove the module. But I realized the module doesn't play nicely with another module that is also enabled by default. I am considering changing my module so it's not be enabled by default. This would break for anyone that has not explicitly enabled it with the enabled="true" configuration setting. Should I wait for v2.0 for this? semver.org mentions the public API and breaking changes, not configuration. Is it generally accepted that configuration is part of the public API?

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  • Issues with the intended behavior of a Service layer?

    - by Rafael Cichocki
    This analysis makes sense, and states anything that avoids code duplication and simplifies maintenance speaks for a service layer. What is the technical behavior? When a service client references a service, does it do so at runtime, or does it happen at compile time? When I change something in the service layer code, will this change be automatically taken into account in all it's clients, or do they need to be individually recompiled? How does this make sense from a testing point of view - I have working code, based on some code from a service, but if that service changes, my code might break?!

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  • What approaches can I take to lower the odds of introducing new bugs in a complex legacy app?

    - by m.edmondson
    Where I work I often have to develop (and bug fix) in an old system (.NET 1) whos code is complete spaghetti - with little thought given to variable names, program structure nor comments. Because of this it takes me ages to understand what bits need changed, and I often 'break' the existing software because I've made a modification. I really really want to spend a couple of months (with colleagues) going through it to refactor but existing developers both can't see the need - nor think theres time for this (the system is massive). I dread having to work on its code as it takes days to fix something only to find out I've broken something else. This obviously makes me look incompetent - so how can I deal with this?

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  • Is there a way to check if redistributed code has been altered?

    - by onlineapplab.com
    I would like to redistribute my app (PHP) in a way that the user gets the front end (presentation) layer which is using the API on my server through a web service. I want the user to be able to alter his part of the app but at the same time exclude such altered app from the normal support and offer support on pay by the hour basis. Is there a way to check if the source code was altered? Only solution I can think of would be to get check sums of all the files then send it through my API and compare them with the original app. Is there any more secure way to do it so it would be harder for the user to break such protection?

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  • HTG Explains: How System Restore Works in Windows

    - by Chris Hoffman
    System Restore is a Windows feature that can help fix some crashes and other computer problems. To know when to use it, you’ll have to understand just how System Restore works. System Restore can’t solve every problem – for example, you can’t use it to restore your personal files if they’re accidentally deleted or modified. However, it’s another tool you can use when your computer isn’t working properly. HTG Explains: How Antivirus Software Works HTG Explains: Why Deleted Files Can Be Recovered and How You Can Prevent It HTG Explains: What Are the Sys Rq, Scroll Lock, and Pause/Break Keys on My Keyboard?

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  • How to Implement a Parallel Workflow

    - by Paul
    I'm trying to implement a parallel split task using a workflow system. I'm using .NET but my process is very simple and I don't want to use WF or anything heavy like that. I've tried using Stateless. So far is was easy to set up and run, but I may be using the wrong tool for the job because I'm not sure how you're supposed to model parallel split workflows, where you have multiple sub-tasks required before you can advance to the next state, but the steps don't require being performed in any particular order. I can easily use the dynamic configuration options to check my data model manually to see if the model is in the correct state (all sub-tasks completed) and can transition to the next state, but this seems to completely break the workflow paradigm. What is the proper, orthodox way to implement a parallel split process? Thanks

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  • Tip #15: How To Debug Unit Tests During Maven Builds

    - by ByronNevins
    It must be really really hard to step through unit tests in a debugger during a maven build.  Right? Wrong! Here is how i do it: 1) Set up these environmental variables: MAVEN_OPTS=-Xmx1024m -Xms256m -XX:MaxPermSize=512mMAVEN_OPTS_DEBUG=-Xmx1024m -Xms256m -XX:MaxPermSize=512m  -Xdebug (no line break here!!)  -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=9999MAVEN_OPTS_REG=-Xmx1024m -Xms256m -XX:MaxPermSize=512m 2) create 2 scripts or aliases like so:  maveny.bat: set MAVEN_OPTS=%MAVEN_OPTS_DEBUG% mavenn.bat: set MAVEN_OPTS=%MAVEN_OPTS_REG%    To debug do this: run maveny.bat run mvn install attach your debugger to port 9999 (set breakpoints of course) When maven gets to the unit test phase it will hit your breakpoint and wait for you. When done debugging simply run mavenn.bat Notes If it takes a while to do the build then you don't really need to set the suspend=y flag. If you set the suspend=n flag then you can just leave it -- but only one maven build can run at a time because of the debug port conflict.

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  • How To Install and Use ADB, the Android Debug Bridge Utility

    - by Chris Hoffman
    ADB, Android Debug Bridge, is a command-line utility included with Google’s Android SDK. ADB can control your device over USB from a computer, copy files back and forth, install and uninstall apps, run shell commands, and more. We’ve covered some other tricks that require ADB in the past, including backing up and restoring your smartphone or tablet and installing Android apps to your SD card by default. ADB is used for a variety of geeky Android tricks. Image Credit: LAI Ryanne on Flickr HTG Explains: How Antivirus Software Works HTG Explains: Why Deleted Files Can Be Recovered and How You Can Prevent It HTG Explains: What Are the Sys Rq, Scroll Lock, and Pause/Break Keys on My Keyboard?

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  • ASP.NET AJAX Release History : Q1 2010 SP2 (version 2010.1.519)

    Common for all controls What's Fixed Fixed: Problem with RegisterWithScriptManager=false (MVC) and browsers without gzip support Fixed: $telerik.getLocation implementation, in case the element is a child of an element with position:fixed Visual Studio Extensions What's New Improved: Visual Studio 2010 support for upgrade notifications What's Fixed Fixed: Code language selection in WebSite does not work. RadAjax What's Fixed Fixed: RadAjax controls break on AJAX callback with ToolkitScriptManager...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • How can I gain access to a player instance in a Minecraft mod?

    - by Andrew Graber
    I'm creating Minecraft mod with a pickaxe that takes away experience when you break a block. The method for taking away experience from a player is addExperience on EntityPlayer, so I need to get an instance of EntityPlayer for the player using my pickaxe when the pickaxe breaks a block, so that I can remove the appropriate amount of experience. My pickaxe class currently looks like this: public class ExperiencePickaxe extends ItemPickaxe { public ExperiencePickaxe(int ItemID, EnumToolMaterial material){ super(ItemID, material); } public boolean onBlockDestroyed(ItemStack par1ItemStack, World par2World, int par3, int par4, int par5, int par6, EntityLiving par7EntityLiving) { if ((double)Block.blocksList[par3].getBlockHardness(par2World, par4, par5, par6) != 0.0D) { EntityPlayer e = new EntityPlayer(); // create an instance e.addExperience(-1); } return true; } } Obviously, I cannot actually create a new EntityPlayer since it is an abstract class. How can I get access to the player using my pickaxe?

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  • Does anybody know what happens to money spent in the Ubuntu One Music Store?

    - by Dave
    I remember reading on the Canonical website around the launch of the Ubuntu One Music store that after revenue was divided between Canonical, 7 digital and the artists involved that all profit or a significant percentage would be donated to a charity. This information has either disappeared from their website or my detective skills have failed me once more. Does anybody happen to understand the break down of revenue generated by the Ubuntu One Music Store or even know where to find this information. Also it would be useful to know which charity benefits from this. (Not that that would impact upon my purchases or send me running to iTunes. ;) Promise)

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  • Android Bitmap : collision Detecting [on hold]

    - by user2505374
    I am writing an Android game right now and I would need some help in the collision of the wall on screen. When I drag the ball in the top and right it able to collide in wall but when I drag it faster it was able to overlap in the wall. public boolean onTouchEvent(MotionEvent event) { int x = (int) event.getX(); int y = (int) event.getY(); switch (event.getAction()) { // if the player moves case MotionEvent.ACTION_MOVE: { if (playerTouchRect.contains(x, y)) { boolean left = false; boolean right = false; boolean up = false; boolean down = false; boolean canMove = false; boolean foundFinish = false; if (x != pLastXPos) { if (x < pLastXPos) { left = true; } else { right = true; } pLastXPos = x; } if (y != pLastYPos) { if (y < pLastYPos) { up = true; } else { down = true; } pLastYPos = y; } plCellRect = getRectFromPos(x, y); newplRect.set(playerRect); newplRect.left = x - (int) (playerRect.width() / 2); newplRect.right = x + (int) (playerRect.width() / 2); newplRect.top = y - (int) (playerRect.height() / 2); newplRect.bottom = y + (int) (playerRect.height() / 2); int currentRow = 0; int currentCol = 0; currentRow = getRowFromYPos(newplRect.top); currentCol = getColFromXPos(newplRect.right); if(!canMove){ canMove = mapManager.getCurrentTile().pMaze[currentRow][currentCol] == Cell.wall; canMove =true; } finishTest = mapManager.getCurrentTile().pMaze[currentRow][currentCol]; foundA = finishTest == Cell.valueOf(letterNotGet + ""); canMove = mapManager.getCurrentTile().pMaze[currentRow][currentCol] != Cell.wall; canMove = (finishTest == Cell.floor || finishTest == Cell.pl) && canMove; if (canMove) { invalidate(); setTitle(); } if (foundA) { mapManager.getCurrentTile().pMaze[currentRow][currentCol] = Cell.floor; // finishTest letterGotten.add(letterNotGet); playCurrentLetter(); /*sounds.play(sExplosion, 1.0f, 1.0f, 0, 0, 1.5f);*/ foundS = letterNotGet == 's'; letterNotGet++; }if(foundS){ AlertDialog.Builder builder = new AlertDialog.Builder(mainActivity); builder.setTitle(mainActivity.getText(R.string.finished_title)); LayoutInflater inflater = mainActivity.getLayoutInflater(); View view = inflater.inflate(R.layout.finish, null); builder.setView(view); View closeButton =view.findViewById(R.id.closeGame); closeButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View clicked) { if(clicked.getId() == R.id.closeGame) { mainActivity.finish(); } } }); AlertDialog finishDialog = builder.create(); finishDialog.show(); } else { Log.d(TAG, "INFO: updated player position"); playerRect.set(newplRect); setTouchZone(); updatePlayerCell(); } } // end of (CASE) if playerTouch break; } // end of (SWITCH) Case motion }//end of Switch return true; }//end of TouchEvent private void finish() { // TODO Auto-generated method stub } public int getColFromXPos(int xPos) { val = xPos / (pvWidth / mapManager.getCurrentTile().pCols); if (val == mapManager.getCurrentTile().pCols) { val = mapManager.getCurrentTile().pCols - 1; } return val; } /** * Given a y pixel position, return the row of the cell it is in This is * used when determining the type of adjacent Cells. * * @param yPos * y position in pixels * @return The cell this position is in */ public int getRowFromYPos(int yPos) { val = yPos / (pvHeight / mapManager.getCurrentTile().pRows); if (val == mapManager.getCurrentTile().pRows) { val = mapManager.getCurrentTile().pRows - 1; } return val; } /** * When preserving the position we need to know which cell the player is in, * so calculate it from the centre on its Rect */ public void updatePlayerCell() { plCell.x = (playerRect.left + (playerRect.width() / 2)) / (pvWidth / mapManager.getCurrentTile().pCols); plCell.y = (playerRect.top + (playerRect.height() / 2)) / (pvHeight / mapManager.getCurrentTile().pRows); if (mapManager.getCurrentTile().pMaze[plCell.y][plCell.x] == Cell.floor) { for (int row = 0; row < mapManager.getCurrentTile().pRows; row++) { for (int col = 0; col < mapManager.getCurrentTile().pCols; col++) { if (mapManager.getCurrentTile().pMaze[row][col] == Cell.pl) { mapManager.getCurrentTile().pMaze[row][col] = Cell.floor; break; } } } mapManager.getCurrentTile().pMaze[plCell.y][plCell.x] = Cell.pl; } } public Rect getRectFromPos(int x, int y) { calcCell.left = ((x / cellWidth) + 0) * cellWidth; calcCell.right = calcCell.left + cellWidth; calcCell.top = ((y / cellHeight) + 0) * cellHeight; calcCell.bottom = calcCell.top + cellHeight; Log.d(TAG, "Rect: " + calcCell + " Player: " + playerRect); return calcCell; } public void setPlayerRect(Rect newplRect) { playerRect.set(newplRect); } private void setTouchZone() { playerTouchRect.set( playerRect.left - playerRect.width() / TOUCH_ZONE, playerRect.top - playerRect.height() / TOUCH_ZONE, playerRect.right + playerRect.width() / TOUCH_ZONE, playerRect.bottom + playerRect.height() / TOUCH_ZONE); } public Rect getPlayerRect() { return playerRect; } public Point getPlayerCell() { return plCell; } public void setPlayerCell(Point cell) { plCell = cell; }

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  • Plurality [Sci-Fi Video]

    - by Asian Angel
    It is the year 2023 in New York City and the Bentham Grid has been online for two years. All that you are is tied to your DNA signature and no cash, ID cards, or keys are required now. Things run smoothly until multiple versions of people start showing up…and then it all starts to fall apart. PLURALITY [via Geeks are Sexy] HTG Explains: How Antivirus Software Works HTG Explains: Why Deleted Files Can Be Recovered and How You Can Prevent It HTG Explains: What Are the Sys Rq, Scroll Lock, and Pause/Break Keys on My Keyboard?

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  • Breaking 1NF to model subset constraints. Does this sound sane?

    - by Chris Travers
    My first question here. Appologize if it is in the wrong forum but this seems pretty conceptual. I am looking at doing something that goes against conventional wisdom and want to get some feedback as to whether this is totally insane or will result in problems, so critique away! I am on PostgreSQL 9.1 but may be moving to 9.2 for this part of this project. To re-iterate: Does it seem sane to break 1NF in this way? I am not looking for debugging code so much as where people see problems that this might lead. The Problem In double entry accounting, financial transactions are journal entries with an arbitrary number of lines. Each line has either a left value (debit) or a right value (credit) which can be modelled as a single value with negatives as debits and positives as credits or vice versa. The sum of all debits and credits must equal zero (so if we go with a single amount field, sum(amount) must equal zero for each financial journal entry). SQL-based databases, pretty much required for this sort of work, have no way to express this sort of constraint natively and so any approach to enforcing it in the database seems rather complex. The Write Model The journal entries are append only. There is a possibility we will add a delete model but it will be subject to a different set of restrictions and so is not applicable here. If and when we allow deletes, we will probably do them using a simple ON DELETE CASCADE designation on the foreign key, and require that deletes go through a dedicated stored procedure which can enforce the other constraints. So inserts and selects have to be accommodated but updates and deletes do not for this task. My Proposed Solution My proposed solution is to break first normal form and model constraints on arrays of tuples, with a trigger that breaks the rows out into another table. CREATE TABLE journal_line ( entry_id bigserial primary key, account_id int not null references account(id), journal_entry_id bigint not null, -- adding references later amount numeric not null ); I would then add "table methods" to extract debits and credits for reporting purposes: CREATE OR REPLACE FUNCTION debits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount < 0 THEN $1.amount * -1 ELSE NULL END; $$; CREATE OR REPLACE FUNCTION credits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount > 0 THEN $1.amount ELSE NULL END; $$; Then the journal entry table (simplified for this example): CREATE TABLE journal_entry ( entry_id bigserial primary key, -- no natural keys :-( journal_id int not null references journal(id), date_posted date not null, reference text not null, description text not null, journal_lines journal_line[] not null ); Then a table method and and check constraints: CREATE OR REPLACE FUNCTION running_total(journal_entry) returns numeric language sql immutable as $$ SELECT sum(amount) FROM unnest($1.journal_lines); $$; ALTER TABLE journal_entry ADD CONSTRAINT CHECK (((journal_entry.running_total) = 0)); ALTER TABLE journal_line ADD FOREIGN KEY journal_entry_id REFERENCES journal_entry(entry_id); And finally we'd have a breakout trigger: CREATE OR REPLACE FUNCTION je_breakout() RETURNS TRIGGER LANGUAGE PLPGSQL AS $$ BEGIN IF TG_OP = 'INSERT' THEN INSERT INTO journal_line (journal_entry_id, account_id, amount) SELECT NEW.id, account_id, amount FROM unnest(NEW.journal_lines); RETURN NEW; ELSE RAISE EXCEPTION 'Operation Not Allowed'; END IF; END; $$; And finally CREATE TRIGGER AFTER INSERT OR UPDATE OR DELETE ON journal_entry FOR EACH ROW EXECUTE_PROCEDURE je_breaout(); Of course the example above is simplified. There will be a status table that will track approval status allowing for separation of duties, etc. However the goal here is to prevent unbalanced transactions. Any feedback? Does this sound entirely insane? Standard Solutions? In getting to this point I have to say I have looked at four different current ERP solutions to this problems: Represent every line item as a debit and a credit against different accounts. Use of foreign keys against the line item table to enforce an eventual running total of 0 Use of constraint triggers in PostgreSQL Forcing all validation here solely through the app logic. My concerns are that #1 is pretty limiting and very hard to audit internally. It's not programmer transparent and so it strikes me as being difficult to work with in the future. The second strikes me as being very complex and required a series of contraints and foreign keys against self to make work, and therefore it strikes me as complex, hard to sort out at least in my mind, and thus hard to work with. The fourth could be done as we force all access through stored procedures anyway and this is the most common solution (have the app total things up and throw an error otherwise). However, I think proof that a constraint is followed is superior to test cases, and so the question becomes whether this in fact generates insert anomilies rather than solving them. If this is a solved problem it isn't the case that everyone agrees on the solution....

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