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• Trying to find a recent - PHP book - that utilizes SOLID principles! [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 the - SOLID acronym - 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 happens to know, 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! Well it looks like we aren't supposed to ask about best books, so nevermind this question! Sorry about that!

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• How to scroll hex tiles?

  - by Chris Evans

  I don't seem to be able to find an answer to this one. I have a map of hex tiles. I wish to implement scrolling. Code at present: drawTilemap = function() { actualX = Math.floor(viewportX / hexWidth); actualY = Math.floor(viewportY / hexHeight); offsetX = -(viewportX - (actualX * hexWidth)); offsetY = -(viewportY - (actualY * hexHeight)); for(i = 0; i < (10); i++) { for(j = 0; j < 10; j++) { if(i % 2 == 0) { x = (hexOffsetX * i) + offsetX; y = j * sourceHeight; } else { x = (hexOffsetX * i) + offsetX; y = hexOffsetY + (j * sourceHeight); } var tileselected = mapone[actualX + i][j]; drawTile(x, y, tileselected); } } } The code I've written so far only handles X movement. It doesn't yet work the way it should do. If you look at my example on jsfiddle.net below you will see that when moving to the right, when you get to the next hex tile along, there is a problem with the X position and calculations that have taken place. It seems it is a simple bit of maths that is missing. Unfortunately I've been unable to find an example that includes scrolling yet. http://jsfiddle.net/hd87E/1/ Make sure there is no horizontal scroll bar then trying moving right using the - right arrow on the keyboard. You will see the problem as you reach the end of the first tile. Apologies for the horrid code, I'm learning! Cheers

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• How to organize a larger project with several sub-projects and their dependencies?

  - by RoToRa

  As a software developer until now, I've mostly worked on projects that were quite "monolithic" with hardly any dependencies on other projects, without building automation (no Make, Ant, Maven, etc.) and kept on a simple version control system (mostly Subversion) with just a few easily managed version branches. Now together with some friends I'm planning a project that is intended to run on multiple platforms (mostly mobile: Android, iOS, Kindle, Windows, etc.), thus written in several languages and on different development platforms. This will lead to many dependencies: All projects sharing the same resources (e.g. images) or projects dependent on each other (e.g. a core Java library project used by the Android and other Java based implementations). So what I need is some basic information on how to answer questions such as: How would the VCS be structured? Would a client-base or a decentralized VCS be better? How to decide building automation system(s) to use? Since this quite an open question I guess for now it would be great if you could point me to any books or web resources that you can recommend for this topic.

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• Checking preconditions or not

  - by Robert Dailey

  I've been wanting to find a solid answer to the question of whether or not to have runtime checks to validate input for the purposes of ensuring a client has stuck to their end of the agreement in design by contract. For example, consider a simple class constructor: class Foo { public: Foo( BarHandle bar ) { FooHandle handle = GetFooHandle( bar ); if( handle == NULL ) { throw std::exception( "invalid FooHandle" ); } } }; I would argue in this case that a user should not attempt to construct a Foo without a valid BarHandle. It doesn't seem right to verify that bar is valid inside of Foo's constructor. If I simply document that Foo's constructor requires a valid BarHandle, isn't that enough? Is this a proper way to enforce my precondition in design by contract? So far, everything I've read has mixed opinions on this. It seems like 50% of people would say to verify that bar is valid, the other 50% would say that I shouldn't do it, for example consider a case where the user verifies their BarHandle is correct, but a second (and unnecessary) check is also being done inside of Foo's constructor.

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• Directory error when trying to create a new user

  - by Tom Brossman

  I added a second user 'shirley' in Settings - User Accounts, and set a password. The account type is Standard. In 11.04, this worked and I logged in and had a functioning desktop for this user. How is this done in 11.10? When I try to log in as this user I have this error: Nautilus could not create the required folder "/home/shirley/.config/nautilus". Before running Nautilus, please create the following folder, or set permissions such that Nautilus can create it. The only option then is to click OK, this dumps me out to full-screen Nautilus, like this: There is no launcher or visible way to start any programs. Print screen doesn't take a screengrab. The desktop is similar to this question but I get no terminal when I press CTRL+ALT+T. I have to press CTRL+ALT+F2 and restart from the terminal to get out of this. This answer is to install gnome-system-tools. Shouldn't I be able to add a second user with the default install? EDIT: I tried the deluser+adduser suggestion, there was no change after trying it. Here is what I got: tom@desktop:~$ sudo deluser shirley [sudo] password for tom: Removing user `shirley' ... Warning: group `shirley' has no more members. Done tom@desktop:~$ sudo adduser shirley Adding user `shirley' ... Adding new group `shirley' (1001) Adding new user shirley' (1001) with groupshirley' The home directory '/home/shirley' already exists. Not copying from `/etc/skel'. Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully Changing user information for shirley Enter the new value, or press ENTER for the default Full Name []: Room Number []: Work Phone []: Home Phone []: Other []: Is the information correct? [Y/n] y What has gone so wrong with simply adding a second user? Am I the only one having this problem? I'd reinstall if that fixed things, but this is a fresh install only a few days old.

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• Find non-ascii characters from a UTF-8 string

  - by user10607

  I need to find the non-ASCII characters from a UTF-8 string. my understanding: UTF-8 is a superset of character encoding in which 0-127 are ascii characters. So if in a UTF-8 string , a characters value is Not between 0-127, then it is not a ascii character , right? Please correct me if i'm wrong here. On the above understanding i have written following code in C : Note: I'm using the Ubuntu gcc compiler to run C code utf-string is xvab c long i; char arr[] = "xvab c"; printf("length : %lu \n", sizeof(arr)); for(i=0; i<sizeof(arr); i++){ char ch = arr[i]; if (isascii(ch)) printf("Ascii character %c\n", ch); else printf("Not ascii character %c\n", ch); } Which prints the output like: length : 9 Ascii character x Not ascii character Not ascii character ? Not ascii character ? Ascii character a Ascii character b Ascii character Ascii character c Ascii character To naked eye length of xvab c seems to be 6, but in code it is coming as 9 ? Correct answer for the xvab c is 1 ...i.e it has only 1 non-ascii character , but in above output it is coming as 3 (times Not ascii character). How can i find the non-ascii character from UTF-8 string, correctly. Please guide on the subject.

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• MatheMagics - Guess My Age - Method 2

  - by PointsToShare

  © 2011 By: Dov Trietsch. All rights reserved MatheMagic – Guess My Age – Method 2 The Mathemagician stands on the stage and asks an adult to do the following: ·         Do the next few steps on your calculator, or the calculator in your phone, or even on a piece of paper. ·         Do it silently! Don’t tell me the results until I ask for them directly ·         Multiply your age by 2. ·         Add 7 to the result ·         Multiply the result by 5. ·         Tell me the result. I will nonetheless immediately tell you what your age is. How do I do this? Let’s do the algebra. Let A denote your age (2A + 7) 5 = 10A + 35 so it is of the 3 digit form XY5 Now make two numbers out of the result - The last digit and the number before it. The Last digit is obviously 5, the other 2 (or 3 for a centenarian) and this number is the age + 3. Example: I am 76 years old and here is what happens when I do the steps 76 x 2 = 152 152 + 7 = 159 159 x 5 = 795 This is made of 79 and 5. And … 79 – 3 = 76 A note to the socially aware mathemagician – it is safer to do it with a man. The chances of a veracious answer are much, much higher! The trick may be accomplished on any 2 or 3 digit number, not just one’s age, but if you want to know your date’s age, it’s a good way to elicit it. That’s All Folks PS for more Ageless “Age” mathemagics go to www.mgsltns.com/games.htm and also here: http://geekswithblogs.net/PointsToShare/archive/2011/11/15/mathemagics---guess-my-age-method-1.aspx

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• Tree Surgeon 2.0 - The future on the T4 Express

  - by Malcolm Anderson

  If you've never been a fan of TreeSurgeon (http://treesurgeon.codeplex.com/) then skip this post.However, if have been there have been some interesting developments over the last couple of years.The biggest one is T4Recently Bill Simser wrote a detailed post about the potential future of tree surgeon, called "Tree Surgeon - Alive and Kicking or Dead and Buried" He raised the question:Times have changed. Since that last release in 2008 so much has changed for .NET developers. The question is, today is the project still viable? Do we still need a tool to generate a project tree given that we have things like scaffolding systems, NuGet, and T4 templates. Or should we just give the project its rightful and respectful send off as its had a good life and has outlived its usefulness.For myself, the answer is, keep it.I've spent the last couple of years doing agile engineering coaching and architecture and from my experience, I can tell you, there are a lot of shops out there that would benefit from having Tree Surgeon as a viable product.  Many would benefit simply from having the software engineering information that is embedded in the tree surgeon site be floating around their conversation.Little things like, keep all of your software needed to run the build, with the build in the version control system.Have your developers and the build system using the same build.Have a one-touch buildSeparate your code from your interfacePut unit tests in first, not lastI've seen companies with great developers suffer from the problems that naturally come from builds taking 3 and 4 hours to run.  It takes work to get that build down to 10 minutes, but the benefits are always worth it.  Tree Surgeon gives you a leg up, by starting you off with a project that you can drop into your Continuous Integration system, right out of the box.Well, it used to be right out of the box.  Today, you have to play with the project to make it work for you, but even with the issues (it hasn't been updated since 2008) it still gives you a framework, with logical separations that you can build from.If you have used Tree Surgeon in the past, take a few minutes and drop a comment about what difference it made in your development style, and what you are doing differently today because of it.

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• Wordpress blog penalized by Google search - what's wrong?

  - by pawelbrodzinski

  I have a blog (http://blog.brodzinski.com), which is wordpress.org blog with pretty popular Thesis theme with almost no other customizations. Some time ago it was penalized by Google search - it simply stopped appearing in search results even for search terms it used to be top result, like my name - Pawel Brodzinski - which isn't anything close to popular search term. To be exact the site has been penalized on Nov 18. It started popping up in search result on Dec 23 but only for a few days. Since Dec 27 it is out again. I know Google guidelines and I'm not aware to break any of them. I submitted reconsideration request after I noticed penalty. It was proceeded and there was no change whatsoever (no surprise as it seems the site was penalized again). I checked diagnostics in webmaster tools and neither any malware was detected nor any strange search terms popped up. I read related threads on Google webmasters forum but found none of solutions working for me. I posted a thread on Google webmasters forum (http://www.google.com/support/forum/p/Webmasters/thread?tid=546339f49d4a03bc&hl=en) and the only answer I got was to check for duplicate content. Well, there is some duplicate content published on the web but it is true for vast majority of blogs and it doesn't seem to be a reason for a penalty. Also before Dec 27 I was able to remove duplicate content from a couple of sites which were republishing my feed but this doesn't change the situation - the site was penalized again. The problem is I have no idea what can be wrong with the website or how to find it out. To make the problem worse I'm no webmaster, I just run a wordpress blog, which supposed to be easy.

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• What are the requirements to test a website using jquery.get() ? [migrated]

  - by Frankie

  I am working on a simple website. It has to search quite a few text files in different sub-folders. The rest of the page uses jquery, so I would like to use it for this also. The function I am looking at is .get() for downloading the files. So my main question is, can I test this on my local computer (Ubuntu Linux) or do I have to have it uploaded to a server? Also, if there's a better way to go about this, that would be nice to know. However, I'm more worried about getting it working. Thanks, Frankie PS: Heres the JS/jQuery code for downloading the files to an array. g_lists = new Array(); $(":checkbox").each(function(i){ if ($(this).attr("name") != "0") { var path = "../" + $(this).attr("name") + ".txt"; $("#bot").append("<br />" + path); // debug $.get(path, function(data){ g_lists[i] = data; $("#bot").html(data); }); } else { g_lists[i] = ""; } }); Edit: Just a note about the path variable. I think it's correct, but I'm not 100% sure. I'm new to web development. Here's some examples it produces and the directory tree of the site. Maybe it will help, can't hurt. . +-- include ¦   +-- jquery.js ¦   +-- load.js +-- index.xhtml +-- style.css +-- txt    +-- Scripting_Tools    +-- Editors.txt    +-- Other.txt Examples of path: ../txt/Scripting_Tools/Editors.txt ../txt/Scripting_Tools/Other.txt Well I'm a new user, so I can't "answer" my own question, so I'll just post it here: After asking for help on a IRC chat channel specific to jQuery, I was told I could use this on a local host. To do this I installed Apache web server, and copied my site into it's directory. More information on setting it up can be found here: http://www.howtoforge.com/ubuntu_debian_lamp_server Then to run the site I navigated my browser to "localhost" and everything works.

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• Ubuntu 13.04 alongside Windows 8 - How to partition from Windows

  - by mengelkoch

  I plan to install Ubuntu 13.04 alongside Windows 8, and I'm looking for a CLEAR answer on how to conduct partitioning appropriately. I'm very new to all of this so a thorough explanation with minimal jargon would be great. I have an Acer Aspire M5 x64 with 6G RAM. I think I already figured out how to deal with the fast startup, UEFI and SecureBoot issues (I disabled fast startup and disabled Secure Boot). I am able to boot into Ubuntu from a LiveUSB, and I think I am ready to install Ubuntu. Note - despite some advice found here, I do have to disable SecureBoot to boot 13.04 from my LiveUSB. From what I have read here, it seems that I should (at least at first) create the partitions from WITHIN Windows 8, not from the LiveUSB, to avoid reported problems. I have run compmgmt.msc and I see the existing partitions. I see the following: Disk 0: 400 MB Recovery; 300 MB EFI System; Acer (C:) 444.95 GB (Boot, Page File, Crash Dump, Primary Partition); 20 GB Recovery Disk 1: 3.74 GB Primary Partition; 14.90 GB Primary Partition I gather I need to create a mounting point '/' Partition (??), a swap partition, and a home partition. Please explain what these are, how big they should be, how I create them from Windows Disk Management, and anything else I need to know. Eventually, I plan to fully replace Windows 8 with Ubuntu, but for now I want to run alongside Windows 8 and not screw things up. I don't have any critical files saved on this computer yet. Thanks.

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• Team Software Development using Ruby on Rails

  - by Panoy

  I used to work alone on small to medium sized programming projects before and have no experience working in a team environment. Currently, there will be 3 of us in an in-house software development team that is tasked to develop a number of software for an academic institution. We have decided to use the web for the majority of the projects and are planning to choose Ruby on Rails for this and I would like to ask for your inputs, advices and approaches with regards to software development as a team using the RoR web framework. One thing that has really confounded me is how you divide the programming tasks of a project if there are 3 of you that are really doing the coding. It’s obvious that we as developers approach a problem in a modular way and finish it one after another. If the project consists of 3 modules, should each one of us focus on each of those modules? Would it be faster that way? How about if the 3 of us would focus on one module first (that’s what I really prefer). Is using a distributed version control system such as Git the answer to this type of problem? Please don’t forget to put your tips and experiences with regards to team software development. Cheers!

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• What's the best way to manage error logging for exceptions?

  - by Peter Boughton

  Introduction If an error occurs on a website or system, it is of course useful to log it, and show the user a polite message with a reference code for the error. And if you have lots of systems, you don't want this information dotted around - it is good to have a single centralised place for it. At the simplest level, all that's needed is an incrementing id and a serialized dump of the error details. (And possibly the "centralised place" being an email inbox.) At the other end of the spectrum is perhaps a fully normalised database that also allows you to press a button and see a graph of errors per day, or identifying what the most common type of error on system X is, whether server A has more database connection errors than server B, and so on. What I'm referring to here is logging code-level errors/exceptions by a remote system - not "human-based" issue tracking, such as done with Jira,Trac,etc. Questions I'm looking for thoughts from developers who have used this type of system, specifically with regards to: What are essential features you couldn't do without? What are good to have features that really save you time? What features might seem a good idea, but aren't actually that useful? For example, I'd say a "show duplicates" function that identifies multiple occurrence of an error (without worrying about 'unimportant' details that might differ) is pretty essential. A button to "create an issue in [Jira/etc] for this error" sounds like a good time-saver. Just to re-iterate, what I'm after is practical experiences from people that have used such systems, preferably backed-up with why a feature is awesome/terrible. (If you're going to theorise anyway, at the very least mark your answer as such.)

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• Rope Colliding with a Rectangle

  - by Colton

  I have my rope, and I have my rectangles. The rope is similar to the implementation found here: http://nehe.gamedev.net/tutorial/rope_physics/17006/ Now, I want to make the rope properly collide with the rectangle such that the rope will not pass through a rectangle, and wrap around the rectangle and all that good stuff. Currently, I have it set so no rope node can pass through a rect (successfully), however, this means a rope segment can still pass through a block. Ex: So the question is, what can I do to fix this? What I have tried: I create a rectangle between two nodes of a rope, calculate rotation between the nodes, and get myself a transformed rectangle. I can successfully detect a collision between rope segments and a (non-transformed) rectangle. Create a new node or pivot point around the corner of the block, and rearrange nodes to point to the corner node. Trouble is determining what corner the rope segment is passing through. And then the current rope setup goes wonky (based on verlet integration, so a sudden change in position causes the rope to wiggle like a seismograph during a magnitude 8 earth quake.) Among other issues that might be solvable, but its turning into a case by case thing, which doesn't seem right. I think the best answer here would just be a link to a tutorial (I simply can't find any, most lead to box2D or farseer, but I want to at least learn how it works before I hide behind an engine).

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• What are some general guidelines for setting up an iOS project I will want to personally publish but sell in the future?

  - by RLH

  I have an idea for a personal iOS project that I would like to write and release to the iOS store. I'm the type of developer who enjoys developing and publishing. I want to write quality software and take care of my customers. Assuming that I wrote an application that had reasonable success, there is a fair chance that I would want to sell the ownership rights of the app to another party and I'd use the proceeds to develop my next personal project which, in turn, I'd probably want to sell in the future. With that said, what are some general guidelines for creating, making and publishing an iOS project that I will eventually want to transfer to another company/developer? I know this is a bit of a broad question, but I request that the given advice be a general list of tips, suggestions and pitfalls to avoid. If any particular bullet point on your list needs more explanation, I'll either search for the answer or post a new question specific to that requirement. Thank you! Note Regarding this Question I am posting this question on Programmers.SO because I think that this is an issue of software architecting, seeking advice for setting a new application project and publishing a project to the Apple iOS store-- all within the requirements for questions on this site.

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• Javascript Canvas Drawing Efficiency

  - by jujumbura

  I have just recently started some experiments with game development in Javascript/HTML5, and so far it has been going pretty well. I have a simple test scene running with some basic input handling, and a hundred-ish drawImage() calls with a few transforms. This all runs great on Chrome, but unfortunately, it already chugs on Firefox. I am using a very large canvas ( 1920 x 1080 ), but it doesn't seem like I should be hitting my limit already. So on that note, I was hoping to ask a few questions: 1) What exactly is done on the CPU vs. the GPU in terms of canvas and drawImage()? I'm afraid the answer is probably "it depends on the browser", but can anybody give me some rules of thumb? I naively imagined that each drawImage call results in a textured quad on the GPU with the canvas effectively being a render target, but I'm wondering if I'm pretty far off base there... 2) I have seen posts here and there with people saying not to use the translate(), rotate(), scale() functions when drawing on the canvas. Am I adding a lot of overhead just by adding a translate() call, as opposed to passing in the x,y to drawImage()? Some people suggest using "transate3d", etc., which are CSS properties, but I'm not sure how to use them within a scene. Can they be used for animated sprites within a single canvas? 3) I have also seen a lot of posts with people mentioning that pre-building canvases and then re-using them is a lot faster than issuing all the individual draw calls again. I am guessing that my background should definitely be pre-built into a canvas, but how far should I take this? Should I maintain an individual canvas for each sprite, to cache all static image data when not animating? Thank you much for your advice!

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• How to understand computer science as a whole?

  - by MrCellophane

  I am a college student in Computer Science, I have been studying CS for a long time. But even till today, I still feel so confused about a lot of things. First of all, I have solid foundation in alg, data structure, and OOP, but I don't have a clear understanding of the whole system of the subject. I studied database, alg, data structure, OOP, network, software engineering, OS, and a lot of courses. I know what they are, but I don't know how to connect them together. Is there a way to have a clear understanding of the architecture of the subject? And is there a way to know what technology is used to do what? For example, in interviews, when people ask me alg, data str, Java, OS or any other specific field, I could answer, but when they ask some other very general about the field, I have no idea. Well, I know my question maybe a little bit confusing, but what my situation is I don't even know how to ask a clear question. I don't know my question, it's totally a mess in my head. Is there a way to make it clear?

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• Building a template engine - starting point

  - by Anirudh

  We're building a Django-based project with a template component. This component will be separate from the project as such and can be Django/Python, Node, Java or whatever works. The template has to be rendered into HTML. The templates will contain references to objects with properties that are defined in the DB, say, a Bus. For eg, it could be something like [object type="vehicle" weight="heavy"] and it would have to pull a random object from the DB fulfilling the criteria : type="vehicle" weight="heavy" (bus/truck/jet) and then substitute that tag with an image, say, of a Bus. Also it would have to be able to handle some processing. Eg: What is [X type="integer" lte="10"] + [Y type="integer" lte="10"] [option X+Y correct_ans="true"] [option X-Y correct_ans="false"] [option X+y+1 correct_ans="false"] The engine would be expected to fill in a random integer value <= 10 for X and Y and show radioboxes for each of the options. Would also have to store the fact that the first option is the correct answer. Does it to make sense to write something from the scratch? Or is it better to use an existing templating system (like Django's own templating system) as a starting point? Any suggestions on how I can approach this?

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• Logic / Render phases with a single thread

  - by DevilWithin

  The question I have may generate different opinions from different developers, but I'd still like to have an answer on this. Its all about the updating and rendering steps of the game loop, and their use under multi and single threaded environments. Currently, there is one thread running, which takes care of sequentially executing events , logic and rendering. Sometimes, the logic part may wish to change the game state to something else, and in between do some loading of files. The result is that the game hangs completely while loading, and then proceeds to normal rendering of the new state. To go around this, i could make another thread, do the loading there while the main thread renders a smooth loading animation, and then proceed normally. The real question is about if i don't create another thread. I could refresh the screen from the logic thread, and provide some basic loading screen, which could be not so smoothly updated while the files load. In fact, this approach is not loved by a lot of developers, as it scrambles render code in the logic step, which may cause problems of different sorts.. Hope its clear!

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• Input/Output console window in XNA

  - by Will Bagley

  I am currently making a simple game in XNA but am at a point where testing various aspect gets a bit tricky, especially when you have to wait till you have 1000 score to see if your animation is playing correctly etc. Of course i could just edit the starting variable in the code before I launched but I have recently been interested in trying to implement a console style window which can print out values and take input to alter public variables during run-time. I am aware that VS has the immediate window which achieves a similar thing but i would prefer mine is an actual part of the game with the intention that the user may have limited access to it in the future. Some of the key things i have yet to find an answer to after looking around for a while are: how i would support free text entry how i would access variables during runtime how i would edit these variable I have also read about using a property grid from windows form aps (and partially reflection) which looked like it could simplify a lot of things but i am not sure how I would get that running inside my XNA game window or how i would get it to not look out of place (as the visual aspect of is seems to be aimed just for development time viewing). All in all I'm quite open to any suggestions on how to approach this task as currently I'm not sure where to start. Thanks in advance.

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• Empty interface to combine multiple interfaces

  - by user1109519

  Suppose you have two interfaces: interface Readable { public void read(); } interface Writable { public void write(); } In some cases the implementing objects can only support one of these but in a lot of cases the implementations will support both interfaces. The people who use the interfaces will have to do something like: // can't write to it without explicit casting Readable myObject = new MyObject(); // can't read from it without explicit casting Writable myObject = new MyObject(); // tight coupling to actual implementation MyObject myObject = new MyObject(); None of these options is terribly convenient, even more so when considering that you want this as a method parameter. One solution would be to declare a wrapping interface: interface TheWholeShabam extends Readable, Writable {} But this has one specific problem: all implementations that support both Readable and Writable have to implement TheWholeShabam if they want to be compatible with people using the interface. Even though it offers nothing apart from the guaranteed presence of both interfaces. Is there a clean solution to this problem or should I go for the wrapper interface? UPDATE It is in fact often necessary to have an object that is both readable and writable so simply seperating the concerns in the arguments is not always a clean solution. UPDATE2 (extracted as answer so it's easier to comment on) UPDATE3 Please beware that the primary usecase for this is not streams (although they too must be supported). Streams make a very specific distinction between input and output and there is a clear separation of responsibilities. Rather, think of something like a bytebuffer where you need one object you can write to and read from, one object that has a very specific state attached to it. These objects exist because they are very useful for some things like asynchronous I/O, encodings,...

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• Make sniqt recognize all tray abilities (or create a working indicator in Qt)

  - by hakermania

  There is this old thread of mine: How do I create a working indicator with Qt/C++? where I was suggested to use the QSystemTray library for making a tray icon in Ubuntu for my application. Sniqt is a program that takes care of the rest. As known, Ubuntu has got rid of tray icons. Instead, it now uses indicators and only indicators. Sniqt converts the Qt tray icons into working indicators. The problem is that it doesn't do a very decent convertion. Actions like single click, middle click etc do not work, while they do in systems that support tray icons. Is there a way to have these actions back? Can I use QSystemTray icon and still have these interesting (and very helpful, in my occasion) actions in Ubuntu? I would be glad to know the answer to the other thread I talked about earlier (how to make a working indicator using the GTK libraries and prevent the crash), as well. Link for Sniqt bug: https://bugs.launchpad.net/sni-qt/+bug/1027652

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• Algorithmic problem - quickly finding all #'s where value %x is some given value

  - by Steve B.

  Problem I'm trying to solve, apologies in advance for the length: Given a large number of stored records, each with a unique (String) field S. I'd like to be able to find through an indexed query all records where Hash(S) % N == K for any arbitrary N, K (e.g. given a million strings, find all strings where HashCode(s) % 17 = 5. Is there some way of memoizing this so that we can quickly answer any question of this form without doing the % on every value? The motivation for this is a system of N distributed nodes, where each record has to be assigned to at least one node. The nodes are numbered 0 - (K-1) , and each node has to load up all of the records that match it's number: If we have 3 nodes Node 0 loads all records where Hash % 3 ==0 Node 1 loads all records where Hash % 3 ==1 Node 2 loads all records where Hash % 3 ==2 adding a 4th node, obviously all the assignments have to be recomputed - Node 0 loads all records where Hash % 4 ==0 ... etc I'd like to easily find these records through an indexed query without having to compute the mod individually. The best I've been able to come up with so far: If we take the prime factors of N (p1 * p2 * ... ) if N % M == I then p % M == I % p for all of N's prime factors e.g. 10 nodes : N % 10 == 6 then N % 2 = 0 == 6 %2 N % 5 = 1 == 6 %5 so storing an array of the "%" of N for the first "reasonable" number of primes for my data set should be helpful. For example in the above example we store the hash and the primes HASH PRIMES (array of %2, %3, %5, %7, ... ]) 16 [0 1 1 2 .. ] so looking for N%10 == 6 is equivalent to looking for all values where array[1]==1 and array[2] == 1. However, this breaks at the first prime larger than the highest number I'm storing in the factor table. Is there a better way?

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• Windows 7 and Ubuntu Boot/Corruption Problems

  - by Kiraisuki

  I searched around, but I couldn't find the answer to why Windows 7 Ultimate 64x and Ubuntu 12.04 LTS 64x could'nt live together happily on my Asus G1s-X1 laptop. I had Windows 7 Ultimate 64x installed on the laptop when I bought it (bought it used, it comes with Vista new) and I wanted to try out Ubuntu and see what all the hype about the free OS was. I installed Ubuntu on an external 80GB iomega HDD with Windows 7 on my main drive. They both work fine for about 2-3 weeks, until Ubuntu suddenly is unable to boot. A few days after Ubuntu fails, Windows corrupts majorly (winload.exe, ntkrnlpa.exe, and various others corrupt randomly) and Windows Recovery Environment is completely useless. Booting to a live USB with Ubuntu and trying to reinstall it fails, and trying to wipe the main drive and install it there fails as well (something about my graphics card.) I managed to get Windows 7 Ultimate 64x back up and running (after many disk formats) but now I am left with a broken (and invisible) Ubuntu installation on the external drive. Is there any way to get the broken and non-bootable Ubuntu installation off the HDD without damaging or erasing the many files and programs installed and stored on the 80GB drive?

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• Friday Tips #6, Part 2

  - by Chris Kawalek

  Here is a question about updating Oracle VM: Question: How can I perform Oracle VM 3 server updates from Oracle VM Manager? Answer by Gregory King, Principal Best Practices Consultant, Oracle VM Product Management: Server Update Manager is a built-in feature of the Oracle VM Manager. Basically, Server Update Manager automatically configures YUM updates on all the Oracle VM Servers, pointing each to our Unbreakable Linux Network (ULN) update channel for Oracle VM. The servers periodically check with our Oracle YUM repository and notify the Oracle VM Manager that an update is available for each server. Actual server updates must be triggered by the Oracle VM administrator – they are not executed automatically. At this point, you can use the Oracle VM Manager to put a server into maintenance mode which live migrates all the running Oracle VM Guests to other Oracle VM Servers in the server pool. Once all the Oracle VM Guests have been migrated, the Oracle VM administrator can trigger the update on the server. The entire process is documented in the Installation and Upgrade Guide of Oracle VM Documentation so I won’t spend time detailing the steps. However, configuring the Server Update Manager is exceedingly simple. Simply navigate to the Tools and Resources tab in the Oracle VM Manager, select the link for Server Update Manager and ensure the following values are added to the text boxes as shown in the illustration below: YUM Base URL: http://public-yum.oracle.com/repo/OracleVM/OVM3/latest/x86_64 YUM GPG Key: file:///etc/pki/rpm-gpg/RPM-GPG-KEY-oracle Every server in the pool will be automatically configured for YUM updates once you choose the Apply button. Many thanks to Greg and Rick for providing the answers to this week's questions. If you want to ask us something, hit up Twitter and use hashtag #AskOracleVirtualization. See you next week! -Chris 

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