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  • Ways to ensure unique instances of a class?

    - by Peanut
    I'm looking for different ways to ensure that each instance of a given class is a uniquely identifiable instance. For example, I have a Name class with the field name. Once I have a Name object with name initialised to John Smith I don't want to be able to instantiate a different Name object also with the name as John Smith, or if instantiation does take place I want a reference to the orginal object to be passed back rather than a new object. I'm aware that one way of doing this is to have a static factory that holds a Map of all the current Name objects and the factory checks that an object with John Smith as the name doesn't already exist before passing back a reference to a Name object. Another way I could think of off the top of my head is having a static Map in the Name class and when the constructor is called throwing an exception if the value passed in for name is already in use in another object, however I'm aware throwing exceptions in a constructor is generally a bad idea. Are there other ways of achieving this?

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  • How is technical debt best measured? What metric(s) are most useful?

    - by throp
    If I wanted to help a customer understand the degree of technical debt in his application, what would be the best metric to use? I've stumbled across Erik Doernenburg's code toxicity, and also Sonar's technical debt plugin, but was wondering what others exist. Ideally, I'd like to say "system A has a score of 100 whereas system B has a score of 50, so system A will most likely be more difficult to maintain than system B". Obviously, I understand that boiling down a complex concepts like "technical debt" or "maintainability" into a single number might be misleading or inaccurate (in some cases), however I need a simple way to convey the to a customer (who is not hands-on in the code) roughly how much technical debt is built into their system (relative to other systems), for the goal of building a case for refactoring/unit tests/etc. Again, I'm looking for one single number/graph/visualization, and not a comprehensive list of violations (e.g. CheckStyle, PMD, etc.).

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  • Do 2D games have a future? [closed]

    - by Griffin
    I'm currently working on a 2D soft-body physics engine (since none exist right now -_-), but I'm worried that there's no point to spending what will most likely be years on it. Although I love working on it, I doubt such an engine would get any income considering anyone willing to pay money for the library will likely to be working in 3D. Do 2D games have any sort of future in the game industry? Should I just drop my engine and find something meaningful to work on? Bonus: I've been trying to think of a unique way to implement my physics engine in a 2d game by looking at games that are multiple dimensions, but still in 2d perspective like Paper Mario. Any ideas?

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  • What are the major challenges in creating a platform such as StackOverflow?

    - by gablin
    Let us assume you were to create a platform such as StackOverflow. It needs to be functional, fast and scalable, just like SO, in order to be successful. What are the major challenges you would face in such a task? I'm looking for technical challenges rather than problems such as how to advertise it and stuff like that. (I'm not looking for ways of creating a new site to challenge SO; I'm just interested in how difficult it would be to create it if it didn't already exist.)

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  • Why is there only one configuration management tool in the main repository?

    - by David
    How is it that Cfengine does not exist in the Ubuntu (10.04 LTS) Main Repository? I can't find a discussion of this anywhere (using Google). The only configuration management in Ubuntu Main seems to be Puppet. I looked for a wide variety of others as well - all from Wikipedia's list of configuration management tools - and none of them are present in Ubuntu main. I looked for bcfg2, opensymbolic, radmind, smartfrog, spacewalk, staf, synctool, chef - none are present. From my vantage point as a system administrator, I would have expected to find at least bcfg2, puppet, cfengine, and chef (as the most widely used tools). Why is cfengine (or chef and others) not included in Ubuntu main? Why is there only one configuration management tool in Ubuntu main? By the way - the reason this is important in the context of server administration is because Ubuntu main is fully supported by the Ubuntu team with updates and security updates; the other repositories are not.

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  • Messaging technologies between applications ?

    - by Samuel
    Recently, I had to create a program to send messages between two winforms executable. I used a tool with simple built-in functionalities to prevent having to figure out all the ins and outs of this vast quantity of protocols that exist. But now, I'm ready to learn more about the internals difference between each of theses protocols. I googled a couple of them but it would be greatly appreciate to have a good reference book that gives me a clean idea of how each protocol works and what are the pros and cons in a couple of context. Here is a list of nice protocols that I found: Shared memory TCP List item Named Pipe File Mapping Mailslots MSMQ (Microsoft Queue Solution) WCF I know that all of these protocols are not specific to a language, it would be nice if example could be in .net. Thank you very much.

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  • Google Webmaster Tools is showing duplicate URLs based on page title differences

    - by Praveen Reddy
    I have 700+ title tag duplicates showing in WMT. Every first link in that picture is as duplicate link of second one. I don't know from where the first link got indexed by Google when that link doesn't exist in the site. It's showing the title of every page as link. Original link: http://www.sitename.com/job/407/Swedish-plus-Any-other-Nordic-Language-Customer-Service-Representative-Dublin-Ireland. Duplicate link: http://www.sitename.com/job/407/Swedish-plus-Any-other-Nordic-Language-Customer-Service-Representative-Dublin-Ireland-Ireland. How can this happen? I have checked entire site I didn't find where the second version is linked. I have no images linked to with duplicated version of URL.

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  • Changes to keyboard layout resetted on restart

    - by Matthieu Napoli
    I edited /usr/share/X11/xkb/symbols/fr to customize the french-dvorak layout. I then selected french-dvorak layout (instead of french). Now when I restart Ubuntu, I end up with the non-edited french-dvorak (my changes are ignored). But if I switch to french, then back to french-dvorak, my changes are now taken into account... How can I have my custom french-dvorak on startup? Is there some sort of cached version of the keyboard layout? I don't understand how it can switch me to the official french-dvorak because I changed it, so it should no longer exist.

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  • Problem with the installation of VirtualBox

    - by Antonis Grigoriadis
    I am trying to install virtualbox and make it work but it doesn't seem I can. In the image you can seem the output. If I run VBoxManage --version I get: WARNING: The character device /dev/vboxdrv does not exist. Please install the virtualbox-dkms package and the appropriate headers, most likely linux-headers-generic. You will not be able to start VMs until this problem is fixed. 4.3.10_Ubuntur93012 But virtualbox-dkms is already installed and at the latest version. So I tried to reinstall it and i got this: Any help will be appreciated. EDIT: The output after reconfigure (@M.Tarun suggestion): EDIT 2: Also installed the sources as @Hmayag instructed, purged virtualbox and installed it again but I got the same problem.

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  • How to code a 4x shader/filter which emulates arcade crt display behavior?

    - by Arthur Wulf White
    I want to write a shader/filer probably in adobe Pixel Bender that will do the best job possible in emulating the fill of an oldskul monochromatic arcade CRT screen. Much like this here: http://filthypants.blogspot.com/2012/07/customizing-cgwgs-crt-pixel-shader.html Here are some attributes I know will exist in this filter: It will take in a low res image 160 x 120 and return a medium res image 640 x 480. It will add scanlines It will blur the color channels to create that color bleeding effect It will distort the shape of the image from a perfect rectangle into a rounder shape. The question is, could you please provide any other attributes that are beneficial to emulating an arcade CRT feel and links and resources on coding these effects. Thanks

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  • Experiments in Wackiness: Allowing percents, angle-brackets, and other naughty things in the ASP.NET

    - by The Official Microsoft IIS Site
    Just because you CAN do something doesn't mean you SHOULD. However, it's always nice to do something crazy so that you can better understand a system. Warning: There is no warranty implied here. I'm loading the gun and showing you where to point it. If you point it at your foot, that's your business. Safety mechanisms exist for a reason and if you're going to to use this tip to just "get an app to work" but you're not sure why it's broken and you're just...(read more)

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  • Need advice on design in Ruby On Rails

    - by Elad
    For personal educational purposes I am making a site for a conference. One of the object that exist in a conference is a session, which has different states and in each state it has slightly different attributes: When submitted it has a speaker (User in the system), Title and abstract. When under review it has reviews and comments (in addition to the basic data) When accepted it has a defined time-slot but no reviewers anymore. I feel that it is not the best thing to add a "status" attributes and start adding many if statements... So I thought it would be better to have different classes for each state each with it's own validations and behaviors. What do you think about this design? Do you have a better idea? *I must add this out of frustration: I had several edits of the question, including one major change but no one actually gave any hint or clue on which direction should i take or where is a better place to ask this... Hardly helpful.

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  • How do I create a permanent Bash alias?

    - by Bakhtiyor
    I would like to create an alias to rm command in order to have a confirmation message after executing this command. So I am creating an alias like this alias rm='rm -i'. But as far as I know this is a temporary alias and it lives until you close the terminal. As it is explained here to save alias permanently I need to execute ~/.bash_aliases or ~/.bashrc commands in terminal and add my alias there. But when I execute ~/.bashrc I get following error message : bash: /home/bakhtiyor/.bashrc: Permission denied When I run ~/.bash_aliases I get another error message like this: bash: /home/bakhtiyor/.bash_aliases: File or directory doesn't exist. What is the actual problem and how can I solve it?

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  • Create bootable USB install image from command line?

    - by j-g-faustus
    I'm trying to create a bootable USB image to install Ubuntu on a new computer. I have done this before following the "create USB drive" instructions for Ubuntu desktop, but I don't have an Ubuntu desktop available. How can I do the same using only the command line? Things I've tried: Create bootable USB on Mac OS X following the ubuntu.com "create USB drive" instructions for Mac: Doesn't boot. usb-creator: According to apt-cache search usb-creator and Wikipedia usb-creator only exists as a graphical tool. "Create manually" instructions at help.ubuntu.com: None of the files and directories described (e.g. casper, filesystem.manifest, menu.lst) exist in the ISO image, and I don't know what has replaced them. (At my disposal is Mac OS X and Ubuntu server; I have neither Ubuntu desktop nor Windows.)

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  • Create .deb form gambas2 project

    - by Mauricio Andrés
    I have been working with Gambas 2 (the one in the software center), Actially I took the source code of other program and create a new program basen on that. But now that I finished, I can't create .deb files, gambas show me this error: La creación del paquete ha fallado. Package.MakeDebPackage.368: File or directory does not exist So I dont know what to do now, I really need this program. I tried with Gambas 3, but is too much work to do that the program based in Gmabas 2 works in Gambas 3, also I tried creating a .deb package and gambas get frozen. Please some help

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  • Grub bootloader goes fail to boot in dual boot system after installing Ubuntu 12.10

    - by K.K Patel
    I had 12.04 with my dual boot system. Yesterday I downloaded Ubuntu 12.10 make bootable USB and choose Upgrade option in Installer. After installation Grub failed to boot my machine. I tried following to fix grub bootloder . Same problem I fixed with Ubuntu 12.04 using live USB but this solution not work for Ubuntu 12.10. Now coming at exactly where this solution goes fail. I followed this steps after booting Live USB and opening terminal. 1) sudo fdisk -l to see where Linux is installed 2) sudo mount /dev/sda9 /mnt where sda9 is my linux partition 3) sudo mount /dev/sda9 /mnt/boot 4) sudo mount --bind /dev /mnt/dev 5) sudo chroot /mnt (No problems with this steps done perfectly) 6) grub-install /dev/sda when I type command I got error that source_dir doesn't exist Please specify --target or --directory How can I solve this ?

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  • How can I make QSSTV recognise my sound device

    - by hellocatfood
    After reading this article from Instructables I wanted to try it out in Ubuntu. Luckily QSSTV is available but I'm having problems getting it to work properly. When pressing the green light (to receive data) I get this error: After going to Options Configure Interfaces I discovered that it's attempting to use /dev/dsp which doesn't appear to exist. In my /dev folder there are no files that reference sound devices and I've tried all of the devices in /dev/snd but unfortunately none of them work. Is there a specific audio device that I should be linking to?

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  • Methods of learning / teaching programming

    - by Mark Avenius
    When I was in school, I had a difficult time getting into programming because of a catch-22 in the learning process: I didn't know how to write anything because I didn't know what keywords and commands meant. For example (as a student, I would think), "what does this using namespace std; thing do anyway? I didn't know what keywords and commands meant because I hadn't written anything. This basically led me to spending countless long night cursing the compiler as I made minor tweaks to my assignments until they would compile (and hopefully perform whatever operation they were supposed to). Is there a teaching/learning method that anyone uses that gets around this catch-22? I am trying to make this non-argumentative, which is why I don't want to know the 'best' method, but rather which methods exist.

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  • Optical Illusion Freezes Water In Place [Video]

    - by Jason Fitzpatrick
    This clever optical illusion uses sound frequency and a digital camera to “freeze” water in time and space. YouTube user MrBibio explains the hack: Creating the illusion of a static flow of water using sound. Of course this isn’t my idea and plenty more refined examples already exist. I tried this same experiment years ago but using a strobe light, but it’s harsh on the eyes after a while and hard to video successfully. It only dawned on me shortly before making this that for video purposes, no strobe light is required. This is because the frame rate and shutter of the camera is doing a similar job to the strobe. The speaker-as-frequency-generator model is definitely easier on the eyes than similar experiments that rely on high-speed strobes. How to Stress Test the Hard Drives in Your PC or Server How To Customize Your Android Lock Screen with WidgetLocker The Best Free Portable Apps for Your Flash Drive Toolkit

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  • SPRoleAssignment Crazy Caviats

    - by MOSSLover
    I’m not sure if this bug exists on any other environment, but here are a few issues I ran into when trying to use SPRoleAssignment and SPGroup: When trying to use Web.Groups[“GroupName”] it basically told me the group did not exist, so I had to change the code to use Web.SiteGroups[“GroupName”]. I could not add the Role Assignment to the Web and run a Web.Update() without adding an additional Web.AllowUnsafeUpdates= true; , however on my virtual machine I could do a Web.Update() without the extra piece of code.  I kept receiving an error in my browser stating that I should hit the back button and update my permissions. So after fixing those two issues I was able to copy the permissions from a page item into a Site for my migration.  Hopefully, one of you can learn from my error messages if you have any issues in the future. Technorati Tags: SPRoleAssignment,MOSS,SPGroup

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  • Extending Blend for Visual Studio 2013

    - by Chris Skardon
    Originally posted on: http://geekswithblogs.net/cskardon/archive/2013/11/01/extending-blend-for-visual-studio-2013.aspxSo, I got a comment yesterday on my post about Extending Blend 4 and Blend for Visual Studio 2012 asking if I knew how to get it working for Blend for Visual Studio 2013.. My initial thoughts were, just change the location to get the blend dlls from Visual Studio 11.0 to 12.0 and you’re all set, so I went to do that, only to discover that the dlls I normally reference, well – they don’t exist. So… I’ve made a presumption that the actual process of using MEF etc is still the same. I was wrong. So, the route to discovery – required DotPeek and opening a few of blends dlls.. Browsing through the Blend install directory (./Microsoft Visual Studio 12.0/Blend/) I notice the .addin files: So I decide to peek into the SketchFlow dll, then promptly remember SketchFlow is quite a big thing, and hunting through there is not ideal, luckily there is another dll using an .addin file, ‘Microsoft.Expression.Importers.Host’, so we’ll go for that instead. We can see it’s still using the ‘IPackage’ formula, but where is that sucker? Well, we just press F12 on the ‘IPackage’ bit and DotPeek takes us there, with a very handy comment at the top: // Type: Microsoft.Expression.Framework.IPackage // Assembly: Microsoft.Expression.Framework, Version=12.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a // MVID: E092EA54-4941-463C-BD74-283FD36478E2 // Assembly location: C:\Program Files (x86)\Microsoft Visual Studio 12.0\Blend\Microsoft.Expression.Framework.dll Now we know where the IPackage interface is defined, so let’s just try writing a control. Last time I did a separate dll for the control, this time I’m not, but it still works if you want to do it that way. Let’s build a control! STEP 1 Create a new WPF application Naming doesn’t matter any more! I have gone with ‘Hello2013’ (see what I did there?) STEP 2 Delete: App.Config App.xaml MainWindow.xaml We won’t be needing them STEP 3 Change your application to be a Class Library instead. (You might also want to delete the ‘vshost’ stuff in your output directory now, as they only exist for hosting the WPF app, and just cause clutter) STEP 4 Add a reference to the ‘Microsoft.Expression.Framework.dll’ (which you can find in ‘C:\Program Files\Microsoft Visual Studio 12.0\Blend’ – that’s Program Files (x86) if you’re on an x64 machine!). STEP 5 Add a User Control, I’m going with ‘Hello2013Control’, and following from last time, it’s just a TextBlock in a Grid: <UserControl x:Class="Hello2013.Hello2013Control" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="300"> <Grid> <TextBlock>Hello Blend for VS 2013</TextBlock> </Grid> </UserControl> STEP 6 Add a class to load the package – I’ve called it – yes you guessed – Hello2013Package, which will look like this: namespace Hello2013 { using Microsoft.Expression.Framework; using Microsoft.Expression.Framework.UserInterface; public class Hello2013Package : IPackage { private Hello2013Control _hello2013Control; private IWindowService _windowService; public void Load(IServices services) { _windowService = services.GetService<IWindowService>(); Initialize(); } private void Initialize() { _hello2013Control = new Hello2013Control(); if (_windowService.PaletteRegistry["HelloPanel"] == null) _windowService.RegisterPalette("HelloPanel", _hello2013Control, "Hello Window"); } public void Unload(){} } } You might note that compared to the 2012 version we’re no longer [Exporting(typeof(IPackage))]. The file you create in STEP 7 covers this for us. STEP 7 Add a new file called: ‘<PROJECT_OUTPUT_NAME>.addin’ – in reality you can call it anything and it’ll still read it in just fine, it’s just nicer if it all matches up, so I have ‘Hello2013.addin’. Content wise, we need to have: <?xml version="1.0" encoding="utf-8"?> <AddIn AssemblyFile="Hello2013.dll" /> obviously, replacing ‘Hello2013.dll’ with whatever your dll is called. STEP 8 We set the ‘addin’ file to be copied to the output directory: STEP 9 Build! STEP 10 Go to your output directory (./bin/debug) and copy the 3 files (Hello2013.dll, Hello2013.pdb, Hello2013.addin) and then paste into the ‘Addins’ folder in your Blend directory (C:\Program Files\Microsoft Visual Studio 12.0\Blend\Addins) STEP 11 Start Blend for Visual Studio 2013 STEP 12 Go to the ‘Window’ menu and select ‘Hello Window’ STEP 13 Marvel at your new control! Feel free to email me / comment with any problems!

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  • It is possible to hibernate an LXC container?

    - by Jo-Erlend Schinstad
    I know about lxc-freeze and lxc-unfreeze, but as I understand it, these simply pauses the container, similar to sending SIGSTOP and SIGCONT to a process. If I reboot the host, then the containers will cease to exist, right? I would really like a way to save state to persistent storage so that I could resume them at some later time, even the host is rebooted or something like that. I can achieve exactly what I want using VirtualBox by using the "Save machine state" mechanism, but if I could do it with LXC, it would be completely awesome.

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  • Homemaking a 2d soft body physics engine

    - by Griffin
    hey so I've decided to Code my own 2D soft-body physics engine in C++ since apparently none exist and I'm starting only with a general idea/understanding on how physics work and could be simulated: by giving points and connections between points properties such as elasticity, density, mass, shape retention, friction, stickiness, etc. What I want is a starting point: resources and helpful examples/sites that could give me the specifics needed to actually make this such as equations and required physics knowledge. It would be great if anyone out there also would give me their attempts or ideas. finally I was wondering if it was possible to... use the source code of an existing 3D engine such as Bullet and transform it to be 2D based? use the source code of a 2D Rigid body physics engine such as box2d as a starting point?

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  • Is the slow performance of programming languages a bad thing?

    - by Emanuil
    Here's how I see it. There's machine code and it's all that the computers needs in order to run something. The computers don't care about programming languages. It doesn't matter to them if the machine code comes from Perl, Python or PHP. Programming languages exist to serve programmers. Some programming languages run slower than others but that's not necessarily because there is something wrong with them. In many cases it's just because they do more things that otherwise programmers would have to do and by doing these things, they do better what they are supposed to do - serve programmers. So is the slower performance (at runtime) of a programming language really a bad thing?

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  • Stop bots from crawling old links with extensions

    - by Jared
    I've recently switched to MVC3 which is extension-less for the URL's, but Google and Bing have a wealth of links that they are crawling which no longer exist. So I'm trying to find out if there is a way to format robots.txt (or by some other method) to tell google/bing that any link that ends in an extension isn't a valid link... Is this possible? On pages that I'm concerned about a User having saved as a fav I'm displaying a 404 page that lists the links to take once they are redirected to the new page (I decided to not just redirect them as I don't want to maintain these forever). For Google/Bing sake I do have the canonical tag in the header. User-agent: * Allow: / Disallow: /*.* EDIT: I just added the 3rd line (in text above) and it APPEARS to do what I'm wanting. Allow a path, but disallow a file. Can anyone confirm this?

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