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  • Modifying RaspberryPi as perfect linux box [on hold]

    - by Jai Hind Rubik's
    I have just bought one Raspberry pi RaspberryPi. I want to load linux kernel there. Actually my plan is to first load kernel ver sion 2.6.* after that one 3.10.* above that and in boot time I want to load 3.10.* (can choose). just after booting, I want to log in there through my windows machine using client like putty or telnet, on telnet I want see following prompt there: login as: root [email protected]'s password: ********** Last login: Thu Aug 21 22:41:07 2014 from 10.78.235.82 [root@debd ~]# [root@debd ~]#ls [root@debd ~]# Documents ... Can any one tell what kind of modification I needed to do for this? I am college student and have less knowledge managing hardware

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  • Visual Studio 2010: Fun with extensions

    - by BizTalk Visionary
    One of the powerful things that has come into Visual Studio over the last few years has been joy of extensions. With 2010 there seems to be even more!! Of course teaching old dogs like myself new tricks always takes time but interestingly enough some of the rules I learnt early in my working life over 30 years ago still hold true!! A derivation of one that was knocked into during my engineering apprenticeship and associated exams was RTFQ! Read the ‘flippin’ question. (I replaced the original ‘F’ with a more palatable version here!). Today I forgot that rule and didn’t RTFI (I being instructions) and spent a fruitless hour wondering why my Entity Framework POCO generator never appeared in the new project template list when I wanted to add it!! It was simple of course – I had only installed the Entity Framework POCO generator for web sites and not building a web project meant it would never appear!!! A quick look again I found the ‘other’ extension that supported my project type! So RTFI!!

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  • how do we clear new programming concept

    - by Sarang
    In IT world, new latest technologies are generated daily. Every time, every programmer need to learn something & then clear it conceptually to implement. All new technologies are built on some basic concepts. But, these technologies have their own area of development & a developer is supposed to grasp it from very basic. This seems like starting from very beginning to reach till current. What is the best & fast way to learn and grasp a new developed technology ?

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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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  • Use your own domain email and tired of SPAM? SPAMfighter FTW

    - by Dave Campbell
    I wouldn't post this if I hadn't tried it... and I paid for it myself, so don't anybody be thinking I'm reviewing something someone sent me! Long ago and far away I got very tired of local ISPs and 2nd phone lines and took the plunge and got hooked up to cable... yeah I know the 2nd phone line concept may be hard for everyone to understand, but that's how it was in 'the old days'. To avoid having to change email addresses all the time, I decided to buy a domain name, get minimal hosting, and use that for all email into the house. That way if I changed providers, all the email addresses wouldn't have to change. Of course, about a dozen domains later, I have LOTS of pop email addresses and even an exchange address to my client's server... times have changed. What also has changed is the fact that we get SPAM... 'back in the day' when I was a beta tester for the first ISP in Phoenix, someone tried sending an ad to all of us, and what he got in return for his trouble was a bunch of core dumps that locked up his email... if you don't know what a core dump is, ask your grandfather. But in today's world, we're all much more civilized than that, and as with many things, the criminals seem to have much more rights than we do, so we get inundated with email offering all sorts of wild schemes that you'd have to be brain-dead to accept, but yet... if people weren't accepting them, they'd stop sending them. I keep hoping that survival of the smartest would weed out the mental midgets that respond and then the jumk email stop, but that hasn't happened yet anymore than finding high-quality hearing aids at the checkout line of Safeway because of all the dimwits playing music too loud inside their car... but that's another whole topic and I digress. So what's the solution for all the spam? And I mean *all*... on that old personal email address, I am now getting over 150 spam messages a day! Yes I know that's why God invented the delete key, but I took it on as a challenge, and it's a matter of principle... why should I switch email addresses, or convert from [email protected] to something else, or have all my email filtered through some service just because some A-Hole somewhere has a site up trying to phish Ma & Pa Kettle (ask your grandfather about that too) out of their retirement money? Well... I got an email from my cousin the other day while I was writing yet another email rule, and there was a banner on the bottom of his email that said he was protected by SPAMfighter. SPAMfighter huh.... so I took a look at their site, and found yet one more of the supposed tools to help us. But... I read that they're a Microsoft Gold Partner... and that doesn't come lightly... so I took a gamble and here's what I found: I installed it, and had to do a couple things: 1) SPAMfighter stuffed the SPAMfighter folder into my client's exchange address... I deleted it, made a new SPAMfighter folder where I wanted it to go, then in the SPAMfighter Clients settings for Outlook, I told it to put all spam there. 2) It didn't seem to be doing anything. There's a ribbon button that you can select "Block", and I did that, wondering if I was 'training' it, but it wasn't picking up duplicates 3) I sent email to support, and wrote a post on the forum (not to self: reply to that post). By the time the folks from the home office responded, it was the next day, and first up, SPAMfighter knocked down everything that came through when Outlook opend... two thumbs up! I disabled my 'garbage collection' rule from Outlook, and told Outlook not to use the junk folder thinking it was interfering. 4) Day 2 seemed to go about like Day 1... but I hung in there. 5) Day 3 is now a whole new day... I had left Outlook open and hadn't looked at the PC since sometime late yesterday afternoon, and when I looked this morning, *every bit* of spam was in the SPAMfighter folder!! I'm a new paying customer After watching SPAMfighter work this morning, I've purchased a 1-year license, and I now can sit and watch as emails come in and disappear from my inbox into the SPAMfighter folder. No more continual tweaking of the rules. I've got SPAMfighter set to 'Very Hard' filtering... personally I'd rather pull the few real emails out of the SPAMfighter folder than pull spam out of the real folders. Yes this is simply another way of using the delete key, but you know what? ... it feels good :) Here's a screenshot of the stats after just about 48 hours of being onboard: Note that all the ones blocked by me were during Day 1 and 2... I've blocked none today, and everything is blocked. Stay in the 'Light!

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  • Edit menu permission issue

    - by user3541568
    i'm an Lubuntu user, but i suppose it concerns everyone. For menu editing there are 3 GUIs: lxmed, menulibre, alacarte. great! Still the ISSUE is that if i start as administrator, for example: gram@gram-pc:~$ alacarte will edit menu, till the time i close app. it doesn't have permission for that... so nothing in menu has been changed... gram@gram-pc:~$ gksudo alacarte or root@gram-pc:/# alacarte will open completely different menu with completely different items... how can i grand permission to edit my-not-root-menu?

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  • Artist, Looking to lean how to program games, where do I start? [on hold]

    - by Christopher Hindson
    I have bean an artist for many years now I am very comfortable with using Photoshop and Flash but I want to learn how to but together my own games, I bean doing my own research into this and at the moment I am at little bit stuck on witch direction to go down. So my question is witch programming language should I learn? I have already bean looking into this what i understand is that Gamemaker with its built in language (GML) is one of the most friendly to people who are new to the game making world. I have played around with this program and was pretty happy with it but I want more also you can use Unity with language such as C and javascript and then games built with Java witch looks interesting. One more thing before you send your answer in at this moment in time I would only be able to make 2D game but 3D isn't out of the picture.

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  • Where did my hard drive go?

    - by Mike Carron
    I installed XBMCbuntu 11.0 to my Zotac Zbox AD03 with an OCZ Reflex 4 256gb SSK. The install worked fine and I was getting accustomed to the appearance and operation. When I attempted to boot from power-off the BIOS could no longer find the SSD. It refused to boot and when I checked in the BIOS, the SSD was missing from the boot list (it was there prior to the install). I rebooted from the install CD but when the system started it could not find the SSD. I replaced the SSD with a fresh one of the same type and reinstalled XBMCbuntu. This time I rebooted from the system several times successfully but when I shut it down and tried to cold boot, this drive was also gone. Does the installation do something strange to the boot record that could cause a BIOS to lose it? How do I fix this? mike

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  • AndEngine Sprite position

    - by Kirill Kulakov
    I had noticed the AndEngine a few days ago, and I tried to create basic game with a few Sprites.Sure, the engine makes the development process much more easier.However I found the sprite lacking a major functionally: Whenever there is a need to refer to the position of an Sprite the engine manipulates the position based on the top-left corner of sprite,this is not the best thing because there is a need to subtract/add the width/height to its position in order to refer to its center.However when we refer to he scale of the Sprite it scaled according to its center point (which is great) I find it very confusing to refer to its position each time differently.I solved that by extending the Sprite class and implementing my methods of setCenter and getCenter, I guess that not the best way to do so. Do you have any suggestion?

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  • Oracle Fusion CRM and Lotus Notes Integration by iEnterprises

    - by Richard Lefebvre
    Integrate Oracle Fusion CRM and Lotus Notes in one easy step with nothing to install other than a 'plugin' for your Lotus Notes client. The Lotus Notes Connector for Oracle Fusion CRM developed by iEnterprises is an easy to use tool that allows you to instantly synchronize your Lotus Notes email, calendar, ToDos and PAB (Personal Address Book) to and from your Oracle Fusion CRM system. It removes the need for time consuming copy and paste between these two systems. For more information, a solution data-sheet and/or to request a trial please visit .... http://www.ienterprises.com/products/lotus-notes-connector/connector-for-fusion.html or contact Matt Hatherley ([email protected])

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  • Continuously asking for partial upgrade

    - by udinnet
    I just upgraded my Ubuntu 11.10 to 12.04 after the announcement of the final release of Ubuntu 12.04. The upgrade process went fine. But now when I run the update manager it asks for a partial upgrade. But the funny thing is it installs 84 new packages in installation step, remove all the 84 packages in the cleaning step!!! This is happening recursively(Every time I launch the update manager). Please can you suggest something? Logs can be found in the launchpad bug page. https://bugs.launchpad.net/ubuntu/+source/update-manager/+bug/990449

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  • When will my old page stop appearing on Google?

    - by Bane
    I recently bought a new address for my Blogger blog, from yannbane.blogspot.com to www.yannbane.com. However, www.yannbane.com addresses do not appear when they are searched for! Is this natural? How much time will it take for Google to update its index? yannbane.blogspot.com 301's to www.yannbane.com. Both are added to my Webmaster Tools account, but it shows no data for www.yannbane.com (strangely). And, finally, is there something I could do to speed up the process?

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  • Why should I adopt MVC?

    - by Andrew
    I decided to get my hands wet and got the YII framework for PHP. I created my first application, then created new controller, model and view. Connected to database, got my record passed from controller to the view and printed the hello world. I am confused now. If I have to do the same thing for each page, this seems like a nightmare to me. In each controller I have to do a lot of same operations - declare variables, and pass them to views. I also need to create models for each page and this is all confusing to me. In my idea the main goal of development is to avoid duplication, but what I see here is lots and lots of duplicated code. Please advise and clarify. Maybe you could suggest a good reading about MVC and coding patterns and best practices in MVC. Because so far, it takes much more time to create a small site using MVC than using my own programming schema.

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  • Silverlight 4 Twitter Client - Part 2

    - by Max
    We will create a few classes now to help us with storing and retrieving user credentials, so that we don't ask for it every time we want to speak with Twitter for getting some information. Now the class to sorting out the credentials. We will have this class as a static so as to ensure one instance of the same. This class is mainly going to include a getter setter for username and password, a method to check if the user if logged in and another one to log out the user. You can get the code here. Now let us create another class to facilitate easy retrieval from twitter xml format results for any queries we make. This basically involves just creating a getter setter for all the values that you would like to retrieve from the xml document returned. You can get the format of the xml document from here. Here is what I've in my Status.cs data structure class. using System; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Ink; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes;  namespace MaxTwitter.Classes { public class Status { public Status() {} public string ID { get; set; } public string Text { get; set; } public string Source { get; set; } public string UserID { get; set; } public string UserName { get; set; } } }  Now let us looking into implementing the Login.xaml.cs, first thing here is if the user is already logged in, we need to redirect the user to the homepage, this we can accomplish using the event OnNavigatedTo, which is fired when the user navigates to this particular Login page. Here you utilize the navigate to method of NavigationService to goto a different page if the user is already logged in. if (GlobalVariable.isLoggedin())         this.NavigationService.Navigate(new Uri("/Home", UriKind.Relative));  On the submit button click event, add the new event handler, which would save the perform the WebClient request and download the results as xml string. WebRequest.RegisterPrefix("https://", System.Net.Browser.WebRequestCreator.ClientHttp);  The following line allows us to create a web client to create a web request to a url and get back the string response. Something that came as a great news with SL 4 for many SL developers.   WebClient myService = new WebClient(); myService.AllowReadStreamBuffering = true; myService.UseDefaultCredentials = false; myService.Credentials = new NetworkCredential(TwitterUsername.Text, TwitterPassword.Password);  Here in the following line, we add an event that has to be fired once the xml string has been downloaded. Here you can do all your XLINQ stuff.   myService.DownloadStringCompleted += new DownloadStringCompletedEventHandler(TimelineRequestCompleted);   myService.DownloadStringAsync(new Uri("https://twitter.com/statuses/friends_timeline.xml"));  Now let us look at implementing the TimelineRequestCompleted event. Here we are not actually using the string response we get from twitter, I just use it to ensure the user is authenticated successfully and then save the credentials and redirect to home page. public void TimelineRequestCompleted(object sender, System.Net.DownloadStringCompletedEventArgs e) { if (e.Error != null) { MessageBox.Show("This application must be installed first"); }  If there is no error, we can save the credentials to reuse it later.   else { GlobalVariable.saveCredentials(TwitterUsername.Text, TwitterPassword.Password); this.NavigationService.Navigate(new System.Uri("/Home", UriKind.Relative)); } } Ok so now login page is done. Now the main thing – running this application. This credentials stuff would only work, if the application is run out of the browser. So we need fiddle with a few Silverlioght project settings to enable this. Here is how:    Right click on Silverlight > properties then check the "Enable running application out of browser".    Then click on Out-Of-Browser settings and check "Require elevated trust…" option. That's it, all done to run. Now press F5 to run the application, fix the errors if any. Then once the application opens up in browser with the login page, right click and choose install.  Once you install, it would automatically run and you can login and can see that you are redirected to the Home page. Here are the files that are related to this posts. We will look at implementing the Home page, etc… in the next post. Please post your comments and feedbacks; it would greatly help me in improving my posts!  Thanks for your time, catch you soon.

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  • How can I deal with actor translations and other "noise" in third-party motion capture data?

    - by Charles
    I'm working on a game, and I've run into a problem with motion capture data. My team is using 3DS Max 2011 and trying to put free motion capture files on our models. The problem we're having is it has become extremely hard to find motion capture data that stays in place. We've found some great motion captures of things like walking and jumping but the actors themselves move within the data, so when we attach these animations to our models and bring them into XNA, the models walk forward even when they should technically be standing still (and then there's also the problem of them resetting at the end of the animation). How can we clean up, at runtime or asset-processing time, the animation in these motion capture files?

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  • CPU Usage in Very Large Coherence Clusters

    - by jpurdy
    When sizing Coherence installations, one of the complicating factors is that these installations (by their very nature) tend to be application-specific, with some being large, memory-intensive caches, with others acting as I/O-intensive transaction-processing platforms, and still others performing CPU-intensive calculations across the data grid. Regardless of the primary resource requirements, Coherence sizing calculations are inherently empirical, in that there are so many permutations that a simple spreadsheet approach to sizing is rarely optimal (though it can provide a good starting estimate). So we typically recommend measuring actual resource usage (primarily CPU cycles, network bandwidth and memory) at a given load, and then extrapolating from those measurements. Of course there may be multiple types of load, and these may have varying degrees of correlation -- for example, an increased request rate may drive up the number of objects "pinned" in memory at any point, but the increase may be less than linear if those objects are naturally shared by concurrent requests. But for most reasonably-designed applications, a linear resource model will be reasonably accurate for most levels of scale. However, at extreme scale, sizing becomes a bit more complicated as certain cluster management operations -- while very infrequent -- become increasingly critical. This is because certain operations do not naturally tend to scale out. In a small cluster, sizing is primarily driven by the request rate, required cache size, or other application-driven metrics. In larger clusters (e.g. those with hundreds of cluster members), certain infrastructure tasks become intensive, in particular those related to members joining and leaving the cluster, such as introducing new cluster members to the rest of the cluster, or publishing the location of partitions during rebalancing. These tasks have a strong tendency to require all updates to be routed via a single member for the sake of cluster stability and data integrity. Fortunately that member is dynamically assigned in Coherence, so it is not a single point of failure, but it may still become a single point of bottleneck (until the cluster finishes its reconfiguration, at which point this member will have a similar load to the rest of the members). The most common cause of scaling issues in large clusters is disabling multicast (by configuring well-known addresses, aka WKA). This obviously impacts network usage, but it also has a large impact on CPU usage, primarily since the senior member must directly communicate certain messages with every other cluster member, and this communication requires significant CPU time. In particular, the need to notify the rest of the cluster about membership changes and corresponding partition reassignments adds stress to the senior member. Given that portions of the network stack may tend to be single-threaded (both in Coherence and the underlying OS), this may be even more problematic on servers with poor single-threaded performance. As a result of this, some extremely large clusters may be configured with a smaller number of partitions than ideal. This results in the size of each partition being increased. When a cache server fails, the other servers will use their fractional backups to recover the state of that server (and take over responsibility for their backed-up portion of that state). The finest granularity of this recovery is a single partition, and the single service thread can not accept new requests during this recovery. Ordinarily, recovery is practically instantaneous (it is roughly equivalent to the time required to iterate over a set of backup backing map entries and move them to the primary backing map in the same JVM). But certain factors can increase this duration drastically (to several seconds): large partitions, sufficiently slow single-threaded CPU performance, many or expensive indexes to rebuild, etc. The solution of course is to mitigate each of those factors but in many cases this may be challenging. Larger clusters also lead to the temptation to place more load on the available hardware resources, spreading CPU resources thin. As an example, while we've long been aware of how garbage collection can cause significant pauses, it usually isn't viewed as a major consumer of CPU (in terms of overall system throughput). Typically, the use of a concurrent collector allows greater responsiveness by minimizing pause times, at the cost of reducing system throughput. However, at a recent engagement, we were forced to turn off the concurrent collector and use a traditional parallel "stop the world" collector to reduce CPU usage to an acceptable level. In summary, there are some less obvious factors that may result in excessive CPU consumption in a larger cluster, so it is even more critical to test at full scale, even though allocating sufficient hardware may often be much more difficult for these large clusters.

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  • What can I put in my software development blog to make it a good showcase of me?

    - by Sean
    I have been itching to write a software development blog for some time now. The best advice I've received about blog writing is "Write the blog you would have want to read". Its good advice but its only half the story, Once you write a blog it becomes your showcase on the Internet, it is bound to come up on any search conducted by a future colleague or employer. It can be a good thing or it can do some serious damage. So if there are any hiring managers out there, can you give me a few pointers on what it is in a blog that give you a good impression about candidate and/or the kind of stuff that causes you to throw the candidate's resume to the nearest bean? Does a blog have to come up with a clever piece of code every week? (Don’t think I can manage it) Is it OK to blog more then not about development methods to improved quality and productivity (have a lot of ideas about that). Can I blog about stuff I did not try first hand but seems noteworthy?

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  • How to drag from a background window to the front window

    - by Luis Alvarado
    Is the following I will explain possible with a key combination? Here is the image: As you can see, the terminal is the focus window (Front window) and Nautilus is in the background (Back Window). How can I grab a folder or file from Nautilus without loosing focus on the terminal (Without making the terminal go to the background and Nautilus to the front) and drop it in the terminal?. What I want is not to have to ALT+TAB again just to do this. Options like resizing the windows to fit the screen are not what I am looking for. Like in the image, we have a fullscreen window that we want it to stay like that. We can drag the terminal window around but anytime I access the background nautilus window, I should not loose focus on the terminal (It should not go to the background every time I access Nautilus). Maybe like a key combination that freezes the current focus windows positions and I can drag from background windows to background windows or background windows to the front focused one.

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  • How to review the current state of open source vs. closed source graphics drivers?

    - by Bucic
    How to know whether it's worth it to replace open source drivers installed by default with proprietary ones. Are there any benchmarks? Major known issues summaries. I don't mean 'at the time of writing this post'. I mean an up-to-date status on how the drivers compare. This page https://help.ubuntu.com/community/BinaryDriverHowto/ certainly doesn't do much on the matter, nor it even mentions Intel. EDIT: I've just learned there is no Intel proprietary driver because they made their drivers open source http://askubuntu.com/a/17395/29347

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  • Purple start screen - no splash screen

    - by Peter
    After installing Ubuntu 11.10 on a new computer everything worked fine for a few weeks and now suddenly when starting up Ubuntu I get a blank purple screen with no "ubuntu" splash and the 5 dots but the system does start up. What has happened to loose the ubuntu splash screen? Also, I've checked in the grub startup and it has "quiet splash" in the linux line. I have an ATI radeon 5450 graphics card which needed nomodeset to be added to the grub line when booting for the first time off the install CD but now this line has disappeared from the grub startup. Can anyone help. Thanks

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  • Different ways of solving problems in code.

    - by Erin
    I now program in C# for a living but before that I programmed in python for 5 years. I have found that I write C# very differently than most examples I see on the web. Rather then writing things like: foreach (string bar in foo) { //bar has something doen to it here } I write code that looks like this. foo.ForEach( c => c.someActionhere() ) Or var result = foo.Select( c => { //Some code here to transform the item. }).ToList(); I think my using code like above came from my love of map and reduce in python - while not exactly the same thing, the concepts are close. Now it's time for my question. What concepts do you take and move with you from language to language; that allow you to solve a problem in a way that is not the normal accepted solution in that language?

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  • Upgrade Ubuntu 11.10 to 12.10

    - by Daniel Minassian
    To whoever can help, I want to update the ubuntu on my laptop to 12.10 from the current version 11.10, when i click on the update manager i get a partial update gui, if i click cancel on that i get the gui for update which has three buttons check, install updates and upgrade. The upgrade button upgrades only to 12.04.1.LTS, when i press check it checks and gives me this error "W:Failed to fetch h t t p://lb.archive.ubuntu.com/ubuntu/dists/precise/main/i18n/Index No Hash entry in Release file /var/lib/apt/lists/partial/lb.archive.ubuntu.com_ubuntu_dists_precise_main_i18n_Index , W:Failed to fetch h t t p://lb.archive.ubuntu.com/ubuntu/dists/precise/multiverse/i18n/Index No Hash entry in Release file /var/lib/apt/lists/partial/lb.archive.ubuntu.com_ubuntu_dists_precise_multiverse_i18n_Index , W:Failed to fetch http://lb.archive.ubuntu.com/ubuntu/dists/precise/restricted/i18n/Index No Hash entry in Release file /var/lib/apt/lists/partial/lb.archive.ubuntu.com_ubuntu_dists_precise_restricted_i18n_Index , W:Failed to fetch http://lb.archive.ubuntu.com/ubuntu/dists/precise/universe/i18n/Index No Hash entry in Release file /var/lib/apt/lists/partial/lb.archive.ubuntu.com_ubuntu_dists_precise_universe_i18n_Index , E:Some index files failed to download. They have been ignored, or old ones used instead." Thank you for your time and help, Daniel Minassian

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  • Google I/O 2012 - Advanced Design for Engineers

    Google I/O 2012 - Advanced Design for Engineers Alex Faaborg, Christian Robertson Design isn't black magic, it's a field that people can learn. In this talk two elite designers from Google will give you an advanced crash course in interactive and visual design. Topics will include mental models, natural mappings, metaphors, mode errors, visual hierarchies, typography and gestalt principles. Correctly applied this knowledge can drastically improve the quality of your work. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 158 9 ratings Time: 55:50 More in Science & Technology

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  • What if you don't have code samples to give a prospective employer?

    - by lucks
    What do you do when you don't have any good code samples available when asked by a prospective employer? I like to consider myself a fairly capable developer but I can't share any of the software I've been writing for my company the last few years. Unfortunately, I haven't been able to find the time to put much work in my personal projects either. Basically, I don't think I can find any code samples that are a good representative of my skills that I can share. Any ideas? Thanks in advance.

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  • Subterranean IL: The ThreadLocal type

    - by Simon Cooper
    I came across ThreadLocal<T> while I was researching ConcurrentBag. To look at it, it doesn't really make much sense. What's all those extra Cn classes doing in there? Why is there a GenericHolder<T,U,V,W> class? What's going on? However, digging deeper, it's a rather ingenious solution to a tricky problem. Thread statics Declaring that a variable is thread static, that is, values assigned and read from the field is specific to the thread doing the reading, is quite easy in .NET: [ThreadStatic] private static string s_ThreadStaticField; ThreadStaticAttribute is not a pseudo-custom attribute; it is compiled as a normal attribute, but the CLR has in-built magic, activated by that attribute, to redirect accesses to the field based on the executing thread's identity. TheadStaticAttribute provides a simple solution when you want to use a single field as thread-static. What if you want to create an arbitary number of thread static variables at runtime? Thread-static fields can only be declared, and are fixed, at compile time. Prior to .NET 4, you only had one solution - thread local data slots. This is a lesser-known function of Thread that has existed since .NET 1.1: LocalDataStoreSlot threadSlot = Thread.AllocateNamedDataSlot("slot1"); string value = "foo"; Thread.SetData(threadSlot, value); string gettedValue = (string)Thread.GetData(threadSlot); Each instance of LocalStoreDataSlot mediates access to a single slot, and each slot acts like a separate thread-static field. As you can see, using thread data slots is quite cumbersome. You need to keep track of LocalDataStoreSlot objects, it's not obvious how instances of LocalDataStoreSlot correspond to individual thread-static variables, and it's not type safe. It's also relatively slow and complicated; the internal implementation consists of a whole series of classes hanging off a single thread-static field in Thread itself, using various arrays, lists, and locks for synchronization. ThreadLocal<T> is far simpler and easier to use. ThreadLocal ThreadLocal provides an abstraction around thread-static fields that allows it to be used just like any other class; it can be used as a replacement for a thread-static field, it can be used in a List<ThreadLocal<T>>, you can create as many as you need at runtime. So what does it do? It can't just have an instance-specific thread-static field, because thread-static fields have to be declared as static, and so shared between all instances of the declaring type. There's something else going on here. The values stored in instances of ThreadLocal<T> are stored in instantiations of the GenericHolder<T,U,V,W> class, which contains a single ThreadStatic field (s_value) to store the actual value. This class is then instantiated with various combinations of the Cn types for generic arguments. In .NET, each separate instantiation of a generic type has its own static state. For example, GenericHolder<int,C0,C1,C2> has a completely separate s_value field to GenericHolder<int,C1,C14,C1>. This feature is (ab)used by ThreadLocal to emulate instance thread-static fields. Every time an instance of ThreadLocal is constructed, it is assigned a unique number from the static s_currentTypeId field using Interlocked.Increment, in the FindNextTypeIndex method. The hexadecimal representation of that number then defines the specific Cn types that instantiates the GenericHolder class. That instantiation is therefore 'owned' by that instance of ThreadLocal. This gives each instance of ThreadLocal its own ThreadStatic field through a specific unique instantiation of the GenericHolder class. Although GenericHolder has four type variables, the first one is always instantiated to the type stored in the ThreadLocal<T>. This gives three free type variables, each of which can be instantiated to one of 16 types (C0 to C15). This puts an upper limit of 4096 (163) on the number of ThreadLocal<T> instances that can be created for each value of T. That is, there can be a maximum of 4096 instances of ThreadLocal<string>, and separately a maximum of 4096 instances of ThreadLocal<object>, etc. However, there is an upper limit of 16384 enforced on the total number of ThreadLocal instances in the AppDomain. This is to stop too much memory being used by thousands of instantiations of GenericHolder<T,U,V,W>, as once a type is loaded into an AppDomain it cannot be unloaded, and will continue to sit there taking up memory until the AppDomain is unloaded. The total number of ThreadLocal instances created is tracked by the ThreadLocalGlobalCounter class. So what happens when either limit is reached? Firstly, to try and stop this limit being reached, it recycles GenericHolder type indexes of ThreadLocal instances that get disposed using the s_availableIndices concurrent stack. This allows GenericHolder instantiations of disposed ThreadLocal instances to be re-used. But if there aren't any available instantiations, then ThreadLocal falls back on a standard thread local slot using TLSHolder. This makes it very important to dispose of your ThreadLocal instances if you'll be using lots of them, so the type instantiations can be recycled. The previous way of creating arbitary thread-static variables, thread data slots, was slow, clunky, and hard to use. In comparison, ThreadLocal can be used just like any other type, and each instance appears from the outside to be a non-static thread-static variable. It does this by using the CLR type system to assign each instance of ThreadLocal its own instantiated type containing a thread-static field, and so delegating a lot of the bookkeeping that thread data slots had to do to the CLR type system itself! That's a very clever use of the CLR type system.

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