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• Installing gtk-config and/or fsv in Ubuntu 10.10

  - by Wayne Werner

  Hi, I'm trying to install the File System Visualizer (think "It's a UNIX System! I know this!" from Jurassic Park) on Ubuntu 10.10. I've got the .tar.gz downloaded, and extracted. However, when I ./configure, I get this output: loading cache ./config.cache checking for a BSD compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking whether make sets ${MAKE}... yes checking for working aclocal... found checking for working autoconf... found checking for working automake... found checking for working autoheader... found checking for working makeinfo... missing checking for gcc... gcc checking whether the C compiler (gcc ) works... yes checking whether the C compiler (gcc ) is a cross-compiler... no checking whether we are using GNU C... yes checking whether gcc accepts -g... yes checking how to run the C preprocessor... gcc -E checking for ranlib... ranlib checking for POSIXized ISC... no checking for dirent.h that defines DIR... yes checking for opendir in -ldir... no checking for ANSI C header files... yes checking whether time.h and sys/time.h may both be included... yes checking for strings.h... yes checking for sys/time.h... yes checking for unistd.h... yes checking for working const... yes checking for mode_t... yes checking for uid_t in sys/types.h... yes checking for pid_t... yes checking for size_t... yes checking for comparison_fn_t... yes checking for st_blocks in struct stat... yes checking whether struct tm is in sys/time.h or time.h... time.h checking for working alloca.h... yes checking for alloca... yes checking for working fnmatch... yes checking for strftime... yes checking for getcwd... yes checking for gettimeofday... yes checking for mktime... yes checking for strcspn... yes checking for strdup... yes checking for strspn... yes checking for strtod... yes checking for strtoul... yes checking for scandir... yes checking for inline... inline checking for off_t... yes checking for unistd.h... (cached) yes checking for getpagesize... yes checking for working mmap... yes checking for argz.h... yes checking for limits.h... yes checking for locale.h... yes checking for nl_types.h... yes checking for malloc.h... yes checking for string.h... yes checking for unistd.h... (cached) yes checking for sys/param.h... yes checking for getcwd... (cached) yes checking for munmap... yes checking for putenv... yes checking for setenv... yes checking for setlocale... yes checking for strchr... yes checking for strcasecmp... yes checking for strdup... (cached) yes checking for __argz_count... yes checking for __argz_stringify... yes checking for __argz_next... yes checking for stpcpy... yes checking for LC_MESSAGES... yes checking whether NLS is requested... yes checking whether included gettext is requested... no checking for libintl.h... yes checking for gettext in libc... yes checking for msgfmt... /usr/bin/msgfmt checking for dcgettext... yes checking for gmsgfmt... /usr/bin/msgfmt checking for xgettext... /usr/bin/xgettext checking for gtk-config... no checking for GTK - version >= 1.2.1... no *** The gtk-config script installed by GTK could not be found *** If GTK was installed in PREFIX, make sure PREFIX/bin is in *** your path, or set the GTK_CONFIG environment variable to the *** full path to gtk-config. configure: error: Cannot find proper GTK+ version Obviously it's looking for gtk-config. However, apparently it doesn't exist in the repos anymore. Then this post mentioned that gtkglarea solved their problem, as mentioned in this file. Of course that poster neatly forgets to mention exactly what and how gtkglarea solved their problem, and Google is mostly devoid of information on the problem. So I come here asking for help! I would like to install fsv, but it tells me gtk-config doesn't exist. How can I fix this problem in Ubuntu 10.10? Thanks!

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• Blender has weird fuzzy misbehaving icon in launcher

  - by TreefrogInc

  I got Blender 2.58 (stable) from blender.org (downloaded the package, extracted it). Everything works fine, but the only thing that bugs me is that the icon in the launcher (when I open it) is really fuzzy. I guess that's no big deal, but when I select "Keep in Launcher" and close Blender, the icon doesn't work when I try to open it again. Then, I created a Launcher on my desktop with the path to the blender executable, slapped on a shiny new non-fuzzy .svg icon that came with the package, and dragged the (desktop) Launcher to my (Unity) Launcher. Now, when I click on the new launcher, it keeps showing the flashing thing that says it's opening the program, and then the old fuzzy icon comes back but doesn't replace the new icon. Even after Blender opens, the new icon is still flashing. What is wrong with my launcher?

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• What If Nintendo Made Children’s Books?

  - by Jason Fitzpatrick

  What if the great minds at Nintendo had directed their energy towards children’s literature? These humorous cover mock-ups show us what the titles may have looked like. Hit up the link below for more books from the Nintendo universe; if you have a clever idea for a game-based children’s book that should exist, sound off in the comments. Videogame Children’s Books [via Neatorama] 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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• Find Nearest Object

  - by ultifinitus

  I have a fairly sizable game engine created, and I'm adding some needed features, such as this, how do I find the nearest object from a list of points? In this case, I could simply use the Pythagorean theorem to find the distance, and check the results. I know I can't simply add x and y, because that's the distance to the object, if you only took right angle turns. However I'm wondering if there's something else I could do? I also have a collision system, where essentially I turn objects into smaller objects on a smaller grid, kind of like a minimap, and only if objects exist in the same gridspace do I check for collisions, I could do the same thing, only make the gridspace larger to check for closeness. (rather than checking every. single. object) however that would take additional setup in my base class and clutter up the already cluttered object. TL;DR Question: Is there something efficient and accurate that I can use to detect which object is closest, based on a list of points and sizes?

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• What’s the opposite of abstraction?

  - by Ollie Saunders

  As I understand it, abstraction is the term we use for when more meaning is created out of something simpler without altering it. It is derived from the latin verb abstrahere (to ‘draw away’). For instance, text is just one abstraction of binary data—as are bitmaps. So, in computers, text and bitmaps exist on top of (are implemented in terms of) binary data. My question is: what is the opposite term? If I want to know the possible more basic things that bitmaps could be implemented in terms of other than binary data—things like tiles for a mosaic or fabric patches for a patchwork quilt—what am I asking for? Is there a word for that? Abstraction has connotations of generalization and the opposite process of that is specialization. IDK whether that helps.

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• How can you learn to design nice looking websites?

  - by Richard

  I am a moderately capable web developer. I can put stuff where I want it to go and put some JQuery stuff in there if I need to. However, if I am making my own website (which I am starting to do) I have no idea how to design it. If someone was to sit next to me a point to the screen and say "put this picture there, text there" I can do that quite easily. But designing my own site with my choice of colours and text will look like a toddler has invented it. Does anyone know any websites/books I can look at or has anyone got any tips on the basics of non-toddler web design?

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• An Alphabet of Eponymous Aphorisms, Programming Paradigms, Software Sayings, Annoying Alliteration

  - by Brian Schroer

  Malcolm Anderson blogged about “Einstein’s Razor” yesterday, which reminded me of my favorite software development “law”, the name of which I can never remember. It took much Wikipedia-ing to find it (Hofstadter’s Law – see below), but along the way I compiled the following list: Amara’s Law: We tend to overestimate the effect of a technology in the short run and underestimate the effect in the long run. Brook’s Law: Adding manpower to a late software project makes it later. Clarke’s Third Law: Any sufficiently advanced technology is indistinguishable from magic. Law of Demeter: Each unit should only talk to its friends; don't talk to strangers. Einstein’s Razor: “Make things as simple as possible, but not simpler” is the popular paraphrase, but what he actually said was “It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience”, an overly complicated quote which is an obvious violation of Einstein’s Razor. (You can tell by looking at a picture of Einstein that the dude was hardly an expert on razors or other grooming apparati.) Finagle's Law of Dynamic Negatives: Anything that can go wrong, will—at the worst possible moment. - O'Toole's Corollary: The perversity of the Universe tends towards a maximum. Greenspun's Tenth Rule: Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp. (Morris’s Corollary: “…including Common Lisp”) Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law. Issawi’s Omelet Analogy: One cannot make an omelet without breaking eggs - but it is amazing how many eggs one can break without making a decent omelet. Jackson’s Rules of Optimization: Rule 1: Don't do it. Rule 2 (for experts only): Don't do it yet. Kaner’s Caveat: A program which perfectly meets a lousy specification is a lousy program. Liskov Substitution Principle (paraphrased): Functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it Mason’s Maxim: Since human beings themselves are not fully debugged yet, there will be bugs in your code no matter what you do. Nils-Peter Nelson’s Nil I/O Rule: The fastest I/O is no I/O.    Occam's Razor: The simplest explanation is usually the correct one. Parkinson’s Law: Work expands so as to fill the time available for its completion. Quentin Tarantino’s Pie Principle: “…you want to go home have a drink and go and eat pie and talk about it.” (OK, he was talking about movies, not software, but I couldn’t find a “Q” quote about software. And wouldn’t it be cool to write a program so great that the users want to eat pie and talk about it?) Raymond’s Rule: Computer science education cannot make anybody an expert programmer any more than studying brushes and pigment can make somebody an expert painter.  Sowa's Law of Standards: Whenever a major organization develops a new system as an official standard for X, the primary result is the widespread adoption of some simpler system as a de facto standard for X. Turing’s Tenet: We shall do a much better programming job, provided we approach the task with a full appreciation of its tremendous difficulty, provided that we respect the intrinsic limitations of the human mind and approach the task as very humble programmers.  Udi Dahan’s Race Condition Rule: If you think you have a race condition, you don’t understand the domain well enough. These rules didn’t exist in the age of paper, there is no reason for them to exist in the age of computers. When you have race conditions, go back to the business and find out actual rules. Van Vleck’s Kvetching: We know about as much about software quality problems as they knew about the Black Plague in the 1600s. We've seen the victims' agonies and helped burn the corpses. We don't know what causes it; we don't really know if there is only one disease. We just suffer -- and keep pouring our sewage into our water supply. Wheeler’s Law: All problems in computer science can be solved by another level of indirection... Except for the problem of too many layers of indirection. Wheeler also said “Compatibility means deliberately repeating other people's mistakes.”. The Wrong Road Rule of Mr. X (anonymous): No matter how far down the wrong road you've gone, turn back. Yourdon’s Rule of Two Feet: If you think your management doesn't know what it's doing or that your organisation turns out low-quality software crap that embarrasses you, then leave. Zawinski's Law of Software Envelopment: Every program attempts to expand until it can read mail. Zawinski is also responsible for “Some people, when confronted with a problem, think 'I know, I'll use regular expressions.' Now they have two problems.” He once commented about X Windows widget toolkits: “Using these toolkits is like trying to make a bookshelf out of mashed potatoes.”

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• How to test a 3D rendering engine?

  - by YoYo

  Me and some friends developing simple 3D rendering engine as practice for the university. We used Ogre 3d as prototype and now we are developing it from base The engine is wrapped up in simple game that asks the user to select shape (circle, triangle, square...), color and dimensions and renders the image to the screen. It also enables to move and rotate the shape on screen using mouse. We would like to test automate the view rendering. I could not find any test framework for this issue and I would like to know how 3D test is done in non manual matter

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• Visual Studio 2012 - Express vs Professional

  - by Dan

  I'm having trouble finding a feature comparison between Visual Studio 2012 express edition and the professional edition. I'm using the trial Profession version at the moment, but it'll run out soon, so I need to make a decision whether to purchase the full version. Obviously I can just try both initially and see if the express edition is suitable, but the problem is that there are that many features in Visual Studio, there might be a really useful feature that was missing in the standard edition that I didn't even know existed! Or I didn't spot was missing until later down the line. I could really do with a feature comparison list like the one for all non-express editions here. It's a shame that page doesn't include the express edition. (as a side note, there doesn't seem to be a visual-studio-2012 tag, so I had to just use visual-studio. Could someone with enough rep to create tags add a visual-studio-2012 tag?)

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• Oracle SOA and the Sun acquisition

  - by Demed L'Her

  I just presented the SOA product strategy at the Oracle + Sun Welcome Event this morning in Redwood Shores, after 2 earlier sessions on that same topic in Atlanta and Reston. That made me realize that I still haven’t blogged about the Sun acquisition – you might wonder how I managed to ignore the elephant in the room! Reality is that we have been very busy lately working with our new colleagues from Sun on a joint strategy and the resulting engineering plans. Let me help you navigate the Oracle website by giving you the links you really need if your main focus of area is integration and SOA technologies: Entry point into all material relating to the Sun acquisition (and since you are there you might want to check the non-SOA content, such as the hardware story that is quite interesting) Hasan Rizvi’s webcast on the combined SOA strategy Schedule and registration for the live Welcome Events taking place around the world – a great opportunity to ask questions that are not answered in the material we have posted on the web So with this welcome to the Sun customers and Java CAPS users!   Technorati Tags: jcaps,java caps,sun,soa,oracle,glassfish esb,seebeyond,acquisition

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• Migrating SQL Server Databases – The DBA’s Checklist (Part 2)

  - by Sadequl Hussain

  Continuing from Part 1  , our Migration Checklist continues: Step 5: Update statistics It is always a good idea to update the statistics of the database that you have just installed or migrated. To do this, run the following command against the target database: sp_updatestats The sp_updatestats system stored procedure runs the UPDATE STATISTICS command against every user and system table in the database.  However, a word of caution: running the sp_updatestats against a database with a compatibility level below 90 (SQL Server 2005) will reset the automatic UPDATE STATISTICS settings for every index and statistics of every table in the database. You may therefore want to change the compatibility mode before you run the command. Another thing you should remember to do is to ensure the new database has its AUTO_CREATE_STATISTICS and AUTO_UPDATE_STATISTICS properties set to ON. You can do so using the ALTER DATABASE command or from the SSMS. Step 6: Set database options You may have to change the state of a database after it has been restored. If the database was changed to single-user or read-only mode before backup, the restored copy will also retain these settings. This may not be an issue when you are manually restoring from Enterprise Manager or the Management Studio since you can change the properties. However, this is something to be mindful of if the restore process is invoked by an automated job or script and the database needs to be written to immediately after restore. You may want to check the database’s status programmatically in such cases. Another important option you may want to set for the newly restored / attached database is PAGE_VERIFY. This option specifies how you want SQL Server to ensure the physical integrity of the data. It is a new option from SQL Server 2005 and can have three values: CHECKSUM (default for SQL Server 2005 and latter databases), TORN_PAGE_DETECTION (default when restoring a pre-SQL Server 2005 database) or NONE. Torn page detection was itself an option for SQL Server 2000 databases. From SQL Server 2005, when PAGE_VERIFY is set to CHECKSUM, the database engine calculates the checksum for a page’s contents and writes it to the page header before storing it in disk. When the page is read from the disk, the checksum is computed again and compared with the checksum stored in the header.  Torn page detection works much like the same way in that it stores a bit in the page header for every 512 byte sector. When data is read from the page, the torn page bits stored in the header is compared with the respective sector contents. When PAGE_VERIFY is set to NONE, SQL Server does not perform any checking, even if torn page data or checksums are present in the page header.  This may not be something you would want to set unless there is a very specific reason.  Microsoft suggests using the CHECKSUM page verify option as this offers more protection. Step 7: Map database users to logins A common database migration issue is related to user access. Windows and SQL Server native logins that existed in the source instance and had access to the database may not be present in the destination. Even if the logins exist in the destination, the mapping between the user accounts and the logins will not be automatic. You can use a special system stored procedure called sp_change_users_login to address these situations. The procedure needs to be run against the newly attached or restored database and can accept four parameters. Depending on what you want to do, you may be using less than four though. The first parameter, @Action, can take three values. When you specify @Action = ‘Report’, the system will provide you with a list of database users which are not mapped to any login. If you want to map a database user to an existing SQL Server login, the value for @Action will be ‘Update_One’. In this case, you will only need to provide the database user name and the login it will map to. So if your newly restored database has a user account called “bob” and there is already a SQL Server login with the same name and you want to map the user to the login, you will execute a query like the following: sp_change_users_login         @Action = ‘Update_One’,         @UserNamePattern = ‘bob’,         @LoginName = ‘bob’ If the login does not exist, you can instruct SQL Server to create the login with the same name. In this case you will need to provide a password for the login and the value of the @Action parameter will be ‘Auto_Fix’. If the login already exists, it will be automatically mapped to the user account. Unfortunately sp_change_users_login system stored procedure cannot be used to map database users to trusted logins (Windows accounts) in SQL Server. You will need to follow a manual process to re-map the database user accounts.  Continues…

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• Ways to use your skills as a developer to give back to the community/charities.

  - by Ryan Hayes

  Recently I came upon a community event called GiveCamp. GiveCamp is a weekend-long event where technology professionals from designers, developers and database administrators to marketers and web strategists donate their time to provide solutions for non-profit organizations. Since its inception in 2007, the GiveCamp program has provided benefits to over 150 charities, with a value of developer and designer time exceeding $1,000,000 in services! Coming from a very rural part of the country where there is a huge opportunity for charity events like this, it got me wondering. Are there other large movements like GiveCamp that are out there? GiveCamp is sponsored by Microsoft, so of course most are run through .NET user groups. Are there other flavors of it? Different types? Java/Python/other open source charity movements? If not, how do you give back?

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• ASP.NET Web API and Simple Value Parameters from POSTed data

  - by Rick Strahl

  In testing out various features of Web API I've found a few oddities in the way that the serialization is handled. These are probably not super common but they may throw you for a loop. Here's what I found. Simple Parameters from Xml or JSON Content Web API makes it very easy to create action methods that accept parameters that are automatically parsed from XML or JSON request bodies. For example, you can send a JavaScript JSON object to the server and Web API happily deserializes it for you. This works just fine:public string ReturnAlbumInfo(Album album) { return album.AlbumName + " (" + album.YearReleased.ToString() + ")"; } However, if you have methods that accept simple parameter types like strings, dates, number etc., those methods don't receive their parameters from XML or JSON body by default and you may end up with failures. Take the following two very simple methods:public string ReturnString(string message) { return message; } public HttpResponseMessage ReturnDateTime(DateTime time) { return Request.CreateResponse<DateTime>(HttpStatusCode.OK, time); } The first one accepts a string and if called with a JSON string from the client like this:var client = new HttpClient(); var result = client.PostAsJsonAsync<string>(http://rasxps/AspNetWebApi/albums/rpc/ReturnString, "Hello World").Result; which results in a trace like this: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnString HTTP/1.1Content-Type: application/json; charset=utf-8Host: rasxpsContent-Length: 13Expect: 100-continueConnection: Keep-Alive "Hello World" produces… wait for it: null. Sending a date in the same fashion:var client = new HttpClient(); var result = client.PostAsJsonAsync<DateTime>(http://rasxps/AspNetWebApi/albums/rpc/ReturnDateTime, new DateTime(2012, 1, 1)).Result; results in this trace: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnDateTime HTTP/1.1Content-Type: application/json; charset=utf-8Host: rasxpsContent-Length: 30Expect: 100-continueConnection: Keep-Alive "\/Date(1325412000000-1000)\/" (yes still the ugly MS AJAX date, yuk! This will supposedly change by RTM with Json.net used for client serialization) produces an error response: The parameters dictionary contains a null entry for parameter 'time' of non-nullable type 'System.DateTime' for method 'System.Net.Http.HttpResponseMessage ReturnDateTime(System.DateTime)' in 'AspNetWebApi.Controllers.AlbumApiController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Basically any simple parameters are not parsed properly resulting in null being sent to the method. For the string the call doesn't fail, but for the non-nullable date it produces an error because the method can't handle a null value. This behavior is a bit unexpected to say the least, but there's a simple solution to make this work using an explicit [FromBody] attribute:public string ReturnString([FromBody] string message) andpublic HttpResponseMessage ReturnDateTime([FromBody] DateTime time) which explicitly instructs Web API to read the value from the body. UrlEncoded Form Variable Parsing Another similar issue I ran into is with POST Form Variable binding. Web API can retrieve parameters from the QueryString and Route Values but it doesn't explicitly map parameters from POST values either. Taking our same ReturnString function from earlier and posting a message POST variable like this:var formVars = new Dictionary<string,string>(); formVars.Add("message", "Some Value"); var content = new FormUrlEncodedContent(formVars); var client = new HttpClient(); var result = client.PostAsync(http://rasxps/AspNetWebApi/albums/rpc/ReturnString, content).Result; which produces this trace: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnString HTTP/1.1Content-Type: application/x-www-form-urlencodedHost: rasxpsContent-Length: 18Expect: 100-continue message=Some+Value When calling ReturnString:public string ReturnString(string message) { return message; } unfortunately it does not map the message value to the message parameter. This sort of mapping unfortunately is not available in Web API. Web API does support binding to form variables but only as part of model binding, which binds object properties to the POST variables. Sending the same message as in the previous example you can use the following code to pick up POST variable data:public string ReturnMessageModel(MessageModel model) { return model.Message; } public class MessageModel { public string Message { get; set; }} Note that the model is bound and the message form variable is mapped to the Message property as would other variables to properties if there were more. This works but it's not very dynamic. There's no real easy way to retrieve form variables (or query string values for that matter) in Web API's Request object as far as I can discern. Well only if you consider this easy:public string ReturnString() { var formData = Request.Content.ReadAsAsync<FormDataCollection>().Result; return formData.Get("message"); } Oddly FormDataCollection does not allow for indexers to work so you have to use the .Get() method which is rather odd. If you're running under IIS/Cassini you can always resort to the old and trusty HttpContext access for request data:public string ReturnString() { return HttpContext.Current.Request.Form["message"]; } which works fine and is easier. It's kind of a bummer that HttpRequestMessage doesn't expose some sort of raw Request object that has access to dynamic data - given that it's meant to serve as a generic REST/HTTP API that seems like a crucial missing piece. I don't see any way to read query string values either. To me personally HttpContext works, since I don't see myself using self-hosted code much.© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• How do I recover a BTRFS filesystem with "parent transid verify failed" errors?

  - by Evan P.

  I've got an external USB disk running btrfs. I use it for backups, and each time I do a backup I take a snapshot. However, it's giving me this error now: parent transid verify failed on 109973766144 wanted 1823 found 1821 parent transid verify failed on 109973766144 wanted 1823 found 1821 Obviously, this is a non-critical disk, but I have a few files on here that aren't available elsewhere. Is there any way to recover data from this disk? Maybe by mounting one of the snapshots as root?

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• Google présente le Nexus S fabriqué par Samsung, tournant sous Android 2.3 et équipé du NFC

  Google présente le Nexus S fabriqué par Samsung, au design épuré et équipé du NFC Mise à jour du 07.12.2010 par Katleen Cette fois-ci, c'est officiel. Le Nexus One aura un successeur, et c'est bel et bien cet appareil qu'Eric Schmidt avait furtivement montré il y a quelques semaines lors d'une conférence. Le second smartphone estampillé Google a été fabriqué par Samsung, qui a du le fabriquer en respectant scrupuleusement un cahier des charges très précis, en matière de hardware et de design. Son exclusivité ? Etre le premier à tourner sous Android 2.3 (Gingerbread) en version "pure" (non remodelée par les opérateurs, ni par Samsung). Autre grand pas en avant : l'inclusion d...

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• Can we replace XML with JSON entirely?

  - by Saeed Neamati

  I'm sure lots of developers are familiar with XML and JSON, and they've used both of them. Thus no point in explaining what they are, and what is their purpose, even in brief. If we try to map their concepts, we can say (correct me if I'm wrong): XML tags are equivalent to JSON {} XML attributes are equivalent to JSON properties XML tag collection is equivalent to JSON [] The only thing I can think of, which doesn't exist in JSON, is XML Namespaces. The question is, considering this mapping, and considering that JSON is highly lighter in this mapping, can we see a world in future (or at least theoretically think of a world) without XML, but with JSON doing everything XML does? Can we use JSON everywhere XML is used? PS: Please note that I've seen this question. It's something entirely different from what I'm asking here. Thus please don't mention duplicate.

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• C# 4.0: Covariance And Contravariance In Generics

  - by Paulo Morgado

  C# 4.0 (and .NET 4.0) introduced covariance and contravariance to generic interfaces and delegates. But what is this variance thing? According to Wikipedia, in multilinear algebra and tensor analysis, covariance and contravariance describe how the quantitative description of certain geometrical or physical entities changes when passing from one coordinate system to another.(*) But what does this have to do with C# or .NET? In type theory, a the type T is greater (>) than type S if S is a subtype (derives from) T, which means that there is a quantitative description for types in a type hierarchy. So, how does covariance and contravariance apply to C# (and .NET) generic types? In C# (and .NET), variance applies to generic type parameters and not to the resulting generic type. A generic type parameter is: covariant if the ordering of the generic types follows the ordering of the generic type parameters: Generic<T> = Generic<S> for T = S. contravariant if the ordering of the generic types is reversed from the ordering of the generic type parameters: Generic<T> = Generic<S> for T = S. invariant if neither of the above apply. If this definition is applied to arrays, we can see that arrays have always been covariant because this is valid code: object[] objectArray = new string[] { "string 1", "string 2" }; objectArray[0] = "string 3"; objectArray[1] = new object(); However, when we try to run this code, the second assignment will throw an ArrayTypeMismatchException. Although the compiler was fooled into thinking this was valid code because an object is being assigned to an element of an array of object, at run time, there is always a type check to guarantee that the runtime type of the definition of the elements of the array is greater or equal to the instance being assigned to the element. In the above example, because the runtime type of the array is array of string, the first assignment of array elements is valid because string = string and the second is invalid because string = object. This leads to the conclusion that, although arrays have always been covariant, they are not safely covariant – code that compiles is not guaranteed to run without errors. In C#, the way to define that a generic type parameter as covariant is using the out generic modifier: public interface IEnumerable<out T> { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> { T Current { get; } bool MoveNext(); } Notice the convenient use the pre-existing out keyword. Besides the benefit of not having to remember a new hypothetic covariant keyword, out is easier to remember because it defines that the generic type parameter can only appear in output positions — read-only properties and method return values. In a similar way, the way to define a type parameter as contravariant is using the in generic modifier: public interface IComparer<in T> { int Compare(T x, T y); } Once again, the use of the pre-existing in keyword makes it easier to remember that the generic type parameter can only be used in input positions — write-only properties and method non ref and non out parameters. Because covariance and contravariance apply only to the generic type parameters, a generic type definition can have both covariant and contravariant generic type parameters in its definition: public delegate TResult Func<in T, out TResult>(T arg); A generic type parameter that is not marked covariant (out) or contravariant (in) is invariant. All the types in the .NET Framework where variance could be applied to its generic type parameters have been modified to take advantage of this new feature. In summary, the rules for variance in C# (and .NET) are: Variance in type parameters are restricted to generic interface and generic delegate types. A generic interface or generic delegate type can have both covariant and contravariant type parameters. Variance applies only to reference types; if you specify a value type for a variant type parameter, that type parameter is invariant for the resulting constructed type. Variance does not apply to delegate combination. That is, given two delegates of types Action<Derived> and Action<Base>, you cannot combine the second delegate with the first although the result would be type safe. Variance allows the second delegate to be assigned to a variable of type Action<Derived>, but delegates can combine only if their types match exactly. If you want to learn more about variance in C# (and .NET), you can always read: Covariance and Contravariance in Generics — MSDN Library Exact rules for variance validity — Eric Lippert Events get a little overhaul in C# 4, Afterward: Effective Events — Chris Burrows Note: Because variance is a feature of .NET 4.0 and not only of C# 4.0, all this also applies to Visual Basic 10.

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• Animations in FBX exported from Maya are anchored in the wrong place

  - by Simon P Stevens

  We are trying to export a model and animation from Maya into Unity3d. In Maya, the model is anchored (pivot point) at the feet (and the body moves up and down). However after we have performed the FBX export, and imported the file into Unity the model is now appears to be anchored by the waist/head and the feet move. These example videos probably help explain the problem more clearly: Example video - Maya - Correct Example video - Unity - Wrong We have also noticed that if we take the FBX file and import it back into Maya we have exactly the same problem. It seems to be that the constraints no longer work after the FBX is reimported back to Maya, which just kills the connection between the joints and the control objects. When we exported the FBX we have tried checking the 'bake animations' check box. The fact that the same problem exist when importing the FBX back into both Maya and Unity suggests that the source of the problem is most likely with the Maya FBX export. Has anyone encountered this problem before and have any ideas how to fix it?

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• How do I share files with someone who does not have a ubuntu one account

  - by Bob

  I tried to search for an answer, except that, uhhh there is no search. I want to share a Ubuntu One folder with people who do not have a Ubuntu One account. Is that possible? I found this answer in the faq, "Yes! Since Ubuntu 10.04 LTS, Ubuntu One supports sharing files publicly. Right click on a file already synchronized by Ubuntu One and select "Publish via Ubuntu One". Right-click on the file again and select "Copy Ubuntu One public URL". You can now paste the URL and share it with whoever you want." That doesn't seem to help me with 11.04. There is no 'Publish via Ubuntu One' button in 11.04. Does anyone know if there is a way to share files with non-ubuntu users? If so, how? Thanks In Advance, Bob

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• Can't get TRIM test to work

  - by Matthew Marcus

  So I'm attempting to install TRIM using the walkthrough here: How to enable TRIM? But everytime I attempt to run the hdparm command, I get the following when I try to run it w/ sda: reading sector 5805056: FAILED: Input/output error and I get this when running it with sda1: /dev/sda1: Device /dev/sda1 has non-zero LBA starting offset of 2048. Please use an absolute LBA with the /dev/ entry for the full device, rather than a partition name. /dev/sda1 is probably a partition of /dev/sda (?) The absolute LBA of sector 5807104 from /dev/sda1 should be 5809152 Aborting. I'm running Natty in a VBox on Windows 7. Someone PLEASE help.. I keep getting this "consistency check" message on boot of my machine and I think it's because Ubuntu is writing to the same sectors on the VHD too much.. need to get trim working on this thing.. Thanks.

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• Best way of storing voxels

  - by opiop65

  This should be a pretty easy question to answer, and I'm not looking for how to store the voxels data wise, I'm looking for the theory. Currently, my voxel engine has no global list of tiles. Each chunk has it's own list, and its hard to do things like collision detection or anything that may use tiles that are outside of its own chunk. I recently worked on procedural terrain with a non voxel engine. Now, I want to start using heightmaps in my voxel engine. But, I have a problem. If each chunk has its own list, then it will be pretty difficult to implement the heightmaps. My real question is, is should I store a global list of voxels independent of the chunks? And then I can just easily perform collision detection and terrain generation. However, it would probably be harder to do things such as frustum culling. So how should I store them?

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• How do I turn 'off' a (hosted) domain's web server while leaving email intact?

  - by foregon

  I have a web hosting account at HostGator (for a domain registered with GoDaddy), where I would like to only use email, and completely turn off the website/webserver (for that domain), such that it actually gives the following error like any other domain which isn't pointing to anything, so in Firefox it would be: Or in Chrome it would be: So I am not looking for just a blank page or server 403 error, but literally for it to act like it doesn't exist and the only way someone would know that the domain is in use, is if they WHOIS search it or know any of the email addresses on the main server. N.B. the domain is the parent domain in the HostGator account and other websites (which need to still be operational) are under it, but I'm thinking with DNS settings it can still be configured while keeping the one hosting account. How would I configure this?

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• Visualize flowchart diagram with multiple end symbols

  - by platzhirsch

  I am looking for a standardize way to visualize the following hierarchical logic: The state of the thread is represented by the answers to the hierarchical set of question You can read this listing like a flowchart, you iterate over the questions decide, go one step deeper and so on. Therefore I thought the best way to visualize it, using a flowchart. The problem is, in this hierarchical set it is possible to end in more than one state and its totally valid. I have never seen a flowchart where you can enter more than one state. Is it still possible and I am missing the right symbol to present this logic or are flowchart not fitting anyway? What other graphical representation could I use, is there something fitting in UML? A non-deterministic state machine seems not to be intuitive enough, transfering it into a deterministic state machine would result in to many states, and so on.

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• 'Development dashboard' web application

  - by espais

  Hi all, I am not sure if something like this exists in that it is ready out of the box. I currently have some web space that I use for various projects, and I would like to setup an area for some friends and I to develop web applications together. My ideal setup would be to create a folder, say, webdev.domain.com. We could all go to this domain, login, and then be able to setup new applications, pick which language will be used, setup database tables, allow HTML based file uploading, and create sub-folders to basically have a test bed for the applications. In retrospect, it seems like I'm describing a limited version of cpanel. I could come up with something in Drupal I'm sure, but I don't want to have to really spend time configuring much. Like I said, I want to install it and have minimal configuration. Does something like this exist (preferably in open-source)?

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• New Exadata Book Available Soon

  - by Rob Reynolds

  Oracle Press is set to released the first book on data warehouse performance and Exadata on March 14th. Achieving Extreme Performance with Oracle Exadata , by my colleagues Rick Greenwald, Robert Stackowiak, Maqsood Alam, and Mans Bhuller will be available at your favorite booksellers next week. I've seen a sneak peak of the content in this book and its a great way to fully grasp the power of Exadata and how to best apply it to achieve extreme data warehouse performance. From the publisher's description: Achieving Extreme Performance with Oracle Exadata and the Sun Oracle Database Machine is filled with best practices for deployments, hardware sizing, architecting the database machine environments for maximum availability, and backup and recovery. Oracle Database 11gR2 features used within these offerings, as well as migration options and paths for Oracle and non-Oracle databases to Oracle Exadata are covered. This Oracle Press guide also discusses architecture, administration, maintenance, monitoring, and tuning of Oracle Exadata Storage Servers and the Sun Oracle Database Machine. If your company is considering Exadata, or if you need more horsepower out of your data warehouse, I highly recommend grabbing a copy of this book next week.

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