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  • The "FAQ on the correct forum to post at is: " - suggestions and thanks

    At http://forums.asp.net/p/1337412/2699239.aspx#2699239, there is the "FAQ on the correct forum to post at is:".If you have anysuggestions for new links,updates to existing links,notification that a link has gone bador just thanks!please post either to this thread or send me a private message....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Domain masking (and simple page links)

    - by Halik
    How do you set up the domain (Im using godaddy) to mask the server url but to append the sub-page link. Im thinking something like the wikipedia en.wikipedia.org/wiki/something (or, if it would require httpd.conf access, setting it to append the default subpage link eg. '?page_id=2') Currently I can set up the domain to either be masked completely without showing any sub-page links or to simply redirect my domain to my web server.

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  • PHP `virtual()` with Apache MultiViews not working after upgrade to 12.04

    - by Izzy
    I use PHP's virtual() directive quite a lot on one of my sites, including central elements. This worked fine for the last ~10 years -- but after upgrading to 12.04 it somehow got broken. Example setup (simplified) To make it easier to understand, I simplify some things (contents). So say I need a HTML fragment like <P>For further instructions, please look <A HREF='foobar'>here</P> in multiple pages. 10 years ago, I used SSI for that, so it is put into a file in a central place -- so if e.g. the targeted URL changes, I only need to update it in one place. To serve multiple languages, I have Apache's MultiViews enabled -- and at $DOCUMENT_ROOT/central/ there are the files: foobar.html (English variant, and the default) foobar.html.de (German variant). Now in the PHP code, I simply placed: <? virtual("/central/foobar"); ?> and let Apache take care to deliver the correct language variant. The problem As said, this worked fine for about 10 years: German visitors got the German variant, all others the English (depending on their preferred language). But after upgrading to Ubuntu 12.04, it no longer worked: Either nothing was delivered from the virtual() command, or (in connection with framesets) it even ended up in binary gibberish. Trying to figure out what happens, I played with a lot of things. I first thought MultiViews was (somehow) not available anymore -- but calling http://<server>/central/foobar showed the right variant, depending on the configured language preferences. This also proved there was nothing wrong with file permissions. The error.log gave no clues either (no error message thrown). Finally, just as a "last ressort", I changed the PHP command to <? virtual("central/foobar.html"); ?> -- and that very same file was in fact included. But the language dependend stuff obviously did no longer work. Of course I tried to find some change (most likely in PHP's virtual() command), using Google a lot, and also searching the questions here -- unfortunately to no avail. Finally: The question Putting "design questions" aside (surely today I would design things differently -- but at least currently I miss the time to change that for a quite huge amount of pages): What can be done to make it work again? I surely missed something -- but I cannot figure out what...

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  • Ajaxy

    - by Chris Skardon
    Today is the big day, the day I attempt to use Ajax in the app… I’ve never done this (well, tell a lie, I’ve done it in a ‘tutorial’ site, but that was a while ago now), so it’s going to be interesting.. OK, basics first, let’s start with the @Ajax.ActionLink Right, first stab: @Ajax.ActionLink("Click to get latest", "LatestEntry", new AjaxOptions { UpdateTargetId = "ajaxEntrant", InsertionMode = InsertionMode.Replace, HttpMethod = "GET" }) As far as I’m aware, I’m asking to get the ‘LatestEntry’ from the current controller, and in doing so, I will replace the #ajaxEntrant DOM bit with the result. So. I guess I’d better get the result working… To the controller! public PartialResult LatestEntry() { var entrant =_db.Entrants.OrderByDescending(e => e.Id).Single(); return PartialView("_Entrant", entrant); } Pretty simple, just returns the last entry in a PartialView… but! I have yet to make my partial view, so onto that! @model Webby.Entrant <div class="entrant"> <h4>@Model.Name</h4> </div> Again, super simple, (I’m really just testing at this point)… All the code is now there (as far as I know), so F5 and in… And once again, in the traditionally disappointing way of the norm, it doesn’t work, sure… it opens the right view, but it doesn’t replace the #ajaxEntry DOM element, rather it replaces the whole page… The source code (again, as far as I know) looks ok: <a data-ajax="true" data-ajax-method="GET" data-ajax-mode="replace" data-ajax-update="#ajaxEntrants" href="/Entrants/LatestEntrant">Click to get latest</a> Changing the InsertionMode to any of the other modes has the same effect.. It’s not the DOM name either, changing that has the same effect.. i.e. none. It’s not the partial view either, just making that a <p> has (again) no effect… Ahhhhh --- what a schoolboy error… I had neglected (ahem) to actually put the script bit into the calling page (another save from stackoverflow): <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.js")" type="text/javascript"></script> I’ve now stuck that into the _Layout.cshtml view temporarily to aid the development process… :) Onwards and upwards! Chris

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  • Programming and Ubiquitous Language (DDD) in a non-English domain

    - by Sandor Drieënhuizen
    I know there are some questions already here that are closely related to this subject but none of them take Ubiquitous Language as the starting point so I think that justifies this question. For those who don't know: Ubiquitous Language is the concept of defining a (both spoken and written) language that is equally used across developers and domain experts to avoid inconsistencies and miscommunication due to translation problems and misunderstanding. You will see the same terminology show up in code, conversations between any team member, functional specs and whatnot. So, what I was wondering about is how to deal with Ubiquitous Language in non-English domains. Personally, I strongly favor writing programming code in English completely, including comments but ofcourse excluding constants and resources. However, in a non-English domain, I'm forced to make a decision either to: Write code reflecting the Ubiquitous Language in the natural language of the domain. Translate the Ubiquitous Language to English and stop communicating in the natural language of the domain. Define a table that defines how the Ubiquitous Language translates to English. Here are some of my thoughts based on these options: 1) I have a strong aversion against mixed-language code, that is coding using type/member/variable names etc. that are non-English. Most programming languages 'breathe' English to a large extent and most of the technical literature, design pattern names etc. are in English as well. Therefore, in most cases there's just no way of writing code entirely in a non-English language so you end up with mixed languages anyway. 2) This will force the domain experts to start thinking and talking in the English equivalent of the UL, something that will probably not come naturally to them and therefore hinders communication significantly. 3) In this case, the developers communicate with the domain experts in their native language while the developers communicate with each other in English and most importantly, they write code using the English translation of the UL. I'm sure I don't want to go for the first option and I think option 3 is much better than option 2. What do you think? Am I missing other options? UPDATE Today, about year later, having dealt with this issue on a daily basis, I have to say that option 3 has worked out pretty well for me. It wasn't as tedious as I initially feared and translating in real time while talking to the client wasn't a problem either. I also found the following advantages to be true, based on my experience. Translating the UL makes you pay more attention to defining the UL and even the domain itself, especially when you don't know how to translate a term and you have to start looking through dictionaries etc. This has even caused me to reconsider domain modeling decisions a few times. It helps you make your knowledge of the English language more profound. Obviously, your code is much more pleasant to look at instead of being a mind boggling obscenity.

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  • Stairway to XML: Level 7 - Updating Data in an XML Instance

    You need to provide the necessary keywords and define the XQuery and value expressions in your XML DML expression in order to use the modify() method to update element and attribute values in either typed or untyped XML instances in an XML column. Robert Sheldon explains how. "It really helped us isolate where we were experiencing a bottleneck"- John Q Martin, SQL Server DBA. Get started with SQL Monitor today to solve tricky performance problems - download a free trial

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  • SQL Server 2008 Designer Behavior Change: Saving Changes Not Permitted

    - by SAMIR BHOGAYTA
    Warning Message: Saving changes is not permitted. The changes you have made require the following tables to be dropped and re-created. You have either made changes to a table that can't be re-created or enabled the option Prevent saving changes that require the table to be re-created. This is by design and can be quickly fixed in Management Studio by unchecking a property. To fix this in Management Studio, go to Tools - Options then go to the Designer Page and uncheck "Prevent saving changes that require table re-creation"

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  • Car-like Physics - Basic Maths to Simulate Steering

    - by Reanimation
    As my program stands I have a cube which I can control using keyboard input. I can make it move left, right, up, down, back, fourth along the axis only. I can also rotate the cube either left or right; all the translations and rotations are implemented using glm. if (keys[VK_LEFT]) //move cube along xAxis negative { globalPos.x -= moveCube; keys[VK_RIGHT] = false; } if (keys[VK_RIGHT]) //move cube along xAxis positive { globalPos.x += moveCube; keys[VK_LEFT] = false; } if (keys[VK_UP]) //move cube along yAxis positive { globalPos.y += moveCube; keys[VK_DOWN] = false; } if (keys[VK_DOWN]) //move cube along yAxis negative { globalPos.y -= moveCube; keys[VK_UP] = false; } if (FORWARD) //W - move cube along zAxis positive { globalPos.z += moveCube; BACKWARD = false; } if (BACKWARD) //S- move cube along zAxis negative { globalPos.z -= moveCube; FORWARD = false; } if (ROT_LEFT) //rotate cube left { rotX +=0.01f; ROT_LEFT = false; } if (ROT_RIGHT) //rotate cube right { rotX -=0.01f; ROT_RIGHT = false; } I render the cube using this function which handles the shader and position on screen: void renderMovingCube(){ glUseProgram(myShader.handle()); GLuint matrixLoc4MovingCube = glGetUniformLocation(myShader.handle(), "ProjectionMatrix"); glUniformMatrix4fv(matrixLoc4MovingCube, 1, GL_FALSE, &ProjectionMatrix[0][0]); glm::mat4 viewMatrixMovingCube; viewMatrixMovingCube = glm::lookAt(camOrigin,camLookingAt,camNormalXYZ); ModelViewMatrix = glm::translate(viewMatrixMovingCube,globalPos); ModelViewMatrix = glm::rotate(ModelViewMatrix,rotX, glm::vec3(0,1,0)); //manually rotate glUniformMatrix4fv(glGetUniformLocation(myShader.handle(), "ModelViewMatrix"), 1, GL_FALSE, &ModelViewMatrix[0][0]); movingCube.render(); glUseProgram(0); } The glm::lookAt function always points to the screens centre (0,0,0). The globalPos is a glm::vec3 globalPos(0,0,0); so when the program executes, renders the cube in the centre of the screens viewing matrix; the keyboard inputs above adjust the globalPos of the moving cube. The glm::rotate is the function used to rotate manually. My question is, how can I make the cube go forwards depending on what direction the cube is facing.... ie, once I've rotated the cube a few degrees using glm, the forwards direction, relative to the cube, is no longer on the z-Axis... how can I store the forwards direction and then use that to navigate forwards no matter what way it is facing? (either using vectors that can be applied to my code or some handy maths). Thanks.

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  • Merge replication stopping without errors in SQL 2008 R2

    - by Rob Farley
    A non-SQL MVP friend of mine, who also happens to be a client, asked me for some help again last week. I was planning on writing this up even before Rob Volk (@sql_r) listed his T-SQL Tuesday topic for this month. Earlier in the year, I (well, LobsterPot Solutions, although I’d been the person mostly involved) had helped out with a merge replication problem. The Merge Agent on the subscriber was just stopping every time, shortly after it started. With no errors anywhere – not in the Windows Event Log, the SQL Agent logs, not anywhere. We’d managed to get the system working again, but didn’t have a good reason about what had happened, and last week, the problem occurred again. I asked him about writing up the experience in a blog post, largely because of the red herrings that we encountered. It was an interesting experience for me, also because I didn’t end up touching my computer the whole time – just tapping on my phone via Twitter and Live Msgr. You see, the thing with replication is that a useful troubleshooting option is to reinitialise the thing. We’d done that last time, and it had started to work again – eventually. I say eventually, because the link being used between the sites is relatively slow, and it took a long while for the initialisation to finish. Meanwhile, we’d been doing some investigation into what the problem could be, and were suitably pleased when the problem disappeared. So I got a message saying that a replication problem had occurred again. Reinitialising wasn’t going to be an option this time either. In this scenario, the subscriber having the problem happened to be in a different domain to the publisher. The other subscribers (within the domain) were fine, just this one in a different domain had the problem. Part of the problem seemed to be a log file that wasn’t being backed up properly. They’d been trying to back up to a backup device that had a corruption, and the log file was growing. Turned out, this wasn’t related to the problem, but of course, any time you’re troubleshooting and you see something untoward, you wonder. Having got past that problem, my next thought was that perhaps there was a problem with the account being used. But the other subscribers were using the same account, without any problems. The client pointed out that that it was almost exactly six months since the last failure (later shown to be a complete red herring). It sounded like something might’ve expired. Checking through certificates and trusts showed no sign of anything, and besides, there wasn’t a problem running a command-prompt window using the account in question, from the subscriber box. ...except that when he ran the sqlcmd –E –S servername command I recommended, it failed with a Named Pipes error. I’ve seen problems with firewalls rejecting connections via Named Pipes but letting TCP/IP through, so I got him to look into SQL Configuration Manager to see what kind of connection was being preferred... Everything seemed fine. And strangely, he could connect via Management Studio. Turned out, he had a typo in the servername of the sqlcmd command. That particular red herring must’ve been reflected in his cheeks as he told me. During the time, I also pinged a friend of mine to find out who I should ask, and Ted Kruger (@onpnt) ‘s name came up. Ted (and thanks again, Ted – really) reconfirmed some of my thoughts around the idea of an account expiring, and also suggesting bumping up the logging to level 4 (2 is Verbose, 4 is undocumented ridiculousness). I’d just told the client to push the logging up to level 2, but the log file wasn’t appearing. Checking permissions showed that the user did have permission on the folder, but still no file was appearing. Then it was noticed that the user had been switched earlier as part of the troubleshooting, and switching it back to the real user caused the log file to appear. Still no errors. A lot more information being pushed out, but still no errors. Ted suggested making sure the FQDNs were okay from both ends, in case the servers were unable to talk to each other. DNS problems can lead to hassles which can stop replication from working. No luck there either – it was all working fine. Another server started to report a problem as well. These two boxes were both SQL 2008 R2 (SP1), while the others, still working, were SQL 2005. Around this time, the client tried an idea that I’d shown him a few years ago – using a Profiler trace to see what was being called on the servers. It turned out that the last call being made on the publisher was sp_MSenumschemachange. A quick interwebs search on that showed a problem that exists in SQL Server 2008 R2, when stored procedures have more than 4000 characters. Running that stored procedure (with the same parameters) manually on SQL 2005 listed three stored procedures, the first of which did indeed have more than 4000 characters. Still no error though, and the problem as listed at http://support.microsoft.com/kb/2539378 describes an error that should occur in the Event log. However, this problem is the type of thing that is fixed by a reinitialisation (because it doesn’t need to send the procedure change across as a transaction). And a look in the change history of the long stored procs (you all keep them, right?), showed that the problem from six months earlier could well have been down to this too. Applying SP2 (with sufficient paranoia about backups and how to get back out again if necessary) fixed the problem. The stored proc changes went through immediately after the service pack was applied, and it’s been running happily since. The funny thing is that I didn’t solve the problem. He had put the Profiler trace on the server, and had done the search that found a forum post pointing at this particular problem. I’d asked Ted too, and although he’d given some useful information, nothing that he’d come up with had actually been the solution either. Sometimes, asking for help is the most useful thing you can do. Often though, you don’t end up getting the help from the person you asked – the sounding board is actually what you need. @rob_farley

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  • Looking for tips on managing complexity with SCM repositories

    - by Philip Regan
    I am a solo developer in my department and I have a lot of individual projects, all created and managed by me. I started using SVN at ProjectLocker via Versions on the Mac a couple years ago when the variety of projects started getting unwieldy. Scenario 1: Now I have a process that is of reasonable complexity it can be broken up into multiple smaller applications and they all share files. In one phase, there is a single shared file—a constants file—that is shared between a Cocoa app and an iPhone app framework. In the second phase, the iPhone app framework will be used to create individual apps of the same ilk—controller classes and what not will all be the same—but with different content in each. The problem that I am running across is that the file in the first phase is in one repository with the application that started it, and the app framework is in a second, separate repository. Scenario 2: I have another application framework that partially relies on code from an open source project. This is all internal, non-commerical work, but again, the application framework is going to be used to create a variety of unique products and processes. So, now I have an internally managed repository and an externally managed one out of my control. I make little changes to the open source code to meet the needs of my framework when there is an update I download, but I never commit back into the external repository (though, now that I think about it, I don't think I'm committing it to mine either. Oops). The Problem I have all of this set up on my production Mac quite nicely, but duplicating and subsequently maintaining that environment on my laptop has been challenging. For Scenario 1, I've thought of merging these two projects together into the same repository because they are, for all intents and purposes inextricably linked. But, Scenario 2, I think I'm stuck just managing files as best I can. The Question I'm wondering if anyone has any tips on how to manage either of these situations, as well as other complex SCM scenarios when it comes to linking various files from various repositories together. My familiarity with SVN only comes from my work with Versions. It's been great, but I'm a little out of my depth here.

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  • Systems Not Booting after Ubuntu installation

    - by moros
    I recently installed Ubuntu on my PC dual-booted with Windows 7. After rebooting it went through the usual startup screens, but the OS selection screen never shows up. I cannot get either system to boot. I have formatted the partition holding the Ubuntu to no avail and I really don't want to get rid of Windows. I am currently stuck using the Live session disk to boot. Any help is greatly appreciated.

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  • how to create a bootable usb on mac to install ubuntu into a formatted PC?

    - by kutayk
    hi I have a working MacBook Pro and a crashed Windows 7 PC. I was running Ubuntu on my PC but after a recurrent issue now I can't boot either OS. I would like to install only ubuntu to my PC and will make Windows 7 history for good. But I am a bit puzzled with cretatinf bootable usb options on the website. If I create a bootable USB on my MAc following the instructions for MAc OS, would it boot in A PC?

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  • Dell Inspiron 1501 no wired/wireless w/12.04 or13.04

    - by Niven
    I don't know what to do. Every install of either 13.04 and 12.04 on my Dell does not have a working wired or wireless internet connection. However, if I am running from USB in the trial mode I have working internet through a wired connection using the same ethernet cord. I honestly at this point do not know what I can do to fix this issue as I have gone through every possible fix I have found here and in other places.

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  • Connect Spotlight: Rename Instance Name

    - by Lara Rubbelke
    Every now and then customers ask me how they can suggest changes or behavior changes to SQL Server. Many of us are aware of Connect , where you can add feature recommendations and vote on other people’s suggestions. There are a LOT of recommendations, and I know Microsoft values your feedback and suggestions. Sometimes these recommendations are grand, and others are small – in either case, your votes do make a difference on how Microsoft prioritizes features and changes in future releases. Recently,...(read more)

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  • Static site generator with web-based file manager?

    - by user234
    I'm checking around options of static web site generators which led me to lots of articles about them! However, no word is spoken on how to edit files through a browser; it's always assumed you have either DropBox or some FTPish or terminal access. The only generator I could find that includes a browser based admin screen is Kirby (getkirby.com, mentioned at modernstatic.com) Besides the application above, what setup would you recommend to have both static HTML generation and web-based file management? Thanks!

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  • Why can't I link my Skype contacts with the rest in Empathy?

    - by Arturo Torres Sánchez
    I'm using Skype in Empathy thanks to telepathy-haze and pidgin-skype. I've also added MSN, Jabber (Gtalk), and Facebook. When I link contacts from MSN, Gtalk, and Facebook, there's no problem, but if I include a Skype contact, either nothing happens or Empathy crashes and after restarting I see that the Skype contact was never linked. Is the fact that Skype is not natively supported in Telepathy a problem for linking?

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  • What is good for Asp.net developer alternative learning Android or Wordpress? [closed]

    - by satinder singh
    I am a .Net developer, having 2 years experience in ASP.net c#, sql, mysql, now my company provide me to learn new technology. They gave me two options ie Android or Wordpress (I know both are totally different things). Also I found Android (Java) syntax little same as in c#, Wordpress also have good advantage in today's market (freelancing). So I want someone to suggest me what to choose either to go for Android or Wordpress?

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  • 7 Things that High Availability is Not

    Wesley has heard High Availablity touted as all sorts of technological cure-all for busy SysAdmins and DBAs, and now he's taking a stand against it. There are a range of things that High Availability is regularly confused with (either deliberately or innocently), and Wesley's clearing it all up The Future of SQL Server Monitoring "Being web-based, SQL Monitor 2.0 enables you to check on your servers from almost any location" Jonathan Allen.Try SQL Monitor now.

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  • How to take first step for making 2d games in Xcode [on hold]

    - by josh
    I have 2 years experience in Xcode in business and socials Apps. Now I am going into 2d game development so I want to know that how to take first step for making 2d games in Xcode either using external framework or its native iOS games. Looking for game like angry bird. What are the key points I should keep in mind before jumping into 2d games development. Any suggestion or related helping materials share with me. Thanks.

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  • Basic tutorial/introduction for 3d matrices, idealy in c++, without openGl or directX

    - by René Nyffenegger
    I am wondering if there is a simple tutorial that covers the basics of how to initialize rotation, translation and projection matrices, and how to multiply them, and how to get the screen coordinates afterwards for a 3d point. Idealy, the tutorial comes with compilable code and is not dependent on any 3rd party library. Searching the internet, I found lots of tutorials, so this is not the problem. Yet, it seemed all of these either covered openGl or directX, or they were theoretical in nature.

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  • How do you get out of "Flash movie keystroke capture" without a mouse?

    - by dan
    When you browse the web with either Chrome or Firefox and you find a Flash movie or TV show player (e.g. on Hulu), the movie will capture a lot of your keyboard input if you activate it somehow. You can still do basic things like ALT+Tab to switch apps, but basically any web browser keyboard shortcut is inaccessible until you use a mouse to click outside the Flash embed. Is there any way to escape the Flash movie without a mouse?

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  • Aptronyms: fitting the profession to the name

    - by Tony Davis
    Writing a recent piece on the pains of index fragmentation, I found myself wondering why, in SQL Server, you can’t set the equivalent of a fill factor, on a heap table. I scratched my head…who might know? Phil Factor, of course! I approached him with a due sense of optimism only to find that not only did he not know, he also didn’t seem to care much either. I skulked off thinking how this may be the final nail in the coffin of nominative determinism. I’ve always wondered if there was anything in it, though. If your surname is Plumb or Leeks, is there even a tiny, extra percentage chance that you’ll end up fitting bathrooms? Some examples are quite common. I’m sure we’ve all met teachers called English or French, or lawyers called Judge or Laws. I’ve also known a Doctor called Coffin, a Urologist called Waterfall, and a Dentist called Dentith. Two personal favorites are Wolfgang Wolf who ended up managing the German Soccer team, Wolfsburg, and Edmund Akenhead, a Crossword Editor for The Times newspaper. Having forgiven Phil his earlier offhandedness, I asked him for if he knew of any notable examples. He had met the famous Dr. Batty and Dr. Nutter, both Psychiatrists, knew undertakers called Death and Stiff, had read a book by Frederick Page-Turner, and suppressed a giggle at the idea of a feminist called Gurley-Brown. He even managed to better my Urologist example, citing the article on incontinence in the British Journal of Urology (vol.49, pp.173-176, 1977) by A. J. Splatt and D. Weedon. What, however, if you were keen to gently nudge your child down the path to a career in IT? What name would you choose? Subtlety probably doesn’t really work, although in a recent interview, Rodney Landrum did congratulate PowerShell MVP Max Trinidad on being named after a SQL function. Grant “The Memory” Fritchey (OK, I made up that nickname) doesn’t do badly either. Some surnames, seem to offer a natural head start, although I know of no members of the Page-Reid clan in the profession. There are certainly families with the Table surname, although sadly, Little Bobby Tables was merely a legend by xkcd. A member of the well-known Key family would need to name their son Primary, or maybe live abroad, to make their mark. Nominate your examples of people seemingly destined, by name, for their chosen profession (extra points for IT). The best three will receive a prize. Cheers, Tony.

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  • Is throwing an error in unpredictable subclass-specific circumstances a violation of LSP?

    - by Motti Strom
    Say, I wanted to create a Java List<String> (see spec) implementation that uses a complex subsystem, such as a database or file system, for its store so that it becomes a simple persistent collection rather than an basic in-memory one. (We're limiting it specifically to a List of Strings for the purposes of discussion, but it could extended to automatically de-/serialise any object, with some help. We can also provide persistent Sets, Maps and so on in this way too.) So here's a skeleton implementation: class DbBackedList implements List<String> { private DbBackedList() {} /** Returns a list, possibly non-empty */ public static getList() { return new DbBackedList(); } public String get(int index) { return Db.getTable().getRow(i).asString(); // may throw DbExceptions! } // add(String), add(int, String), etc. ... } My problem lies with the fact that the underlying DB API may encounter connection errors that are not specified in the List interface that it should throw. My problem is whether this violates Liskov's Substitution Principle (LSP). Bob Martin actually gives an example of a PersistentSet in his paper on LSP that violates LSP. The difference is that his newly-specified Exception there is determined by the inserted value and so is strengthening the precondition. In my case the connection/read error is unpredictable and due to external factors and so is not technically a new precondition, merely an error of circumstance, perhaps like OutOfMemoryError which can occur even when unspecified. In normal circumstances, the new Error/Exception might never be thrown. (The caller could catch if it is aware of the possibility, just as a memory-restricted Java program might specifically catch OOME.) Is this therefore a valid argument for throwing an extra error and can I still claim to be a valid java.util.List (or pick your SDK/language/collection in general) and not in violation of LSP? If this does indeed violate LSP and thus not practically usable, I have provided two less-palatable alternative solutions as answers that you can comment on, see below. Footnote: Use Cases In the simplest case, the goal is to provide a familiar interface for cases when (say) a database is just being used as a persistent list, and allow regular List operations such as search, subList and iteration. Another, more adventurous, use-case is as a slot-in replacement for libraries that work with basic Lists, e.g if we have a third-party task queue that usually works with a plain List: new TaskWorkQueue(new ArrayList<String>()).start() which is susceptible to losing all it's queue in event of a crash, if we just replace this with: new TaskWorkQueue(new DbBackedList()).start() we get a instant persistence and the ability to share the tasks amongst more than one machine. In either case, we could either handle connection/read exceptions that are thrown, perhaps retrying the connection/read first, or allow them to throw and crash the program (e.g. if we can't change the TaskWorkQueue code).

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  • IDE for visually impaired

    - by Eli Rosencruft
    A visually impaired colleague has asked me to recommend an IDE with easy-to-find and easy-to-use controls for: font size background and foreground colors changing syntax color scheme support for at least C/C++ and Java He would prefer an IDE that is either portable or that has similar versions for Linux, Windows and Mac. He prefers a dark background and light colored fonts and needs to sit very close to the display.

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