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• Cannot assign keys to Wacom scroll wheel anymore

  - by UncleZeiv

  Hi all, my Wacom Graphire 4 used to work perfectly well until, I think, Ubuntu 10.4. At that point something changed in the configuration and I couldn't assign a key to the scroll wheel anymore (note: the pad's scroll wheel, not the mouse's), i.e this command: xsetwacom set "Wacom Graphire4 6x8 pad" AbsWDn "key +" returns silently without error but nothing happens. Same goes for AbsWUp, RelWDn, RelWUp. Apparently though the problem is even deeper as pressing the wheel in a xev window doesn't seem to have any effect. Moreover I am thoroughly confused on how the various pieces (kernel driver, xorg driver, evdev, HAL, xinput?) are supposed to work together and if the wacom module that ships with Ubuntu is the one from linuxwacom or not. Any ideas? I don't want to become an X.org hacker just to understand what's going on... it used to work! NOTE: I have already read question 3940, but that's not the same problem.

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• Why write clean, refactored code?

  - by Shamal Karunarathne

  Hi programming lovers, This is a question I've been asking myself for a long time. Thought of throwing out it to you. From my experience of working on several Java based projects, I've seen tons of codes which we call 'dirty'. The unconventional class/method/field naming, wrong way of handling of exceptions, unnecessarily heavy loops and recursion etc. But the code gives the intended results. Though I hate to see dirty code, it's time taking to clean them up and eventually comes the question of "is it worth? it's giving the desired results so what's the point of cleaning?" In team projects, should there be someone specifically to refactor and check for clean code? Or are there situations where the 'dirty' codes fail to give intended results or make the customers unhappy? Do feel free to comment and reply. And tell me if I'm missing something here. Thanks.

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• Simple question about a cocos2d based game template

  - by Zishan

  I am learning a cocos2d based Game template tutorial from here and now I am at this point of the tutorial. My question is, how can i run 30 different scenes in 30 different levels of 5 chapter? Now I am using this switch (gameData.selectedLevel) { case 1: [SceneManager goChapter1Level1Scene]; break; (... snip a whole lot of lines...) case 30: [SceneManager goChapter5Level6Scene]; break; default: break; } in the "- (void) onPlay: (CCMenuItemImage*) sender" method. But it work only for 6 levels scene of chapter1. Other 4 chapters levels are show as same as 1st chapter levels scene. they are not show their own level scene. can any one please teach me, how can I do this stuff using this game template?

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• Data-tier Applications in SQL Server 2008 R2

  - by BuckWoody

  I had the privilege of presenting to the Adelaide SQL Server User Group in Australia last evening, and I covered the Data Access Component (DAC) and the Utility Control Point (UCP) from SQL Server 2008 R2. Here are some links from that presentation:   Whitepaper: http://msdn.microsoft.com/en-us/library/ff381683.aspx Tutorials: http://msdn.microsoft.com/en-us/library/ee210554(SQL.105).aspx From Visual Studio: http://msdn.microsoft.com/en-us/library/dd193245(VS.100).aspx Restrictions and capabilities by Edition: http://msdn.microsoft.com/en-us/library/cc645993(SQL.105).aspx    Glen Berry's Blog entry on scripts for UCP/DAC: http://www.sqlservercentral.com/blogs/glennberry/archive/2010/05/19/sql-server-utility-script-from-24-hours-of-pass.aspx    Objects supported by a DAC: http://msdn.microsoft.com/en-us/library/ee210549(SQL.105).aspx   Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• What is the best Video Conference integrated solution for Us? [closed]

  - by Andrei B

  we are trying to integrate a simple Video Conferencing (open source) solution into our existing application which is written in C++ and it runs on Linux. I am currently looking at using Ekiga (formely known as GnomeMeeting) or Homer Conferencing (short: Homer). My plan is to "integrate" an existing Video Conferencing client into our existing software. Please give me recommendation on which 3rd party application or library to use to add video conferencing feature to our application. PS: Please don't close this question. I asked it on StackOverflow and it got closed, so where am I supposed to ask this question? If not here, then whats the point of asking lol.

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• Drag Gestures - fractional delta values

  - by Den

  I have an issue with objects moving roughly twice as far as expected when dragging them. I am comparing my application to the standard TouchGestureSample sample from MSDN. For some reason in my application gesture samples have fractional positions and deltas. Both are using same Microsoft.Xna.Framework.Input.Touch.dll, v4.0.30319. I am running both apps using standard Windows Phone Emulator. I am setting my break point immediately after this line of code in a simple Update method: GestureSample gesture = TouchPanel.ReadGesture(); Typical values in my app: Delta = {X:-13.56522 Y:4.166667} Position = {X:184.6956 Y:417.7083} Typical values in sample app: Delta = {X:7 Y:16} Position = {X:497 Y:244} Have anyone seen this issue? Does anyone have any suggestions? Thank you.

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• Silverlight Cream Monday WP7 App Review # 1

  - by Dave Campbell

  I'm going to try something here... if it seems useful, I'll continue, if it doesn't, I'll stop... so give me feedback! There are *lots* of Apps in the WP7 Marketplace, and heaven help me, but the Marketplace sucks for finding stuff. I won't rehash what's already been said in the blogs, but I agree with one and all. I went out last Saturday to find 2 apps that I knew were released, and couldn't do so on my device. Even in the Zune app, it took quite a while to find them... ok, I'll back off a bit, because I just found out I can do 'Search' now if I know the name... I didn't think that was working before. So my thought is on Monday (like today), I will post a review of 5 apps/games I either use or have played with on my device. These are strictly my opinions, you understand, but hey... it's better than a poke in the eye with an iPhone! A few disclaimers:     Feel free to write me about your app and tell me about it. While it would be very cool to receive a whole bunch of xap files to review, at this point, for technical reasons, I'm unable to side-load my device. Since I plan on only doing this one day a week, and only 5, I may never get caught up, so if you send me some info, be patient. Re: games ... remember I'm old... I'm from the era of Colossal Cave and Zork. Duke-Nukem 2D and Captain Comic were awesome. I don't own an XBOX or any other game system, so take game reviews from my perspective -- who knows, it may be refreshing :) I won't pay for an app or game just to try it. If you expect me to test-drive your app, it's going to have to have a Free Trial. In this Issue:   Jingo! is the first app I bought, just to see what the experience was like. It's very much like a game we used to play in school in the Army in 1971 on paper we passed around. Sort of a cross between hangman and Mastermind, you try to figure out the hidden word in 5 tries. You get really good at 5-letter words after a while. I like this because you have to think, and you're not pressured by a clock Jingo! is by James Furdell and is $1.99 I reviewed René Schulte's Pictures Lab a while back, and have not changed my mind. This is an excellent app for playing with any photo on your device... one you've just taken, one you've synced from your PC, or one you've saved from email. I like this because you can get some cool effects for your photos, and it just works. Pictures Lab is by Schulte Software Development and is $1.99 Since I work as a consultant, and from home, I wanted something I could track my time with. I've test-driven all the contenders I could find so far on the phone, and so far I like ONTRACK! the best. If asked, I have some suggestions, but it's probably just the way I work or think. What I do like is I can tap a project to start/stop/restart a counter, and at the end of the day it shows me how much time I've been working. If there's a way to make an adjustment in case you forget to tap the counter, I don't know how to do it, and that's my biggest complaint. I like this because you can get a daily readout which you can also email as a spreadsheet. The daily results display is very good. ONTRACK! is by Qmino and is $2.99 Remember Item 4 above... I've been playing guitar for 48 years... obviously since before the invention of 'tuners', so I'm not as dependent upon these as some folks are. I've tried some in the past and have always felt I can do just as good by ear (I have perfect relative pitch). So, I gave this app by András Velvárt a dance just to see how it works, and it is surprisingly good. If you're used to one of the stage tuners this may take a little getting used to, but it does the job. The difference with this one is there is no real 'null' point inside which you can think your guitar is in tune. The soundwave stays visible on the device, and if it's moving to the right, your string is flat, if it's moving to the left, your string is sharp. Getting it exact might be tricky, but it is exact! If you need to rely on a tuner, this is a good choice in my opinion, exactly because of the sensitivity.. tune up with this and you're dead-on. Guitar Tuner is by Kinabalu Innovation Limited and is $0.99 Popper 2 is the WP7 version of a wildly popular game by Bill Reiss named Dr. Popper. You can get a trial, or you can now get a free lite version of the game. Popper 2 is a fast-paced bubble breaker game. I find it something fun to play when I just want to buzz out, but maybe the best review is that my daughter didn't want to give my phone back when I showed it to her, and always wants to grab my phone to play 'that game'. A fun distraction with great graphics and a great price Popper 2 is by Blue Rose Systems, LLC and is $1.29 Let me know what you think of the idea of doing reviews, or the layout/whatever, and Stay in the 'Light!   Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• Windows no longer display with proprietary ATI Catalyst drivers

  - by Insomniac

  I recently started having an issue that opening any application would would show nothing on screen. At the time I noticed it I assumed it was an incompatibility between the new 14 update so reinstalled the old 13.10 iso I used originally. I have now tried a range of ATI drivers including the latest and the exact file I installed the first time with the same results. I can only assume then that it is one of the updates applied at some point, but have no idea which one or how I would go about rolling these back or getting earlier versions of packages. Is anyone else getting this issue? The system has 2 ati 6850s installed, not in crossfire. The open source drivers work fine but I need the ATI ones for cgminer to work.

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• How to efficiently map tokens to code in a script interpreter?

  - by lithander

  I'm writing an interpreter for a simple scripting language where each line is a complete, executable command. (Like the instructions in assembler) When parsing a line I have to map the requested command to actual code. My current solution looks like this: std::string op, param1, param2; //parse line, identify op, param1, param2 ... //call command specific code if(op == "MOV") ExecuteMov(AsNumber(param1)); else if(op == "ROT") ExecuteRot(AsNumber(param1)); else if(op == "SZE") ExecuteSze(AsNumber(param1)); else if(op == "POS") ExecutePos((AsNumber(param1), AsNumber(param2)); else if(op == "DIR") ExecuteDir((AsNumber(param1), AsNumber(param2)); else if(op == "SET") ExecuteSet(param1, AsNumber(param2)); else if(op == "EVL") ... The more commands are supported the more string comparisions I'll have to do to identify and call the associated method. Can you point me to a more efficient implementation in the described scenario?

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• Do you think code is self documenting?

  - by Desolate Planet

  This is a question that was put to me many years ago as a gradute in a job interview and it's kind of picked at my brain now and again and I've never really found a good answer that satisfies me. The interviewer in question was looking for a black and white answer, there was no middle ground. I never got the chance to ask about the rationale behind the question, but I'm curious why that question would be put to a developer and what you would learn from a yes or no answer? From my own point of view, I can read Java, Python, Delphi etc, but if my manager comes up to me and asks me how far along in a project I am and I say "The code is 80% complete" (and before you start shooting me down, I've heard this uttered in a couple of offices by developers), how exactly is that self documenting? Apologies if this question seems strange, but I'd rather ask and get some opinions on it to gain a better understanding of why it would be put to someone in an interview.

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• Implementing a FSM with ActionScript 2 without using classes?

  - by Up2u

  I have seen several references of A.I. and FSM, but sadly I still can't understand the point of an FSM in AS2.0. Is it a must to create a class for each state? I have a game-project which also it has an A.I., the A.I. has 3 states: distanceCheck, ChaseTarget, and Hit the target. It's an FPS game and played via mouse. I have created the A.I. successfully, but I want to convert it to FSM method... My first state is CheckDistanceState() and in that function I look for the nearest target and trigger the function ChaseState(), there I insert the Hit() function to destroy the enemy, The 3 functions that I created are being called in AI_cursor.onEnterframe. Is there any chance to implement an FSM without the need to create a class? From what I've read before, you have to create a class. I prefer to write the code on frames in flash and I still don't understand how to have external classes.

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• How to set up an environment for android app development?

  - by The Dark Knight

  I have been researching for sometime now regarding the process to install android sdk and associated tools . After visiting Android Developers page, i first installed the android sdk and then installed eclipse plugins for my indigo version from the install softwares options.However, it is mentioned in the developers page : Download the Android SDK. Install the ADT plugin for Eclipse (if you’ll use the Eclipse IDE). Download the latest SDK tools and platforms using the SDK Manager. I have downloaded the sdk and installed the adt plugins for eclipse.I just need to point the eclipse towards the location of the sdk. However, i am stuck at the last step which is asking me to download the latest tools using the sdk manager. The manager interface pops up and i see a lot of options there. I don't know which ones i must select and install. If some one can help me out here and tell me which options to choose and install(if possible, with a screen shot), it will be very beneficial for me.

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• Isolated Unit Tests and Fine Grained Failures

  - by Winston Ewert

  One of the reasons often given to write unit tests which mock out all dependencies and are thus completely isolated is to ensure that when a bug exists, only the unit tests for that bug will fail. (Obviously, an integration tests may fail as well). That way you can readily determine where the bug is. But I don't understand why this is a useful property. If my code were undergoing spontaneous failures, I could see why its useful to readily identify the failure point. But if I have a failing test its either because I just wrote the test or because I just modified the code under test. In either case, I already know which unit contains a bug. What is the useful in ensuring that a test only fails due to bugs in the unit under test? I don't see how it gives me any more precision in identifying the bug than I already had.

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• Is this the right strategy to convert an in-level order binary tree to a doubly linked list?

  - by Ankit Soni

  So I recently came across this question - Make a function that converts a in-level-order binary tree into a doubly linked list. Apparently, it's a common interview question. This is the strategy I had - Simply do a pre-order traversal of the tree, and instead of returning a node, return a list of nodes, in the order in which you traverse them. i.e return a list, and append the current node to the list at each point. For the base case, return the node itself when you are at a leaf. so you would say left = recursive_function(node.left) right = recursive_function(node.right) return(left.append(node.data)).append(right);` Is this the right approach?

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• Recreate JoliCloud app list

  - by Josh

  I was wondering if there was any tutorial on how to recreate the pagination system used on JoliCloud. The system shows the amount of pages at the bottom along with what page you are on. It is kind of like the iOS springboard. I would like for it to get the apps via a MySQL query, but that's besides the point. I've searched Google and have found no answers on how to do this. A screen shot of the pagination system is below.

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• How to enable TRIM on LVM on Ubuntu 12.10?

  - by Siddarth Kaki

  When I reinstalled Ubuntu 12.10 64-bit on my SSD, I chose the option to use LVM in Ubiquity. I am trying to find out how to enable TRIM for my SSD. I came across this article: http://worldsmostsecret.blogspot.com/2012/04/how-to-activate-trim-on-luks-encrypted.html The article states in addition to adding discard and noatime to /etc/fstab , discard must be added to the drive (sdX_crypt) in /etc/crypttab. My problem is the only listings in my /etc/crypttab are several cryptswap; it does not list any sdX_crypt. I currently have a /dev/sda1 (ext2), which is the boot point, and /dev/mapper/ubuntu-root, which is my ext4 partition. Any ideas as to how to enable TRIM?

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• Your Next IT Job

  - by BuckWoody

  Some data professionals have worked (and plan to work) in the same place for a long time. In organizations large and small, the turnover rate just isn’t that high. This has not been my experience. About every 3-5 years I’ve changed either roles or companies. That might be due to the IT environment or my personality (or a mix of the two), but the point is that I’ve had many roles and worked for many companies large and small throughout my 27+ years in IT. At one point this might have been a detriment – a prospective employer looks at the resume and says “it seems you’ve moved around quite a bit.” But I haven’t found that to be the case all the time –in fact, in some cases the variety of jobs I’ve held has been an asset because I’ve seen what works (and doesn’t) in other environments, which can save time and money. So if you’re in the first camp – great! Stay where you are, and continue doing the work you love. but if you’re in the second, then this post might be useful. If you are planning on making a change, or perhaps you’ve hit a wall at your current location, you might start looking around for a better paying job – and there’s nothing wrong with that. We all try to make our lives better, and for some that involves more money. Money, however, isn’t always the primary motivator. I’ve gone to another job that doesn’t have as many benefits or has the same salary as the current job I’m working to gain more experience, get a better work/life balance and so on. It’s a mix of factors that only you know about. So I thought I would lay out a few advantages and disadvantages in the shops I’ve worked at. This post isn’t aimed at a single employer, but represents a mix of what I’ve experienced, and of course the opinions here are my own. You will most certainly have a different take – if so, please post a response! I also won’t mention a specific industry – I’ve worked everywhere from medical firms, legal offices, retail, billing centers, manufacturing, government, even to NASA. I’m focusing here mostly on size and composition. And I’m making some very broad generalizations here – I am fully aware that a small company might have great benefits and a large company might allow a lot of role flexibility.  your mileage may vary – and again, post those comments! Small Company To me a “small company” means around 100 people or less – sometimes a lot less. These can be really fun, frustrating places to to work. Advantages: a great deal of flexibility, a wide range of roles (often at the same time), a large degree of responsibility, immediate feedback, close relationships with co-workers, work directly with your customer. Disadvantages: Too much responsibility, little work/life balance, immature political structure, few (if any) benefits. If the business is family-owned, they can easily violate work/life boundaries. Medium Size company In my experience the next size company I would work for involves from a few hundred people to around five thousand. Advantages: Good mobility – fairly easy to get promoted, acceptable benefits, more defined responsibilities, better work/life balance, balanced load for expertise, but still the organizational structure is fairly simple to understand. Disadvantages: Pay is not always highest, rapid changes in structure as the organization grows, transient workforce. You may not be given the opportunity to work with another technology if someone already “owns” it. Politics are painful at this level as people try to learn how to do it. Large Company When you get into the tens of thousands of folks employed around the world, you’re in a large company. Advantages: Lots of room to move around – sometimes you can work (as I have) multiple jobs through the years and yet stay at the same company, building time for benefits, very defined roles, trained managers (yes, I know some of them are still awful – trust me – I DO know that), higher-end benefits, long careers possible, discounts at retailers and other “soft” benefits, prestige. For some, a higher level of politics (done professionally) is a good thing. Disadvantages: You could become another faceless name in the crowd, might not allow a great deal of flexibility,  large organizational changes might take away any control you have of your career. I’ve also seen large layoffs happen, and good people get let go while “dead weight” is retained. For some, a higher level of politics is distasteful. So what are your experiences? Share with the group! Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Need Japanese IME with Dvorak keyboard with 13.10

  - by user916792

  I recently did a fresh install of 13.10 and enabled Japanese language support. In the past this seemed to work seamlessly with my other keyboard settings when I set up my Dvorak keyboard. But this time when I toggle the IME on it uses the standard QWERTY layout. Typing English uses the Dvorak layout as I expect. This just worked for me in the past to the point where I stopped paying attention to what the underlying IME is and I don't recall any special steps other then choosing my keyboard layout and enabling Japanese. Any help would be appreciated!

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• Getting out of my head

  - by BenCole

  (I put this on SO, but it got a couple close votes saying it belonged here instead...) I've spent the last year as a single person team developing a rich-client application (35,000+ LoC, for what it's worth). It's currently stable and in production. However, I know that my skills were rusty at the beginning of the project, so without a doubt there are major issues to the code. At this point, most of the issues are in architecture, structure, or interactions - the easy problems, even architecture/design problems, have already been weeded out. Unfortunately, I've spent so much time with this project that I'm having a hard time thinking outside of it - approaching it from a new perspective to see the flaws deeply buried or inherent in the design. How do I step outside my head and outside my code so I can get a fresh look at this code so I can make it better? Is this less of an issue than I think it is, or is this a problem for other people as well?

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• What are the pro/cons of Unity3D as a choice to make games ?

  - by jokoon

  We are doing our school project with Unity3d, since they were using Shiva the previous year (which seems horrible to me), and I wanted to know your point of view for this tool. Pros: multi platform, I even heard Google is going to implement it in Chrome everything you need is here scripting languages makes it a good choice for people who are not programming gurus Cons: multiplayer ? proprietary, you are totally dependent of unity and its limit and can't extend it it's less "making a game from scratch" C++ would have been a cool thing I really think this kind of tool is interesting, but is it worth it to use at school for a project that involves more than 3 programming persons ? What do we really learn in term of programming from using this kind of tool (I'm ok with python and js, but I hate C#) ? We could have use Ogre instead, even if we were learning direct x starting january...

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• Automatically zoom out the camera to show all players

  - by user36159

  I am building a game in XNA that takes place in a rectangular arena. The game is multiplayer and each player may go where they like within the arena. The camera is a perspective camera that looks directly downwards. The camera should be automatically repositioned based on the game state. Currently, the xy position is a weighted sum of the xy positions of important entities. I would like the camera's z position to be calculated from the xy coordinates so that it zooms out to the point where all important entities are visible. My current approach is to: hw = the greatest x distance from the camera to an important entity hh = the greatest y distance from the camera to an important entity Calculate z = max(hw / tan(FoVx), hh / tan(FoVy)) My code seems to almost work as it should, but the resulting z values are always too low by a factor of about 4. Any ideas?

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• LVM and cloning HDs

  - by jcea

  Using Linux, I have several backup levels. One of them is a periodical sector by sector copy (using dd) of my laptop harddisk to an external USB disk. Yes, I have other backups too, like remote rsync. This approach (the disk dd) is OK when cloning a HDD with no LVM volumes, since I can plug the external disk anytime and mount the partitions simply mounting /dev/sdb* instead of /dev/sda*. Trivial and handy. Today I moved ALL my harddisk (including the /boot) to LVM. Everything works fine. I will stress it for a couple of days, and then I will do a sector by sector copy to my external harddisk. Now I have a problem, I guess. If in the future I plug the external USB HDD to recover any file, the OS will detect a duplicate LVM configuration, with the same name and the same UUID. Even doing a vgrename (which LVM would be renamed, the internal HDD or the external HDD?), the cloned UUID will not change. Is there any command to change name and UUID? Ideally I would clone the HDD and then change the LVM group name and its UUID, but I don't know how to do it. Another related issue would be... In the past I have booted my laptop using the external disk, using the BIOS boot menu and changing GRUB entries manually to boot from /dev/sdb instead of /dev/sda. But now my current GRUB configuration boots directly from a LVM logical volume, something like: set root='(LVM-root)' in my grub.cfg. So... What is going to happen with duplicated volumes? Any suggestion? I guess I could repartition my external harddisk and change backup strategy from dd to rsync, but this disk has windows installed too, and I really would like to have a physical "real" copy.

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• How does one pluralize <see cref="Notation">'s?

  - by Jordan

  What is the most appropriate way of writing this comment: /// <summary> /// Order - Identifies the ordinal location of this category /// relative to other listed categories. /// </summary> if I'm wanting to wrap "category" in <see> tags? I've considered: /// <summary> /// Order - Identifies the ordinal location of this <see cref="Category"/> /// relative to other listed <see cref="Category"/>'s. /// </summary> Do you see my dilemma? Edit: I should add that I am using Visual Studio's XML Comments. So I am somewhat restricted as to the schema. I believe cref has to point to a valid type reference.

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• Pointing a subdomain to Github Pages

  - by ratage

  I set up an Octopress blog on Github Pages at myusername.github.com. I now want blog.myusername.me (which currently has a Wordpress blog set up) to point to this Octopress blog. So I followed the instructions here on setting up a custom domain: I ran echo 'blog.myusername.me' >> source/CNAME in my Octopress repository, and then ran rake generate and rake deploy to deploy it to Github. I went to Namecheap, and added a new CNAME under my myusername.me domain: "blog - myusername.github.com - CNAME". Waited a couple hours. However, now when I go to myusername.github.com, it redirects me to blog.myusername.me (which is my old Wordpress blog), which seems like the inverse of what I want. (Going to blog.myusername.me directly still shows my Wordpress blog.) I checked http://www.whatsmydns.net/#CNAME/blog.myusername.me and it seems like my DNS has propagated (myusername.github.com shows up in the right-hand side). Any ideas what I'm doing wrong?

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• Using Delegates in C# (Part 1)

  - by rajbk

  This post provides a very basic introduction of delegates in C#. Part 2 of this post can be read here. A delegate is a class that is derived from System.Delegate.  It contains a list of one or more methods called an invocation list. When a delegate instance is “invoked” with the arguments as defined in the signature of the delegate, each of the methods in the invocation list gets invoked with the arguments. The code below shows example with static and instance methods respectively: Static Methods 1: using System; 2: using System.Linq; 3: using System.Collections.Generic; 4: 5: public delegate void SayName(string name); 6: 7: public class Program 8: { 9: [STAThread] 10: static void Main(string[] args) 11: { 12: SayName englishDelegate = new SayName(SayNameInEnglish); 13: SayName frenchDelegate = new SayName(SayNameInFrench); 14: SayName combinedDelegate =(SayName)Delegate.Combine(englishDelegate, frenchDelegate); 15: 16: combinedDelegate.Invoke("Tom"); 17: Console.ReadLine(); 18: } 19: 20: static void SayNameInFrench(string name) { 21: Console.WriteLine("J'ai m'appelle " + name); 22: } 23: 24: static void SayNameInEnglish(string name) { 25: Console.WriteLine("My name is " + name); 26: } 27: } We have declared a delegate of type SayName with return type of void and taking an input parameter of name of type string. On line 12, we create a new instance of this delegate which refers to a static method - SayNameInEnglish.  SayNameInEnglish has the same return type and parameter list as the delegate declaration.  Once a delegate is instantiated, the instance will always refer to the same target. Delegates are immutable. On line 13, we create a new instance of the delegate but point to a different static method. As you may recall, a delegate instance encapsulates an invocation list. You create an invocation list by combining delegates using the Delegate.Combine method (there is an easier syntax as you will see later). When two non null delegate instances are combined, their invocation lists get combined to form a new invocation list. This is done in line 14.  On line 16, we invoke the delegate with the Invoke method and pass in the required string parameter. Since the delegate has an invocation list with two entries, each of the method in the invocation list is invoked. If an unhandled exception occurs during the invocation of one of these methods, the exception gets bubbled up to the line where the invocation was made (line 16). If a delegate is null and you try to invoke it, you will get a System.NullReferenceException. We see the following output when the method is run: My name is TomJ'ai m'apelle Tom Instance Methods The code below outputs the same results as before. The only difference here is we are creating delegates that point to a target object (an instance of Translator) and instance methods which have the same signature as the delegate type. The target object can never be null. We also use the short cut syntax += to combine the delegates instead of Delegate.Combine. 1: public delegate void SayName(string name); 2: 3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: Translator translator = new Translator(); 9: SayName combinedDelegate = new SayName(translator.SayNameInEnglish); 10: combinedDelegate += new SayName(translator.SayNameInFrench); 11:  12: combinedDelegate.Invoke("Tom"); 13: Console.ReadLine(); 14: } 15: } 16: 17: public class Translator { 18: public void SayNameInFrench(string name) { 19: Console.WriteLine("J'ai m'appelle " + name); 20: } 21: 22: public void SayNameInEnglish(string name) { 23: Console.WriteLine("My name is " + name); 24: } 25: } A delegate can be removed from a combination of delegates by using the –= operator. Removing a delegate from an empty list or removing a delegate that does not exist in a non empty list will not result in an exception. Delegates are invoked synchronously using the Invoke method. We can also invoke them asynchronously using the BeginInvoke and EndInvoke methods which are compiler generated.

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