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• MVVM Light V4 preview 2 (BL0015) #mvvmlight

  - by Laurent Bugnion

  Over the past few weeks, I have worked hard on a few new features for MVVM Light V4. Here is a second early preview (consider this pre-alpha if you wish). The features are unit-tested, but I am now looking for feedback and there might be bugs! Bug correction: Messenger.CleanupList is now thread safe This was an annoying bug that is now corrected: In some circumstances, an exception could be thrown when the Messenger’s recipients list was cleaned up (i.e. the “dead” instances were removed). The method is called now and then and the exception was thrown apparently at random. In fact it was really a multi-threading issue, which is now corrected. Bug correction: AllowPartiallyTrustedCallers prevents EventToCommand to work This is a particularly annoying regression bug that was introduced in BL0014. In order to allow MVVM Light to work in XBAPs too, I added the AllowPartiallyTrustedCallers attribute to the assemblies. However, we just found out that this causes issues when using EventToCommand. In order to allow EventToCommand to continue working, I reverted to the previous state by removing the AllowPartiallyTrustedCallers attribute for now. I will work with my friends at Microsoft to try and find a solution. Stay tuned. Bug correction: XML documentation file is now generated in Release configuration The XML documentation file was not generated for the Release configuration. This was a simple flag in the project file that I had forgotten to set. This is corrected now. Applying EventToCommand to non-FrameworkElements This feature has been requested in order to be able to execute a command when a Storyboard is completed. I implemented this, but unfortunately found out that EventToCommand can only be added to Storyboards in Silverlight 3 and Silverlight 4, but not in WPF or in Windows Phone 7. This obviously limits the usefulness of this change, but I decided to publish it anyway, because it is pretty damn useful in Silverlight… Why not in WPF? In WPF, Storyboards added to a resource dictionary are frozen. This is a feature of WPF which allows to optimize certain objects for performance: By freezing them, it is a contract where we say “this object will not be modified anymore, so do your perf optimization on them without worrying too much”. Unfortunately, adding a Trigger (such as EventTrigger) to an object in resources does not work if this object is frozen… and unfortunately, there is no way to tell WPF not to freeze the Storyboard in the resources… so there is no way around that (at least none I can see. In Silverlight, objects are not frozen, so an EventTrigger can be added without problems. Why not in WP7? In Windows Phone 7, there is a totally different issue: Adding a Trigger can only be done to a FrameworkElement, which Storyboard is not. Here I think that we might see a change in a future version of the framework, so maybe this small trick will work in the future. Workaround? Since you cannot use the EventToCommand on a Storyboard in WPF and in WP7, the workaround is pretty obvious: Handle the Completed event in the code behind, and call the Command from there on the ViewModel. This object can be obtained by casting the DataContext to the ViewModel type. This means that the View needs to know about the ViewModel, but I never had issues with that anyway. New class: NotifyPropertyChanged Sometimes when you implement a model object (for example Customer), you would like to have it implement INotifyPropertyChanged, but without having all the frills of a ViewModelBase. A new class named NotifyPropertyChanged allows you to do that. This class is a simple implementation of INotifyPropertyChaned (with all the overloads of RaisePropertyChanged that were implemented in BL0014). In fact, ViewModelBase inherits NotifyPropertyChanged. ViewModelBase does not implement IDisposable anymore The IDisposable interface and the Dispose method had been marked obsolete in the ViewModelBase class already in V3. Now they have been removed. Note: By this, I do not mean that IDisposable is a bad interface, or that it shouldn’t be used on viewmodels. In the contrary, I know that this interface is very useful in certain circumstances. However, I think that having it by default on every instance of ViewModelBase was sending a wrong message. This interface has a strong meaning in .NET: After Dispose has been executed, the instance should not be used anymore, and should be ready for garbage collection. What I really wanted to have on ViewModelBase was rather a simple cleanup method, something that can be executed now and then during runtime. This is fulfilled by the ICleanup interface and its Cleanup method. If your ViewModels need IDisposable, you can still use it! You will just have to implement the interface on the class itself, because it is not available on ViewModelBase anymore. What’s next? I have a couple exciting new features implemented already but that need more testing before they go live… Just stay tuned and by MIX11 (12-14 April 2011), we should see at least a major addition to MVVM Light Toolkit, as well as another smaller feature which is pretty cool nonetheless More about this later! Happy Coding Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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• SQL Server devs–what source control system do you use, if any? (answer and maybe win free stuff)

  - by jamiet

  Recently I noticed a tweet from notable SQL Server author and community dude-at-large Steve Jones in which he asked how many SQL Server developers were putting their SQL Server source code (i.e. DDL) under source control (I’m paraphrasing because I can’t remember the exact tweet and Twitter’s search functionality is useless). The question surprised me slightly as I thought a more pertinent question would be “how many SQL Server developers are not using source control?” because I have been doing just that for many years now and I simply assumed that use of source control is a given in this day and age. Then I started thinking about it. “Perhaps I’m wrong” I pondered, “perhaps the SQL Server folks that do use source control in their day-to-day jobs are in the minority”. So, dear reader, I’m interested to know a little bit more about your use of source control. Are you putting your SQL Server code into a source control system? If so, what source control server software (e.g. TFS, Git, SVN, Mercurial, SourceSafe, Perforce) are you using? What source control client software are you using (e.g. TFS Team Explorer, Tortoise, Red Gate SQL Source Control, Red Gate SQL Connect, Git Bash, etc…)? Why did you make those particular software choices? Any interesting anecdotes to share in regard to your use of source control and SQL Server? To encourage you to contribute I have five pairs of licenses for Red Gate SQL Source Control and Red Gate SQL Connect to give away to what I consider to be the five best replies (“best” is totally subjective of course but this is my blog so my decision is final ), if you want to be considered don’t forget to leave contact details; email address, Twitter handle or similar will do. To start you off and to perhaps get the brain cells whirring, here are my answers to the questions above: Are you putting your SQL Server code into a source control system? As I think I’ve already said…yes. Always. If so, what source control server software (e.g. TFS, Git, SVN, Mercurial, SourceSafe, Perforce) are you using? I move around a lot between many clients so it changes on a fairly regular basis; my current client uses Team Foundation Server (aka TFS) and as part of a separate project is trialing the use of Team Foundation Service. I have used SVN extensively in the past which I am a fan of (I generally prefer it to TFS) and am trying to get my head around Git by using it for ObjectStorageHelper. What source control client software are you using (e.g. TFS Team Explorer, Tortoise, Red Gate SQL Source Control, Red Gate SQL Connect, Git Bash, etc…)? On my current project, Team Explorer. In the past I have used Tortoise to connect to SVN. Why did you make those particular software choices? I generally use whatever the client uses and given that I work with SQL Server I find that the majority of my clients use TFS, I guess simply because they are Microsoft development shops. Any interesting anecdotes to share in regard to your use of source control and SQL Server? Not an anecdote as such but I am going to share some frustrations about TFS. In many ways TFS is a great product because it integrates many separate functions (source control, work item tracking, build agents) into one whole and I’m firmly of the opinion that that is a good thing if for no reason other than being able to associate your check-ins with a work-item. However, like many people there are aspects to TFS source control that annoy me day-in, day-out. Chief among them has to be the fact that it uses a file’s read-only property to determine if a file should be checked-out or not and, if it determines that it should, it will happily do that check-out on your behalf without you even asking it to. I didn’t realise how ridiculous this was until I first used SVN about three years ago – with SVN you make any changes you wish and then use your source control client to determine which files have changed and thus be checked-in; the notion of “check-out” doesn’t even exist. That sounds like a small thing but you don’t realise how liberating it is until you actually start working that way. Hoping to hear some more anecdotes and opinions in the comments. Remember….free software is up for grabs! @jamiet 

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• Fun With the Chrome JavaScript Console and the Pluralsight Website

  - by Steve Michelotti

  Originally posted on: http://geekswithblogs.net/michelotti/archive/2013/07/24/fun-with-the-chrome-javascript-console-and-the-pluralsight-website.aspxI’m currently working on my third course for Pluralsight. Everyone already knows that Scott Allen is a “dominating force” for Pluralsight but I was curious how many courses other authors have published as well. The Pluralsight Authors page - http://pluralsight.com/training/Authors – shows all 146 authors and you can click on any author’s page to see how many (and which) courses they have authored. The problem is: I don’t want to have to click into 146 pages to get a count for each author. With this in mind, I figured I could write a little JavaScript using the Chrome JavaScript console to do some “detective work.” My first step was to figure out how the HTML was structured on this page so I could do some screen-scraping. Right-click the first author - “Inspect Element”. I can see there is a primary <div> with a class of “main” which contains all the authors. Each author is in an <h3> with an <a> tag containing their name and link to their page:     This web page already has jQuery loaded so I can use $ directly from the console. This allows me to just use jQuery to inspect items on the current page. Notice this is a multi-line command. In order to use multiple lines in the console you have to press SHIFT-ENTER to go to the next line:     Now I can see I’m extracting data just fine. At this point I want to follow each URL. Then I want to screen-scrape this next page to see how many courses each author has done. Let’s take a look at the author detail page:       I can see we have a table (with a css class of “course”) that contains rows for each course authored. This means I can get the number of courses pretty easily like this:     Now I can put this all together. Back on the authors page, I want to follow each URL, extract the returned HTML, and grab the count. In the code below, I simply use the jQuery $.get() method to get the author detail page and the “data” variable that is in the callback contains the HTML. A nice feature of jQuery is that I can simply put this HTML string inside of $() and I can use jQuery selectors directly on it in conjunction with the find() method:     Now I’m getting somewhere. I have every Pluralsight author and how many courses each one has authored. But that’s not quite what I’m after – what I want to see are the authors that have the MOST courses in the library. What I’d like to do is to put all of the data in an array and then sort that array descending by number of courses. I can add an item to the array after each author detail page is returned but the catch here is that I can’t perform the sort operation until ALL of the author detail pages have executed. The jQuery $.get() method is naturally an async method so I essentially have 146 async calls and I don’t want to perform my sort action until ALL have completed (side note: don’t run this script too many times or the Pluralsight servers might think your an evil hacker attempting a DoS attack and deny you). My C# brain wants to use a WaitHandle WaitAll() method here but this is JavaScript. I was able to do this by using the jQuery Deferred() object. I create a new deferred object for each request and push it onto a deferred array. After each request is complete, I signal completion by calling the resolve() method. Finally, I use a $.when.apply() method to execute my descending sort operation once all requests are complete. Here is my complete console command: 1: var authorList = [], 2: defList = []; 3: $(".main h3 a").each(function() { 4: var def = $.Deferred(); 5: defList.push(def); 6: var authorName = $(this).text(); 7: var authorUrl = $(this).attr('href'); 8: $.get(authorUrl, function(data) { 9: var courseCount = $(data).find("table.course tbody tr").length; 10: authorList.push({ name: authorName, numberOfCourses: courseCount }); 11: def.resolve(); 12: }); 13: }); 14: $.when.apply($, defList).then(function() { 15: console.log("*Everything* is complete"); 16: var sortedList = authorList.sort(function(obj1, obj2) { 17: return obj2.numberOfCourses - obj1.numberOfCourses; 18: }); 19: for (var i = 0; i < sortedList.length; i++) { 20: console.log(authorList[i]); 21: } 22: });   And here are the results:     WOW! John Sonmez has 44 courses!! And Matt Milner has 29! I guess Scott Allen isn’t the only “dominating force”. I would have assumed Scott Allen was #1 but he comes in as #3 in total course count (of course Scott has 11 courses in the Top 50, and 14 in the Top 100 which is incredible!). Given that I’m in the middle of producing only my third course, I better get to work!

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• Breaking up the Workday– Overcoming the Workaholic Syndrome

  - by dwahlin

  Hi, my name’s Dan Wahlin and I’m a workaholic – I admit it. It’s good from the standpoint that I get a lot done but it also has a lot of cons associated with it as well that I’m not proud of. I literally can’t watch TV without feeling like I should be doing something more productive (although I have no problem going to see movies at a theater or watching sporting events – that’s my escape I guess). On vacation it’s sometimes difficult the first few days to just “let go” of work and enjoy the time with my family. I always feel like I should be checking email and following up with different business projects. Fortunately, my wife knows me really well after 17 years of marriage and “gently” restricts my usage of laptops and other gadgets while we’re out. She also reminds me that constantly burying my face in gadgets just isn’t cool and shows a distinct lack of self control. On a given day I typically put in between 12 (at a minimum) up to 16-18 hours working on projects. My company does .NET consulting (ASP.NET/jQuery, SharePoint and Silverlight) but we also do a lot in the training space so there’s always a client project, some new courseware or some other deliverable that has to be worked on. My normal process for handling that is to just work my butt off and see how much I can get done. That process has worked well for a long time but when you start realizing that your happiness comes from how much work you accomplished that day then you have a problem. That’s especially true if you have kids (which I do….two awesome boys). It’s almost as if working more hours feels like I’m more successful or something which is of course ridiculous. It may actually mean that I’m too distracted or disorganized. Lately I’ve realized that while I’m still productive and always meet my deadlines, I’m really burnt out by the afternoon and have lost some of the excitement I used to have. Part of that’s normal I think given that I’ve been doing this for close to 15 years now, but in thinking through it more I realized that I just need to get away from the desk and take a break. By far, the happiest time of my life was my childhood. Part of that was due to having awesome parents, having far less responsibility (a big factor I suspect), being able to hang-out with friends at school, playing sports, games, etc. but I think a big part of the overall happiness came from being outside a lot. I lived on my bike as a little kid and as I grew up I shared time between riding an ATV all over the place, shooting hoops on the basketball court, playing golf and working on a golf course (all outside work of course).  Being a software developer and trainer I generally spend 95% or more of my day indoors and only see the sun when driving from place to place or by looking out the window (that’s sad because I live in a suburb of Phoenix, AZ where it’s nearly always sunny). I haven’t looked into any scientific studies on the matter, but I’d be willing to bet there’s a direct correlation between overall productivity/happiness and being outside some throughout the day (sunny or not). But, I wasn’t sure what to do about it since I do have a lot of deadlines I need to meet after all. While talking with my wife last night I mentioned how I feel like I’m in a rut and want to get the “fun” back that I used to have. She immediately said that I need to start making time for breaks (a real quick fact – she’s a lot smarter than me and nearly always right). Of course my first thought was that I’d be less productive taking breaks. If I spend 2 hours just relaxing then I’m losing 2 hours of work. But, I thought about it more and realized that I’m probably less productive when I work 10+ hours and only take less than 30 minutes for a lunch break to relax a little. I bet my brain is screaming, “Please let me relax a little so I can figure out these problems you’re trying to resolve!”. So, starting today I’m going to try to break the workaholic habit and spend time outside of the office. That could mean sitting around outside, working out, golfing, or whatever. I’ve decided that no gadgets are allowed during that time and that I shouldn’t work for more than 4 hours straight without taking a break. I have no idea how my little “break the workaholic syndrome” experiment will go or how long it will last, but I’d be very interested in hearing from others on how they keep fresh and focused without working yourself to death. If you have any specific ideas, techniques or practices you follow please share them. There’s a lot more to life than work and some of us (and I’m thinking of myself specifically) need to take a long, hard look at what kind of balance we currently have. I’d hate to look back at my life when I’m 80 years old and say, “The only thing I did was work – I missed out on life!”.

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• XNA RTS A* pathfinding issues

  - by Slayter

  I'm starting to develop an RTS game using the XNA framework in C# and am still in the very early prototyping stage. I'm working on the basics. I've got unit selection down and am currently working on moving multiple units. I've implemented an A* pathfinding algorithm which works fine for moving a single unit. However when moving multiple units they stack on top of each other. I tried fixing this with a variation of the boids flocking algorithm but this has caused units to sometimes freeze and get stuck trying to move but going no where. Ill post the related methods for moving the units below but ill only post a link to the pathfinding class because its really long and i don't want to clutter up the page. These parts of the code are in the update method for the main controlling class: if (selectedUnits.Count > 0) { int indexOfLeader = 0; for (int i = 0; i < selectedUnits.Count; i++) { if (i == 0) { indexOfLeader = 0; } else { if (Vector2.Distance(selectedUnits[i].position, destination) < Vector2.Distance(selectedUnits[indexOfLeader].position, destination)) indexOfLeader = i; } selectedUnits[i].leader = false; } selectedUnits[indexOfLeader].leader = true; foreach (Unit unit in selectedUnits) unit.FindPath(destination); } foreach (Unit unit in units) { unit.Update(gameTime, selectedUnits); } These three methods control movement in the Unit class: public void FindPath(Vector2 destination) { if (path != null) path.Clear(); Point startPoint = new Point((int)position.X / 32, (int)position.Y / 32); Point endPoint = new Point((int)destination.X / 32, (int)destination.Y / 32); path = pathfinder.FindPath(startPoint, endPoint); pointCounter = 0; if (path != null) nextPoint = path[pointCounter]; dX = 0.0f; dY = 0.0f; stop = false; } private void Move(List<Unit> units) { if (nextPoint == position && !stop) { pointCounter++; if (pointCounter <= path.Count - 1) { nextPoint = path[pointCounter]; if (nextPoint == position) stop = true; } else if (pointCounter >= path.Count) { path.Clear(); pointCounter = 0; stop = true; } } else { if (!stop) { map.occupiedPoints.Remove(this); Flock(units); // Move in X ********* TOOK OUT SPEED ********** if ((int)nextPoint.X > (int)position.X) { position.X += dX; } else if ((int)nextPoint.X < (int)position.X) { position.X -= dX; } // Move in Y if ((int)nextPoint.Y > (int)position.Y) { position.Y += dY; } else if ((int)nextPoint.Y < (int)position.Y) { position.Y -= dY; } if (position == nextPoint && pointCounter >= path.Count - 1) stop = true; map.occupiedPoints.Add(this, position); } if (stop) { path.Clear(); pointCounter = 0; } } } private void Flock(List<Unit> units) { float distanceToNextPoint = Vector2.Distance(position, nextPoint); foreach (Unit unit in units) { float distance = Vector2.Distance(position, unit.position); if (unit != this) { if (distance < space && !leader && (nextPoint != position)) { // create space dX += (position.X - unit.position.X) * 0.1f; dY += (position.Y - unit.position.Y) * 0.1f; if (dX > .05f) nextPoint.X = nextPoint.X - dX; else if (dX < -.05f) nextPoint.X = nextPoint.X + dX; if (dY > .05f) nextPoint.Y = nextPoint.Y - dY; else if (dY < -.05f) nextPoint.Y = nextPoint.Y + dY; if ((dX < .05f && dX > -.05f) && (dY < .05f && dY > -.05f)) stop = true; path[pointCounter] = nextPoint; Console.WriteLine("Make Space: " + dX + ", " + dY); } else if (nextPoint != position && !stop) { dX = speed; dY = speed; Console.WriteLine(dX + ", " + dY); } } } } And here's the link to the pathfinder: https://docs.google.com/open?id=0B_Cqt6txUDkddU40QXBMeTR1djA I hope this post wasn't too long. Also please excuse the messiness of the code. As I said before this is early prototyping. Any help would be appreciated. Thanks!

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

  - by Dave Campbell

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

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• Soft lockup after upgrade - cannot install from live CD

  - by nbm

  I dual-boot MacIntel Core 2 duo. nVidia graphics. Ran upgrade from ubuntu 13.10 to 14.04 (64 bit). On restart ran into {numbers} Bug: soft lockup - CPU#0 stuck for 22s! [swapper/0:1] Tried loading earlier kernel: same problem Tried re-installing ubuntu from a liveCD that has worked in the past: version 13.04. Same problem. Tried re-partitioning hard drive using Mac OS X disk utility and then installing ubuntu 14.04LTS from liveCD. Same problem. Not possible to verify liveCD disk (creates same "soft lockup" bug.) Tried installing from the liveCD with version 13.04 that I know works (that's how I got Ubuntu on this machine in the first place.) Same problem. I know this is not a hardware problem as OS X works just fine, I am using it right now on the same machine. I have been using various versions of Ubuntu for 2 years. Things I cannot do: Open a terminal Verify CD image Start ubuntu from CD (same soft lockup problem) This problem is similar to some other questions, none of which have been satisfactorily answered: Ubuntu 14.04 soft lockup on Vostro 3500 Cannot do fresh install of Ubuntu 13.04 while booting from DVD: "soft lockup" bug Live CD stalls when installing Ubuntu 13.10 UPDATE 6/11/14: Following some much-appreciated advice from bain (see below) I burned a 12.04LTS disk and started with kernel parameters: noapic, no1apic, acpi=off, nomodeset, elevator=deadline, and clocksource=jiffies. With all of these parameters I was able to load the 12.04LTS CD ("Try without installing"). It worked fine. However, as soon as I tried to install Ubuntu from the CD, my wired ethernet (eth0) connection would hang. There are already various askubuntu questions and bug reports about this problem, none of which had answers for me. (E.g., dhclient eth0 does nothing, none of the various reset commands does anything, manually setting IP &etc does nothing. I could reliably kill the ethernet connection by clicking "install ubuntu" every single time.) I could go ahead and install 12.04 without an internet connection, but the install would freeze after mostly completing (I tried several times.) There were some relevant error messages in the details of the install output script that, IIRC, had to do with searching for missing files and not being able to access eth0 (internet) to get them. To be honest I gave up at that point and I'm not sure I wrote those down. If I find some notes I will post them. At this point I no longer have Ubuntu on my system. I wiped the partitions and am using exclusively OS X. I am leaving this question in case it helps anyone else with similar problems. I love open source and I love Linux, and the next machine I get I will probably just build from Arch. At the moment I miss repositories and a lot of other things about Ubuntu, but the OS X terminal is 'nix, I can pretty much use all the open source apps I like, and while I am not a fan of the Apple software it gets the job done for me. Unlike Ubuntu, which can't even install. I realize this isn't necessarily a place for a soapbox speech, but when I first installed 12.04 several years ago there were already people in the community complaining that Canonical was going too "commercial". But I loved it. Several years later and all I've seen is Canonical adding more not-so-useful bells and whistles to Ubuntu while continually failing to fix basic problems on upgrades. With a dual-boot (and sometimes triple-boot) system it always took me some tweaking to get an upgrade to work, and to some extent that is okay. But at this point I feel like Canonical ought to just put a price tag on Ubuntu. All I see is more commercialism and advertising and product tie-ins, and ongoing problems do not get fixed. I am a big fan of open-source, not-for profit enterprise. I am also a big fan of for-profit enterprise, which certainly has its place and usefulness. I am not a fan of companies who pretend to be in favor of open source but really are just out to make a buck, and IMNSHO that is what Canonical has become. This is a great community and I wish you all the best, but my next install of Linux will not be Ubuntu.

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• Trouble with AABB collision response and physics

  - by WCM

  I have been racking my brain trying to figure out a problem I am having with physics and basic AABB collision response. I am fairly close as the physics are mostly right. Gravity feels good and movement is solid. The issue I am running into is that when I land on the test block in my project, I can jump off of it most of the time. If I repeatedly jump in place, I will eventually get stuck one or two pixels below the surface of the test block. If I try to jump, I can become free of the other block, but it will happen again a few jumps later. I feel like I am missing something really obvious with this. I have two functions that support the detection and function to return a vector for the overlap of the two rectangle bounding boxes. I have a single update method that is processing the physics and collision for the entity. I feel like I am missing something very simple, like an ordering of the physics vs. collision response handling. Any thoughts or help can be appreciated. I apologize for the format of the code, tis prototype code mostly. The collision detection function: public static bool Collides(Rectangle source, Rectangle target) { if (source.Right < target.Left || source.Bottom < target.Top || source.Left > target.Right || source.Top > target.Bottom) { return false; } return true; } The overlap function: public static Vector2 GetMinimumTranslation(Rectangle source, Rectangle target) { Vector2 mtd = new Vector2(); Vector2 amin = source.Min(); Vector2 amax = source.Max(); Vector2 bmin = target.Min(); Vector2 bmax = target.Max(); float left = (bmin.X - amax.X); float right = (bmax.X - amin.X); float top = (bmin.Y - amax.Y); float bottom = (bmax.Y - amin.Y); if (left > 0 || right < 0) return Vector2.Zero; if (top > 0 || bottom < 0) return Vector2.Zero; if (Math.Abs(left) < right) mtd.X = left; else mtd.X = right; if (Math.Abs(top) < bottom) mtd.Y = top; else mtd.Y = bottom; // 0 the axis with the largest mtd value. if (Math.Abs(mtd.X) < Math.Abs(mtd.Y)) mtd.Y = 0; else mtd.X = 0; return mtd; } The update routine (gravity = 0.001f, jumpHeight = 0.35f, moveAmount = 0.15f): public void Update(GameTime gameTime) { Acceleration.Y = gravity; Position += new Vector2((float)(movement * moveAmount * gameTime.ElapsedGameTime.TotalMilliseconds), (float)(Velocity.Y * gameTime.ElapsedGameTime.TotalMilliseconds)); Velocity.Y += Acceleration.Y; Vector2 previousPosition = new Vector2((int)Position.X, (int)Position.Y); KeyboardState keyboard = Keyboard.GetState(); movement = 0; if (keyboard.IsKeyDown(Keys.Left)) { movement -= 1; } if (keyboard.IsKeyDown(Keys.Right)) { movement += 1; } if (Position.Y + 16 > GameClass.Instance.GraphicsDevice.Viewport.Height) { Velocity.Y = 0; Position = new Vector2(Position.X, GameClass.Instance.GraphicsDevice.Viewport.Height - 16); IsOnSurface = true; } if (Collision.Collides(BoundingBox, GameClass.Instance.block.BoundingBox)) { Vector2 mtd = Collision.GetMinimumTranslation(BoundingBox, GameClass.Instance.block.BoundingBox); Position += mtd; Velocity.Y = 0; IsOnSurface = true; } if (keyboard.IsKeyDown(Keys.Space) && !previousKeyboard.IsKeyDown(Keys.Space)) { if (IsOnSurface) { Velocity.Y = -jumpHeight; IsOnSurface = false; } } previousKeyboard = keyboard; } This is also a full download to the project. https://www.box.com/s/3rkdtbso3xgfgc2asawy P.S. I know that I could do this with the XNA Platformer Starter Kit algo, but it has some deep flaws that I am going to try to live without. I'd rather go the route of collision response via an overlay function. Thanks for any and all insight!

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• Adjusting server-side tickrate dynamically

  - by Stuart Blackler

  I know nothing of game development/this site, so I apologise if this is completely foobar. Today I experimented with building a small game loop for a network game (think MW3, CSGO etc). I was wondering why they do not build in automatic rate adjustment based on server performance? Would it affect the client that much if the client knew this frame is based on this tickrate? Has anyone attempted this before? Here is what my noobish C++ brain came up with earlier. It will improve the tickrate if it has been stable for x ticks. If it "lags", the tickrate will be reduced down by y amount: // GameEngine.cpp : Defines the entry point for the console application. // #ifdef WIN32 #include <Windows.h> #else #include <sys/time.h> #include <ctime> #endif #include<iostream> #include <dos.h> #include "stdafx.h" using namespace std; UINT64 GetTimeInMs() { #ifdef WIN32 /* Windows */ FILETIME ft; LARGE_INTEGER li; /* Get the amount of 100 nano seconds intervals elapsed since January 1, 1601 (UTC) and copy it * to a LARGE_INTEGER structure. */ GetSystemTimeAsFileTime(&ft); li.LowPart = ft.dwLowDateTime; li.HighPart = ft.dwHighDateTime; UINT64 ret = li.QuadPart; ret -= 116444736000000000LL; /* Convert from file time to UNIX epoch time. */ ret /= 10000; /* From 100 nano seconds (10^-7) to 1 millisecond (10^-3) intervals */ return ret; #else /* Linux */ struct timeval tv; gettimeofday(&tv, NULL); uint64 ret = tv.tv_usec; /* Convert from micro seconds (10^-6) to milliseconds (10^-3) */ ret /= 1000; /* Adds the seconds (10^0) after converting them to milliseconds (10^-3) */ ret += (tv.tv_sec * 1000); return ret; #endif } int _tmain(int argc, _TCHAR* argv[]) { int sv_tickrate_max = 1000; // The maximum amount of ticks per second int sv_tickrate_min = 100; // The minimum amount of ticks per second int sv_tickrate_adjust = 10; // How much to de/increment the tickrate by int sv_tickrate_stable_before_increment = 1000; // How many stable ticks before we increase the tickrate again int sys_tickrate_current = sv_tickrate_max; // Always start at the highest possible tickrate for the best performance int counter_stable_ticks = 0; // How many ticks we have not lagged for UINT64 __startTime = GetTimeInMs(); int ticks = 100000; while(ticks > 0) { int maxTimeInMs = 1000 / sys_tickrate_current; UINT64 _startTime = GetTimeInMs(); // Long code here... cout << "."; UINT64 _timeTaken = GetTimeInMs() - _startTime; if(_timeTaken < maxTimeInMs) { Sleep(maxTimeInMs - _timeTaken); counter_stable_ticks++; if(counter_stable_ticks >= sv_tickrate_stable_before_increment) { // reset the stable # ticks counter counter_stable_ticks = 0; // make sure that we don't go over the maximum tickrate if(sys_tickrate_current + sv_tickrate_adjust <= sv_tickrate_max) { sys_tickrate_current += sv_tickrate_adjust; // let me know in console #DEBUG cout << endl << "Improving tickrate. New tickrate: " << sys_tickrate_current << endl; } } } else if(_timeTaken > maxTimeInMs) { cout << endl; if((sys_tickrate_current - sv_tickrate_adjust) > sv_tickrate_min) { sys_tickrate_current -= sv_tickrate_adjust; } else { if(sys_tickrate_current == sv_tickrate_min) { cout << "Please reduce sv_tickrate_min..." << endl; } else{ sys_tickrate_current = sv_tickrate_min; } } // let me know in console #DEBUG cout << "The server has lag. Reduced tickrate to: " << sys_tickrate_current << endl; } ticks--; } UINT64 __timeTaken = GetTimeInMs() - __startTime; cout << endl << endl << "Total time in ms: " << __timeTaken; cout << endl << "Ending tickrate: " << sys_tickrate_current; char test; cin >> test; return 0; }

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• Joining on NULLs

  - by Dave Ballantyne

  A problem I see on a fairly regular basis is that of dealing with NULL values.  Specifically here, where we are joining two tables on two columns, one of which is ‘optional’ ie is nullable.  So something like this: i.e. Lookup where all the columns are equal, even when NULL.   NULL’s are a tricky thing to initially wrap your mind around.  Statements like “NULL is not equal to NULL and neither is it not not equal to NULL, it’s NULL” can cause a serious brain freeze and leave you a gibbering wreck and needing your mummy. Before we plod on, time to setup some data to demo against. Create table #SourceTable ( Id integer not null, SubId integer null, AnotherCol char(255) not null ) go create unique clustered index idxSourceTable on #SourceTable(id,subID) go with cteNums as ( select top(1000) number from master..spt_values where type ='P' ) insert into #SourceTable select Num1.number,nullif(Num2.number,0),'SomeJunk' from cteNums num1 cross join cteNums num2 go Create table #LookupTable ( Id integer not null, SubID integer null ) go insert into #LookupTable Select top(100) id,subid from #SourceTable where subid is not null order by newid() go insert into #LookupTable Select top(3) id,subid from #SourceTable where subid is null order by newid() If that has run correctly, you will have 1 million rows in #SourceTable and 103 rows in #LookupTable.  We now want to join one to the other. First attempt – Lets just join select * from #SourceTable join #LookupTable on #LookupTable.id = #SourceTable.id and #LookupTable.SubID = #SourceTable.SubID OK, that’s a fail.  We had 100 rows back,  we didn’t correctly account for the 3 rows that have null values.  Remember NULL <> NULL and the join clause specifies SUBID=SUBID, which for those rows is not true. Second attempt – Lets deal with those pesky NULLS select * from #SourceTable join #LookupTable on #LookupTable.id = #SourceTable.id and isnull(#LookupTable.SubID,0) = isnull(#SourceTable.SubID,0) OK, that’s the right result, well done and 99.9% of the time that is where its left. It is a relatively trivial CPU overhead to wrap ISNULL around both columns and compare that result, so no problems.  But, although that’s true, this a relational database we are using here, not a procedural language.  SQL is a declarative language, we are making a request to the engine to get the results we want.  How we ask for them can make a ton of difference. Lets look at the plan for our second attempt, specifically the clustered index seek on the #SourceTable   There are 2 predicates. The ‘seek predicate’ and ‘predicate’.  The ‘seek predicate’ describes how SQLServer has been able to use an Index.  Here, it has been able to navigate the index to resolve where ID=ID.  So far so good, but what about the ‘predicate’ (aka residual probe) ? This is a row-by-row operation.  For each row found in the index matching the Seek Predicate, the leaf level nodes have been scanned and tested using this logical condition.  In this example [Expr1007] is the result of the IsNull operation on #LookupTable and that is tested for equality with the IsNull operation on #SourceTable.  This residual probe is quite a high overhead, if we can express our statement slightly differently to take full advantage of the index and make the test part of the ‘Seek Predicate’. Third attempt – X is null and Y is null So, lets state the query in a slightly manner: select * from #SourceTable join #LookupTable on #LookupTable.id = #SourceTable.id and ( #LookupTable.SubID = #SourceTable.SubID or (#LookupTable.SubID is null and #SourceTable.SubId is null) ) So its slightly wordier and may not be as clear in its intent to the human reader, that is what comments are for, but the key point is that it is now clearer to the query optimizer what our intention is. Let look at the plan for that query, again specifically the index seek operation on #SourceTable No ‘predicate’, just a ‘Seek Predicate’ against the index to resolve both ID and SubID.  A subtle difference that can be easily overlooked.  But has it made a difference to the performance ? Well, yes , a perhaps surprisingly high one. Clever query optimizer well done. If you are using a scalar function on a column, you a pretty much guaranteeing that a residual probe will be used.  By re-wording the query you may well be able to avoid this and use the index completely to resolve lookups. In-terms of performance and scalability your system will be in a much better position if you can.

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• [android] How to center buttons on screen horizontally and vertically plus equidistant apart?

  - by marc

  I've been racking my brain (android newbie here, so not hard to do) for awhile trying to figure out how to accomplish this: Desired Layout using a RelativeLayout or something other than AbsoluteLayout which is what this was created with. I'm coming from a Windows programming background where the device adjusts the 'absolute' positioning for you and GUI layout was a non-issue. The first layout works great in the emulator, but doesn't format for my Nexus One or any other screen that differs from the emulator size. I expected this because it's absolutely positioned, but haven't found a solution that will format correctly for different screen sizes. My goal is to have the layout work for different screen sizes and in portrait / landscape. Here's the Code that I'm currently using: [main.xml] <?xml version="1.0" encoding="utf-8"?> <AbsoluteLayout android:layout_width="fill_parent" android:layout_height="fill_parent" xmlns:android="http://schemas.android.com/apk/res/android" > <Button android:id="@+id/Button01" android:layout_width="188px" android:layout_height="100px" android:text="A" android:layout_y="50px" android:layout_x="65px" android:textSize="48sp"/> <Button android:id="@+id/Button02" android:layout_width="188px" android:layout_height="100px" android:text="B" android:layout_y="175px" android:layout_x="65px" android:textSize="48sp"/> <Button android:id="@+id/Button03" android:layout_width="188px" android:layout_height="100px" android:text="C" android:layout_y="300px" android:layout_x="65px" android:textSize="48sp"/> </AbsoluteLayout> Using tidbits from other questions here, I came up with this, it’s closer, but not there yet. <?xml version="1.0" encoding="utf-8"?> <TableLayout android:gravity="center" android:id="@+id/widget49" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android" > <Button android:id="@+id/Button01" android:layout_width="0dip" android:layout_weight="1" android:text="A" android:textSize="48sp"/> <Button android:id="@+id/Button02" android:layout_width="0dip" android:layout_weight="1" android:text="B" android:textSize="48sp"/> <Button android:id="@+id/Button03" android:layout_width="0dip" android:layout_weight="1" android:text="C" android:textSize="48sp"/> </TableLayout> Here’s a picture of the TableLayout: Another Attempt Any help / guidance would be greatly appreciated.

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• Playing an InputStream video in Blackberry JDE.

  - by Jenny

  I think I'm using InputStream incorrectly with a Blackberry 9000 simulator: I found some sample code, http://www.blackberry.com/knowledgecenterpublic/livelink.exe/fetch/2000/348583/800332/1089414/How%5FTo%5F-%5FPlay%5Fvideo%5Fwithin%5Fa%5FBlackBerry%5Fsmartphone%5Fapplication.html?nodeid=1383173&vernum=0 that lets you play video from within a Blackberry App. The code claims it can handle HTTP, but it's taken some fandangling to get it to actually approach doing so: http://pastie.org/609491 Specifically, I'm doing: StreamConnection s = null; s = (StreamConnection)Connector.open("http://10.252.9.15/eggs.3gp"); HttpConnection c = (HttpConnection)s; InputStream i = c.openInputStream(); System.out.println("~~~~~I have a connection?~~~~~~" + c); System.out.println("~~~~~I have a URL?~~~~" + c.getURL()); System.out.println("~~~~~I have a type?~~~~" + c.getType()); System.out.println("~~~~~I have a status?~~~~~~" + c.getResponseCode()); System.out.println("~~~~~I have a stream?~~~~~~" + i); player = Manager.createPlayer(i, c.getType()); I've found that this is the only way I can get an InputStream from an HTTPConnection without causing a: "JUM Error 104: Uncaught NullPointer Exception". (That is, the casting as a StreamConnection, and THEN as an HttpConnection stops it from crashing). However, I'm still not streaming video. Before, a stream wasn't able to be created (it would crash with the null pointer exception). Now, a stream is being made, the debugger claims it's begining to stream video from it...and nothing happens. No video plays. The app doesn't freeze, or crash or anything. I can 'pause' and 'play' freely, and get appropriate debug messages for both. But no video shows up. If I'm playing a video stored locally on the blackberry, everything is fine (it actually plays the video), so I know the Player itself is working fine, I"m just wondering if maybe I have something wrong with my stream? The API says the player can take in an InputStream. Is there a specific kind it needs? How can I query my inputstream to know if it's valid? It existing is further than I've gotten before. -Jenny Edit: I'm on a Blackberry Bold simulator (9000). I've heard that some versions of phones do NOT stream video via HTTP, however, the Bold does. I have yet to see examples of this though. When I go to the internet and point at a blackberry playable video, it attempts to stream, and then asks me to physically download the file (and then plays fine once I download). Edit: Also, I have a physical blackberry Bold, as well, but it can't stream either (I've gone to m.youtube.com, only to get a server/content not found error). Is there something special I need to do to stream RTSP content?

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• Best Practice for Images with Codeigniter : Generating Thumbs or Resizing on the Fly

  - by Steve K

  Hi all, I know there’s been a good deal written on thumbnail generation and the like with CI, but I wanted to explain what I’ve made and see what kind of best-practice advice I could find. Here’s my story… Currently, I have a site which allows users to upload collections of photos to projects they’ve created after first creating an account. Upon account creation, the site generates folders for the users in the following fashion for each of five pre-defined projects: /students/username/project_num/images/thumbs/ (This is to say that within a pre-created students folder, the username, project_num, images and thumbs folders are created recursively five times.) When a user uploads images to a project, I have a gallery controller which uploads the full images into the images folder for the project_num, and then creates a smaller thumbnail which maintains its ratio. So far so good. On the index page of the site, where these thumbnails and full images are displayed, I had a bit of a brain lapse, thinking I could simply output the full image while resizing it via css for a ‘medium-size’ image which would lead to the full-size image when clicked. (To be clear, the path is: Click on thumbnail— Load scaled full-size (medium-size) image via ajax into a display area above thumbs— Click on medium-sized image— Load full size image via lightbox, or something of that nature.) I have everything working to this point, except, as one might imagine, resizing the full-sized images with css doesn’t maintain aspect ratio for the thumbs, which means I need to find the best way to resize these. In thinking about it, I figured I had two options: I could resize the image on the fly when the user clicks a thumbnail to load the medium-sized image via ajax. (I have a method ‘get_image($url)’ in my gallery controller which simply loads a view with an image tag and the image source passed to it, etc.) I thought perhaps I could send it first to my gallery model, resize it there on the fly, and send it on to the view. The problem I’m having is that resizing it on the fly and echoing it out gives me the raw image data (I apologize, I don’t know that’s the right term). I’ve tried using data_uris to format the raw data into something echoable, but with no success. Is this method possible? The second option I considered was to generate a second medium-sized thumbnail when the user uploads the image with maintain_ratio set to true. This method is slightly less ideal, given that when providing a way for the user to delete their projects, I’ll need to scan for an additional set of images to delete. Not a huge deal, definitely, but something I figured could be avoided by generating the medium-sized image on the fly. I hope I’ve been clear in my explanations, if long-winded! I’m very curious to see what suggestions folks have about the best way to handle this. Much thanks for reading, and any suggestions are much-appreciated! Steve K.

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• flash.display.Loader blocks on load in release build

  - by Anders

  I'm loading a swf-file from my program written in as3 using the flash.display.Loader class. When I'm using the debug build configuration in FlashDevelop everything works fine. But when I'm using the release build configuration the program freezes for around two seconds efter the loader sends the progress events and before sending the complete event. This is my program: package { import flash.display.Loader; import flash.display.Sprite; import flash.events.Event; import flash.events.ProgressEvent; import flash.net.URLRequest; import flash.system.LoaderContext; import flash.system.ApplicationDomain; import flash.text.TextField; public class Main extends Sprite { private var frameCounter:int; private var frameCounterField:TextField = new TextField; private var statusField:TextField = new TextField; function Main():void { if (stage) init(); else addEventListener(Event.ADDED_TO_STAGE, init); } private function init(e:Event = null):void { removeEventListener(Event.ADDED_TO_STAGE, init); addEventListener(Event.ENTER_FRAME, frame); frameCounterField.text = "On frame " + frameCounter.toString(); addChild(frameCounterField); statusField.y = 40; statusField.width = 300; addChild(statusField); var context:LoaderContext = new LoaderContext(false, ApplicationDomain.currentDomain, null); var urlReq:URLRequest = new URLRequest("SomeFile.swf"); var loader:Loader = new Loader(); loader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, onProgress); loader.contentLoaderInfo.addEventListener(Event.COMPLETE, onComplete); loader.load(urlReq, context); } private function frame(event:Event):void { frameCounterField.text = "On frame " + (++frameCounter).toString(); } private function onProgress(event:ProgressEvent):void { statusField.appendText("Progress on frame: " + frameCounter.toString() + " Loaded: " + event.bytesLoaded + " / " + event.bytesTotal + "\n"); } private function onComplete(event:Event):void { statusField.appendText("Completed on frame: " + frameCounter.toString() + "\n"); } } } In release I get the following output on the first frame: On frame 1 Progress on frame: 1 Loaded: 0 / 182468 Progress on frame: 1 Loaded: 65536 / 182468 Progress on frame: 1 Loaded: 131072 / 182468 Progress on frame: 1 Loaded: 182468 / 182468 After around two seconds where the program is frozen the line Completed on frame: 2 is added and the 'On frame X' counter starts ticking up. Debug build produces the same output but without the freeze. Not all swf-files I have tried loading triggers the problem. The size of the file doesn't seem to affect anything. I have tried compiling and running on another computer with the same result. What could cause this problem?

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• DynamicMethod for ConstructorInfo.Invoke, what do I need to consider?

  - by Lasse V. Karlsen

  My question is this: If I'm going to build a DynamicMethod object, corresponding to a ConstructorInfo.Invoke call, what types of IL do I need to implement in order to cope with all (or most) types of arguments, when I can guarantee that the right type and number of arguments is going to be passed in before I make the call? Background I am on my 3rd iteration of my IoC container, and currently doing some profiling to figure out if there are any areas where I can easily shave off large amounts of time being used. One thing I noticed is that when resolving to a concrete type, ultimately I end up with a constructor being called, using ConstructorInfo.Invoke, passing in an array of arguments that I've worked out. What I noticed is that the invoke method has quite a bit of overhead, and I'm wondering if most of this is just different implementations of the same checks I do. For instance, due to the constructor matching code I have, to find a matching constructor for the predefined parameter names, types, and values that I have passed in, there's no way this particular invoke call will not end up with something it should be able to cope with, like the correct number of arguments, in the right order, of the right type, and with appropriate values. When doing a profiling session containing a million calls to my resolve method, and then replacing it with a DynamicMethod implementation that mimics the Invoke call, the profiling timings was like this: ConstructorInfo.Invoke: 1973ms DynamicMethod: 93ms This accounts for around 20% of the total runtime of this profiling application. In other words, by replacing the ConstructorInfo.Invoke call with a DynamicMethod that does the same, I am able to shave off 20% runtime when dealing with basic factory-scoped services (ie. all resolution calls end up with a constructor call). I think this is fairly substantial, and warrants a closer look at how much work it would be to build a stable DynamicMethod generator for constructors in this context. So, the dynamic method would take in an object array, and return the constructed object, and I already know the ConstructorInfo object in question. Therefore, it looks like the dynamic method would be made up of the following IL: l001: ldarg.0 ; the object array containing the arguments l002: ldc.i4.0 ; the index of the first argument l003: ldelem.ref ; get the value of the first argument l004: castclass T ; cast to the right type of argument (only if not "Object") (repeat l001-l004 for all parameters, l004 only for non-Object types, varying l002 constant from 0 and up for each index) l005: newobj ci ; call the constructor l006: ret Is there anything else I need to consider? Note that I'm aware that creating dynamic methods will probably not be available when running the application in "reduced access mode" (sometimes the brain just won't give up those terms), but in that case I can easily detect that and just calling the original constructor as before, with the overhead and all.

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• How can I read individual lines of a CSV file into a string array, to then be selectively displayed

  - by Ryan

  I need your help, guys! :| I've got myself a CSV file with the following contents: 1,The Compact,1.8GHz,1024MB,160GB,440 2,The Medium,2.4GHz,1024MB,180GB,500 3,The Workhorse,2.4GHz,2048MB,220GB,650 It's a list of computer systems, basically, that the user can purchase. I need to read this file, line-by-line, into an array. Let's call this array csvline(). The first line of the text file would stored in csvline(0). Line two would be stored in csvline(1). And so on. (I've started with zero because that's where VB starts its arrays). A drop-down list would then enable the user to select 1, 2 or 3 (or however many lines/systems are stored in the file). Upon selecting a number - say, 1 - csvline(0) would be displayed inside a textbox (textbox1, let's say). If 2 was selected, csvline(1) would be displayed, and so on. It's not the formatting I need help with, though; that's the easy part. I just need someone to help teach me how to read a CSV file line-by-line, putting each line into a string array - csvlines(count) - then increment count by one so that the next line is read into another slot. So far, I've been able to paste the numbers of each system into an combobox: Using csvfileparser As New Microsoft.VisualBasic.FileIO.TextFieldParser _ ("F:\folder\programname\programname\bin\Debug\systems.csv") Dim csvalue As String() csvfileparser.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited csvfileparser.Delimiters = New String() {","} While Not csvfileparser.EndOfData csvalue = csvfileparser.ReadFields() combobox1.Items.Add(String.Format("{1}{0}", _ Environment.NewLine, _ csvalue(0))) End While End Using But this only selects individual values. I need to figure out how selecting one of these numbers in the combobox can trigger textbox1 to be appended with just that line (I can handle the formatting, using the string.format stuff). If I try to do this using csvalue = csvtranslator.ReadLine , I get the following error message: "Error 1 Value of type 'String' cannot be converted to '1-dimensional array of String'." If I then put it as an array, ie: csvalue() = csvtranslator.ReadLine , I then get a different error message: "Error 1 Number of indices is less than the number of dimensions of the indexed array." What's the knack, guys? I've spent hours trying to figure this out. Please go easy on me - and keep any responses ultra-simple for my newbie brain - I'm very new to all this programming malarkey and just starting out! :)

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• Java Thread Management and Application Flow

  - by user119179

  I have a Java application that downloads information (Entities) from our server. I use a Download thread to download the data. The flow of the download process is as follows: Log in - The user entity is downloaded Based on the User Entity, download a 'Community' entities List and Display in drop down Based on Community drop down selection, Download and show 'Org Tree' in a JTree Based on Node selection, download Category entities and display in drop down Based on Category selection, download Sub Category entities and display in drop down Based on Sub Category selection download a large data set and save it The download occurs in a thread so the GUI does not 'freeze'. It also allows me to update a Progress Bar. I need help with managing this process. The main problem is when I download entity data I have to find a way to wait for the thread to finish before attempting to get the entity and move to the next step in the app flow. So far I have used a modal dialog to control flow. I start the thread, pop up a modal and then dispose of the modal when the thread is finished. The modal/thread are Observer/Observable the thread does a set changed when it is finished and the dialog disposes. Displaying a modal effectively stops the flow of the application so it can wait for the download to finish. I also tried just moving all the work flow to Observers. All relevant GUI in the process are Observers. Each update method waits for the download to finish and then calls the next piece of GUI which does its own downloading. So far I found these two methods produce code that is hard to follow. I would like to 'centralize' this work flow so other developers are not pulling out their hair when they try to follow it. My Question is: Do you have any suggestions/examples where a work flow such as this can be managed in a way that produces code that is easy to follow? I know 'easy' is a relative term and I know my both my options already work but I would like to get some ideas from other coders while I still have time to change it. Thank you very much.

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• PHP - static DB class vs DB singleton object

  - by Marco Demaio

  I don't want to create a discussion about singleton better than static or better than global, etc. I read dozens of questions about it on SO, but I couldn't come up with an answer to this SPECIFIC question, so I hope someone could now illuminate me buy answering this question with one (or more) real simple EXAMPLES, and not theoretical discussions. In my app I have the typical DB class needed to perform tasks on DB without having to write everywhere in code mysql_connect/mysql_select_db/mysql... (moreover in future I might decide to use another type of DB engine in place of mySQL so obviously I need a class of abstration). I could write the class either as a static class: class DB { private static $connection = FALSE; //connection to be opened //DB connection values private static $server = NULL; private static $usr = NULL; private static $psw = NULL; private static $name = NULL; public static function init($db_server, $db_usr, $db_psw, $db_name) { //simply stores connections values, withour opening connection } public static function query($query_string) { //performs query over alerady opened connection, if not open, it opens connection 1st } ... } or as a Singletonm class: class DBSingleton { private $inst = NULL; private $connection = FALSE; //connection to be opened //DB connection values private $server = NULL; private $usr = NULL; private $psw = NULL; private $name = NULL; public static function getInstance($db_server, $db_usr, $db_psw, $db_name) { //simply stores connections values, withour opening connection if($inst === NULL) $this->inst = new DBSingleton(); return $this->inst; } private __construct()... public function query($query_string) { //performs query over already opened connection, if connection is not open, it opens connection 1st } ... } Then after in my app if I wanto to query the DB i could do //Performing query using static DB object DB:init(HOST, USR, PSW, DB_NAME); DB::query("SELECT..."); //Performing query using DB singleton $temp = DBSingleton::getInstance(HOST, USR, PSW, DB_NAME); $temp->query("SELECT..."); My simple brain sees Singleton has got the only advantage to avoid declaring as 'static' each method of the class. I'm sure some of you could give me an EXAMPLE of real advantage of singleton in this specific case. Thanks in advance.

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• Matching unmatched strings based on a unknown pattern

  - by Polity

  Alright guys, i really hurt my brain over this one and i'm curious if you guys can give me any pointers towards the right direction i should be taking. The situation is this: Lets say, i have a collection of strings (let it be clear that the pattern of this strings is unknown. For a fact, i can say that the string contain only signs from the ASCII table and therefore, i dont have to worry about weird Chinese signs). For this example, i take the following collection of strings (note that the strings dont have to make any human sence so dont try figguring them out :)): "[001].[FOO].[TEST] - 'foofoo.test'", "[002].[FOO].[TEST] - 'foofoo.test'", "[003].[FOO].[TEST] - 'foofoo.test'", "[001].[FOO].[TEST] - 'foofoo.test.sample'", "[002].[FOO].[TEST] - 'foofoo.test.sample'", "-001- BAR.[TEST] - 'bartest.xx1", "-002- BAR.[TEST] - 'bartest.xx1" Now, what i need to have is a way of finding logical groups (and subgroups) of these set of strings, so in the above example, just by rational thinking, you can combine the first 3, the 2 after that and the last 2. Also the resulting groups from the first 5 can be combined in one main group with 2 subgroups, this should give you something like this: { { "[001].[FOO].[TEST] - 'foofoo.test'", "[002].[FOO].[TEST] - 'foofoo.test'", "[003].[FOO].[TEST] - 'foofoo.test'", } { "[001].[FOO].[TEST] - 'foofoo.test.sample'", "[002].[FOO].[TEST] - 'foofoo.test.sample'", } { "-001- BAR.[TEST] - 'bartest.xx1", "-002- BAR.[TEST] - 'bartest.xx1" } } Sorry for the layout above but indenting with 4 spaces doesnt seem to work correctly (or im frakk'n it up). Anyways, I'm not sure how to approach this problem (how to get the result desired as indicated above). First of, i thought of creating a huge set of regexes which would parse most known patterns but the amount of different patterns is just to huge that this isn't realistic. Another think i thought of was parsing each indidual word within a string (so strip all non alphabetic or numeric characters and split by those), and if X% matches, i can assume the strings belong to the same group. (where X wil probably be around 80/90). However, i find the area of speculation kinda big. For example, when matching strings with each 20 words, the change of hitting above 80% is kinda big (that means that 4 words can differ), however when matching only 8 words, 2 words at most can differ. My question to you is, what would be a logical approach in the above situation? Thanks in advance!

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• System.Net.Dns.GetHostAddresses("")

  - by dbasnett

  Yesterday s**ked, and today ain't (sic) looking better. I have an application I have been working on and it can be slow to start when my ISP is down because of DNS. My ISP was down for 3 hours yesterday, so I didn't think much about this piece of code I had added, until I found that it is always slow to start. This code is supposed to return your IP address and my reading of the link suggests that should be immediate, but it isn't, at least on my machine. Oh, and yesterday before the internet went down, I upgraded (oymoron) to XP SP3, and have had other problems. So my questions / request: 1. Am I doing this right? 2. If you run this on your machine does it take 39 seconds to return your IP address? It does on mine. One other note, I did a packet capture and the first request did NOT go on the wire, but the second did, and was answered quickly. So the question is what happened in XP SP3 that I am missing, besides a brain. One last note. If I resolve a FQDN all is well. Public Class Form1 'http://msdn.microsoft.com/en-us/library/system.net.dns.gethostaddresses.aspx ' 'excerpt 'The GetHostAddresses method queries a DNS server 'for the IP addresses associated with a host name. ' 'If hostNameOrAddress is an IP address, this address 'is returned without querying the DNS server. ' 'When an empty string is passed as the host name, 'this method returns the IPv4 addresses of the local host Private Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.Click Dim stpw As New Stopwatch stpw.Reset() stpw.Start() 'originally Dns.GetHostEntry, but slow also Dim myIPs() As System.Net.IPAddress = System.Net.Dns.GetHostAddresses("") stpw.Stop() Debug.WriteLine("'" & stpw.Elapsed.TotalSeconds) If myIPs.Length > 0 Then Debug.WriteLine("'" & myIPs(0).ToString) 'debug '39.8990525 '192.168.1.2 stpw.Reset() stpw.Start() 'originally Dns.GetHostEntry, but slow also myIPs = System.Net.Dns.GetHostAddresses("www.vbforums.com") stpw.Stop() Debug.WriteLine("'" & stpw.Elapsed.TotalSeconds) If myIPs.Length > 0 Then Debug.WriteLine("'" & myIPs(0).ToString) 'debug '0.042212 '63.236.73.220 End Sub End Class

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• Is this a situation where Qt Model/View architecture is not useful?

  - by csmithmaui

  Hi, I am writing a GUI based application where I read a string of values from serial port every few seconds and I need to display most of the values in some type graphical indicator(I was thinking of QprogressBar maybe) that displays the range and the value. Some of the other data that I am parsing from the string are the date and fault codes. Also, the data is hierarchical. I wanted to use the model/view architecture of Qt because I have been interested in MVC stuff for a while but have never quite wrapped my brain around how to implement it very well. As of now, I have subclassed QAbstractItemModel and in the model I read the serial port and wrap the items parsed from the string in a Tree data structure. I can view all of the data in a QtreeView with no issues. I have also began to subclass QAbstractItemView to build my custom view with all of the Graphical Indicators and such. This is where I am getting stuck. It seems to me that in order for me to design a view that knows how to display my custom model the view needs to know exactly how all of the data in the model is organized. Doesn't that defeat the purpose of Model/View? The QTreeView I tested the model with is basically just displaying the model as it is setup in the Tree structure but I don't want to do that because the data is not all of the same type. Is the type of data or the way you would like to present it to the user a determining factor in whether or not you should use this architecture? I always assumed it was just always better to design in an MVC style. It seems to me like it might have been better to just subclass QWidget and then read in from the serial port and update all of subwidgets(graphical indicators, labels, etc...) from the subclass. Essentially, do everything in one class. Does anybody understand this issue that can explain to me either what I am missing or why I shouldn't be doing it this way. As of now I am a little confused. Thanks so much for any help!

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• Rails find over multiple models

  - by kgb

  I think I'm missing something very obvious and its making my brain hurt. class User < ActiveRecord::Base has_one :profile class Profile < ActiveRecord::Base has_one :user belongs_to :team I have a partial that loops through the users and print some basic info, I'm using this partial in my team show page. I had originally written this to return users who's profiles were a member of a team. def show @team = Team.find_by_id(params[:id]) @profiles= Profile.find(:all, :conditions => ['team_id = ?', @team.id]) @users = User.find_by_id(@profiles.user_id) end But quickly realized @profiles was an array, and it looks messy as hell. Stuck as to what my find should look like to select all User who have a profile that is a member of a team. The partial that is working elsewhere for displaying users looks like this <% for user in @users%> <table> <tr> <td> <%= image_tag user.profile.picture.url %> </td> <td> <a href="/users/<%= user.id %>"><%= user.login %></a> </td> <td> <%= user.profile.first_name %> <%= user.profile.second_name %> </td> <td> <%= user.profile.status %> </td> </tr> </table> <% end %> Development log output with updated show and relationships Processing TeamsController#show (for 127.0.0.1 at 2010-03-30 22:06:31) [GET] Parameters: {"id"=>"1"} User Load (1.3ms) SELECT * FROM "users" WHERE ("users"."id" = 3) LIMIT 1 Team Load (1.0ms) SELECT * FROM "teams" WHERE ("teams"."id" = 1) Rendering template within layouts/main Rendering teams/show Completed in 75ms (View: 11, DB: 2) | 200 OK [http://localhost/teams/1]

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• jQuery: Counter, Tricky problem with effects for brainy people.

  - by Marius

  Hello there! I made this counter that I think is cool because it only makes visible changes to the numbers being changed between each time it is triggered. This is the code // counter $('a').click(function(){ var u = ''; var newStr = ''; $('.counter').each(function(){ var len = $(this).children('span').length; $(this).children('span').each(function(){ u = u + $(this).text(); }); v = parseInt(u) + 1; v = v + ''; for (i=v.length - 1; i >= 0; i--) { if (v.charAt(i) == u.charAt(i)) { break; } } slce = len - (v.length - (i + 1)) updates = $(this).children('span').slice(slce); $(updates).fadeTo(100,0).delay(100).each(function(index){ f = i + 1 + index; $(this).text(v.charAt(f)); }).fadeTo(100,1); }); }); Markup: <span class="counter"> <span></span><span></span><span></span><span></span><span></span><span></span><span style="margin-right:4px;">9</span><span>9</span><span>9</span><span>9</span> </span> <a href="">Add + 1</a> The problem is that I previously used queue() function to delay() $(this).text(v.charAt(f)); by 100ms, (without queue the text()-function would not be delayed because it isnt in the fx catergory) so that the text would be updated before the object had faded to opacity = 0. That would look stupid. When adding multiple counters, only one of the counters would count. When removing the queue function, both counters would work, but as you can imagine, the delay of the text() would be gone (as it isnt fx-category). It is probably a bit tricky to make out how I can have multiple counters, and still delay the text()-function by 100ms, but I was hoping there is somebody here with spare brain capacity for these things ;) You can see a (NSFW) problem demo here: Just look underneath the sharing icons and you will notice that the text changes WHILE the objects fade out. Looking for some help to sove this problem. I would like to call the text() function once the text has faded to opacity 0, then fade in once the text() has executed. Thank you for your time.

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• How can I limit the cache used by copying so there is still memory available for other cache?

  - by Peter

  Basic situation: I am copying some NTFS disks in openSuSE. Each one is 2TB. When I do this, the system runs slow. My guesses: I believe it is likely due to caching. Linux decides to discard useful cache (eg. kde4 bloat, virtual machine disks, LibreOffice binaries, Thunderbird binaries, etc.) and instead fill all available memory (24 GB total) with stuff from the copying disks, which will be read only once, then written and never used again. So then any time I use these apps (or kde4), the disk needs to be read again, and reading the bloat off the disk again makes things freeze/hiccup. Due to the cache being gone and the fact that these bloated applications need lots of cache, this makes the system horribly slow. Since it is USB,the disk and disk controller are not the bottleneck, so using ionice does not make it faster. I believe it is the cache rather than just the motherboard going too slow, because if I stop everything copying, it still runs choppy for a while until it recaches everything. And if I restart the copying, it takes a minute before it is choppy again. But also, I can limit it to around 40 MB/s, and it runs faster again (not because it has the right things cached, but because the motherboard busses have lots of extra bandwidth for the system disks). I can fully accept a performance loss from my motherboard's IO capability being completely consumed (which is 100% used, meaning 0% wasted power which makes me happy), but I can't accept that this caching mechanism performs so terribly in this specific use case. # free total used free shared buffers cached Mem: 24731556 24531876 199680 0 8834056 12998916 -/+ buffers/cache: 2698904 22032652 Swap: 4194300 24764 4169536 I also tried the same thing on Ubuntu, which causes a total system hang instead. ;) And to clarify, I am not asking how to leave memory free for the "system", but for "cache". I know that cache memory is automatically given back to the system when needed, but my problem is that it is not reserved for caching of specific things. Question: Is there some way to tell these copy operations to limit memory usage so some important things remain cached, and therefore any slowdowns are a result of normal disk usage and not rereading the same commonly used files? For example, is there a setting of max memory per process/user/file system allowed to be used as cache/buffers?

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• Call HttpWebRequest in another thread as UI with Task class - avoid to dispose object created in Task scope

  - by John

  I would like call HttpWebRequest on another thread as UI, because I must make 200 request or server and downloaded image. My scenation is that I make a request on server, create image and return image. This I make in another thread. I use Task class, but it call automaticaly Dispose method on all object created in task scope. So I return null object from this method. public BitmapImage CreateAvatar(Uri imageUri, int sex) { if (imageUri == null) return CreateDefaultAvatar(sex); BitmapImage image = null; new Task(() => { var request = WebRequest.Create(imageUri); var response = request.GetResponse(); using (var stream = response.GetResponseStream()) { Byte[] buffer = new Byte[response.ContentLength]; int offset = 0, actuallyRead = 0; do { actuallyRead = stream.Read(buffer, offset, buffer.Length - offset); offset += actuallyRead; } while (actuallyRead > 0); image = new BitmapImage { CreateOptions = BitmapCreateOptions.None, CacheOption = BitmapCacheOption.OnLoad }; image.BeginInit(); image.StreamSource = new MemoryStream(buffer); image.EndInit(); image.Freeze(); } }).Start(); return image; } How avoid it? Thank Mr. Jon Skeet try this: private Stream GetImageStream(Uri imageUri) { Byte[] buffer = null; //new Task(() => //{ var request = WebRequest.Create(imageUri); var response = request.GetResponse(); using (var stream = response.GetResponseStream()) { buffer= new Byte[response.ContentLength]; int offset = 0, actuallyRead = 0; do { actuallyRead = stream.Read(buffer, offset, buffer.Length - offset); offset += actuallyRead; } while (actuallyRead > 0); } //}).Start(); return new MemoryStream(buffer); } It return object which is null a than try this: private Stream GetImageStream(Uri imageUri) { Byte[] buffer = null; new Task(() => { var request = WebRequest.Create(imageUri); var response = request.GetResponse(); using (var stream = response.GetResponseStream()) { buffer= new Byte[response.ContentLength]; int offset = 0, actuallyRead = 0; do { actuallyRead = stream.Read(buffer, offset, buffer.Length - offset); offset += actuallyRead; } while (actuallyRead > 0); } }).Start(); return new MemoryStream(buffer); } Method above return null

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