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  • Are There Any Examples of Uncle Bob's High-Falutin' Architecture?

    - by Jordan
    I just finished watching this presentation by Uncle Bob (as well as his "Architecture" section of his "Clean Code" videos), but I'm left wondering: Are there any examples out there of applications that implement this Entity-Boundary-Interactor (or Entity-Boundary-Controller) structure? At one point I downloaded the source code to FitNesse (the acceptance testing project he mentions often as an example of not only high test coverage but good architecture, since they were able to defer the decision to not use a database until the very end), and based on a quick glance of it it appears even this project doesn't seem to fit this pattern. Are there any nontrivial examples of this architecture out in the wild, or should I not bother even looking into it and chalk it up as "it would be great if you could get there, but nobody really does"?

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  • Silverlight Cream for April 20, 2010 -- #842

    - by Dave Campbell
    In this Issue: Zoltan Arvai, Svetla Stoycheva, Alexey Zakharov, Chris Rouw, David Anson(-2-), Bill Reiss, John Papa and Adam Kinney, Chris Klug, CorrinaB, and Mike Snow. Shoutouts: Pete Brown interviewed David Kelley at MIX10: Pete at MIX10: David Kelley on the Prototype WPF and Silverlight Retail Experience Pete Brown also interviewed Emil Stoychev at MIX10: Pete at MIX10: Emil Stoychev on the CompletIT Silverlight Site SilverlightShow has a MIX10 Review by SilverlightShow Live Reporter Cigdem Patlak SilverlightShow also has an Interview with SilverlightShow Article Author Andrej Tozon From SilverlightCream.com: Implementing Push Notifications in Windows Phone 7 Zoltan Arvai has a post up on SilverlightShow discussing Push Notification on WP7 ... what it is, and how to use it. Completit.com - the challenges behind building a corporate website in Silverlight Svetla Stoycheva shows off the new CompleteIT corporate website which is pretty darn cool... and disucusses some of the challenges and solutions Introducing to Halcyone - Silverlight Application Framework: Silverlight Rest Extensions Alexey Zakharov has a tutorial up on a Silverlight application framework he's working on called Halcyone which is available on CodePlex Using the Tag Property during Silverlight Binding Chris Rouw details his SL3 to SL4 conversion and some issues he had, and how he was able to resolve a binding problem using the tag property. Using ContextMenu to implement SplitButton and MenuButton for Silverlight (or WPF) David Anson has a cool discussion up of using the ContextMenu code he put up previously to build a Split button, and includes all the code as usual. Silverlight/WPF Data Visualization Development Release 4 and Windows Phone 7 Charting sample! David Anson updated his Data Visualization because of the new releases, and this time he's including WP7... charting in WP7... ! Space Rocks game step 10: More fun with rocks In episode 10, Bill Reiss shows how to deal with multiple asteroids and all the interaction. Silverlight Training Course (Silverlight 4) Get your serious Silverlight 4 Mojo on with a new SL4 Training kit on Channel 9 ... buncha folks, spearheaded (it looks like) by John Papa and Adam Kinney... Plug-ins and composite applications in Silverlight – pt 3 Chris Klug is back with part 3 of his series on extensions and plug-in loading. So far he's covered a roll-your-own concept and MEF, now he digs into Prism. Transitions, Animations, and Effects with Blend - Part One How cool to have CorrinaB speak at your User Group meeting! ... She did just that in Portland, and instead of simply dropping a deck and some code in her blog, she's giving the run-down on her presentation... always good stuff, Corrina! Tip of the Day #110 – Using Static Resources in Class Libraries Mike Snow's latest tip is about how to create and use a Resource Dictionary. 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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  • SOCharts: Charts by Tags

    - by abhin4v
    Screenshot I created this small app as a weekend hack. It shows the reputations, upvotes, downvotes and accepted answers for a user against the tags for the answers. About I wanted to know how may upvotes I was away from getting the bronze badge for the clojure tag. But I could not find any straightforward way of doing that. So I wrote this app (in Clojure, of course). The SO API is used for the data and the charts are created using the Google Chart API. The charts are opened in the default browser. License Licensed under EPL 1.0. Download If you have Clojure and Leiningen installed, you can simply get the code from https://gist.github.com/725331, save it as socharts.clj and then run lein repl -e "(load \"socharts\")(refer 'socharts.socharts)(-main)" for launching the Swing UI If you don't have Clojure installed, but have Java then download the standalone jar from http://dl.dropbox.com/u/5247/socharts-1.0.0-standalone.jar and run it as javaw -jar socharts-1.0.0-standalone.jar Once the UI is launched, just type your user id in the input box and press <ENTER>. It will take some time to download the data from the SO API (the progress bar shows the download progress) and then it will open the charts in your default browser. You can also run it as a command line app by running lein repl -e "(load \"socharts\")(refer 'socharts.socharts)(-main <userid>)" or java -jar socharts-1.0.0-standalone.jar <userid> where you replace <userid> with your user id. Be warned that because of a missing feature in the SO API, it will fetch the data for each question you have answered. So the maximum limit is 10000 answers (the SO API call limit). Platform All platforms with Java 1.6. Contact You can reach me at abhinav [at] abhinavsarkar [dot] net. Please report bugs/comments/suggestions as answers to this post. Code Code was written in Clojure with the UI in Swing. It is available at https://gist.github.com/725331. It's a public gist so your can fork it if you like to do some changes.

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  • Where I&rsquo;ve Been

    - by Lee Brandt
    Hey all. I am still here. Still kickin’. I’ve been swamped with work and community stuff. But I wanted to post about some of the things going on. Just finished up Twin Cities Code Camp 8, and had a blast! Always good to see these guys. First of all, up-coming speaking engagements: Iowa Code Camp – May 1st in Iowa City, IA [more info] DevLink – August 5-7 in Nashville, TN [more info]   Plus I am organizing a second developer’s conference in Kansas City. Kansas City Developer’s Conference (KCDC) – June 19th in Kansas City [more info]   I will also be doing Lunch & Learns for my company in April and May at JCCC: April 29th, May 12th and May 27th at Johnson County Community College in Kansas City.   So May, June and August are covered. I may just take July off, I could use a break after KCDC is over.

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  • C++ Pointers: Number of levels of Indirection

    - by A B
    In a C++ program that doesn't contain legacy C code, is there a guideline regarding the maximum number of levels of indirection that should be used in the source code? I know that in C (as opposed to C++), some programmers have used pointers to pointers for a multiple dimension array, but for the case of arrays, there are data structures in C++ that can be used to avoid the pointers to pointers. Are users who still create pointers to pointers (or more than this) trying to use pointers to pointers only for performance ETC. reasons? I have tried NOT to use any more than a pointer to a pointer, only in the case that a pointer needed modification; does anyone have any other official or unofficial guidelines or rules regarding the number of levels of indirection?

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  • Concurrent Business Events

    - by Manoj Madhusoodanan
    This blog describes the various business events related to concurrent requests.In the concurrent program definition screen we can see the various business events which are attached to concurrent processing. Following are the actual definition of above business events. Each event will have following parameters. Create subscriptions to above business events.Before testing enable profile option 'Concurrent: Business Intelligence Integration Enable' to Yes. ExampleI have created a scenario.Whenever my concurrent request completes normally I want to send out file as attachment to my mail.So following components I have created.1) Host file deployed on $XXCUST_TOP/bin to send mail.It accepts mail ids,subject and output file.(Code here)2) Concurrent Program to send mail which points to above host file.3) Subscription package to oracle.apps.fnd.concurrent.request.completed.(Code here)Choose a concurrent program which you want to send the out file as attachment.Check Request Completed check box.Submit the program.If it completes normally the business event subscription program will send the out file as attachment to the specified mail id.

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  • Craftsmanship is ALL that Matters

    - by Wayne Molina
    Today, I'm going to talk about a touchy subject: the notion of working in a company that doesn't use the prescribed "best practices" in its software development endeavours.  Over the years I have, using a variety of pseudonyms, asked this question on popular programming forums.  Although I always add in some minor variation of the story to avoid suspicion that it's the same person posting, the crux of the tale remains the same: A Programmer’s Tale A junior software developer has just started a new job at an average company, creating average line-of-business applications for internal use (the most typical scenario programmers find themselves in).  This hypothetical newbie has spent a lot of time reading up on the "theory" of software development, devouring books, blogs and screencasts from well-known and respected software developers in the community in order to broaden his knowledge and "do what the pros do".  He begins his new job, eager to apply what he's learned on a real-world project only to discover that his new teammates doesn't use any of those concepts and techniques.  They hack their way through development, or in a best-case scenario use some homebrew, thrown-together semblance of a framework for their applications that follows not one of the best practices suggested by the “elite” in the software community - things like TDD (TDD as a "best practice" is the only subjective part of this post, but it's included here due to a very large following of respected developers who consider it one), the SOLID principles, well-known and venerable tools, even version control in a worst case and truly nightmarish scenario.  Our protagonist is frustrated that he isn't doing things the "proper" way - a way he's spent personal time digesting and learning about and, more importantly, a way that some of the top developers in the industry advocate - and turns to a forum to ask the advice of his peers. Invariably the answer I, in the guise of the concerned newbie, will receive is that A) I don't know anything and should just shut my mouth and sling code the bad way like everybody else on the team, and B) These "best practices" are fade or a joke, and the only thing that matters is shipping software to your customers. I am here today to say that anyone who says this, or anything like it, is not only full of crap but indicative of exactly the type of “developer” that has helped to give our industry a bad name.  Here is why: One Who Knows Nothing, Understands Nothing On one hand, you have the cognoscenti of the .NET development world.  Guys like James Avery, Jeremy Miller, Ayende Rahien and Rob Conery; all well-respected and noted programmers that are pretty much our version of celebrities.  These guys write blogs, books, and post videos outlining the "correct" way of writing software to make sure it not only works but is maintainable and extensible and a joy to work with.  They tout the virtues of the SOLID principles, or of using TDD/BDD, or using a mature ORM like NHibernate, Subsonic or even Entity Framework. On the other hand, you have Joe Everyman, Lead Software Developer at Initrode Corporation - in our hypothetical story Joe is the junior developer's new boss.  Joe's been with Initrode for 10 years, starting as the company’s very first programmer and over the years building up a little fiefdom of his own until at the present he’s in charge of all Initrode’s software development.  Joe writes code the same way he always has, without bothering to learn much, if anything.  He looked at NHibernate once and found it was "too hard", so he uses a primitive implementation of the TableDataGateway pattern as a wrapper around SqlClient.SqlConnection and SqlClient.SqlCommand instead of an actual ORM (or, in a better case scenario, has created his own ORM); the thought of using LINQ or Entity Framework or really anything other than his own hastily homebrew solution has never occurred to him.  He doesn't understand TDD and considers “testing” to be using the .NET debugger to step through code, or simply loading up an app and entering some values to see if it works.  He doesn't really understand SOLID, and he doesn't care to.  He's worked as a programmer for years, and that's all that counts.  Right?  WRONG. Who would you rather trust?  Someone with years of experience and who writes books, creates well-known software and is akin to a celebrity, or someone with no credibility outside their own minute environment who throws around their clout and company seniority as the "proof" of their ability?  Joe Everyman may have years of experience at Initrode as a programmer, and says to do things "his way" but someone like Jeremy Miller or Ayende Rahien have years of experience at companies just like Initrode, THEY know ten times more than Joe Everyman knows or could ever hope to know, and THEY say to do things "this way". Here's another way of thinking about it: If you wanted to get into politics and needed advice on the best way to do it, would you rather listen to the mayor of Hicktown, USA or Barack Obama?  One is a small-time nobody while the other is very well-known and, as such, would probably have much more accurate and beneficial advice. NOTE: The selection of Barack Obama as an example in no way, shape, or form suggests a political affiliation or political bent to this post or blog, and no political innuendo should be mistakenly read from it; the intent was merely to compare a small-time persona with a well-known persona in a non-software field.  Feel free to replace the name "Barack Obama" with any well-known Congressman, Senator or US President of your choice. DIY Considered Harmful I will say right now that the homebrew development environment is the WORST one for an aspiring programmer, because it relies on nothing outside it's own little box - no useful skill outside of the small pond.  If you are forced to use some half-baked, homebrew ORM created by your Director of Software, you are not learning anything valuable you can take with you in the future; now, if you plan to stay at Initrode for 10 years like Joe Everyman, this is fine and dandy.  However if, like most of us, you want to advance your career outside a very narrow space you will do more harm than good by sticking it out in an environment where you, to be frank, know better than everybody else because you are aware of alternative and, in almost most cases, better tools for the job.  A junior developer who understands why the SOLID principles are good to follow, or why TDD is beneficial, or who knows that it's better to use NHibernate/Subsonic/EF/LINQ/well-known ORM versus some in-house one knows better than a senior developer with 20 years experience who doesn't understand any of that, plain and simple.  Anyone who disagrees is either a liar, or someone who, just like Joe Everyman, Lead Developer, relies on seniority and tenure rather than adapting their knowledge as things evolve. In many cases, the Joe Everymans of the world act this way out of fear - they cannot possibly fathom that a “junior” could know more than them; after all, they’ve spent 10 or more years in the same company, doing the same job, cranking out the same shoddy software.  And here comes a newbie who hasn’t spent 10+ years doing the same things, with a fresh and often radical take on the craft, and Joe Everyman is afraid he might have to put some real effort into his career again instead of just pointing to his 10 years of service at Initrode as “proof” that he’s good, or that he might have to learn something new to improve; in most cases the problem is Joe Everyman, and by extension Initrode itself, has a mentality of just being “good enough”, and mediocrity is the rule of the day. A Thorn Bush is No Place for a Phoenix My advice is that if you work on a team where they don't use the best practices that some of the most famous developers in our field say is the "right" way to do things (and have legions of people who agree), and YOU are aware of these practices and can see why they work, then LEAVE the company.  Find a company where they DO care about quality, and craftsmanship, otherwise you will never be happy.  There is no point in "dumbing" yourself down to the level of your co-workers and slinging code without care to craftsmanship.  In 95% of these situations there will be no point in bringing it to the attention of Joe Everyman because he won't listen; he might even get upset that someone is trying to "upstage" him and fire the newbie, and replace someone with loads of untapped potential with a drone that will just nod affirmatively and grind out the tasks assigned without question. Find a company that has people smart enough to listen to the "best and brightest", and be happy.  Do not, I repeat, DO NOT waste away in a job working for ignorant people.  At the end of the day software development IS a craft, and a level of craftsmanship is REQUIRED for any serious professional.  When you have knowledgeable people with the credibility to back it up saying one thing, and small-time people who are, to put it bluntly, nobodies in the field saying and doing something totally different because they can't comprehend it, leave the nobodies to their own devices to fade into obscurity.  Work for a company that uses REAL software engineering techniques and really cares about craftsmanship.  The biggest issue affecting our career, and the reason software development has never been the respected, white-collar career it was meant to be, is because hacks and charlatans can pass themselves off as professional programmers without following a lick of good advice from programmers much better at the craft than they are.  These modern day snake-oil salesmen entrench themselves in companies by hoodwinking non-technical businesspeople and customers with their shoddy wares, end up in senior/lead/executive positions, and push their lack of knowledge on everybody unfortunate enough to work with/for/under them, crushing any dissent or voices of reason and change under their tyrannical heel and leaving behind a trail of dismayed and, often, unemployed junior developers who were made examples of to keep up the facade and avoid the shadow of doubt being cast upon them. To sum this up another way: If you surround yourself with learned people, you will learn.  Surround yourself with ignorant people who can't, as the saying goes, see the forest through the trees, and you'll learn nothing of any real value.  There is more to software development than just writing code, and the end goal should not be just "shipping software", it should be shipping software that is extensible, maintainable, and above all else software whose creation has broadened your knowledge in some capacity, even if a minor one.  An eager newbie who knows theory and thirsts for knowledge can easily be moulded and taught the advanced topics, but the same can't be said of someone who only cares about the finish line.  This industry needs more people espousing the benefits of software craftsmanship and proper software engineering techniques, and less Joe Everymans who are unwilling to adapt or foster new ways of thinking. Conclusion - I Cast “Protection from Fire” I am fairly certain this post will spark some controversy and might even invite the flames.  Please keep in mind these are opinions and nothing more.  A little healthy rant and subsequent flamewar can be good for the soul once in a while.  To paraphrase The Godfather: It helps to get rid of the bad blood.

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  • Silverlight Cream for June 03, 2010 -- #875

    - by Dave Campbell
    In this Issue: Ben Hodson, Fons Sonnemans, SilverLaw, Mike Snow, John Papa, René Schulte, Walt Ritscher, and David Anson. Shoutouts: René Schulte announced a whole batch of new features for WriteableBitmap that are now available: Filled To The Bursting Point - WriteableBitmapEx 0.9.5.0 Check out John Papa's Sticky Seesmic Desktop Plugin ... download it, play with it... he's going to blog about building plugins later Tim Heuer reported a Silverlight 4 minor update–June 2010 Erik Mork and Crew have a new Podcast up: This Week in Silverlight: Redmond Exodus? From SilverlightCream.com: Tutorial for Configuring Silverlight 4, Entity Framework and WCF RIA Services in Separate Component Assemblies (DLL’s) Ben Hodson is a new author(to me) that submitted his post at SilverlightCream.com... this is a good-looking tutorial on configuring separate component assemblies for all your project pieces. SpiralText in Silverlight 4 Fons Sonnemans had a good time playing with the PathListBox in Blend and produced a demo of text on a Spiral... you can run it right on the post, then grab the code. How To: Starting A Storyboard Not Before The Application Has Completed Loading - Silverlight 4 SilverLaw takes a look at the problem of having a Storyboard start too early, and demonstrates code to avoid the problem. Silverlight Tip of the Day#27 – Displaying Special Characters in XAML Mike Snow's latest Tip of the day is on encoding 'special' characters for use in XAML... simple looking at it, frustrating to debug if you don't do it right. Diving into the RichTextBox (Silverlight TV #31) John Papa talks about the RichTextBox with Mark Rideout in this edition of Silverlight TV. Mark provides a great video tutorial for the control. Push and Pull - Silverlight Webcam Capturing Details Boy, René Schulte doesn't slow down does he?... his latest is (in his words from a section heading) "Silverlight Webcam 101" ... and he means it... this is one to save to OneNote or as a PDF! Looking for Silverlight BiDi or RTL? Use the FlowDirection property If you need RTL or BiDi in Silverlight and you haven't checked it out yet, Walt Ritscher has a nice intro up on using the FlowDirection property, with demos and code. How to: Show text labels on a numeric axis with Silverlight/WPF Toolkit Charting David Anson has another charting puzzle resolved on his site... putting text labels on the dependent axis. 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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  • When should I use—and not use—design patterns?

    - by ashmish2
    In a previous question of mine on Stack Overflow, FredOverflow mentioned in the comments: Note that patterns do not magically improve the quality of your code. and Any measure of quality you can imagine. Patterns are not a panacea. I once wrote a Tetris game with about 100 classes that incorporated all the patterns I knew at the time. Why use a simple if/else if you can use a pattern? OO is good, and patterns are even better, right? No, it was a terrible, over-engineered piece of crap. I am quite confused by these comments: I know design patterns help to make code reusable and readable, but when should I use use design patterns and perhaps more importantly, when should I avoid getting carried away with them?

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  • Does it work when a developer is the project manager's boss?

    - by marabutt
    I am in the planning stage of a project and I am looking to hire a project manager. I would like to do some coding and keep eye on all parts of the project. However, i have a feeling that a project manager will get better results. I have the following options: 1) manage the project and not code 2) hire a project manager and code myself I am worried that the project manager will feel impeded by having the project owner in the development team. If I run the project, the team might fall apart causing the project to fail. To stick within budget, I have to be involved in one capacity or another. Does anyone have experience with this situation, any suggestions? more info: 4 in-house developers each responsible for a specific area. The developers can also outsource work if agreed to by the project manager.

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  • Favorite Visual Studio 2010 Extensions, Update

    - by Scott Dorman
    With the release of the Visual Studio Pro Power Tools (and many other new extensions having been released), my list of favorite Visual Studio extensions has changed. All of these extensions are available in the Visual Studio Gallery. Here is the list of extensions that I currently have installed and find useful: Bing Start Page CodeCompare Collapse Selection In Solution Explorer Collapse Solution Color Picker Completion Extension Analyzer Find Results Highlighter Find Results Tweak (Available from CodePlex) Format Document HelpViewerKeywordIndex HighlightMultiWord Image Insertion Indentation Matcher Extension ItalicComments MoveToRegionVSX Numbered Bookmarks PowerCommands for Visual Studio 2010 Regular Expressions Margin Search Work Items for TFS 2010 Source Outliner Spell Checker Structure Adornment This also installs the following extensions: BlockTagger BlockTaggerImpl SettingsStore SettingsStoreImpl StyleCop Team Founder Server Power Tools TFS Auto Shelve Visual Studio Color Theme Editor Visual Studio Pro Power Tools VS10x Code Map VS10x Code Marker VS10x Collapse All Projects VS10x Editor View Enhancer VS10x Insert Debug Names VS10x Selection Popup VS10x Super Copy Paste VSCommands 2010 Word Wrap with Auto-Indent   Technorati Tags: Visual Studio,Extensions

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  • More on Visual Studio 11 from Scott Guthrie

    - by TATWORTH
    At http://weblogs.asp.net/scottgu/archive/2011/10/30/web-forms-model-binding-part-3-updating-and-validation-asp-net-4-5-series.aspx, Scott Guthrie talks about data binding is ASP.NET 4.5.There is a key statement "Because our GetProducts() method is returning an IQueryable<Product>, users can easily page and sort through the data within our GridView.  Only the 10 rows that are visible on any given page are returned from the database."Consider paging through a large dataset, this is going to give high performance with very little code as the database to IIS server traffic will be reduced.Can't code withoutThe best C# & VB.NET refactoring plugin for Visual Studio

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  • Learning Smalltalk as a Java programmer

    - by VeeKay
    I am a Java programmer willing to learn smalltalk. As of now I am working within the Pharo environment. Trying to switch from Java to Smalltalk is being a bit of a headache, honestly. I would like to learn Smalltalk with the help of a code base available but I believe that there aren't many Smalltalk example projects available on the web. So are there any particular websites that involve learning Smalltalk (Pharo) based on some simple examples? Currently I am taking the help of Pharo By Example doc but I feel it is just not sufficient for me. I am looking for more some code examples in Smalltalk.

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  • Master Data Services Employees Sample Model

    - by Davide Mauri
    I’ve been playing with Master Data Services quite a lot in those last days and I’m also monitoring the web for all available resources on it. Today I’ve found this freshly released sample available on MSDN Code Gallery: SQL Server Master Data Services Employee Sample Model http://code.msdn.microsoft.com/SSMDSEmployeeSample This sample shows how Recursive Hierarchies can be modeled in order to represent a typical organizational chart scenario where a self-relationship exists on the Employee entity. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Is there a standard way to store 3D meshes to easily communicate between libraries?

    - by awiebe
    In a 3D game lots of different systems need to know about geometry data, however the only way they seem to be able to agree to on in representing it by an array of triangles. Can anyone recommend a good geometry manipulation library that will allow me to easily integrate the drawing library(OpenGL), the physics engine(Bullet), Serialization(Several 3D file formats) and my own code(objective-c++). Focus on the a representation between the drawing library and the physics engine. Also if the library can triangulate a mesh definition that would be very helpful. My code can work around what exists already.

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  • Do Not Optimize Without Measuring

    - by Alois Kraus
    Recently I had to do some performance work which included reading a lot of code. It is fascinating with what ideas people come up to solve a problem. Especially when there is no problem. When you look at other peoples code you will not be able to tell if it is well performing or not by reading it. You need to execute it with some sort of tracing or even better under a profiler. The first rule of the performance club is not to think and then to optimize but to measure, think and then optimize. The second rule is to do this do this in a loop to prevent slipping in bad things for too long into your code base. If you skip for some reason the measure step and optimize directly it is like changing the wave function in quantum mechanics. This has no observable effect in our world since it does represent only a probability distribution of all possible values. In quantum mechanics you need to let the wave function collapse to a single value. A collapsed wave function has therefore not many but one distinct value. This is what we physicists call a measurement. If you optimize your application without measuring it you are just changing the probability distribution of your potential performance values. Which performance your application actually has is still unknown. You only know that it will be within a specific range with a certain probability. As usual there are unlikely values within your distribution like a startup time of 20 minutes which should only happen once in 100 000 years. 100 000 years are a very short time when the first customer tries your heavily distributed networking application to run over a slow WIFI network… What is the point of this? Every programmer/architect has a mental performance model in his head. A model has always a set of explicit preconditions and a lot more implicit assumptions baked into it. When the model is good it will help you to think of good designs but it can also be the source of problems. In real world systems not all assumptions of your performance model (implicit or explicit) hold true any longer. The only way to connect your performance model and the real world is to measure it. In the WIFI example the model did assume a low latency high bandwidth LAN connection. If this assumption becomes wrong the system did have a drastic change in startup time. Lets look at a example. Lets assume we want to cache some expensive UI resource like fonts objects. For this undertaking we do create a Cache class with the UI themes we want to support. Since Fonts are expensive objects we do create it on demand the first time the theme is requested. A simple example of a Theme cache might look like this: using System; using System.Collections.Generic; using System.Drawing; struct Theme { public Color Color; public Font Font; } static class ThemeCache { static Dictionary<string, Theme> _Cache = new Dictionary<string, Theme> { {"Default", new Theme { Color = Color.AliceBlue }}, {"Theme12", new Theme { Color = Color.Aqua }}, }; public static Theme Get(string theme) { Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } return cached; } } class Program { static void Main(string[] args) { Theme item = ThemeCache.Get("Theme12"); item = ThemeCache.Get("Theme12"); } } This cache does create font objects only once since on first retrieve of the Theme object the font is added to the Theme object. When we let the application run it should print “Creating new font” only once. Right? Wrong! The vigilant readers have spotted the issue already. The creator of this cache class wanted to get maximum performance. So he decided that the Theme object should be a value type (struct) to not put too much pressure on the garbage collector. The code Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } does work with a copy of the value stored in the dictionary. This means we do mutate a copy of the Theme object and return it to our caller. But the original Theme object in the dictionary will have always null for the Font field! The solution is to change the declaration of struct Theme to class Theme or to update the theme object in the dictionary. Our cache as it is currently is actually a non caching cache. The funny thing was that I found out with a profiler by looking at which objects where finalized. I found way too many font objects to be finalized. After a bit debugging I found the allocation source for Font objects was this cache. Since this cache was there for years it means that the cache was never needed since I found no perf issue due to the creation of font objects. the cache was never profiled if it did bring any performance gain. to make the cache beneficial it needs to be accessed much more often. That was the story of the non caching cache. Next time I will write something something about measuring.

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  • Bullet physics debug drawing not working

    - by Krishnabhadra
    Background I am following on from this question, which isn't answered yet. Basically I have a cube and a UVSphere in my scene, with UVSphere on the top of the cube without touching the cube. Both exported from blender. When I run the app The UVSphere does circle around the cube for 3 or 4 times and jump out of the scene. What I actually expect was the sphere to fall on top of the cube. What this question about From the comment to the linked question, I got to know about bullet debug drawing, which helps in debugging by drawing outline of physics bodies which are normally invisible. I did some research on that and came up with the code given below. From whatever I have read, below code should work, but it doesn't. My Code My bullet initialization code. -(void) initializeScene { /*Setup physics world*/ _physicsWorld = [[CC3PhysicsWorld alloc] init]; [_physicsWorld setGravity:0 y:-9.8 z:0]; /*Setting up debug draw*/ MyDebugDraw *draw = new MyDebugDraw; draw->setDebugMode(draw->getDebugMode() | btIDebugDraw::DBG_DrawWireframe ); _physicsWorld._discreteDynamicsWorld->setDebugDrawer(draw); /*Setup camera and lamb*/ ………….. //This simpleCube.pod contains the cube [self addContentFromPODFile: @"simpleCube.pod"]; //This file contains sphere [self addContentFromPODFile: @"SimpleSphere.pod"]; [self createGLBuffers]; CC3MeshNode* cubeNode = (CC3MeshNode*)[self getNodeNamed:@"Cube"]; CC3MeshNode* sphereNode = (CC3MeshNode*)[self getNodeNamed:@"Sphere"]; // both cubeNode and sphereNode are not nil from this point float *cVertexData = (float*)((CC3VertexArrayMesh*)cubeNode.mesh) .vertexLocations.vertices; int cVertexCount = ((CC3VertexArrayMesh*)cubeNode.mesh) .vertexLocations.vertexCount; btTriangleMesh* cTriangleMesh = new btTriangleMesh(); int offset = 0; for (int i = 0; i < (cVertexCount / 3); i++) { unsigned int index1 = offset; unsigned int index2 = offset+6; unsigned int index3 = offset+12; cTriangleMesh->addTriangle( btVector3(cVertexData[index1], cVertexData[index1+1], cVertexData[index1+2]), btVector3(cVertexData[index2], cVertexData[index2+1], cVertexData[index2+2]), btVector3(cVertexData[index3], cVertexData[index3+1], cVertexData[index3+2])); offset += 18; } [self releaseRedundantData]; /*Create a triangle mesh from the vertices*/ btBvhTriangleMeshShape* cTriMeshShape = new btBvhTriangleMeshShape(cTriangleMesh,true); btCollisionShape *sphereShape = new btSphereShape(1); gTriMeshObject = [_physicsWorld createPhysicsObjectTrimesh:cubeNode shape:cTriMeshShape mass:0 restitution:1.0 position:cubeNode.location]; sphereObject = [_physicsWorld createPhysicsObject:sphereNode shape:sphereShape mass:1 restitution:0.1 position:sphereNode.location]; sphereObject.rigidBody->setDamping(0.1,0.8); /*Enable debug drawing*/ _physicsWorld._discreteDynamicsWorld->debugDrawWorld(); } And My btIDebugDraw implementation (MyDebugDraw.h) //MyDebugDraw.h class MyDebugDraw: public btIDebugDraw{ int m_debugMode; public: virtual void drawLine(const btVector3& from,const btVector3& to ,const btVector3& color); virtual void drawContactPoint(const btVector3& PointOnB ,const btVector3& normalOnB,btScalar distance ,int lifeTime,const btVector3& color); virtual void reportErrorWarning(const char* warningString); virtual void draw3dText(const btVector3& location ,const char* textString); virtual void setDebugMode(int debugMode); virtual int getDebugMode() const; }; void MyDebugDraw::drawLine(const btVector3& from,const btVector3& to ,const btVector3& color){ LogInfo(@"Works!!"); glPushMatrix(); glColor4f(color.getX(), color.getY(), color.getZ(), 1.0); const GLfloat line[] = { from.getX()*1, from.getY()*1, from.getZ()*1, //point A to.getX()*1, to.getY()*1,to.getZ()*1 //point B }; glVertexPointer( 3, GL_FLOAT, 0, &line ); glPointSize( 5.0f ); glDrawArrays( GL_POINTS, 0, 2 ); glDrawArrays( GL_LINES, 0, 2 ); glPopMatrix(); } void MyDebugDraw::drawContactPoint(const btVector3 &PointOnB ,const btVector3 &normalOnB, btScalar distance ,int lifeTime, const btVector3 &color){ } void MyDebugDraw::reportErrorWarning(const char *warningString){ } void MyDebugDraw::draw3dText(const btVector3 &location , const char *textString){ } void MyDebugDraw::setDebugMode(int debugMode){ } int MyDebugDraw::getDebugMode() const{ return DBG_DrawWireframe; } My Problem The drawLine method is getting called. I can see the cube and sphere in place. Sphere again does some circling around the cube before jumping off. No debug lines are getting drawn.

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  • A way for an Upstart event to be sent whenever ecryptfs homedir mounted/unmounted?

    - by David Olivier
    I have an encrypted homedir (ecryptfs) and I'm wanting to run a private mysql daemon with the database files in my homedir. The daemon should be started whenever the homedir is mounted, and stopped before the homedir is unmounted. It seems I have to write an Upstart script, which doesn't seem too hard; the problem is triggering it. Is there already any Upstart event that is sent on these occasions? Or must I insert an "initctl emit" somewhere? Where? It seems the encrypted homedir is mounted whenever I either open my GUI session or ssh to my account. Is there a common place in these two processes where I might insert code? (I don't want to patch and compile any C code, just insert maybe a few lines somewere.) David

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  • C# 4.0: Covariance And Contravariance In Generics

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

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  • Launching a URL from an OOB Silverlight Application

    So I'm working on this code browser mostly to help me with my fading memory. In the app I want to be able to launch a url. So I do my normal thing and put a line of code that looks like this:System.Windows.Browser.HtmlPage.Window.Navigate(new Uri(ThisURI), "_blank");I was agast when I realized that this didn't work, for that matter it didn't even blow... grr... but with a bit of research I found that the hyper link button worked so a ended up making a little class like this:public class MyHyperLink...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • CCNet TFS Migration - Dealing with left over folders

    - by Michael Stephenson
    Im currently in the process of migrating our many BizTalk projects from MKS source control to TFS.  While we will be using TFS for work item tracking and source control etc we will be continuing to use Cruise Control for continuous integration although im updating this to CCNet 1.5 at the same time. Ill post a few things as much as a reminder to myself about some of the problems we come across. Problem After the first build of our code the next time a build is triggered an error is encountered by the TFS source control block refreshing the source code. System.IO.IOException: The directory is not empty.    at System.IO.Directory.DeleteHelper(String fullPath, String userPath, Boolean recursive)    at System.IO.Directory.Delete(String fullPath, String userPath, Boolean recursive)    at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vsts.deleteDirectory(String path)    at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vsts.GetSource(IIntegrationResult result)    at ThoughtWorks.CruiseControl.Core.IntegrationRunner.Build(IIntegrationResult result)    at ThoughtWorks.CruiseControl.Core.IntegrationRunner.Integrate(IntegrationRequest request) System.IO.IOException: The directory is not empty. at System.IO.Directory.DeleteHelper(String fullPath, String userPath, Boolean recursive) at System.IO.Directory.Delete(String fullPath, String userPath, Boolean recursive) at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vsts.deleteDirectory(String path) at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vsts.GetSource(IIntegrationResult result) at ThoughtWorks.CruiseControl.Core.IntegrationRunner.Build(IIntegrationResult result) at ThoughtWorks.CruiseControl.Core.IntegrationRunner.Integrate(IntegrationRequest request) Project: Bupa.BPI.Documents Date of build: 2011-01-28 14:54:21 Running time: 00:00:05 Integration Request: Build (ForceBuild) triggered from VMOPBZDEV11 Solution The problem seems to be with a folder called TestLocations which is created by the build process and used along with the file adapter as a way to get messages into BizTalk.  For some reason the source control block when it does a full refresh of the code does not get rid of this folder and then complains thats a problem and fails the build. Interestingly there are other folders created by the build which are deleted fine.  My assumption is that this if something to do with the file adapter polling the directory.  However note that we have not had this problem with other source control blocks in the past. To workaround this I have added a prebuild task to the ccnet.config file to delete this folder before the source control block is executed.  See below for example < prebuild> exec>executable>cmd.exe</executable>buildArgs>/c "if exist "C:\<MyCode>\TestLocations" rd /s /q "C:\<MyCode>\TestLocations""</buildArgs>exec> prebuild> < < < </ </

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  • Using your own gameloop logic on iphone?

    - by kkan
    I'm currently working on moving some android-ndk code to the iphone and have hit a wall. I'm new to iphone development, and from looking at some samples it seems that the main loop is handled for you and all you've got to do is override the render method on the view to handle the rendering and add a selector to handle the update methods. The render method itself lookslike it's attached to the windows refresh. But in android I've got my own game loop that controls the rendering and updates using c++ time.h. is it possible to implement the same here bypassing apple's loop? I'd really like the keep the structures of the code similar. Thanks!

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