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  • Qt4Dotnet on Mac OS X

    - by Tony
    Hello everyone. I'm using Qt4Dotnet project in order to port application originally written in C# on Linux and Mac. Port to Linux hasn't taken much efforts and works fine. But Mac (10.4 Tiger) is a bit more stubborn. The problem is: when I try to start my application it throws an exception. Exception states that com.trolltech.qt.QtJambi_LibraryInitializer is unable to find all necessary ibraries. QtJambi library initializer uses java.library.path VM environment variable. This variable includes current working directory. I put all necessary libraries in a working directory. When I try to run the application from MonoDevelop IDE, initializer is able to load one library, but the other libraries are 'missing': An exception was thrown by the type initializer for com.trolltech.qt.QtJambi_LibraryInitializer --- java.lang.RuntimeException: Loading library failed, progress so far: No 'qtjambi-deployment.xml' found in classpath, loading libraries via 'java.library.path' Loading library: 'libQtCore.4.dylib'... - using 'java.library.path' - ok, path was: /Users/chin/test/bin/Debug/libQtCore.4.dylib Loading library: 'libqtjambi.jnilib'... - using 'java.library.path' Both libQtCore.4.dylib and libqtjambi.jnilib are in the same directory. When I try to run it from the command prompt, the initializer is unable to load even libQtCore.4.dylib. I'm using Qt4Dotnet v4.5.0 (currently the latest) with QtJambi v4.5.2 libraries. This might be the source of the problem, but I'm neither able to compile Qt4Dotnet v4.5.2 by myself nor to find QtJambi v4.5.0 libraries. Project's page states that some sort of patch should be applied to QtJambi's source code in order to be compatible with Mono framework, but this patch hasn't been released yet. Without this patch application crashes in a strange manner (other than library seek fault). I must note that original QtJambi loads all necessary libraries perfectly, so it might be issues of IKVM compiler used to translate QtJambi into .Net library. Any suggestions how can I overcome this problem?

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  • float** allocation limit + serialized struct problem. Need advice!

    - by jmgunn
    basically im getting an allocation limit error/warning when i create a float** array. the function i am calling to fill the float** retrieves data from a struct loaded from a file. The function works fine when i use one object but when i load 2 objects into memory i get the limit error. I am pretty sure this is to do with byte alignment or a similar thing because my struct is saved with a float** member which i am sure you are not susposed to do !?! Please confirm this! The next question i have now is how to save/serialize the float** member of this struct? I cant really afford to put an upper bound on the array ie "float [10000][3]" because i need/want to use this structure as a base for many other types of objects that may have well under the upper bound. Stroking my chin here! Any help/advice will recieve my highest gratitude. BTW these said struct objects will be used in a game/graphics package, the float** is a float[3] array for storing vertices in a model. Much thanks in advance

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  • Silverlight Cream for December 12, 2010 -- #1008

    - by Dave Campbell
    In this Issue: Michael Washington, Samuel Jack, Alfred Astort(-2-), Nokola(-2-), Avi Pilosof, Chris Klug, Pete Brown, Laurent Bugnion(-2-), and Jaime Rodriguez(-2-, -3-). Above the Fold: Silverlight: "Sharing resources and styles between projects in Silverlight" Chris Klug WP7: "Windows Phone Application Performance at Silverlight Firestarter" Jaime Rodriguez Training: "Silverlight View Model (MVVM) - A Play In One Act" Michael Washington Shoutouts: Koen Zwikstra announced the availability of the first Silverlight Spy 4 Preview 1 Gavin Wignall announced the Launch of Festive game built with Silverlight 4, hosted on Azure ... free to play. From SilverlightCream.com: Silverlight View Model (MVVM) - A Play In One Act Michael Washington has an interesting take on writing a blog post with this 'play' version of Silverlight View Models and Expression Blend with a heaping dose of Behaviors added in for flavoring. Build a Windows Phone Game in 3 days – Day 1 Samuel Jack is attempting to build a WP7 game in 3 days including downloading the tools and an XNA book... interesting to see where he's headed wth this venture. 4 of 10 - Make sure your finger can hit the target and text is legible Continuing with a series of tips from the folks reviewing apps for the marketplace via Alfred Astort is this number 4 -- touch target size and legible text. 5 of 10 - Give feedback on touch and progress within your UI Alfred Astort's number 5 is also up, and continues the touch discussion with this tip about giving the user feedback on their touch. Fantasia Painter Released for Windows Phone 7 + Tips Nokola took the release of his Fantasia Painter on WP& as an opportunity not only to blog about the fact that we can go buy it, but has a blog full of hints and tips that he gathered while working on it. Games for Windows Phone 7 Resources: Reducing Load Times, RPG Kit; Other Nokola also blogged about the release of the new games education pack, and gives up the cursor he uses in his videos after being asked... The simplest way to do design-time ViewModels with MVVM and Blend. Avi Pilosof attacks the design-time ViewModel issue in Blend with a 'no code' solution. Sharing resources and styles between projects in Silverlight Chris Klug is talking about sharing resources and styles across a large Silverlight project... near and dear to my heart at this moment. Dynamically Generating Controls in WPF and Silverlight Pete Brown has a post up that's generated some interest... creating controls at runtime... and he's demonstrating several different ways for both Silverlight and WPF #twitter for Windows Phone 7 protips (#wp7) Laurent Bugnion was posting these great tips for Twitter for WP7 and rolled all 16 of them up into a blog post... check them and the app out... Increasing touch surface (#wp7dev) Laurent Bugnion's most current post should be of great interest to WP7 devs... providing more touch surface for your user's fat fingers, err, I mean their fat fingerings :) ... great information and samples ... and interesting it is a fail point as listed by Alfred Astort above. Windows Phone Application Performance at Silverlight Firestarter This material from Jaime Rodriguez actually hit prior to his Firestarter presentation, but should be required reading for anyone doing a WP7 app... great Performance tips from the trenches... slide deck, cheat-sheet, and code. UpdateSourceTrigger on Windows Phone data bindings Another post from Jaime Rodriguez actually went through a couple revisions already.. how about a WP7 TextBox that fires notifications to the ViewModel when the text changes? ... would you like a behavior with that? Details on the Push Notification app limits Jaime Rodriguez has yet another required reading post up on Push Notification limits ... what it really entails and how you can be a good WP7 citizen by the way you program your app. 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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  • Review: ComponentOne Studio for Entity Framework

    - by Tim Murphy
    While I have always been a fan of libraries that improve coding efficiency and reduce code redundancy I have mostly been using ones that were in the public domain.  As part of the Geeks With Blogs Influencers program a got my hands on ComponentOne’s Studio for Entity Framework.  Below are my thought after working with the product for several weeks. My coding preference has always been maintainable code that is reusable across an enterprises protfolio.  Because of this my focus in reviewing this product is less on the RAD components and more on its benefits for layered applications using code first Entity Framework. Before we get into the pros and cons here is a summary of the main feature listed for SEF. Unified Data Context Virtual Data Access More Powerful Data Binding Pros The first thing that I found to my liking is the C1DataSource. It basically manages a cache for your Entity Model context.  Under RAD conditions this is setup automatically when you drop the object on a your design surface.  If you are like me and want to abstract you data management into a library it takes a little more work, but it is still acceptable and gains the same benefits. The second feature that I found beneficial is the definition of views with improved sorting and filtering.  Again the ease of use of these features is greater on the RAD side but no capabilities are missing when manipulating object in code. Linq has become my friend over the last couple of years and it was great to see that ComponentOne had ensured that it remained a first class citizen in their design.  When you look into this product yourself I would suggest taking a dive into LiveLinq which allow the joining of different data source types. As I went through discovering the features of this framework I appreciated the number of examples that they supplied for different uses.  Besides showing how to use SEF with WinForms, WPF and Silverlight they also showed how to accomplish tasks both RAD, code only and MVVM approaches. Cons The only area that I would really like to see improvement is in there level of detail in their documentation.  Specifically I would like to have seen some of the supporting code explained, such as what some supporting object did, in the examples instead of having to go to the programmer’s reference. I did find some times where currently existing projects had some trouble determining scope that the RAD controls were allowed, but I expect this is something that is in part end user related. Summary Overall I found the Studio for Entity Framework capable and well thought out.  If you are already using the Entity Framework this product will fit into your environment with little effort in return for greater flexibility and greater robustness in your solutions. Whether the $895 list price for a standard version works for you will depend on your return on investment. Smaller companies with only a small number of projects may not be able to stomach it, you get a full featured product that is supported by a well established company.  The more projects and the more code you have the greater your return on investment will be. Personally I intend to apply this product to some production systems and will probably have some tips and tricks in the future. del.icio.us Tags: ComponentOne,Studio for Entity Framework,Geeks With Blogs,Influencers,Product Reviews

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  • Top 5 Mobile Apps To Keep Track Of Cricket Scores [ICC World Cup]

    - by Gopinath
    The ICC World Cup 2011 has started with a bang today and the first match between India vs Bangladesh was a cracker. India trashed Bangladesh with a huge margin, thanks to Sehwag for scoring an entertaining 175 runs in 140 runs. At the moment it’s very clear that whole India is gripped with cricket fever and so the rest of fans across the globe. Couple of days ago we blogged about how to watch live streaming of ICC cricket world cup online for free as well as top 10 websites to keep track live scores on your computers. What about tracking live cricket scores on mobiles phones? Here is our guide to top mobile apps available for Symbian(Nokia), Android, iOS and Windows mobiles. By the way, we are covering free apps alone in this post. Why to waste money when free apps are available? SnapTu – Symbian Mobile App SnapTu is a multi feature application that lets you to track live cricket scores, read latest news and check stats published on cric info. SnapTu has tie up with Cric Info and accessing all of CricInfo website on your mobile is very easy. Along with live scores, SnapTu also lets you access your Facebook, Twitter and Picassa on your mobile. This is my favourite application to track cricket on Symbian mobiles. Download SnapTu for your mobiles here Yahoo! Cricket – Symbian & iOS App Yahoo! Cricket Scores is another dedicated application to catch up with live scores and news on your Nokia mobiles and iPhones. This application is developed by Yahoo!, the web giant as well as the official partner of ICC. Features of the app at a glance Cricket: Get a summary page with latest scores, upcoming matches and details of the recent matches News: View sections devoted to the latest news, interviews and photos Statistics: Find the latest team and player stats Download Yahoo! Cricket For Symbian Phones   Download Yahoo! Cricket For iOS ESPN CricInfo – Android and iOS App Is there any site that is better than CricInfo to catch up with latest cricket news and live scores? I say No. ESPN CricInfo is the best website available on the web to get up to the minute  cricket information with in-depth analysis from cricket experts. The live commentary provided by CricInfo site is equally enjoyable as watching live cricket on TV. CricInfo guys have their official applications for Android mobiles and iOS devices and you accessing ball by ball updates on these application is joy. Download ESPN Crick Info App: Android Version, iPhone Version NDTV Cricket – Android, iOS and Blackberry App NDTV Cricket App is developed by NDTV, the most popular English TV news channel in India. This application provides live coverage of international and domestic cricket (Test, ODI & T20) along with latest News, Photos, Videos and Stats. This application is available for iOS devices(iPhones, iPads, iPod Touch), Android mobiles and Blackberry devices. Download NDTV Cricket for iOS here & here    Download NDTV Apps For Rest of OSs ECB Cricket – Symbian, iOS & Android App If you are an UK citizen then  this may be the right application to download for getting live cricket score updates as well as latest news about England Cricket Board. ECB Cricket is an official application of England Cricket Board Download ECB Cricket : Android Version, iPhone Version, Symbian Version Are there any better apps that we missed to feature in this list? This article titled,Top 5 Mobile Apps To Keep Track Of Cricket Scores [ICC World Cup], was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • Kill all the project files!

    - by jamiet
    Like many folks I’m a keen podcast listener and yesterday my commute was filled by listening to Scott Hunter being interviewed on .Net Rocks about the next version of ASP.Net. One thing Scott said really struck a chord with me. I don’t remember the full quote but he was talking about how the ASP.Net project file (i.e. the .csproj file) is going away. The rationale being that the main purpose of that file is to list all the other files in the project, and that’s something that the file system is pretty good at. In Scott’s own words (that someone helpfully put in the comments): A file that lists files is really redundant when the OS already does this Romeliz Valenciano correctly pointed out on Twitter that there will still be a project.json file however no longer will there be a need to keep a list of files in a project file. I suspect project.json will simply contain a list of exclusions where necessary rather than the current approach where the project file is a list of inclusions. On the face of it this seems like a pretty good idea. I’ve long been a fan of convention over configuration and this is a great example of that. Instead of listing all the files in a separate file, just treat all the files in the directory as being part of the project. Ostensibly the approach is if its in the directory, its part of the project. Simple. Now I’m not an ASP.net developer, far from it, but it did occur to me that the same approach could be applied to the two Visual Studio project types that I am most familiar with, SSIS & SSDT. Like many people I’ve long been irritated by SSIS projects that display a faux file system inside Solution Explorer. As you can see in the screenshot below the project has Miscellaneous and Connection Managers folders but no such folders exist on the file system: This may seem like a minor thing but it means useful Solution Explorer features like Show All Files and Open Folder in Windows Explorer don’t work and quite frankly it makes me feel like a second class citizen in the Microsoft ecosystem. I’m a developer, treat me like one. Don’t try and hide the detail of how a project works under the covers, show it to me. I’m a big boy, I can handle it! Would it not be preferable to simply treat all the .dtsx files in a directory as being part of a project? I think it would, that’s pretty much all the .dtproj file does anyway (that, and present things in a non-alphabetic order – something else that wildly irritates me), so why not just get rid of the .dtproj file? In the case of SSDT the .sqlproj actually does a whole lot more than simply list files because it also states the BuildAction of each file (Build, NotInBuild, Post-Deployment, etc…) but I see no reason why the convention over configuration approach can’t help us there either. Want to know which is the Post-deployment script? Well, its the one called Post-DeploymentScript.sql! Simple! So that’s my new crusade. Let’s kill all the project files (well, the .dtproj & .sqlproj ones anyway). Are you with me? @Jamiet

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  • An Actionable Common Approach to Federal Enterprise Architecture

    - by TedMcLaughlan
    The recent “Common Approach to Federal Enterprise Architecture” (US Executive Office of the President, May 2 2012) is extremely timely and well-organized guidance for the Federal IT investment and deployment community, as useful for Federal Departments and Agencies as it is for their stakeholders and integration partners. The guidance not only helps IT Program Planners and Managers, but also informs and prepares constituents who may be the beneficiaries or otherwise impacted by the investment. The FEA Common Approach extends from and builds on the rapidly-maturing Federal Enterprise Architecture Framework (FEAF) and its associated artifacts and standards, already included to a large degree in the annual Federal Portfolio and Investment Management processes – for example the OMB’s Exhibit 300 (i.e. Business Case justification for IT investments).A very interesting element of this Approach includes the very necessary guidance for actually using an Enterprise Architecture (EA) and/or its collateral – good guidance for any organization charged with maintaining a broad portfolio of IT investments. The associated FEA Reference Models (i.e. the BRM, DRM, TRM, etc.) are very helpful frameworks for organizing, understanding, communicating and standardizing across agencies with respect to vocabularies, architecture patterns and technology standards. Determining when, how and to what level of detail to include these reference models in the typically long-running Federal IT acquisition cycles wasn’t always clear, however, particularly during the first interactions of a Program’s technical and functional leadership with the Mission owners and investment planners. This typically occurs as an agency begins the process of describing its strategy and business case for allocation of new Federal funding, reacting to things like new legislation or policy, real or anticipated mission challenges, or straightforward ROI opportunities (for example the introduction of new technologies that deliver significant cost-savings).The early artifacts (i.e. Resource Allocation Plans, Acquisition Plans, Exhibit 300’s or other Business Case materials, etc.) of the intersection between Mission owners, IT and Program Managers are far easier to understand and discuss, when the overlay of an evolved, actionable Enterprise Architecture (such as the FEA) is applied.  “Actionable” is the key word – too many Public Service entity EA’s (including the FEA) have for too long been used simply as a very highly-abstracted standards reference, duly maintained and nominally-enforced by an Enterprise or System Architect’s office. Refreshing elements of this recent FEA Common Approach include one of the first Federally-documented acknowledgements of the “Solution Architect” (the “Problem-Solving” role). This role collaborates with the Enterprise, System and Business Architecture communities primarily on completing actual “EA Roadmap” documents. These are roadmaps grounded in real cost, technical and functional details that are fully aligned with both contextual expectations (for example the new “Digital Government Strategy” and its required roadmap deliverables - and the rapidly increasing complexities of today’s more portable and transparent IT solutions.  We also expect some very critical synergies to develop in early IT investment cycles between this new breed of “Federal Enterprise Solution Architect” and the first waves of the newly-formal “Federal IT Program Manager” roles operating under more standardized “critical competency” expectations (including EA), likely already to be seriously influencing the quality annual CPIC (Capital Planning and Investment Control) processes.  Our Oracle Enterprise Strategy Team (EST) and associated Oracle Enterprise Architecture (OEA) practices are already engaged in promoting and leveraging the visibility of Enterprise Architecture as a key contributor to early IT investment validation, and we look forward in particular to seeing the real, citizen-centric benefits of this FEA Common Approach in particular surface across the entire Public Service CPIC domain - Federal, State, Local, Tribal and otherwise. Read more Enterprise Architecture blog posts for additional EA insight!

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  • Is This Your Idea of Disaster Recovery?

    - by rickramsey
    Don't just make do with less. Protect what you've got. By, for instance, deploying Oracle Solaris 10 inside a zone cluster. "Wait," you say, "what is a zone cluster?" It is a zone deployed across different physical servers. "Who would do that!" you ask in a mild panic. Why, an upstanding sysadmin citizen interested in protecting his or her employer's investment with appropriate high availability and disaster recovery. If one server gets wiped out by Hurricane Sandy along with pretty much the entire East Coast of the USA, your zone continues to run on the other server(s). Provided you set them up in Edinburgh. This white paper (pdf) explains what a zone cluster is and how to use it. If a white paper reminds you of having to read War and Peace in school, just use this Oracle RAC and Solaris Cluster Cheat Sheet, instead. "But wait!" you exclaim. "I didn't realize Solaris 10 offered zone clusters!" I didn't, either! And in an earlier version of this blog post I said that zone clusters were only available with Oracle Solaris 11. But Karoly Vegh pointed me to the documentation for Oracle Solaris Cluster 3.3, which explains how to manage zone clusters in Oracle Solaris 10. Bite my fist! So, the point I was trying to make is not just that you can run Oracle Solaris 10 zone clusters, but that you can run them in an Oracle Solaris 11 environment. Now let's return to our conversation and pick up where we left off ... "Oh no! Whatever shall I do?" Fear not. Remember how Oracle Solaris 11 lets you create a Solaris 10 branded zone inside a system running Oracle Solaris 11? Well, the Solaris Cluster engineers thought that was a bang-up idea, and decided to extend Oracle Solaris Cluster so that you could run your Solaris 10 applications inside the protective cocoon of an Oracle Solaris 11 zone cluster. Take advantage of the installation improvements and network virtualization capabilities of Oracle Solaris 11 while still running your application on Oracle Solaris 10. You Luddite, you. That capability is in the latest release of Oracle Solaris Cluster, version 4.1, which became available last Friday. "Last Friday! Is it too late to get a copy?" You can still get a free copy from our download center (see below). And, if you'd like to know what other goodies the 4.1 release of Oracle Solaris Cluster provides, see: What's New In Oracle Solaris Cluster 4.1 (pdf) Free download Oracle Solaris Cluster 4.1 (SPARC or x86) Tech Article: How to Upgrade to Oracle Solaris Cluster 4.0, by Tim Read. As always, you can get the latest information about Oracle Solaris Cluster, plus technical how-to articles, documentation, and more from Oracle Solaris Cluster Resource Page for Sysadmins and Developers. And don't forget about the online launch of Oracle Solaris 11.1 and Oracle Solaris Cluster 4.1, scheduled for Nov 7. "I feel so much better, now!" Think nothing of it. That's what we're here for. - Rick Website Newsletter Facebook Twitter

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  • Dallas First Regionals 2012&ndash; For Inspiration and Recognition of Science and Technology

    - by T
    Wow!  That is all I have to say after the last 3 days. Three full fun filled days in a world that fed the geek, sparked the competitor, inspired the humanitarian, encouraged the inventor, and continuously warmed my heart.  As part of the Dallas First Regionals, I was awed by incredible students who teach as much as they learn, inventive and truly caring mentors that make mentoring look easy, and completely passionate and dedicated volunteers that bring meaning to giving all that you have and making events fun and safe for all.  If you have any interest in innovation, robotics, or highly motivated students, I can’t recommend anything any higher than visiting a First Robotics event. This is my third year with First and I was honored enough to serve the Dallas First Regionals as both a Web Site evaluator and as the East Field Volunteer Coordinator.  This was also the first year my daughter volunteered with me.  My daughter and I both recognize how different the First program is from other team events.  The difference with First is that everyone is a first class citizen.   It is a difference we can feel through experiencing and observing interactions between executives, respected engineers, students, and event staff.  Even with a veracious competition, you still find a lot of cooperation and we never witnessed any belittling between teams or individuals. First Robotics coined the term “Gracious Professionalism”.   It's a way of doing things that encourages high-quality work, emphasizes the value of others, and respects individuals and the community.1 I was introduced to this term as the Volunteer Coordinator when I was preparing the volunteer instructional speech.  Through the next few days, I discovered it is truly core to everything that First does.  One of the ways First accomplishes Gracious Professionalism is by utilizing another term they came up with which is “CoopertitionTM”. At FIRST, CoopertitionTM is displaying unqualified kindness and respect in the face of fierce competition.1   One of the things I never liked about sports was the need to “destroy” the other team.  First has really found a way to integrate CoopertitionTM  into the rules so teams can be competitive and part of that competition rewards cooperation. Oh and did I mention it has ROBOTS!!!  This year it had basket ball playing Kinect connected, remote controlled, robots!  There are not words for how exciting these games are.  You HAVE to check out this years game, Rebound Rumble, on youtube or you can view live action on Dallas First Video (as of this posting, the recording haven’t posted yet but should be there soon).  There are also some images below. Whatever it is, these students get it and exemplify it and these mentors ooze with it.  I am glad that First supports these events so we can all learn and be inspired by these exceptional students and mentors.  I know that no matter how much I give, it will never compare to what I gain volunteering at First.  Even if you don’t have time to volunteer, you owe it to yourself to go check out one of these events.  See what the future holds, be inspired, be encouraged, take some knowledge, leave some knowledge and most of all, have FUN.  That is what First is all about and thanks to First, I get it.   First Dallas Regionals 2012 VIEW SLIDE SHOW DOWNLOAD ALL 1.  USFirst http://www.usfirst.org/aboutus/gracious-professionalism

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  • Learn Many Languages

    - by Jeff Foster
    My previous blog, Deliberate Practice, discussed the need for developers to “sharpen their pencil” continually, by setting aside time to learn how to tackle problems in different ways. However, the Sapir-Whorf hypothesis, a contested and somewhat-controversial concept from language theory, seems to hold reasonably true when applied to programming languages. It states that: “The structure of a language affects the ways in which its speakers conceptualize their world.” If you’re constrained by a single programming language, the one that dominates your day job, then you only have the tools of that language at your disposal to think about and solve a problem. For example, if you’ve only ever worked with Java, you would never think of passing a function to a method. A good developer needs to learn many languages. You may never deploy them in production, you may never ship code with them, but by learning a new language, you’ll have new ideas that will transfer to your current “day-job” language. With the abundant choices in programming languages, how does one choose which to learn? Alan Perlis sums it up best. “A language that doesn‘t affect the way you think about programming is not worth knowing“ With that in mind, here’s a selection of languages that I think are worth learning and that have certainly changed the way I think about tackling programming problems. Clojure Clojure is a Lisp-based language running on the Java Virtual Machine. The unique property of Lisp is homoiconicity, which means that a Lisp program is a Lisp data structure, and vice-versa. Since we can treat Lisp programs as Lisp data structures, we can write our code generation in the same style as our code. This gives Lisp a uniquely powerful macro system, and makes it ideal for implementing domain specific languages. Clojure also makes software transactional memory a first-class citizen, giving us a new approach to concurrency and dealing with the problems of shared state. Haskell Haskell is a strongly typed, functional programming language. Haskell’s type system is far richer than C# or Java, and allows us to push more of our application logic to compile-time safety. If it compiles, it usually works! Haskell is also a lazy language – we can work with infinite data structures. For example, in a board game we can generate the complete game tree, even if there are billions of possibilities, because the values are computed only as they are needed. Erlang Erlang is a functional language with a strong emphasis on reliability. Erlang’s approach to concurrency uses message passing instead of shared variables, with strong support from both the language itself and the virtual machine. Processes are extremely lightweight, and garbage collection doesn’t require all processes to be paused at the same time, making it feasible for a single program to use millions of processes at once, all without the mental overhead of managing shared state. The Benefits of Multilingualism By studying new languages, even if you won’t ever get the chance to use them in production, you will find yourself open to new ideas and ways of coding in your main language. For example, studying Haskell has taught me that you can do so much more with types and has changed my programming style in C#. A type represents some state a program should have, and a type should not be able to represent an invalid state. I often find myself refactoring methods like this… void SomeMethod(bool doThis, bool doThat) { if (!(doThis ^ doThat)) throw new ArgumentException(“At least one arg should be true”); if (doThis) DoThis(); if (doThat) DoThat(); } …into a type-based solution, like this: enum Action { DoThis, DoThat, Both }; void SomeMethod(Action action) { if (action == Action.DoThis || action == Action.Both) DoThis(); if (action == Action.DoThat || action == Action.Both) DoThat(); } At this point, I’ve removed the runtime exception in favor of a compile-time check. This is a trivial example, but is just one of many ideas that I’ve taken from one language and implemented in another.

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  • Optimal Data Structure for our own API

    - by vermiculus
    I'm in the early stages of writing an Emacs major mode for the Stack Exchange network; if you use Emacs regularly, this will benefit you in the end. In order to minimize the number of calls made to Stack Exchange's API (capped at 10000 per IP per day) and to just be a generally responsible citizen, I want to cache the information I receive from the network and store it in memory, waiting to be accessed again. I'm really stuck as to what data structure to store this information in. Obviously, it is going to be a list. However, as with any data structure, the choice must be determined by what data is being stored and what how it will be accessed. What, I would like to be able to store all of this information in a single symbol such as stack-api/cache. So, without further ado, stack-api/cache is a list of conses keyed by last update: `(<csite> <csite> <csite>) where <csite> would be (1362501715 . <site>) At this point, all we've done is define a simple association list. Of course, we must go deeper. Each <site> is a list of the API parameter (unique) followed by a list questions: `("codereview" <cquestion> <cquestion> <cquestion>) Each <cquestion> is, you guessed it, a cons of questions with their last update time: `(1362501715 <question>) (1362501720 . <question>) <question> is a cons of a question structure and a list of answers (again, consed with their last update time): `(<question-structure> <canswer> <canswer> <canswer> and ` `(1362501715 . <answer-structure>) This data structure is likely most accurately described as a tree, but I don't know if there's a better way to do this considering the language, Emacs Lisp (which isn't all that different from the Lisp you know and love at all). The explicit conses are likely unnecessary, but it helps my brain wrap around it better. I'm pretty sure a <csite>, for example, would just turn into (<epoch-time> <api-param> <cquestion> <cquestion> ...) Concerns: Does storing data in a potentially huge structure like this have any performance trade-offs for the system? I would like to avoid storing extraneous data, but I've done what I could and I don't think the dataset is that large in the first place (for normal use) since it's all just human-readable text in reasonable proportion. (I'm planning on culling old data using the times at the head of the list; each inherits its last-update time from its children and so-on down the tree. To what extent this cull should take place: I'm not sure.) Does storing data like this have any performance trade-offs for that which must use it? That is, will set and retrieve operations suffer from the size of the list? Do you have any other suggestions as to what a better structure might look like?

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  • How to display strings in activity 3 from activity 1, 2? [migrated]

    - by user107160
    I need to get strings values from two different activities say activity1 and activity2, each activity should have maximum 4 edittext field..so totally eight fields should be displayed orderly in activity3. I have tried the code which is not displaying in the activity3. Look at code, Activity1 String namef = fname.getText().toString(); Intent first = new Intent(AssessmentActivity.this, Second.class); first.putExtra("list1", namef); startActivity(first); String namel = lname.getText().toString(); Intent second = new Intent(AssessmentActivity.this, Second.class); second.putExtra("list2", namel); startActivity(second); String phone = mob.getText().toString(); Intent third = new Intent(AssessmentActivity.this, Second.class); third.putExtra("list3", phone); startActivity(third); String mailid = email.getText().toString(); Intent fourth = new Intent(AssessmentActivity.this, Second.class); fourth.putExtra("list4", mailid); startActivity(fourth); Activity2 String cont = addr.getText().toString(); Intent fifth = new Intent(Second.this, Third.class); fifth.putExtra("list5", cont); startActivity(fifth); String db = dob.getText().toString(); Intent sixth = new Intent(Second.this, Third.class); sixth.putExtra("list6", db); startActivity(sixth); String nation = citizen.getText().toString(); Intent Seventh = new Intent(Second.this, Third.class); Seventh.putExtra("list7", nation); startActivity(Seventh); String subject = course.getText().toString(); Intent Eight = new Intent(Second.this, Third.class); Eight.putExtra("list8", subject); startActivity(Eight); *Activity3* TextView first = (TextView)findViewById(R.id.textView2); String fieldone = getIntent().getStringExtra("list1" ); first.setText(fieldone); TextView second = (TextView)findViewById(R.id.textView3); String fieldtwo = getIntent().getStringExtra("list2" ); second.setText(fieldtwo); TextView third = (TextView)findViewById(R.id.textView4); String fieldthree = getIntent().getStringExtra("list3" ); third.setText(fieldthree); TextView fourth = (TextView)findViewById(R.id.textView5); String fieldfour = getIntent().getStringExtra("list4" ); fourth.setText(fieldfour); TextView fifth = (TextView)findViewById(R.id.textView6); String fieldfive = getIntent().getStringExtra("list5" ); fifth.setText(fieldfive); TextView sixth = (TextView)findViewById(R.id.textView7); String fieldsix = getIntent().getStringExtra("list6" ); sixth.setText(fieldsix); TextView seventh = (TextView)findViewById(R.id.textView8); String fieldseven = getIntent().getStringExtra("list7" ); seventh.setText(fieldseven); TextView eight = (TextView)findViewById(R.id.textView3); String fieldeight = getIntent().getStringExtra("list8"); eight.setText(fieldeight);

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  • Blackberry storm 9530 tracing touch events while scrolling

    - by SWATI
    hey in my screen there is a an edit field and 2 custom button fields as "OK" and "CANCEL" Below buttonfield there are some more focussable label fields when i write a name in edit field and press enter then focus comes to "OK" button but how to set focus on "CANCEL" button. Moreover while scrolling the focus does not automatically move ahead??? what to do may be i m confused with touch events and their handling!!! Kindly help!!!!!!!!!!!! Code: txt_Name = new EditField(TextField.NO_NEWLINE) { public void paint(net.rim.device.api.ui.Graphics g) { g.setColor(Color.MAROON); super.paint(g); } }; txt_Name.setFont(font); v1 = new VerticalFieldManager(); v1.add(txt_Name ); ButtonField btn1 = new ButtonField("OK",ButtonField.CONSUME_CLICK); ButtonField btn2 = new ButtonField("CANCEL",ButtonField.CONSUME_CLICK); v2 = new VerticalFieldManager(); v2.add(btn1); v2.add(btn2); LabelField l1 = new LabelField("Hello Moon ",Field.Focussable); LabelField l2 = new LabelField("Hello Citizen",Field.Focussable); LabelField l3 = new LabelField("Hello People",Field.Focussable); LabelField l4 = new LabelField("Hello world",Field.Focussable); v3 = new VerticalFieldManager(); v3.add(l1); v3.add(l2); v3.add(l3); v3.add(l4); add(v1); add(v2); add(v3); } protected boolean navigationClick(int status, int time) { if(OK.isFocus()) { //execute some code return true; } if(CANCEL.isFocus()) { //execute some code return true; } }

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  • Loading one page inside another

    - by Robin I Knight
    User 'Citizen' provided an answer to the iframe situation with the ajax script from dynamic drive. As I predicted it although it loads one page inside another it does not work with the calculation scripts, collapsible panels, validation form. All of it simply not working. I have set up a test page that has the exact same HEAD section as the page that is loaded inside it, so it is not s problem of script location. Take a look and see if you can tell me what is going on. Baring in mind this is just a test page. On the test page the entire page is loaded from another and as you can see all the collapsible panels are open, all calculations except the duration are not working because another file that is loaded by ajax on the original page is not loading in this one, the accordion menu us not working and the validation form is not validating. It is as if all script triggers have been removed and left behind but like I said the HEAD section of the parent page contains all of the scripts as well. Any ideas http://www.divethegap.com/scuba-diving-programmes-dive-the-gap/programme-pages/dahab-divemaster/test.php

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  • 7 reasons you had to be at JavaOne Latin America 2012

    - by Bruno.Borges
    Yesterday was 12/12/12, and everybody went crazy on Twitter with cool memes like this one. And maybe you are now wondering why I mentioned 7 (seven) on the blog title. Because I want to play numbers? Yes! Today is 7 days after JavaOne Latin America 2012 is over (... and I had to figure out an excuse for taking so long to blog about it...). So unless you were at JavaOne Latin America this year, here are 7 things you missed: OTN Lounge mini-theatreThere was a mini-theatre holding several lightning talks. We had people from SouJava JUG, GoJava JUG, Globalcode, and several other Java gurus and companies running demos, talks, and even more. For example, @drspockbr talked about the ScrumToys project, that demonstrates the power of JSF. Hands On Lab for JAX-RS and WebSocketsOne of the cool things to do during JavaOne is to come to these Hands On labs and really do something using new technologies with the help of experts. This one in particular, was covered by me, Arun Gupta, and Reza Rahman. The HOL had more people than laptops (and we had 48 laptops!) interested on understanding and learning about the new stuff that is coming within Java EE 7. Things like JAX-RS, Server-sent Events and WebSockets. Hey, if you want to try this HOL by yourself, it is available on Github, so go for it! If you have questions, just let me know! Java Community KeynoteThis keynote presented a lot of cool things like startups using Java in their projects, the Duke Awards, SouJava winning the JCP Outstanding Award, the Java Band, and even more! It was really a space where the Java community could present what they are doing and what they want to do. There's a lot of interest on the Adopt-a-JSR program and the Adopt-OpenJDK. There's also an Adopt-a-JavaEE-JSR program! Take a look if you want to participate and Make the Future Java. Java EE (JMS, JAX-RS) sessions from Reza Rahman, the HeavyMetal guyReza is a well know professional and Java EE enthusiast from the communitty who just joined Oracle this year. His sessions were very well attended, perhaps because of a high interest on the new things coming to Java EE 7 like JMS 2.0 and JAX-RS 2.0. If you want to look at what he did at this JavaOne edition, read his blog post. By the way, if you like Java and heavymetal, you should follow him on Twitter as well! :-) Java EE (WebSockets, HTML5) sessions from Arun Gupta, the GlassFish guyIf you don't know Arun Gupta, no worries. You will have time to know about him while you read his Java EE 6 Pocket Guide. Arun has been evangelizing Java EE for a long time, and is now spreading his word about the new upcoming version Java EE 7. He gave one talk about HTML5 Productivity on the Java EE 7 platform, and another one on building web apps with WebSockets. Pretty neat! Arun blogged about JavaOne Latin America as well. Read it here. Java Embedded and JavaFXIf there are two things that are really trending in the Java World right now besides Java EE 7, certainly they are JavaFX and Java Embedded. There were 14 talks covering Java Embedded, from Java Cards to Raspberry.pi, from Java ME to Java on your TV with Ginga-J. The Internet of Things is becoming true, and Java is the only platform today that can connect it all in an standardized and concise way. JavaFX gained a lot of attention too. There were 8 sessions covering what the platform has to offer in terms of Rich User Experience. The JavaFX Scene Builder is an awesome tool to start playing designing an UI, and coding for JavaFX is like coding Swing with 8 hands, one holding your coffee cup. You can achieve a lot, with your two hands (unless, you really have 8 hands, then you can achieve 4 times more :-). If you want to read more about JavaFX, go to Stephen Chin's blog post. GlassFish and Friends Party, 1st edition at JavaOne Lating AmericaThis is probably the thing that I'm most proud. We brought to Brasil the tradition of holding a happy hour for all GlassFish, Java EE friends. This party started almost 7 years ago in San Francisco, and it was about time to bring it to Brazil! The party happened on Tuesday night, right after JavaOne General Keynote, at the Tribeca Pub. We had about 80 attendees and met a lot of Java EE developers there! People from JUGs, Oracle, Locaweb and Red Hat showed up too, including some execs from Oracle that didn't resist and could not miss a party like this one.Lots of caipirinhas, beer and food to everyone, some cool music... even The Fish walking around the party with Juggy!You can see more photos from the party on an album I shared with the recently created GlassFish Brasil community on Google+ here (but you may be more interested in joining the GlassFish english community). There's also more pictures that Arun took and shared on this link. So now you may want to consider coming to Brazil next year! Java EE 7 is on its way, and Brazil is happily and patiently waiting for it, with a lot of enthusiasm. By the way, GlassFish and Java EE 6 just celebrated a Happy Birthday!

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  • JavaOne Latin America Opening Keynotes

    - by Tori Wieldt
    Originally published on blogs.oracle.com/javaone It was a great first day at JavaOne Brazil, which included the Java Strategy and Java Technical keynotes. Henrik Stahl, Senior Director, Product Management for Java opened the keynotes by saying that this is the third year for JavaOne Latin America. He explained, "You know what they say, the first time doesn't count, the second time is a habit and the third time it's a tradition!" He mentioned that he was thrilled that this is largest JavaOne in Brazil to date, and he wants next year to be larger. He said that Oracle knows Latin America is an important hub for development.  "We continually come back to Latin America because of the dedication the community has with driving the continued innovation for Java," he said. Stahl explained that Oracle and the Java community must continue to innovate and Make the Future Java together. The success of Java depends on three important factors: technological innovation, Oracle as a strong steward of Java, and community participation. "The Latin American Java Community (especially in Brazil) is a shining example of how to be positive contributor to Java," Stahl said. Next, George Saab, VP software dev, Java Platform Group at Oracle, discussed some of the recent and upcoming changes to Java. "In addition to the incremental improvements to Java 7, we have also increased the set of platforms supported by Oracle from Linux, Windows, and Solaris to now also include Mac OS X and Linux/ARM for ARM-based PCs such as the Raspberry Pi and emerging ARM based microservers."  Saab announced that EA builds for Linux ARM Hard Float ABI will be available by the end of the year.  Staffan Friberg, Product Manager, Java Platform Group, provided an overview of some of the language coming in Java 8, including Lambda, remove of PermGen, improved data and time APIs and improved security, Java 8 development is moving along. He reminded the audience that they can go to OpenJDK to see this development being done in real-time, and that there are weekly early access builds of OracleJDK 8 that developers can download and try today. Judson Althoff, Senior Vice President, Worldwide Alliances and Channels and Embedded Sales, was invited to the stage, and the audience was told that "even though he is wearing a suit, he is still pretty technical." Althoff started off with a bang: "The Internet of Things is on a collision course with big data and this is a huge opportunity for developers."  For example, Althoff said, today cars are more a data device than a mechanical device. A car embedded with sensors for fuel efficiency, temperature, tire pressure, etc. can generate a petabyte of data A DAY. There are similar examples in healthcare (patient monitoring and privacy requirements creates a complex data problem) and transportation management (sending a package around the world with sensors for humidity, temperature and light). Althoff then brought on stage representatives from three companies that are successful with Java today, first Axel Hansmann, VP Strategy & Marketing Communications, Cinterion. Mr. Hansmann explained that Cinterion, a market leader in Latin America, enables M2M services with Java. At JavaOne San Francisco, Cinterion launched the EHS5, the smallest 3g solderable module, with Java installed on it. This provides Original Equipment Manufacturers (OEMs) with a cost effective, flexible platform for bringing advanced M2M technology to market.Next, Steve Nelson, Director of Marketing for the Americas, at Freescale explained that Freescale is #1 in Embedded Processors in Wired and Wireless Communications, and #1 in Automotive Semiconductors in the Americas. He said that Java provides a mature, proven platform that is uniquely suited to meet the requirements of almost any type of embedded device. He encouraged University students to get involved in the Freescale Cup, a global competition where student teams build, program, and race a model car around a track for speed.Roberto Franco, SBTVD Forum President, SBTVD, talked about Ginga, a Java-based standard for television in Brazil. He said there are 4 million Ginga TV sets in Brazil, and they expect over 20 million TV sets to be sold by the end of 2014. Ginga is also being adopted in other 11 countries in Latin America. Ginga brings interactive services not only at TV set, but also on other devices such as tablets,  PCs or smartphones, as the main or second screen. "Interactive services is already a reality," he said, ' but in a near future, we foresee interactivity enhanced TV content, convergence with OTT services and a big participation from the audience,  all integrated on TV, tablets, smartphones and second screen devices."Before he left the stage, Nandini Ramani thanked Judson for being part of the Java community and invited him to the next Geek Bike Ride in Brazil. She presented him an official geek bike ride jersey.For the Technical Keynote, a "blue screen of death" appeared. With mock concern, Stephin Chin asked the rest of the presenters if they could go on without slides. What followed was a interesting collection of demos, including JavaFX on a tablet, a look at Project Easel in NetBeans, and even Simon Ritter controlling legos with his brainwaves! Stay tuned for more dispatches.

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  • JavaOne Latin America Opening Keynotes

    - by Tori Wieldt
    It was a great first day at JavaOne Brazil, which included the Java Strategy and Java Technical keynotes. Henrik Stahl, Senior Director, Product Management for Java opened the keynotes by saying that this is the third year for JavaOne Latin America. He explained, "You know what they say, the first time doesn't count, the second time is a habit and the third time it's a tradition!" He mentioned that he was thrilled that this is largest JavaOne in Brazil to date, and he wants next year to be larger. He said that Oracle knows Latin America is an important hub for development.  "We continually come back to Latin America because of the dedication the community has with driving the continued innovation for Java," he said. Stahl explained that Oracle and the Java community must continue to innovate and Make the Future Java together. The success of Java depends on three important factors: technological innovation, Oracle as a strong steward of Java, and community participation. "The Latin American Java Community (especially in Brazil) is a shining example of how to be positive contributor to Java," Stahl said. Next, George Saab, VP software dev, Java Platform Group at Oracle, discussed some of the recent and upcoming changes to Java. "In addition to the incremental improvements to Java 7, we have also increased the set of platforms supported by Oracle from Linux, Windows, and Solaris to now also include Mac OS X and Linux/ARM for ARM-based PCs such as the Raspberry Pi and emerging ARM based microservers."  Saab announced that EA builds for Linux ARM Hard Float ABI will be available by the end of the year.  Staffan Friberg, Product Manager, Java Platform Group, provided an overview of some of the language coming in Java 8, including Lambda, remove of PermGen, improved data and time APIs and improved security, Java 8 development is moving along. He reminded the audience that they can go to OpenJDK to see this development being done in real-time, and that there are weekly early access builds of OracleJDK 8 that developers can download and try today. Judson Althoff, Senior Vice President, Worldwide Alliances and Channels and Embedded Sales, was invited to the stage, and the audience was told that "even though he is wearing a suit, he is still pretty technical." Althoff started off with a bang: "The Internet of Things is on a collision course with big data and this is a huge opportunity for developers."  For example, Althoff said, today cars are more a data device than a mechanical device. A car embedded with sensors for fuel efficiency, temperature, tire pressure, etc. can generate a petabyte of data A DAY. There are similar examples in healthcare (patient monitoring and privacy requirements creates a complex data problem) and transportation management (sending a package around the world with sensors for humidity, temperature and light). Althoff then brought on stage representatives from three companies that are successful with Java today, first Axel Hansmann, VP Strategy & Marketing Communications, Cinterion. Mr. Hansmann explained that Cinterion, a market leader in Latin America, enables M2M services with Java. At JavaOne San Francisco, Cinterion launched the EHS5, the smallest 3g solderable module, with Java installed on it. This provides Original Equipment Manufacturers (OEMs) with a cost effective, flexible platform for bringing advanced M2M technology to market.Next, Steve Nelson, Director of Marketing for the Americas, at Freescale explained that Freescale is #1 in Embedded Processors in Wired and Wireless Communications, and #1 in Automotive Semiconductors in the Americas. He said that Java provides a mature, proven platform that is uniquely suited to meet the requirements of almost any type of embedded device. He encouraged University students to get involved in the Freescale Cup, a global competition where student teams build, program, and race a model car around a track for speed.Roberto Franco, SBTVD Forum President, SBTVD, talked about Ginga, a Java-based standard for television in Brazil. He said there are 4 million Ginga TV sets in Brazil, and they expect over 20 million TV sets to be sold by the end of 2014. Ginga is also being adopted in other 11 countries in Latin America. Ginga brings interactive services not only at TV set, but also on other devices such as tablets,  PCs or smartphones, as the main or second screen. "Interactive services is already a reality," he said, ' but in a near future, we foresee interactivity enhanced TV content, convergence with OTT services and a big participation from the audience,  all integrated on TV, tablets, smartphones and second screen devices."Before he left the stage, Nandini Ramani thanked Judson for being part of the Java community and invited him to the next Geek Bike Ride in Brazil. She presented him an official geek bike ride jersey.For the Technical Keynote, a "blue screen of death" appeared. With mock concern, Stephin Chin asked the rest of the presenters if they could go on without slides. What followed was a interesting collection of demos, including JavaFX on a tablet, a look at Project Easel in NetBeans, and even Simon Ritter controlling legos with his brainwaves! Stay tuned for more dispatches.

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  • JavaDay Taipei 2014 Trip Report

    - by reza_rahman
    JavaDay Taipei 2014 was held at the Taipei International Convention Center on August 1st. Organized by Oracle University, it is one of the largest Java developer events in Taiwan. This was another successful year for JavaDay Taipei with a fully sold out venue packed with youthful, energetic developers (this was my second time at the event and I have already been invited to speak again next year!). In addition to Oracle speakers like me, Steve Chin and Naveen Asrani, the event also featured a bevy of local speakers including Taipei Java community leaders. Topics included Java SE, Java EE, JavaFX, cloud and Big Data. It was my pleasure and privilege to present one of the opening keynotes for the event. I presented my session on Java EE titled "JavaEE.Next(): Java EE 7, 8, and Beyond". I covered the changes in Java EE 7 as well as what's coming in Java EE 8. I demoed the Cargo Tracker Java EE BluePrints. I also briefly talked about Adopt-a-JSR for Java EE 8. The slides for the keynote are below (click here to download and view the actual PDF): It appears your Web browser is not configured to display PDF files. No worries, just click here to download the PDF file. In the afternoon I did my JavaScript + Java EE 7 talk titled "Using JavaScript/HTML5 Rich Clients with Java EE 7". This talk is basically about aligning EE 7 with the emerging JavaScript ecosystem (specifically AngularJS). The talk was completely packed. The slide deck for the talk is here: JavaScript/HTML5 Rich Clients Using Java EE 7 from Reza Rahman The demo application code is posted on GitHub. The code should be a helpful resource if this development model is something that interests you. Do let me know if you need help with it but the instructions should be fairly self-explanatory. I am delivering this material at JavaOne 2014 as a two-hour tutorial. This should give me a little more bandwidth to dig a little deeper, especially on the JavaScript end. I finished off Java Day Taipei with my talk titled "Using NoSQL with ~JPA, EclipseLink and Java EE" (this was the last session of the conference). The talk covers an interesting gap that there is surprisingly little material on out there. The talk has three parts -- a birds-eye view of the NoSQL landscape, how to use NoSQL via a JPA centric facade using EclipseLink NoSQL, Hibernate OGM, DataNucleus, Kundera, Easy-Cassandra, etc and how to use NoSQL native APIs in Java EE via CDI. The slides for the talk are here: Using NoSQL with ~JPA, EclipseLink and Java EE from Reza Rahman The JPA based demo is available here, while the CDI based demo is available here. Both demos use MongoDB as the data store. Do let me know if you need help getting the demos up and running. After the event the Oracle University folks hosted a reception in the evening which was very well attended by organizers, speakers and local Java community leaders. I am extremely saddened by the fact that this otherwise excellent trip was scarred by terrible tragedy. After the conference I joined a few folks for a hike on the Maokong Mountain on Saturday. The group included friends in the Taiwanese Java community including Ian and Robbie Cheng. Without warning, fatal tragedy struck on a remote part of the trail. Despite best efforts by us, the excellent Taiwanese Emergency Rescue Team and World class Taiwanese physicians we were unable to save our friend Robbie Cheng's life. Robbie was just thirty-four years old and is survived by his younger brother, mother and father. Being the father of a young child myself, I can only imagine the deep sorrow that this senseless loss unleashes. Robbie was a key member of the Taiwanese Java community and a Java Evangelist at Sun at one point. Ironically the only picture I was able to take of the trail was mere moments before tragedy. I thought I should place him in that picture in profoundly respectful memoriam: Perhaps there is some solace in the fact that there is something inherently honorable in living a bright life, dying young and meeting one's end on a beautiful remote mountain trail few venture to behold let alone attempt to ascend in a long and tired lifetime. Perhaps I'd even say it's a fate I would not entirely regret facing if it were my own. With that thought in mind it seems appropriate to me to quote some lyrics from the song "Runes to My Memory" by legendary Swedish heavy metal band Amon Amarth idealizing a fallen Viking warrior cut down in his prime: "Here I lie on wet sand I will not make it home I clench my sword in my hand Say farewell to those I love When I am dead Lay me in a mound Place my weapons by my side For the journey to Hall up high When I am dead Lay me in a mound Raise a stone for all to see Runes carved to my memory" I submit my deepest condolences to Robbie's family and hope my next trip to Taiwan ends in a less somber note.

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  • BI&EPM in Focus June 2014

    - by Mike.Hallett(at)Oracle-BI&EPM
    Applications Webcast Centre – A Library of Discussion and Research for Best Practice: Achieving Reliable Planning, Budgeting and Forecasting Talent Analytics and Big Data – Is HR ready for the challenge Enterprise Data – The cost of non-quality Customers Josephine Niemiec from ADP talks about Oracle Hyperion Workforce Planning at Collaborate 2014 (link) Video Chris Nelms from Ameren talks about Oracle BI Spend and Procurement Analytics at Collaborate 2014 (link) Video Leggett & Platt Leverages Oracle Hyperion EPM and Demantra (link) Video Pella Corporation Accelerates Close Cycle by Cutting Time for Financial Consolidation from Three Days to Less Than One Day (link) Secretaría General de Administración de Justicia en España Enhances Citizen Services with Near-Real-Time Business Intelligence Gleaned from 500 Databases  (link) Bellco Credit Union Speeds Budget Development by 30%—Gains Insight into Specific Branch and Financial Product Profitability  (link)  Video QDQ media Speeds up Financial Reporting by 24x, Gains Business Agility, and Integrates Seamlessly into Corporate Accounting System  (link) Westfield Group Maximizes Shopping Mall Revenue, Shortens Year-End Financial Consolidation by 75%  (link)  IL&FS Transportation Networks Shortens Financial Consolidation and Reporting Cycle by Eight Days, Gains In-Depth Insight into Business Performance   (link) Angel Trains Optimizes Rail Operations for Purchasing, Sourcing, and Project Management to Meet Challenges of Evolving Rail Industry  (link) Enterprise Performance Management June 11, at Oracle Utrecht, NL: Morning session: Explore Planning and Budgeting in the Cloud (link) June 12, London: PureApps Presents: Best Practice Financial Consolidation and Reporting Workshop (link) July 3, Koln: Oracle Hyperion Business Analytics Roundtable (link) Blog: What's Your Tax Strategy? Automate the Operational Transfer Pricing Process (link) YouTube Video: Automate Tax Reporting with Oracle Hyperion Tax Provision (link) YouTube Video: Introducing Oracle Hyperion Planning’s Tablet Optimized Interface (link) OracleEPMWebcasts @ YouTube (link) Partner webcasts: Wednesday, 4 June, 5.00 GMT - Case Study:  Lessons Learned from Edgewater Ranzal's Internal Implementation of Oracle Planning & Budgeting Cloud Service (PBCS) - Learn more and register here! Thursday, 5 June, 4.00 GMT - Achieving Accountable Care Using Oracle Technology - Learn more and register here! Tuesday, 17 June, 4.00 GMT - Optimizing Performance for Oracle EPM Systems - Learn more and register here! Oracle University Blog: The Coolest Features Available with Oracle Hyperion 11.1.2.3 – Training from OU to help you to best use them (link) Support: Proactive Support: EPM Hyperion Planning 11.1.2.3.500 Using RMI Service [Blog] Proactive Support: Planning and Budgeting Cloud Service Videos (link) Planning and Budgeting Cloud Service (PBCS) 11.1.2.3.410 Patch Bundle [Doc ID 1670981.1] Hyperion Analytic Provider Services 11.1.2.2.106 Patch Set Update [Doc ID 1667350.1] Hyperion Essbase 11.1.2.2.106 Patch Set Update [Doc ID 1667346.1] Hyperion Essbase Administration Services 11.1.2.2.106 Patch Set Update [Doc ID 1667348.1] Hyperion Essbase Studio 11.1.2.2.106 Patch Set Update [Doc ID 1667329.1] Hyperion Smart View 11.1.2.5.210 Patch Set Update [Doc ID 1669427.1] Using HPCM, HSF or DRM Communities (link) Business Intelligence June 12, Birmingham, UK: Oracle Big Data at Work - Use Cases and Architecture (link) June 17, London: Oracle at Cloud & Big Data World Forums (link) June 17, Partner Webcast: Transform your Planning Capabilities with Peloton's CloudAccelerator for Oracle PBCS (link) June 19, London: Oracle at the Whitehall Media Big Data Analytics Conference and Exhibition (link) June 19, London: Partner Event - Agile BI Conference by Peak Indicators [link] June 25, Munich: Oracle Special Day auf der TDWI 2014 Konferenz (link) July 15, London: Oracle Endeca Information Discovery Workshop (link) July 16, London: BI Applications Workshop – Financial Analytics & Procurement Analytics (link) July 17, London: BI Applications Workshop – HR Analytics (link) Milan, Italy: L’Osservatorio Big Data Analytics & Business Intelligence with Politecnico di Milano (link) OBIA 11.1.1.8.1 - Now Available [Blog] What’s New in OBIA 11.1.1.8.1 [Blog] BI Blog: A closer look at Oracle BI Applications 11.1.1.8.1 release (link) Press Release: BI Applications Deliver Greater Insight into Talent and Procurement (link) Support Blog: OBIA 11.1.1.8.1 Upgrade Guide & Documentation (link) YouTube Video: Glenn Hoormann of Ludus talks to us about Oracle Business Intelligence and ERP at Collaborate 2014 (Link) YouTube Video: Performance Architects talks about key BI and Mobile trends, including Endeca at Collaborate 2014 (link) Big Data Blog: 3 Keys for Using Big Data Effectively for Enhanced Customer Experience (link) Big Data Lite Demo VM 3.0 Now Available on OTN BI Blog: Data Relationship Governance - Workflow in a Bottle (link) MDM Blog: Register for Product Data Management Weekly Cloudcasts (link) MDM Blog: Improve your Customer Experience with High Quality Information (link) MDM Blog: Big Data Challenges & Considerations (link) Oracle University: Oracle BI Applications 11g: Implementation using ODI (link) Proactive Support: Monthly Index [Blog] My Oracle Support: Partner Accreditation for Business Analytics Support [Blog] OBIEE 11g Test-to-Production (T2P) / Clone Procedures Guide [Blog] Normal 0 false false false EN-GB X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Workarounds for supporting MVVM in the Silverlight TreeView Control

    - by cibrax
    MVVM (Model-View-ViewModel) is the pattern that you will typically choose for building testable user interfaces either in WPF or Silverlight. This pattern basically relies on the data binding support in those two technologies for mapping an existing model class (the view model) to the different parts of the UI or view. Unfortunately, MVVM was not threated as first citizen for some of controls released out of the box in the Silverlight runtime or the Silverlight toolkit. That means that using data binding for implementing MVVM is not always something trivial and usually requires some customization in the existing controls. In ran into different problems myself trying to fully support data binding in controls like the tree view or the context menu or things like drag & drop.  For that reason, I decided to write this post to show how the tree view control or the tree view items can be customized to support data binding in many of its properties. In first place, you will typically use a tree view for showing hierarchical data so the view model somehow must reflect that hierarchy. An easy way to implement hierarchy in a model is to use a base item element like this one, public abstract class TreeItemModel { public abstract IEnumerable<TreeItemModel> Children; } You can later derive your concrete model classes from that base class. For example, public class CustomerModel { public string FullName { get; set; } public string Address { get; set; } public IEnumerable<OrderModel> Orders { get; set; } }   public class CustomerTreeItemModel : TreeItemModel { public CustomerTreeItemModel(CustomerModel customer) { }   public override IEnumerable<TreeItemModel> Children { get { // Return orders } } } The Children property in the CustomerTreeItem model implementation can return for instance an ObservableCollection<TreeItemModel> with the orders, so the tree view will automatically subscribe to all the changes in the collection. You can bind this model to the tree view control in the UI by using a Hierarchical data template. <e:TreeView x:Name="TreeView" ItemsSource="{Binding Customers}"> <e:TreeView.ItemTemplate> <sdk:HierarchicalDataTemplate ItemsSource="{Binding Children}"> <!-- TEMPLATE --> </sdk:HierarchicalDataTemplate> </e:TreeView.ItemTemplate> </e:TreeView> An interesting behavior with the Children property and the Hierarchical data template is that the Children property is only invoked before the expansion, so you can use lazy load at this point (The tree view control will not expand the whole tree in the first expansion). The problem with using MVVM in this control is that you can not bind properties in model with specific properties of the TreeView item such as IsSelected or IsExpanded. Here is where you need to customize the existing tree view control to support data binding in tree items. public class CustomTreeView : TreeView { public CustomTreeView() { }   protected override DependencyObject GetContainerForItemOverride() { CustomTreeViewItem tvi = new CustomTreeViewItem(); Binding expandedBinding = new Binding("IsExpanded"); expandedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsExpandedProperty, expandedBinding); Binding selectedBinding = new Binding("IsSelected"); selectedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsSelectedProperty, selectedBinding); return tvi; } }   public class CustomTreeViewItem : TreeViewItem { public CustomTreeViewItem() { }   protected override DependencyObject GetContainerForItemOverride() { CustomTreeViewItem tvi = new CustomTreeViewItem(); Binding expandedBinding = new Binding("IsExpanded"); expandedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsExpandedProperty, expandedBinding); Binding selectedBinding = new Binding("IsSelected"); selectedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsSelectedProperty, selectedBinding); return tvi; } } You basically need to derive the TreeView and TreeViewItem controls to manually add a binding for the properties you need. In the example above, I am adding a binding for the “IsExpanded” and “IsSelected” properties in the items. The model for the tree items now needs to be extended to support those properties as well, public abstract class TreeItemModel : INotifyPropertyChanged { bool isExpanded = false; bool isSelected = false;   public abstract IEnumerable<TreeItemModel> Children { get; }   public bool IsExpanded { get { return isExpanded; } set { isExpanded = value; if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("IsExpanded")); } }   public bool IsSelected { get { return isSelected; } set { isSelected = value; if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("IsSelected")); } }   public event PropertyChangedEventHandler PropertyChanged; } However, as soon as you use this custom tree view control, you lose all the automatic styles from the built-in toolkit themes because they are tied to the control type (TreeView in this case).  The only ugly workaround I found so far for this problem is to copy the styles from the Toolkit source code and reuse them in the application.

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  • Telerik Releases a new Visual Entity Designer

    Love LINQ to SQL but are concerned that it is a second class citizen? Need to connect to more databases other than SQL Server? Think that the Entity Framework is too complex? Want a domain model designer for data access that is easy, yet powerful? Then the Telerik Visual Entity Designer is for you. Built on top of Telerik OpenAccess ORM, a very mature and robust product, Teleriks Visual Entity Designer is a new way to build your domain model that is very powerful and also real easy to use. How easy? Ill show you here. First Look: Using the Telerik Visual Entity Designer To get started, you need to install the Telerik OpenAccess ORM Q1 release for Visual Studio 2008 or 2010. You dont need to use any of the Telerik OpenAccess wizards, designers, or using statements. Just right click on your project and select Add|New Item from the context menu. Choose Telerik OpenAccess Domain Model from the Visual Studio project templates. (Note to existing OpenAccess users, dont run the Enable ORM wizard or any other OpenAccess menu unless you are building OpenAccess Entities.) You will then have to specify the database backend (SQL Server, SQL Azure, Oracle, MySQL, etc) and connection. After you establish your connection, select the database objects you want to add to your domain model. You can also name your model, by default it will be NameofyourdatabaseEntityDiagrams. You can click finish here if you are comfortable, or tweak some advanced settings. Many users of domain models like to add prefixes and suffixes to classes, fields, and properties as well as handle pluralization. I personally accept the defaults, however, I hate how DBAs force underscores on me, so I click on the option to remove them. You can also tweak your namespace, mapping options, and define your own code generation template to gain further control over the outputted code. This is a very powerful feature, but for now, I will just accept the defaults.   When we click finish, you can see your domain model as a file with the .rlinq extension in the Solution Explorer. You can also bring up the visual designer to view or further tweak your model by double clicking on the model in the Solution Explorer.  Time to use the model! Writing a LINQ Query Programming against the domain model is very simple using LINQ. Just set a reference to the model (line 12 of the code below) and write a standard LINQ statement (lines 14-16).  (OpenAccess users: notice the you dont need any using statements for OpenAccess or an IObjectScope, just raw LINQ against your model.) 1: using System; 2: using System.Linq; 3: //no need for anOpenAccess using statement 4:   5: namespace ConsoleApplication3 6: { 7: class Program 8: { 9: static void Main(string[] args) 10: { 11: //a reference tothe data context 12: NorthwindEntityDiagrams dat = new NorthwindEntityDiagrams(); 13: //LINQ Statement 14: var result = from c in dat.Customers 15: where c.Country == "Germany" 16: select c; 17:   18: //Print out the company name 19: foreach (var cust in result) 20: { 21: Console.WriteLine("CompanyName: " + cust.CompanyName); 22: } 23: //keep the consolewindow open 24: Console.Read(); 25: } 26: } 27: } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Lines 19-24 loop through the result of our LINQ query and displays the results. Thats it! All of the super powerful features of OpenAccess are available to you to further enhance your experience, however, in most cases this is all you need. In future posts I will show how to use the Visual Designer with some other scenarios. Stay tuned. Enjoy! Technorati Tags: Telerik,OpenAccess,LINQ 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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  • Agile Testing Days 2012 – My First Conference!

    - by Chris George
    I’d like to give you a bit of background first… so please bear with me! In 1996, whilst studying for my final year of my degree, I applied for a job as a C++ Developer at a small software house in Hertfordshire  After bodging up the technical part of the interview I didn’t get the job, but was offered a position as a QA Engineer instead. The role sounded intriguing and the pay was pretty good so in the absence of anything else I took it. Here began my career in the world of software testing! Back then, testing/QA was often an afterthought, something that was bolted on to the development process and very much a second class citizen. Test automation was rare, and tools were basic or non-existent! The internet was just starting to take off, and whilst there might have been testing communities and resources, we were certainly not exposed to any of them. After 8 years I moved to another small company, and again didn’t find myself exposed to any of the changes that were happening in the industry. It wasn’t until I joined Red Gate in 2008 that my view of testing and software development as a whole started to expand. But it took a further 4 years for my view of testing to be totally blown open, and so the story really begins… In May 2012 I was fortunate to land the role of Head of Test Engineering. Soon after, I received an email with details for the “Agile Testi However, in my new role, I decided that it was time to bite the bullet and at least go to one conference. Perhaps I could get some new ideas to supplement and support some of the ideas I already had.ng Days” conference in Potsdam, Germany. I looked over the suggested programme and some of the talks peeked my interest. For numerous reasons I’d shied away from attending conferences in the past, one of the main ones being that I didn’t see much benefit in attending loads of talks when I could just read about stuff like that on the internet. So, on the 18th November 2012, myself and three other Red Gaters boarded a plane at Heathrow bound for Potsdam, Germany to attend Agile Testing Days 2012. Tutorial Day – “Software Testing Reloaded” We chose to do the tutorials on the 19th, I chose the one titled “Software Testing Reloaded – So you wanna actually DO something? We’ve got just the workshop for you. Now with even less powerpoint!”. With such a concise and serious title I just had to see what it was about! I nervously entered the room to be greeted by tables, chairs etc all over the place, not set out and frankly in one hell of a mess! There were a few people in there playing a game with dice. Okaaaay… this is going to be a long day! Actually the dice game was an exercise in deduction and simplification… I found it very interesting and is certainly something I’ll be using at work as a training exercise! (I won’t explain the game here cause I don’t want to let the cat out of the bag…) The tutorial consisted of several games, exploring different aspects of testing. They were all practical yet required a fair amount of thin king. Matt Heusser and Pete Walen were running the tutorial, and presented it in a very relaxed and light-hearted manner. It was really my first experience of working in small teams with testers from very different backgrounds, and it was really enjoyable. Matt & Pete were very approachable and offered advice where required whilst still making you work for the answers! One of the tasks was to devise several strategies for testing some electronic dice. The premise was that a Vegas casino wanted to use the dice to appeal to the twenty-somethings interested in tech, but needed assurance that they were as reliable and random as traditional dice. This was a very interesting and challenging exercise that forced us to challenge various assumptions, determine/clarify requirements but most of all it was frustrating because the dice made a very very irritating beeping noise. Multiple that by at least 12 dice and I was dreaming about them all that night!! Some of the main takeaways that were brilliantly demonstrated through the games were not to make assumptions, challenge requirements, and have fun testing! The tutorial lasted the whole day, but to be honest the day went very quickly! My introduction into the conference experience started very well indeed, and I would talk to both Matt and Pete several times during the 4 days. Days 1,2 & 3 will be coming soon…  

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  • VS2010 crashes when opening a vsp generated using VS 2012

    - by Tarun Arora
    I recently profiled some web applications using Visual Studio 2012, a vsp (Visual Studio Profile) file was generated as a result of the profiling session. I could successfully open the vsp file in Visual Studio 2012 as expected but when I tried to open the vsp file in Visual Studio 2010 the VS2010 IDE crashed. As a responsible citizen I raised bug # 762202 on Microsoft Connect site using the Microsoft Visual Studio 2012 Feedback Client. Note – In case you didn’t already know, VSP generated in Visual Studio 2012 is not backward compatible. Please refer below for the steps to reproduce the issue and the resolution of the connect bug. 1. Behaviour and Steps to Reproduce the Issue Description I have generated a vsp file by using the Visual Studio 2012 Standalone profiler. When I try and open the vsp file in Visual Studio 2010 the IDE crashes. I understand that a vsp generated by using VS 2012 cannot be opened in VS 2010, but the IDE crashing is not the behaviour I would expect to see. Steps to Reproduce the Issue 1. Pick up the Stand lone profiler from the VS 2012 installation media. The folder has both x 64 and x86 installer, since the machine I am using is x64 bit. I have installed the x64 version of the standalone profiler. 2. I have configured the system path by setting the 'environment variable' path to where the profiler is installed. In my case this is, C:\Program Files (x86)\Microsoft Visual Studio 11.0\Team Tools\Performance Tools 3. Created a new environment variable _NT_SYMBOL_PATH and set its value to CACHE*C:\SYMBOLSCACHE;SRV*C:\SYMBOLSCACHE*HTTP://MSDL.MICROSOFT.COM/DOWNLOAD/SYMBOLS;\\FOO\BUILD1234 4. Open up CMD as an administrator and run 'VSPerfASPNETCmd /tip http://localhost:56180/ /o:C:\Temp\SampleEISK.vsp' 5. This generates the following message on the cmd       Microsoft (R) VSPerf ASP.NET Command, Version 11.0.0.0     Copyright (C) Microsoft Corporation. All rights reserved.     Configuring and attaching to ASP.NET process. Please wait.     Setting up profiling environment.     Starting monitor.     Launching ASP.NET service.     Attaching Monitor to process.     Launching Internet Explorer.     The profiler is attached to ASP.net. Please run your application scenario now.     Press Enter to stop data collection...   6. I perform certain actions and then I come back to the cmd and hit enter to shut down the profiling. Once I do this, the following message is written to the cmd, Press Enter to stop data collection... Profiling now shut down. Report file "C:\Temp\SampleEISK.vsp" was generated. Running VsPerfReport, packing symbols into the .VSP. Shutting down profiling and restarting ASP.NET. Please wait. Restarting w3wp.exe.   7. I look in the C:\Temp folder and I can see the SampleEISK.vsp file generated. I can successfully open this file in Visual Studio 2012. 8. When I am trying to open the vsp file in VS 2010 the VS 2010 IDE crashes. Kaboooom! What I would expect to happen I expect to receive a message "VS 2010 does not support the vsp file generated by VS 2012". What actually happened The VS 2010 IDE crashed 2. Resolution This is a valid bug! However, there isn’t much value in releasing a hotfix for this issue. Refer below to the resolution provided by the Visual Studio Profiler Team.  Thank you for taking the time to report this issue. We completely agree that Visual Studio 2010 should not crash. However in this particular case this is not a bug we are going to retroactively release a fix to 2010 for at this point. Given that a fix would not unblock the scenario of opening a 2012 created file on Visual Studio 2010, and there is not an active update channel for Visual Studio 2010 other than manually locating and installing hot fixes, we will not be fixing this particular issue. Best Regards, Visual Studio Profiler Team   Though it would be great to improve the behaviour however, this is not a defect that would stop you from progressing in any way. It’s important to note however that VSP files generated by Visual Studio 2012 are not backward compatible so you should refrain from opening these files in Visual Studio 2010.

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  • Followup: Python 2.6, 3 abstract base class misunderstanding

    - by Aaron
    I asked a question at Python 2.6, 3 abstract base class misunderstanding. My problem was that python abstract base classes didn't work quite the way I expected them to. There was some discussion in the comments about why I would want to use ABCs at all, and Alex Martelli provided an excellent answer on why my use didn't work and how to accomplish what I wanted. Here I'd like to address why one might want to use ABCs, and show my test code implementation based on Alex's answer. tl;dr: Code after the 16th paragraph. In the discussion on the original post, statements were made along the lines that you don't need ABCs in Python, and that ABCs don't do anything and are therefore not real classes; they're merely interface definitions. An abstract base class is just a tool in your tool box. It's a design tool that's been around for many years, and a programming tool that is explicitly available in many programming languages. It can be implemented manually in languages that don't provide it. An ABC is always a real class, even when it doesn't do anything but define an interface, because specifying the interface is what an ABC does. If that was all an ABC could do, that would be enough reason to have it in your toolbox, but in Python and some other languages they can do more. The basic reason to use an ABC is when you have a number of classes that all do the same thing (have the same interface) but do it differently, and you want to guarantee that that complete interface is implemented in all objects. A user of your classes can rely on the interface being completely implemented in all classes. You can maintain this guarantee manually. Over time you may succeed. Or you might forget something. Before Python had ABCs you could guarantee it semi-manually, by throwing NotImplementedError in all the base class's interface methods; you must implement these methods in derived classes. This is only a partial solution, because you can still instantiate such a base class. A more complete solution is to use ABCs as provided in Python 2.6 and above. Template methods and other wrinkles and patterns are ideas whose implementation can be made easier with full-citizen ABCs. Another idea in the comments was that Python doesn't need ABCs (understood as a class that only defines an interface) because it has multiple inheritance. The implied reference there seems to be Java and its single inheritance. In Java you "get around" single inheritance by inheriting from one or more interfaces. Java uses the word "interface" in two ways. A "Java interface" is a class with method signatures but no implementations. The methods are the interface's "interface" in the more general, non-Java sense of the word. Yes, Python has multiple inheritance, so you don't need Java-like "interfaces" (ABCs) merely to provide sets of interface methods to a class. But that's not the only reason in software development to use ABCs. Most generally, you use an ABC to specify an interface (set of methods) that will likely be implemented differently in different derived classes, yet that all derived classes must have. Additionally, there may be no sensible default implementation for the base class to provide. Finally, even an ABC with almost no interface is still useful. We use something like it when we have multiple except clauses for a try. Many exceptions have exactly the same interface, with only two differences: the exception's string value, and the actual class of the exception. In many exception clauses we use nothing about the exception except its class to decide what to do; catching one type of exception we do one thing, and another except clause catching a different exception does another thing. According to the exception module's doc page, BaseException is not intended to be derived by any user defined exceptions. If ABCs had been a first class Python concept from the beginning, it's easy to imagine BaseException being specified as an ABC. But enough of that. Here's some 2.6 code that demonstrates how to use ABCs, and how to specify a list-like ABC. Examples are run in ipython, which I like much better than the python shell for day to day work; I only wish it was available for python3. Your basic 2.6 ABC: from abc import ABCMeta, abstractmethod class Super(): __metaclass__ = ABCMeta @abstractmethod def method1(self): pass Test it (in ipython, python shell would be similar): In [2]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods method1 Notice the end of the last line, where the TypeError exception tells us that method1 has not been implemented ("abstract methods method1"). That was the method designated as @abstractmethod in the preceding code. Create a subclass that inherits Super, implement method1 in the subclass and you're done. My problem, which caused me to ask the original question, was how to specify an ABC that itself defines a list interface. My naive solution was to make an ABC as above, and in the inheritance parentheses say (list). My assumption was that the class would still be abstract (can't instantiate it), and would be a list. That was wrong; inheriting from list made the class concrete, despite the abstract bits in the class definition. Alex suggested inheriting from collections.MutableSequence, which is abstract (and so doesn't make the class concrete) and list-like. I used collections.Sequence, which is also abstract but has a shorter interface and so was quicker to implement. First, Super derived from Sequence, with nothing extra: from abc import abstractmethod from collections import Sequence class Super(Sequence): pass Test it: In [6]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods __getitem__, __len__ We can't instantiate it. A list-like full-citizen ABC; yea! Again, notice in the last line that TypeError tells us why we can't instantiate it: __getitem__ and __len__ are abstract methods. They come from collections.Sequence. But, I want a bunch of subclasses that all act like immutable lists (which collections.Sequence essentially is), and that have their own implementations of my added interface methods. In particular, I don't want to implement my own list code, Python already did that for me. So first, let's implement the missing Sequence methods, in terms of Python's list type, so that all subclasses act as lists (Sequences). First let's see the signatures of the missing abstract methods: In [12]: help(Sequence.__getitem__) Help on method __getitem__ in module _abcoll: __getitem__(self, index) unbound _abcoll.Sequence method (END) In [14]: help(Sequence.__len__) Help on method __len__ in module _abcoll: __len__(self) unbound _abcoll.Sequence method (END) __getitem__ takes an index, and __len__ takes nothing. And the implementation (so far) is: from abc import abstractmethod from collections import Sequence class Super(Sequence): # Gives us a list member for ABC methods to use. def __init__(self): self._list = [] # Abstract method in Sequence, implemented in terms of list. def __getitem__(self, index): return self._list.__getitem__(index) # Abstract method in Sequence, implemented in terms of list. def __len__(self): return self._list.__len__() # Not required. Makes printing behave like a list. def __repr__(self): return self._list.__repr__() Test it: In [34]: a = Super() In [35]: a Out[35]: [] In [36]: print a [] In [37]: len(a) Out[37]: 0 In [38]: a[0] --------------------------------------------------------------------------- IndexError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() /home/aaron/projects/test/test.py in __getitem__(self, index) 10 # Abstract method in Sequence, implemented in terms of list. 11 def __getitem__(self, index): ---> 12 return self._list.__getitem__(index) 13 14 # Abstract method in Sequence, implemented in terms of list. IndexError: list index out of range Just like a list. It's not abstract (for the moment) because we implemented both of Sequence's abstract methods. Now I want to add my bit of interface, which will be abstract in Super and therefore required to implement in any subclasses. And we'll cut to the chase and add subclasses that inherit from our ABC Super. from abc import abstractmethod from collections import Sequence class Super(Sequence): # Gives us a list member for ABC methods to use. def __init__(self): self._list = [] # Abstract method in Sequence, implemented in terms of list. def __getitem__(self, index): return self._list.__getitem__(index) # Abstract method in Sequence, implemented in terms of list. def __len__(self): return self._list.__len__() # Not required. Makes printing behave like a list. def __repr__(self): return self._list.__repr__() @abstractmethod def method1(): pass class Sub0(Super): pass class Sub1(Super): def __init__(self): self._list = [1, 2, 3] def method1(self): return [x**2 for x in self._list] def method2(self): return [x/2.0 for x in self._list] class Sub2(Super): def __init__(self): self._list = [10, 20, 30, 40] def method1(self): return [x+2 for x in self._list] We've added a new abstract method to Super, method1. This makes Super abstract again. A new class Sub0 which inherits from Super but does not implement method1, so it's also an ABC. Two new classes Sub1 and Sub2, which both inherit from Super. They both implement method1 from Super, so they're not abstract. Both implementations of method1 are different. Sub1 and Sub2 also both initialize themselves differently; in real life they might initialize themselves wildly differently. So you have two subclasses which both "is a" Super (they both implement Super's required interface) although their implementations are different. Also remember that Super, although an ABC, provides four non-abstract methods. So Super provides two things to subclasses: an implementation of collections.Sequence, and an additional abstract interface (the one abstract method) that subclasses must implement. Also, class Sub1 implements an additional method, method2, which is not part of Super's interface. Sub1 "is a" Super, but it also has additional capabilities. Test it: In [52]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods method1 In [53]: a = Sub0() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Sub0 with abstract methods method1 In [54]: a = Sub1() In [55]: a Out[55]: [1, 2, 3] In [56]: b = Sub2() In [57]: b Out[57]: [10, 20, 30, 40] In [58]: print a, b [1, 2, 3] [10, 20, 30, 40] In [59]: a, b Out[59]: ([1, 2, 3], [10, 20, 30, 40]) In [60]: a.method1() Out[60]: [1, 4, 9] In [61]: b.method1() Out[61]: [12, 22, 32, 42] In [62]: a.method2() Out[62]: [0.5, 1.0, 1.5] [63]: a[:2] Out[63]: [1, 2] In [64]: a[0] = 5 --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: 'Sub1' object does not support item assignment Super and Sub0 are abstract and can't be instantiated (lines 52 and 53). Sub1 and Sub2 are concrete and have an immutable Sequence interface (54 through 59). Sub1 and Sub2 are instantiated differently, and their method1 implementations are different (60, 61). Sub1 includes an additional method2, beyond what's required by Super (62). Any concrete Super acts like a list/Sequence (63). A collections.Sequence is immutable (64). Finally, a wart: In [65]: a._list Out[65]: [1, 2, 3] In [66]: a._list = [] In [67]: a Out[67]: [] Super._list is spelled with a single underscore. Double underscore would have protected it from this last bit, but would have broken the implementation of methods in subclasses. Not sure why; I think because double underscore is private, and private means private. So ultimately this whole scheme relies on a gentleman's agreement not to reach in and muck with Super._list directly, as in line 65 above. Would love to know if there's a safer way to do that.

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  • My block is not retaining some of its objects

    - by Drew Crawford
    From the Blocks documentation: In a reference-counted environment, by default when you reference an Objective-C object within a block, it is retained. This is true even if you simply reference an instance variable of the object. I am trying to implement a completion handler pattern, where a block is given to an object before the work is performed and the block is executed by the receiver after the work is performed. Since I am being a good memory citizen, the block should own the objects it references in the completion handler and then they will be released when the block goes out of scope. I know enough to know that I must copy the block to move it to the heap since the block will survive the stack scope in which it was declared. However, one of my objects is getting deallocated unexpectedly. After some playing around, it appears that certain objects are not retained when the block is copied to the heap, while other objects are. I am not sure what I am doing wrong. Here's the smallest test case I can produce: typedef void (^ActionBlock)(UIView*); In the scope of some method: NSObject *o = [[[NSObject alloc] init] autorelease]; mailViewController = [[[MFMailComposeViewController alloc] init] autorelease]; NSLog(@"o's retain count is %d",[o retainCount]); NSLog(@"mailViewController's retain count is %d",[mailViewController retainCount]); ActionBlock myBlock = ^(UIView *view) { [mailViewController setCcRecipients:[NSArray arrayWithObjects:@"[email protected]",nil]]; [o class]; }; NSLog(@"mailViewController's retain count after the block is %d",[mailViewController retainCount]); NSLog(@"o's retain count after the block is %d",[o retainCount]); Block_copy(myBlock); NSLog(@"o's retain count after the copy is %d",[o retainCount]); NSLog(@"mailViewController's retain count after the copy is %d",[mailViewController retainCount]); I expect both objects to be retained by the block at some point, and I certainly expect their retain counts to be identical. Instead, I get this output: o's retain count is 1 mailViewController's retain count is 1 mailViewController's retain count after the block is 1 o's retain count after the block is 1 o's retain count after the copy is 2 mailViewController's retain count after the copy is 1 o (subclass of NSObject) is getting retained properly and will not go out of scope. However mailViewController is not retained and will be deallocated before the block is run, causing a crash.

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