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• EE vs Computer Science: Effect on Developers' Approaches, Styles?

  - by DarenW

  Are there any systematic differences between software developers (sw engineers, architect, whatever job title) with an electronics or other engineering background, compared to those who entered the profession through computer science? By electronics background, I mean an EE degree, or a self-taught electronics tinkerer, other types of engineers and experimental physicists. I'm wondering if coming into the software-making professions from a strong knowledge of flip flops, tristate buffers, clock edge rise times and so forth, usually leads to a distinct approach to problems, mindsets, or superior skills at certain specialties and lack of skills at others, when compared to the computer science types who are full of concepts like abstract data types, object orientation, database normalization, who speak of "closures" in programming languages - things that make little sense to the soldering iron crowd until they learn enough programming. The real world, I'm sure, offers a wild range of individual exceptions, but for the most part, can you say there are overall differences? Would these have hiring implications e.g. (to make up something) "never hire an electron wrangler to do database design"? Could knowing about any differences help job seekers find something appropriate more effectively? Or provide enlightenment or some practical advice for those who find themselves misfits in a particular job role? (Btw, I've never taken any computer science classes; my impression of exactly what they cover is fuzzy. I'm an electronics/physics/art type, myself.)

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• What is the best way to exploit multicores when making multithread games?

  - by Keeper

  Many people suggest to write a program, and then start optimizing it. But I think that when it's coming to multithreading with multicore, a little think ahead is required. I've read about using threads, and experienced it myself during some courses at the university (still a student). The big question is simple, but a bit abstract: What thread related steps in game design do I need to take, before implementation? Now trying to be more specific. Let's say, as an example, that I'm making a small board game (like Monopoly) that I want to be multithreaded. My goal Is that this multithreaded game will exploit the best of the multicore system, lets say 4-6 cores (like in i7 processors). My answer to this question at the moment is, one thread for each of these four basic components: GUI User Input / Output AI (computer rival) Other game related calculations (like shortest path from A to B, or level up status change) I'm not an expert (yet!), and I'm sure there are better answers out there. Any suggestion, answer, different approach will be helpful. Some thoughts: Maybe splitting the main database is a good way.. (or total disaster.. )

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• Semantic coupling vs. large class

  - by user106587

  I have hardware I communicate with via TCP. This hardware accepts ~40 different commands/requests with about 20 different responses. I've created a HardwareProxy class which has a TcpClient to send and receive data. I didn't like the idea of having 40 different methods to send the commands/requests, so I started down the path of having a single SendCommand method which takes an ICommand and returns an IResponse, this results in 40 different SpecificCommand classes. The problem is this requires semantic coupling, i.e. the method that invokes SendCommand receives an IResponse which it has to downcast to SpecificResponse, I use a future map which I believe ensures the appropriate SpecificResponse, but I get the impression this code smells. Besides the semantic coupling, ICommand and IResponse are essentially empty abstract classes (Marker Interfaces) and this seems suspicious to me. If I go with the 40 methods I don't think I have broken the single responisbility principle as the responsibility of the HardwareProxy class is to act as the hardware, which has all of these commands. This route is just ugly, plus I'd like to have Asynchronous versions, so there'd be about 80 methods. Is it better to bite the bullet and have a large class, accept the coupling and MarkerInterfaces for a smaller soultuion, or am I missing a better way? Thanks.

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• Natural talent vs experience [on hold]

  - by Tord Johansson Munk

  Hi i have a question for you guys if you had a choice of hiring one of two programmers. One of them is a natural born programming talent, he has been programming since he was 14 year old and he has been programming all sorts of things by him self, 3d renders,games,his own frameworks, he is really good at algorithms and problem solving. He is now about 25 years old and is looking for a job after some unchallenged years of college the only experience he has is working on his own/university stuff and some open source project. This guy spends all his free time programming and has several pet projects at home. The other person is a 37 year old career programmer. He has been programming since he graduated from university at the age of 26 and have been working since then. He did not have an interest in programming before university. During his studies he discovered that programming was fun and challenging but it never was a "passion". During his career he mainly worked with "enterprise" platforms such as .net or javaEE. He mainly have done database business applications and thus is lacking skills of the young talent like abstract problem solving or algorithms. But he know the tools he has been using during the years and is reliable and almost always makes his boss happy. He keeps him self updated in the platform and tools he has and is using. But outside the office walls he don't touch any code at all. Witch one would you hire? Would you favor one of them in certain projects? Do you think that if the young talent learns his tools he will be a better programmer than the older one? Would your decision be different if both of them where lacking a degree? or if only one of them was lacking a degree be the old and experienced or the young genius.

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• RetinaPad Enables Retina Display for iPhone Apps on the iPad

  - by Jason Fitzpatrick

  RetinaPad is an iPad application that actives the Retina Display resolution on iPhone applications to increase the clarity on the iPad. It’s a feature that should be built-in but is currently only available for jailbroken iPads. The premise is simple. Currently iPads lack support for the Retina Display level resolution that iPhone apps are capable of if displaying. RetinaPad allows you to stop using the ugly and blocky simple doubling available on the iPad and start accessing the higher resolution Retina Display mode for iPhone applications on the iPad. It’s such a trivial thing that it’s outright shameful Apple doesn’t include it by default. You should have to jailbreak your device to unlock functionality that should be there right from the factory. Check out the demo video below to see it in action: Fire up your jailbroken iPad, launch Cydia and search for RetinaPad. Retina Pad is $2.99, iPad only. How to Enable Google Chrome’s Secret Gold IconHTG Explains: What’s the Difference Between the Windows 7 HomeGroups and XP-style Networking?Internet Explorer 9 Released: Here’s What You Need To Know

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• Java game design question (graphical objects)

  - by vemalsar

  Hello Guys, I'm beginner in game development, in Java and here on this site too and I have a game design question. Please comment my idea: I have a main loop which call update and draw method. I want to use an ArrayList which store graphical objects, they have coordinate and image or text to draw and my game objects extends this class. In update, I can choose which objects should be put in the array and in draw method I'll display the elements of array on the screen. I'm using a buffer and draw first there, but it is not important now I guess...Here is a simple (not full) code, only the logic: public class GamePanel extends JPanel implements KeyListener { ArrayList<graphicalObjects> graphArray = new ArrayList<graphicalObjects>(); public void update() { //change the game scene, update the graphArray, process input etc. } public void draw() { //draws every element of graphArray to a JPanel } public static main(String[] args) { while(true) { update(); draw(); } } } My questions: Should have I use interface or abstract class for graphicalObjects? graphicalObjects class and the ArrayList really needs or there is some better solution? How to draw objects? They draw themself with their own method or in the draw method I have to draw manually based on graphicalObjects variables (x,y coordinates, image etc.)? If this conception is wrong, please suggest another one! All comments are welcome and sorry if this is dumb question, thanks!

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• What are some ways to separate game logic from animations and the draw loop?

  - by TMV

  I have only previously made flash games, using MovieClips and such to separate out my animations from my game logic. Now I am getting into trying my hand at making a game for Android, but the game programming theory around separating these things still confuses me. I come from a background of developing non game web applications so I am versed in more MVC like patterns and am stuck in that mindset as I approach game programming. I want to do things like abstract my game by having, for example, a game board class that contains the data for a grid of tiles with instances of a tile class that each contain properties. I can give my draw loop access to this and have it draw the game board based on the properties of each tile on the game board, but I don't understand where exactly animation should go. As far as I can tell, animation sort of sits between the abstracted game logic (model) and the draw loop (view). With my MVC mindset, it's frustrating trying to decide where animation is actually supposed to go. It would have quite a bit of data associated with it like a model, but seemingly needs to be very closely coupled with the draw loop in order to have things like frame independent animation. How can I break out of this mindset and start thinking about patterns that make more sense for games?

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• Hello!

  - by barryoreilly

  After many months of deliberating I have finally gotten around to starting this blog! The reason for doing this is the large number of half finished articles lying around on my hard disk, unpublished and unloved. These articles have been of huge benefit to me, and have been written in an attempt to consolidate my own thinking, in order to help me structure my thoughts and ideas as I have tried to digest new ideas and understand abstract theories. It is my hope that by tidying up these articles and publishing them here that I can continue this learning process by getting feedback on the ideas from within the developer community. i have worked with .NET for 8 years now, and have worked with ASP.NET, SQL Server, Windows programming as well as general network administration. Since 2004 my focus has been on integration, web services, and more often than not Biztalk Server. The last two years have seen me focus on SOA and WCF, and the Managed Services Engine, so this is probably where the main focus of the blog will to start with, but there are so many fun things to play with these days that i have no idea where it will end up.....   Barry

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• How do I boot to a windows recovery partition from GRUB on a Toshiba computer?

  - by Andy Groff

  This should be simple but I cannot figure out how to do it. I've been dual booting ubuntu and vista for a while. About 8 months ago, I realized my windows partition got corrupt and does not boot. This wasn't a problem since I didn't need it anyways, but now I do need windows. Using the disk manager I can see a partition called Toshiba System Volume which is 1.6 GB and one called HDD Recovery which is 7.8 GB. I assume the second one is what I need and i'm not sure what the first one is for. Anyways, how do I boot to this one? Is it a matter of configuring GRUB to boot to it? Once I do boot to it will it let me only reformat my windows partition, or is it going to restore the entire hard drive to factory condition? I assume I'll get the general windows installer which lets me choose the partition but, as you can probably tell, I've never used a recover partition. Should I burn the contents of the partition to a disk and boot to that? Sorry if this is obvious but I'm confused and cannot figure this out.

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• Is there such thing like a "refactoring/maintainability group" role in software companies?

  - by dukeofgaming

  So, I work in a company that does embedded software development, other groups focus in the core development of different products' software and my department (which is in another geographical location) which is located at the factory has to deal with software development as well, but across all products, so that we can also fix things quicker when the lines go down due to software problems with the product. In other words, we are generalists while other groups specialize on each product. Thing is, it is kind of hard to get involved in core development when you are distributed geographically (well, I know it really isn't that hard, but there might be unintended cultural/political barriers when it comes to the discipline of collaborating remotely). So I figured that, since we are currently just putting fires out and somewhat being idle/sub-utilized (even though we are a new department, or maybe that is the reason), I thought that a good role for us could be detecting areas of opportunity of refactoring and rearchitecting code and all other implementations that might have to do with stewarding maintainability and modularity. Other groups aren't focused on this because they don't have the time and they have aggressive deadlines, which damage the quality of the code (eternal story of software projects) The thing is that I want my group/department to be recognized by management and other groups with this role officially, and I'm having trouble to come up with a good definition/identity of our group for this matter. So my question is: is this role something that already exists?, or am I the first one to make something like this up?

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• Single CAS web application in a cluster

  - by Dolf Dijkstra

  Recently a customer wanted to set up a cluster of CAS nodes to be used together with WebCenter Sites. In the process of setting this up they realized that they needed to create a web application per managed server. They did not want to have this management burden but would like to have one web application deployed to multiple nodes. The reason that there is a need for a unique application per node is that the web-application contains information that needs to be unique per node, the postfix for the ticket id.  My customer would like to externalize the node specific configuration to either a specific classpath per managed server or to system properties set at startup.It turns out that the postfix for ticket ids is managed through a property host.name and that this property can be externalized.The host.name property is used in: /webapps/cas/WEB-INF/spring-configuration/uniqueIdGenerators.xmlIt is set in /webapps/cas/WEB-INF/spring-configuration/propertyFileConfigurer.xmlin a PropertyPlaceholderConfigurer.The documentation for PropertyPlaceholderConfigurer:http://static.springsource.org/spring/docs/2.0.x/api/org/springframework/beans/factory/config/PropertyPlaceholderConfigurer.htmlThis indicates that the properties defined through the PropertyPlaceHolderConfigurer can be externalized.To enable this externalization you would need to change host.properties so it is generic for all the managed servers and thus can be reused for all the managed servers: host.name=${cluster.node.id}Next step is to change the startup scripts for the managed servers and add a system property for -Dcluster.node.id=<something unique and stable>.Viola, the postfix is externalized and the web application can be shared amongst the cluster nodes.

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• Designing object oriented programming

  - by Pota Onasys

  Basically, I want to make api calls using an SDK I am writing. I have the following classes: Car CarData (stores input values needed to create a car like model, make, etc) Basically to create a car I do the following: [Car carWithData: cardata onSuccess: successHandler onError: errorHandler] that basically is a factory method that creates instance of Car after making an API call request and populating the new Car class with the response and passes that instance to the successHandler. So "Car" has the above static method to create that car, but also has non-static methods to edit, delete cars (which would make edit, delete API calls to the server) So when the Car create static method passes a new car to the successHandler by doing the following: successHandler([[Car alloc] initWithDictionary: dictionary) The success handler can go ahead and use that new car to do the following: [car update: cardata] [car delete] considering the new car object now has an ID for each car that it can pass to the update and delete API calls. My questions: Do I need a cardata object to store user inputs or can I store them in the car object that would also later store the response from all of the api calls? How can I improve this model? With regards to CarData, note that there might be different inputs for the different API calls. So create function might need to know model, make, etc, but find function might need to know the number of items to find, the limit, the start id, etc.

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• tips, guidelines, points to remember for rendering professional code?

  - by ronnieaka

  I'm talking about giving clients professional looking code. The whole nine yards, everything you hardcore professional highly experienced programmers here probably do when coding freelance or for the company you work in. I'm fresh out of college and I'm going into freelance. I just want to be sure that my first few projects leave a good after-taste of professionalism imprinted on the clients' minds. When I Googled what i'm asking here, I was given pages that showed various websites and tools that let you make flashy websites and templates etc. The $N package and such stuff. I can't recall the word experts use for it. Standard, framework [i know that's not it]. English isn't my first language so I'm sorry I don't really don't know the exact phrase for it. That abstract way of writing code so that you don't come across as a sloppy programmer. That above mentioned way for programming websites and desktop software [in python/C/C++/Java]. EDIT: i can work on the accruing vast knowledge and know-how and logic building etc. what i'm asking for is the programming standard/guidelines you guys follow so that the client on seeing code feels that its a professional solution. Like comment blocks, a particular indentation style something like that. Is there any book on it or specific list of points for enterprise type coding by them? Especially here as in my case, for building websites [php for now..], and desktop software [c/c++/java/python]

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• Classes as a compilation unit

  - by Yannbane

  If "compilation unit" is unclear, please refer to this. However, what I mean by it will be clear from the context. Edit: my language allows for multiple inheritance, unlike Java. I've started designing+developing my own programming language for educational, recreational, and potentially useful purposes. At first, I've decided to base it off Java. This implied that I would have all the code be written inside classes, and that code compiles to classes, which are loaded by the VM. However, I've excluded features such as interfaces and abstract classes, because I found no need for them. They seemed to be enforcing a paradigm, and I'd like my language not to do that. I wanted to keep the classes as the compilation unit though, because it seemed convenient to implement, familiar, and I just liked the idea. Then I noticed that I'm basically left with a glorified module system, where classes could be used either as "namespaces", providing constants and functions using the static directive, or as templates for objects that need to be instantiated ("actual" purpose of classes in other languages). Now I'm left wondering: what are the benefits of having classes as compilation units? (Also, any general commentary on my design would be much appreciated.)

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• What are the memory-management capabilities of MySQL + JDBC (in light of autonomic computing)?

  - by Adel

  I'm interested in implementing some kind of autonomic-computing functionality using MySQL. By autonomic-computing I mean roughly some failsafe abilities, whereby the application appears to be at least slightly "intelligent" For reference, the main parts of autonomic computing we'd like are the "self-configuring" and "self-healing" features (the other two - "self-optimizing" and "self-protecting", are too abstract/futuristic for us, at this time). Sofor example, if we have a sample Java application that utilizes a MySQL database, we might want to automatically restart the MySQL database if we take up too much memory. Or maybe we want to have the ability to dynamiccally adjust the database memory as needed. So for example, when we start the application the database begins with a 56 Megabyte buffer; but then as we insert so many rows we want to have it automatically jump up to 512 MB, then to 1024, until a max of 4096 MB. Does all of the above suggest that MySQL is too "weak" for the task? Do you suggest using Oracle database? My professor believes that by using Java we can basically make up for any memory-management deficiencies that MySQL has in relation to Oracle DB. I'm new to MySQL , but have experience with Oracle. If all of the above sounds wishy-washy, it is because I'm still fleshing it out. thanks

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• Day in the Life of Agile - The Forge Michigan November 27, 2012

  - by csmith18119

  Went to training at The Forge yesterday and did a Day in the life of Agile with Pillar.  It was pretty good. Check them out at: http://pillartechnology.com/ Abstract: A single-day agile project simulation that is engaging, educational, provocative, and fun. This simulation introduces concepts like time-boxed iterations, User Stories, collective estimation, commitment to a product owner for iteration scope, formal verification ritual at iteration conclusion, tracking velocity, and making results big and visible through charts. The exercise is designed to simulate not only how agile teams and practices work, but the inevitable challenges that arise as teams attempt to adopt such practices. One of the best parts of this training was getting some hands on experience with agile.  We used a program called Scratch to create an arcade video game.  Our team chose Frogger.  We had 3 iterations at 20 minutes each.  I think we did pretty good but in the panic of trying to get a bunch done in only 20 minutes made it interesting. To check out our project, I uploaded it to my CodePlex site Download Source Code (Under Scratch/Frogger) Cool class! I highly recommend if you get the opportunity.

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• eSTEP TechCast - November 2012

  - by uwes

  Dear partner, we are pleased to announce our next eSTEP TechCast on Thursday 1st of November and would be happy if you could join. Please see below the details for the next TechCast.Date and time:Thursday, 01. November 2012, 11:00 - 12:00 GMT (12:00 - 13:00 CET; 15:00 - 16:00 GST) Title:  Update on Solaris 11 Abstract:Oracle announced an update on Solaris 11 on Oracle OpenWorld. Join us in this call to get a brief summary of the enhancements and how they help to build better solutions for your customers. Target audience: Tech Presales Speaker: Jörg Möllenkamp Call Info:Call-in-toll-free number: 08006948154 (United Kingdom)Call-in-toll-free number: +44-2081181001 (United Kingdom) Show global numbers Conference Code: 803 594 3Security Passcode: 9876Webex Info (Oracle Web Conference) Meeting Number: 599 775 167Meeting Password: tech2011 Playback / Recording / Archive: The webcasts will be recorded and will be available shortly after the event in the eSTEP portal under the Events tab, where you could find also material from already delivered eSTEP TechCasts. Use your email-adress and PIN: eSTEP_2011 to get access. Feel free to have a look. We are happy to get your comments and feedback. Thanks and best regards, Partner HW Enablement EMEA

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• Create Adjustable Depth of Field Photos with a DSLR

  - by Jason Fitzpatrick

  If you’re fascinating by the Lytro camera–a camera that let’s you change the focus after you’ve taken the photo–this DSLR hack provides a similar post-photo focus processing without the $400 price tag. Photography tinkers at The Chaos Collective came up with a clever way of mimicking the adjustable depth-of-field adjustment effect from the Lytro camera. The secret sauce in their technique is setting the camera to manual focus and capturing a short 2-3 second video clip while they rotate the focus through the entire focal range. From there, they use a simple applet to separate out each frame of the video. Check out the interactive demo below: Anywhere you click in the photo shifts the focus to that point, just like the post processing in the Lytro camera. It’s a different approach to the problem but it yields roughly the same output. Hit up the link below for the full run down on their technique and how you can get started using it with your own video-enabled DLSR. Camera HACK: DOF-Changeable Photos with an SLR [via Hack A Day] Secure Yourself by Using Two-Step Verification on These 16 Web Services How to Fix a Stuck Pixel on an LCD Monitor How to Factory Reset Your Android Phone or Tablet When It Won’t Boot

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• How can one find software development work that involves directly the final end user?

  - by RJa

  I've worked in software development for 15 years and, while there have been signficant personal achievements and a lot of experience, I've always felt detached from the man/woman-on-the-street, the every day person, how it affects their lives, in a number of ways: the technologies: embedded software, hidden away, stuff not seen by the everyday person. Or process technology supporting manufactured products the size of the systems, meaning many jobs, divided up, work is abstract, not one person can see the whole picture the organisations: large, with departments dealing with different areas, the software, the hardware, the marketing, the sales, the customer support the locations and hours: out-of-town business parks away from the rest of society, fixed locations, inflexible: 9-5 everyday This to me seems typical of the companies I worked for and see elsewhere. Granted, there are positives such as the technology itself and usually being among high calibre co-workers, but the above points frustrate me about the industry because they detach the work from its meaning. How can one: change these things in an existing job, or compensate for them? find other work that avoids these and connects with the final end user? Job designs tend to focus on the job content and technical requirements rather than how the job aims to fulfil end user needs, is meaningful.

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• Win8 x64 Laptop (Samsung) unable to boot after installing Ubuntu

  - by user285872

  I posted here a while back and no one was able to help me so I am going to try to explain my problem better. I have a Samsung series 7 Ultrabook and I connected a USB optical drive with an Ubuntu 14.04 installation disc. I did not set or change any of my partitions, however, as I mainly wanted to just be able to boot from the disc and fool around with Ubuntu. Upon restarting my computer I get a blue-screen message saying: Recovery Your PC needs to be repiared The Boot configuration date file is missing some required information. File: \BCD Error Code: 0xc000000d You'll need to use the recovery tools on your installing media. If you don't have any installation media (like a disc or USB device), contact your system administrator or PC manufacturer. However I am never given the option to even try to boot to anything. When I turn my computer on the optical drive spins and then after a moment or two comes to a halt. I turned off safeboot and switched it to CSM (I believe that is what it is called) mode, and that makes it so when I turn my computer on it takes me to a Windows Recovery screen. I am able to change the date I want to recover and view all the applications installed, however upon recovering Windows says "All boot options are tried. Press key to recover with factory image using Recovery or any other keys for next boot loop iteration." It seems to be stuck in a loop. Can someone please help me?! I'm so confused and nothing is working!

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• Problem installing qtbase

  - by teucer

  I am getting the following error when installing "qtbase" package for R: [ 68%] Building CXX object smoke/qt/CMakeFiles/smokeqt.dir/x_1.cpp.o /home/mroot/qtbase/kdebindings-build/smoke/qt/x_1.cpp: In static member function ‘static void __smokeqt::x_QAbstractPrintDialog::x_8(Smoke::StackItem*)’: /home/mroot/qtbase/kdebindings-build/smoke/qt/x_1.cpp:4893: error: cannot allocate an object of abstract type ‘__smokeqt::x_QAbstractPrintDialog’ /home/mroot/qtbase/kdebindings-build/smoke/qt/x_1.cpp:4834: note: because the following virtual functions are pure within ‘__smokeqt::x_QAbstractPrintDialog’: /usr/include/qt4/QtGui/qabstractprintdialog.h:89: note: virtual int QAbstractPrintDialog::exec() /home/mroot/qtbase/kdebindings-build/smoke/qt/x_1.cpp: In constructor ‘__smokeqt::x_QAbstractPrintDialog::x_QAbstractPrintDialog()’: /home/mroot/qtbase/kdebindings-build/smoke/qt/x_1.cpp:4896: error: no matching function for call to ‘QAbstractPrintDialog::QAbstractPrintDialog()’ /usr/include/qt4/QtGui/qabstractprintdialog.h:116: note: candidates are: QAbstractPrintDialog::QAbstractPrintDialog(const QAbstractPrintDialog&) /usr/include/qt4/QtGui/qabstractprintdialog.h:113: note: QAbstractPrintDialog::QAbstractPrintDialog(QAbstractPrintDialogPrivate&, QPrinter*, QWidget*) /usr/include/qt4/QtGui/qabstractprintdialog.h:86: note: QAbstractPrintDialog::QAbstractPrintDialog(QPrinter*, QWidget*) make[3]: *** [smoke/qt/CMakeFiles/smokeqt.dir/x_1.cpp.o] Error 1 make[3]: Leaving directory `/home/mroot/qtbase/kdebindings-build' make[2]: *** [smoke/qt/CMakeFiles/smokeqt.dir/all] Error 2 make[2]: Leaving directory `/home/mroot/qtbase/kdebindings-build' make[1]: *** [all] Error 2 make[1]: Leaving directory `/home/mroot/qtbase/kdebindings-build' make: *** [all] Error 2 ERROR: compilation failed for package ‘qtbase’ * removing ‘/home/mroot/R/i686-pc-linux-gnu-library/2.12/qtbase’ Any ideas?

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• Repository query conditions, dependencies and DRY

  - by vFragosop

  To keep it simple, let's suppose an application which has Accounts and Users. Each account may have any number of users. There's also 3 consumers of UserRepository: An admin interface which may list all users Public front-end which may list all users An account authenticated API which should only list it's own users Assuming UserRepository is something like this: class UsersRepository extends DatabaseAbstraction { private function query() { return $this->database()->select('users.*'); } public function getAll() { return $this->query()->exec(); } // IMPORTANT: // Tons of other methods for searching, filtering, // joining of other tables, ordering and such... } Keeping in mind the comment above, and the necessity to abstract user querying conditions, How should I handle querying of users filtering by account_id? I can picture three possible roads: 1. Should I create an AccountUsersRepository? class AccountUsersRepository extends UserRepository { public function __construct(Account $account) { $this->account = $account; } private function query() { return parent::query() ->where('account_id', '=', $this->account->id); } } This has the advantage of reducing the duplication of UsersRepository methods, but doesn't quite fit into anything I've read about DDD so far (I'm rookie by the way) 2. Should I put it as a method on AccountsRepository? class AccountsRepository extends DatabaseAbstraction { public function getAccountUsers(Account $account) { return $this->database() ->select('users.*') ->where('account_id', '=', $account->id) ->exec(); } } This requires the duplication of all UserRepository methods and may need another UserQuery layer, that implements those querying logic on chainable way. 3. Should I query UserRepository from within my account entity? class Account extends Entity { public function getUsers() { return UserRepository::findByAccountId($this->id); } } This feels more like an aggregate root for me, but introduces dependency of UserRepository on Account entity, which may violate a few principles. 4. Or am I missing the point completely? Maybe there's an even better solution? Footnotes: Besides permissions being a Service concern, in my understanding, they shouldn't implement SQL query but leave that to repositories since those may not even be SQL driven.

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• Domain model integration using JSON capable DTOs

  - by g-makulik

  I'm a bit confused about architectural choices for the java/web-applications world. The background is I have a system with certain hardware components (that introduce system immanent active behavior) and a configuration database for system meta and HW-components configuration data (these are even usually self contained, since the HW-components persist configuration data anyway). For realization of the configuration/status data exchange protocol with the HW-components we have chosen the Google Protobuf format, which works well for the directly wired communication with these components. Now we want to develop an abstract model (domain model) for those HW-components and I have the feeling that a plain Java class model would fit best for this (c++ implementation seems to have too much implementation/integration overhead with viable language-bridge interfaces). Google Protobuf message definitions could still serve well to describe DTO objects used to interact with a domain model API. But integrating Google Protobuf messages client side for e.g. data binding in the current view doesn't seem to be a good choice. I'm thinking about some extra serialization features, e.g. for JSON based data exchange with the views/controllers. Most lightweight solutions seem to involve a python based presentation layer using JSON based data transfer (I'm at least not sure to be fully informed about this). Is there some lightweight (applicable for a limited ARM Linux platform) framework available, supporting such architecture to realize a web-application?

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• Discrete Math and Computing Course

  - by ShrimpCrackers

  I was recently admitted into a Computing and Software Systems program (basically software engineering) and one of the first courses I'll be taking is called Mathematical Principles of Computing. The course description: "Integrating mathematical principles with detailed instruction in computer programming. Explores mathematical reasoning and discrete structures through object-oriented programming. Includes algorithm analysis, basic abstract data types, and data structures." I'm not a fan of math, but I've been doing well in all my math classes mostly A's and B's ever since I started two years ago, and I've been doing math every quarter - never took a quarter without math - so I've been doing it all in sequence without gaps. However, I'm worried about this class. I've read briefly on what discrete math is and from what my advisor told me, its connection with computer science is that it has alot to do with proving algorithms. One thing that my instructors briefly touched on and never went into detail was proving algorithms, and when I tried, I just wasn't very good at mathematical induction. It's one of the things that I ignored every time it showed up in a homework problem (usually in Calculus III which I'm finishing up right now). Questions: 1. What can I expect from this class? 2. How can I prepare myself for this class? 3. Other tips? Thank you.

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• What's is the point of PImpl pattern while we can use interface for same purpose in C++?

  - by ZijingWu

  I see a lot of source code which using PIMPL idiom in C++. I assume Its purposes are hidden the private data/type/implementation, so it can resolve dependence, and then reduce compile time and header include issue. But interface class in C++ also have this capability, it can also used to hidden data/type and implementation. And to hidden let the caller just see the interface when create object, we can add an factory method in it declaration in interface header. The comparison is: Cost: The interface way cost is lower, because you doesn't even need to repeat the public wrapper function implementation void Bar::doWork() { return m_impl->doWork(); }, you just need to define the signature in the interface. Well understand: The interface technology is more well understand by every C++ developer. Performance: Interface way performance not worse than PIMPL idiom, both an extra memory access. I assume the performance is same. Following is the pseudocode code to illustrate my question: // Forward declaration can help you avoid include BarImpl header, and those included in BarImpl header. class BarImpl; class Bar { public: // public functions void doWork(); private: // You doesn't need to compile Bar.cpp after change the implementation in BarImpl.cpp BarImpl* m_impl; }; The same purpose can be implement using interface: // Bar.h class IBar { public: virtual ~IBar(){} // public functions virtual void doWork() = 0; }; // to only expose the interface instead of class name to caller IBar* createObject(); So what's the point of PIMPL?

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