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  • Did C++11 address concerns passing std lib objects between dynamic/shared library boundaries? (ie dlls and so)?

    - by Doug T.
    One of my major complaints about C++ is how hard in practice it is to pass std library objects outside of dynamic library (ie dll/so) boundaries. The std library is often header-only. Which is great for doing some awesome optimizations. However, for dll's, they are often built with different compiler settings that may impact the internal structure/code of a std library containers. For example, in MSVC one dll may build with iterator debugging on while another builds with it off. These two dlls may run into issues passing std containers around. If I expose std::string in my interface, I can't guarantee the code the client is using for std::string is an exact match of my library's std::string. This leads to hard to debug problems, headaches, etc. You either rigidly control the compiler settings in your organization to prevent these issues or you use a simpler C interface that won't have these problems. Or specify to your clients the expected compiler settings they should use (which sucks if another library specifies other compiler settings). My question is whether or not C++11 tried to do anything to solve these issues?

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  • WordPress mod_rewrite redirect specific folders

    - by Ps Cjef
    As a new user, I'm not allowed to post more than two hyperlinks here. So I have added a space after every http (ignore them and read as full URLs). System: Debian Etch, Apache 2.2 I have a WordPress instance with multiple blogs. I would like to redirect some of the folders based on the year and month, while leaving other folders go to the actual locations. Example: I have archives for a few years, like 2010, 2011 and 2012: http ://mydomain.com/wordpress/myblog/2010/02 http ://mydomain.com/wordpress/myblog/2011/01 http ://mydomain.com/wordpress/myblog/2012/01 I would like to redirect all 2010 and 2011 posts to another blog with the same folder structure: http ://mydomain.com/wordpress/myotherblog/2010/02 http ://mydomain.com/wordpress/myotherblog/2011/01 and so on. I would like to have 2012 and beyond to go to the actual site (http ://mydomain.com/wordpress/myblog/2012/01). I tried mod_rewrite with the following, one rule at a time to test redirection for just one year (and to expand later for other years), and none of them worked! * RewriteEngine is already on since there are some default WordPress rewrites. * RewriteBase is set to http://mydomain.com/wordpress/ . * I put my rule before all the other default WordPress rules are processed. Didn't work solution #1 RedirectMatch 301 /myblog/2010/(.*) /myotherblog/2010/$1 Didn't work solution #2 RewriteRule /myblog/2010/(.*) http ://mydomain.com/myotherblog/2010/$1 [R=301] Didn't work solution #3 RedirectPermanent /myblog/2010/(.*) http ://mydomain.com/myotherblog/2010/$1 I've also tried the above rules with and without a fully qualified URL for the new location. The rewrite log, with log level set to 9, did not provide any useful information. It shows that it looks at the pattern specified against the URL (as mentioned in the rule), but finally what happens is a passthrough to http ://mydomain.com/myblog/ for all URLs or a 500 Internal Server Error. Any ideas on where I could be going wrong or any alternative solutions?

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  • ArchBeat Link-o-Rama for November 6, 2012

    - by Bob Rhubart
    OAM/OVD JVM Tuning | @FusionSecExpert Vinay from the Oracle Fusion Middleware Architecture Group (the infamous A-Team) shares a process for analyzing and improving performance in Oracle Virtual Directory and Oracle Access Manager. Architects Matter: Making sense of the people who make sense of enterprise IT Why do architects matter? Oracle Enterprise Architect Eric Stephens suggests that you ask yourself that question the next time you take the elevator to the Oracle offices on the 45th floor of the Willis Tower in Chicago, Illinois (or any other skyscraper, for that matter). If you had to take the stairs to get to those offices, who would you blame? "You get the picture," he says. "Architecture is essential for any necessarily complex structure, be it a building or an enterprise." (Read the article...) SOA Galore: New Books for Technical Eyes Only Shake up up your technical skills with this trio of new technical books from community members covering SOA and BPM. Thought for the Day "It goes against the grain of modern education to teach students to program. What fun is there to making plans, acquiring discipline, organizing thoughts, devoting attention to detail, and learning to be self critical?" — Alan Perlis (April 1, 1922 – February 7, 1990) Source: SoftwareQuotes.com

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  • Why is quicksort better than other sorting algorithms in practice?

    - by Raphael
    This is a repost of a question on cs.SE by Janoma. Full credits and spoils to him or cs.SE. In a standard algorithms course we are taught that quicksort is O(n log n) on average and O(n²) in the worst case. At the same time, other sorting algorithms are studied which are O(n log n) in the worst case (like mergesort and heapsort), and even linear time in the best case (like bubblesort) but with some additional needs of memory. After a quick glance at some more running times it is natural to say that quicksort should not be as efficient as others. Also, consider that students learn in basic programming courses that recursion is not really good in general because it could use too much memory, etc. Therefore (and even though this is not a real argument), this gives the idea that quicksort might not be really good because it is a recursive algorithm. Why, then, does quicksort outperform other sorting algorithms in practice? Does it have to do with the structure of real-world data? Does it have to do with the way memory works in computers? I know that some memories are way faster than others, but I don't know if that's the real reason for this counter-intuitive performance (when compared to theoretical estimates).

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  • Focusing and Selecting the Text in ASP.NET TextBox Controls

    When a browser displays the HTML sent from a web server it parses the received markup into a Document Object Model, or DOM, which models the markup as a hierarchical structure. Each element in the markup - the <form> element, <div> elements, <p> elements, <input> elements, and so on - are represented as a node in the DOM and can be programmatically accessed from client-side script. What's more, the nodes that make up the DOM have functions that can be called to perform certain behaviors; what functions are available depend on what type of element the node represents. One function common to most all node types is focus, which gives keyboard focus to the corresponding element. The focus function is commonly used in data entry forms, search pages, and login screens to put the user's keyboard cursor in a particular textbox when the web page loads so that the user can start typing in his search query or username without having to first click the textbox with his mouse. Another useful function is select, which is available for <input> and <textarea> elements and selects the contents of the textbox. This article shows how to call an HTML element's focus and select functions. We'll look at calling these functions directly from client-side script as well as how to call these functions from server-side code. Read on to learn more! Read More >

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  • CMS and Databases vs. DIY

    - by hozza
    I have been programming for many years now, primarily in PHP and the like and would consider myself an intermediate programmer. Some of my online projects have now gone global and very widely used, i am now in deep thought about scalability etc. All of my systems so far are written in PHP, no known database structure such as MySQL etc. Instead our databases use an 'operating system style' method of storing information, files and folders if you will. We also do not use any outside/third-party software or CMS, so far this has work out extremely well. Most people, when they hear about the way we do things, criticize and say that is an idiotic idea but normally after seeing our systems in more dept are converted to our way of doing things. Is it really that bad to not use a standard databasing systems and only using the one (slightly heavier than others) language of PHP? How well on the face of it will this kind of setup scale? N.B. Our systems include things such as account and user management, documentation development and task/project managing.

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  • JavaScript and callback nesting

    - by Jake King
    A lot of JavaScript libraries (notably jQuery) use chaining, which allows the reduction of this: var foo = $(".foo"); foo.stop(); foo.show(); foo.animate({ top: 0 }); to this: $(".foo").stop().show().animate({ top: 0 }); With proper formatting, I think this is quite a nice syntactic capability. However, I often see a pattern which I don't particularly like, but appears to be a necessary evil in non-blocking models. This is the ever-present nesting of callback functions: $(".foo").animate({ top: 0, }, { callback: function () { $.ajax({ url: 'ajax.php', }, { callback: function () { ... } }); } }); And it never ends. Even though I love the ease non-blocking models provide, I hate the odd nesting of function literals it forces upon the programmer. I'm interesting in writing a small JS library as an exercise, and I'd love to find a better way to do this, but I don't know how it could be done without feeling hacky. Are there any projects out there that have resolved this problem before? And if not, what are the alternatives to this ugly, meaningless code structure?

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  • WINAPI beginner guidance question

    - by gekod
    I'm learning to develop windows applications using WINAPI and plain C. Now I got a bit confused with all those handles and would like to ask if you guys could teach me some good practices to structure and handle controls and windows. Here's where I get confused: Using the IDs declared in the resources for each object, we can get their handles using GetDlgItem(). Now what if we don't know their parent, which is needed by this function. One example: We have the main window created at launch. Then we register two new window classes and create a window for each new class and we create a message function for each too. Now if inside one of the children windows I create a button and inside the other child window I create a text label. Now when we click the button inside of child window A the label in child window B shall be modified to whatever. The WM_COMMAND for the button is interpreted inside the message loop for child window A. Now what would be the best and more elegant way to access the text label inside the child window B? I am in the process of learning the WINAPI and just want to learn it right from the start instead of producing Hacked code that someday becomes unreadable and to later have to adapt to a new way of programing.

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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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  • PyQt application architecture

    - by L. De Leo
    I'm trying to give a sound structure to a PyQt application that implements a card game. So far I have the following classes: Ui_Game: this describes the ui of course and is responsible of reacting to the events emitted by my CardWidget instances MainController: this is responsible for managing the whole application: setup and all the subsequent states of the application (like starting a new hand, displaying the notification of state changes on the ui or ending the game) GameEngine: this is a set of classes that implement the whole game logic Now, the way I concretely coded this in Python is the following: class CardWidget(QtGui.QLabel): def __init__(self, filename, *args, **kwargs): QtGui.QLabel.__init__(self, *args, **kwargs) self.setPixmap(QtGui.QPixmap(':/res/res/' + filename)) def mouseReleaseEvent(self, ev): self.emit(QtCore.SIGNAL('card_clicked'), self) class Ui_Game(QtGui.QWidget): def __init__(self, window, *args, **kwargs): QtGui.QWidget.__init__(self, *args, **kwargs) self.setupUi(window) self.controller = None def place_card(self, card): cards_on_table = self.played_cards.count() + 1 print cards_on_table if cards_on_table <= 2: self.played_cards.addWidget(card) if cards_on_table == 2: self.controller.play_hand() class MainController(object): def __init__(self): self.app = QtGui.QApplication(sys.argv) self.window = QtGui.QMainWindow() self.ui = Ui_Game(self.window) self.ui.controller = self self.game_setup() Is there a better way other than injecting the controller into the Ui_Game class in the Ui_Game.controller? Or am I totally off-road?

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  • Advertising on personalized pages behind a login

    - by johneth
    I am currently building a web app which requires a user to log in. After they log in, they can see the content they've added to the web app, and things that the web app has done with the content they added. The URL structure won't differentiate different users (e.g. all user's 'homepage' would be example.com/home, not something like example.com/username/home). This is much the same way that Facebook works (all FB user's messages are at facebook.com/messages, for example). This presents a problem with advertising. I know that you can use AdSense behind a login, but as far as I'm aware, that's for things like forums, where everyone sees the same things (which wouldn't be the case in this site). I also know that I could put AdSense on the pages without allowing it to log in, which would produce inferior ads. I'm fairly certain it would be against the Terms of Service to give AdSense a login to a 'dummy' account with typical content, as it would not be seeing the same thing as every other user (which is impossible, as they all see different things). So, my question is: Is there an ad network, or other method, that can serve ads behind a login, maybe based on keywords rather than content?

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  • What is the recommended MongoDB schema for this quiz-engine scenario?

    - by hughesdan
    I'm working on a quiz engine for learning a foreign language. The engine shows users four images simultaneously and then plays an audio file. The user has to match the audio to the correct image. Below is my MongoDB document structure. Each document consists of an image file reference and an array of references to audio files that match that image. To generate a quiz instance I select four documents at random, show the images and then play one audio file from the four documents at random. The next step in my application development is to decide on the best document schema for storing user guesses. There are several requirements to consider: I need to be able to report statistics at a user level. For example, total correct answers, total guesses, mean accuracy, etc) I need to be able to query images based on the user's learning progress. For example, select 4 documents where guess count is 10 and accuracy is <=0.50. The schema needs to be optimized for fast quiz generation. The schema must not cause future scaling issues vis a vis document size. Assume 1mm users who make an average of 1000 guesses. Given all of this as background information, what would be the recommended schema? For example, would you store each guess in the Image document or perhaps in a User document (not shown) or a new document collection created for logging guesses? Would you recommend logging the raw guess data or would you pre-compute statistics by incrementing counters within the relevant document? Schema for Image Collection: _id "505bcc7a45c978be24000005" date 2012-09-21 02:10:02 UTC imageFileName "BD3E134A-C7B3-4405-9004-ED573DF477FE-29879-0000395CF1091601" random 0.26997075392864645 user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioFiles [ 0 { audioFileName "C3669719-9F0A-4EB5-A791-2C00486665ED-30305-000039A3FDA7DCD2" user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioLanguage "English" date 2012-09-22 01:15:04 UTC } 1 { audioFileName "C3669719-9F0A-4EB5-A791-2C00486665ED-30305-000039A3FDA7DCD2" user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioLanguage "Spanish" date 2012-09-22 01:17:04 UTC } ]

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  • XML Rules Engine and Validation Tutorial with NIEM

    - by drrwebber
    Our new XML Validation Framework tutorial video is now available. See how to easily integrate code-free adaptive XML validation services into your web services using the Java CAMV validation engine. CAMV allows you to build fault tolerant content checking with XPath that optionally use SQL data lookups. This can provide warnings as well as error conditions to tailor your validation layer to exactly meet your business application needs. Also available is developing test suites using Apache ANT scripting of validations.  This allows a community to share sets of conformance checking test and tools . On the technical XML side the video introduces XPath validation rules and illustrates and the concepts of XML content and structure validation. CAM validation templates allow contextual parameter driven dynamic validation services to be implemented compared to using a static and brittle XSD schema approach.The SQL table lookup and code list validation are discussed and examples presented.Features are highlighted along with a demonstration of the interactive generation of actual live XML data from a SQL data store and then validation processing complete with errors and warnings detection.The presentation provides a primer for developing web service XML validation and integration into a SOA approach along with examples and resources. Also alignment with the NIEM IEPD process for interoperable information exchanges is discussed along with NIEM rules services.The CAMV engine is a high performance scalable Java component for rapidly implementing code-free validation services and methods. CAMV is a next generation WYSIWYG approach that builds from older Schematron coding based interpretative runtime tools and provides a simpler declarative metaphor for rules definition. See: http://www.youtube.com/user/TheCAMeditor

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  • Should this code/logic be included in Business Objects class or a separate class?

    - by aspdotnetuser
    I have created a small application which has a three tier architecture and I have business object classes to represent entities such as User, Orders, UserType etc. In these classes I have methods that are executed when the Constuctor method of, for example, User is called. These methods perform calculations and generate details that setup data for attributes that are part of each User object. Here is the structure for the project in Visual Studio: Here is some code from the business object class User.cs: Public Class User { public string Name { get; set; } public int RandomNumber { get; set; } etc public User { Name = GetName(); RandomNumber = GetRandomNumber(); } public string GetName() { .... return name; } public int GetRandomNumber() { ... return randomNumber; } } Should this logic be included in the Business Object classes or should it be included in a Utilities class of some kind? Or in the business rules?

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  • Use a SQL Database for a Desktop Game

    - by sharethis
    Developing a Game Engine I am planning a computer game and its engine. There will be a 3 dimensional world with first person view and it will be single player for now. The programming language is C++ and it uses OpenGL. Data Centered Design Decision My design decision is to use a data centered architecture where there is a global event manager and a global data manager. There are many components like physics, input, sound, renderer, ai, ... Each component can trigger and listen to events. Moreover, each component can read, edit, create and remove data. The question is about the data manager. Whether to Use a Relational Database Should I use a SQL Database, e.g. SQLite or MySQL, to store the game data? This contains virtually all game content like items, characters, inventories, ... Except of meshes and textures which are even more performance related, so I will keep them in memory. Is a SQL database fast enough to use it for realtime reading and writing game informations, like the position of a moving character? I also need to care about cross-platform compatibility. Aside from keeping everything in memory, what alternatives do I have? Advantages Would Be The advantages of using a relational database like MySQL would be the data orientated structure which allows fast computation. I would not need objects for representing entities. I could easily query data of objects near the player needed for rendering. And I don't have to take care about data of objects far away. Moreover there would be no need for savegames since the hole game state is saved in the database. Last but not least, expanding the game to an online game would be relative easy because there already is a place where the hole game state is stored.

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  • When is it too late to go back to coding from a management role? [closed]

    - by LeoLambrettra
    Problem solving keeps the mind sharp and if you are like me then it makes you happy. But what if you went from coding up to Team Lead and then to Project Manager? I have a team of 12 and on a good salary but lately have been thinking that the politics and admin tasks of being middle level management in an Investment Bank is not the right path to happiness. I used to be able to design and code as well as manage but lately it's all budgets, admin tasks and people problems. At 39 is it too late to go be a senior developer again? Basically - Team Lead in a flat structure with good people rocks. But if half your team is offshore then it loses something - There's a lot of politics in Project Management and so many meetings that even if you want to code you start letting your team down by missing deadlines and only suited for small units of work The coding skills haven't gone so to pick up WCF services it just takes a bit of reading and then playing around. I reckon I could switch to a Hedge Fund and go back to developing and be far happier and get more money. My 2 doubts though are 1. Mid life crisis in that I'd get bored with coding again 2. Or maybe I'd like it but there aren't many dev jobs for 40+ so I'd be throwing away a high level management role that took 7 years at thee one bank to get to0 Anybody else made to switch back and survived?

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  • Correct way to inject dependencies in Business logic service?

    - by Sri Harsha Velicheti
    Currently the structure of my application is as below Web App -- WCF Service (just a facade) -- Business Logic Services -- Repository - Entity Framework Datacontext Now each of my Business logic service is dependent on more than 5 repositories ( I have interfaces defined for all the repos) and I am doing a Constructor injection right now(poor mans DI instead of using a proper IOC as it was determined that it would be a overkill for our project). Repositories have references to EF datacontexts. Now some of the methods in the Business logic service require only one of the 5 repositories, so If I need to call that method I would end up instantiating a Service which will instatiate all 5 repositories which is a waste. An example: public class SomeService : ISomeService { public(IFirstRepository repo1, ISecondRepository repo2, IThirdRepository repo3) {} // My DoSomething method depends only on repo1 and doesn't use repo2 and repo3 public DoSomething() { //uses repo1 to do some stuff, doesn't use repo2 and repo3 } public DoSomething2() { //uses repo2 and repo3 to do something, doesn't require repo1 } public DoSomething3() { //uses repo3 to do something, doesn't require repo1 and repo2 } } Now if my I have to use DoSomething method on SomeService I end up creating both IFirstRepository,ISecondRepository and IThirdRepository but using only IFirstRepository, now this is bugging me, I can seem to accept that I am un-necessarily creating repositories and not using them. Is this a correct design? Are there any better alternatives? Should I be looking at Lazy instantiation Lazy<T> ?

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  • Resurrecting a 5,000 line test plan that is a decade old

    - by ale
    I am currently building a test plan for the system I am working on. The plan is 5,000 lines long and about 10 years old. The structure is like this: 1. test title precondition: some W needs to be set up, X needs to be completed action: do some Y postcondition: message saying Z is displayed 2. ... What is this type of testing called ? Is it useful ? It isn't automated.. the tests would have to be handed to some unlucky person to run through and then the results would have to be given to development. It doesn't seem efficient. Is it worth modernising this method of testing (removing tests for removed features, updating tests where different postconditions happen, ...) or would a whole different approach be more appropriate ? We plan to start unit tests but the software requires so much work to actually get 'units' to test - there are no units at present ! Thank you.

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  • Game planning and software design? I feel that UML is not convenient

    - by user1542
    In my university, they always emphasize and hype about UML design and stuff, in which I feel it is not going to work well with game structure design. Now, I just want a professional advice on how should I begin my game designing? The story is I have some skill in programming and have done many minor game such as getting some 2D platformer working to some extend. The problems that I find about my program is the poor quality design. After coding for a while, things start to break down due to poor planning (When I add new feature, it tends to make me have to recode the whole program). However, to plan everything out without a single design flaw is a bit too ideal. Therefore, any advice to how should I plan my game? How should I put it into visible pictures, so that me and my friends are able to overview the designs? I planned to start coding a game with my friend. This is going to be my first teamwork, so any professional advices would be a pleasure. Is there any other alternatives than UML? Another question is how does "prototyping" normally looks like?

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  • MVC design patterns

    - by insane-36
    I have an application and it does not use a very good structure. However it seems to me that I have tried to stick to mvc design pattern but a senior engineer claims that I have no design patterns and code are mesh. How I have structured the code : I have couple of nsmanagedobject model classes which represents model in my case and a reskit library which encapsulates the nsurlconnection and url request. I fetch the request from the view controller itself and then when the request get completed I create predicate and then populate it in tableview. Wherever I need custom view either I create it in nib or create in a custom subclass of UIView. I have use delegation pattern and notification to communication to view controller, views and block callback with restkit. But, the senior engineer is very new to ios. He has been doing it for 2 months now but he is a good java programmer. So, what is mvc pattern ? Is core data model not working as a model objects, view controller as controller and views. I dont seem to find any other places or any other cases to create my own model object since the most of the models are used as NSManagedObject subclass.

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  • How do 2D physics engines solve the problem of resolving collisions along tiled walls/floors in non-grid-based worlds?

    - by ssb
    I've been working on implementing my SAT algorithm which has been coming along well, but I've found that I'm at a wall when it comes to its actual use. There are plenty of questions regarding this issue on this site, but most of them either have no clear, good answer or have a solution based on checking grid positions. To restate the problem that I and many others are having, if you have a tiled surface, like a wall or a floor, consisting of several smaller component rectangles, and you traverse along them with another rectangle with force being applied into that structure, there are cases where the object gets caught on a false collision on an edge that faces the inside of the shape. I have spent a lot of time thinking about how I could possibly solve this without having to resort to a grid-based system, and I realized that physics engines do this properly. What I want to know is how they do this. What do physics engines do beyond basic SAT that allows this kind of proper collision resolution in complex environments? I've been looking through the source code to Box2D trying to find out how they do it but it's not quite as easy as looking at a Collision() method. I think I'm not good enough at physics to know what they're doing mathematically and not good enough at programming to know what they're doing programmatically. This is what I aim to fix.

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  • Most efficient way to store this collection of moduli and remainders?

    - by Bryan
    I have a huge collection of different moduli and associated with each modulus a fairly large list of remainders. I want to store these values so that I can efficiently determine whether an integer is equivalent to any one of the remainders with respect to any of the moduli (it doesn't matter which, I just want a true/false return). I thought about storing these values as a linked-list of balanced binary trees, but I was wondering if there is a better way? EDIT Perhaps a little more detail would be helpful. As for the size of this structure, it will be holding about 10s of thousands of (prime-1) moduli and associated to each modulus will be a variable amount of remainders. Most moduli will only have one or two remainders associated to it, but a very rare few will have a couple hundred associated to it. This is part of a larger program which handles numbers with a couple thousand (decimal) digits. This program will benefit more from this table being as large as possible and being able to be searched quickly. Here's a small part of the dataset where the moduli are in parentheses and the remainders are comma separated: (46) k = 20 (58) k = 15, 44 (70) k = 57 (102) k = 36, 87 (106) k = 66 (156) k = 20, 59, 98, 137 (190) k = 11, 30, 68, 87, 125, 144, 182 (430) k = 234 (520) k = 152, 282 (576) k = 2, 11, 20, 29, 38, 47, 56, 65, 74, ...(add 9 each time), 569 I had said that the moduli were prime, but I was wrong they are each one below a prime.

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  • Helping to Reduce Page Compression Failures Rate

    - by Vasil Dimov
    When InnoDB compresses a page it needs the result to fit into its predetermined compressed page size (specified with KEY_BLOCK_SIZE). When the result does not fit we call that a compression failure. In this case InnoDB needs to split up the page and try to compress again. That said, compression failures are bad for performance and should be minimized.Whether the result of the compression will fit largely depends on the data being compressed and some tables and/or indexes may contain more compressible data than others. And so it would be nice if the compression failure rate, along with other compression stats, could be monitored on a per table or even on a per index basis, wouldn't it?This is where the new INFORMATION_SCHEMA table in MySQL 5.6 kicks in. INFORMATION_SCHEMA.INNODB_CMP_PER_INDEX provides exactly this helpful information. It contains the following fields: +-----------------+--------------+------+ | Field | Type | Null | +-----------------+--------------+------+ | database_name | varchar(192) | NO | | table_name | varchar(192) | NO | | index_name | varchar(192) | NO | | compress_ops | int(11) | NO | | compress_ops_ok | int(11) | NO | | compress_time | int(11) | NO | | uncompress_ops | int(11) | NO | | uncompress_time | int(11) | NO | +-----------------+--------------+------+ similarly to INFORMATION_SCHEMA.INNODB_CMP, but this time the data is grouped by "database_name,table_name,index_name" instead of by "page_size".So a query like SELECT database_name, table_name, index_name, compress_ops - compress_ops_ok AS failures FROM information_schema.innodb_cmp_per_index ORDER BY failures DESC; would reveal the most problematic tables and indexes that have the highest compression failure rate.From there on the way to improving performance would be to try to increase the compressed page size or change the structure of the table/indexes or the data being stored and see if it will have a positive impact on performance.

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  • What is involved with writing a lobby server?

    - by Kira
    So I'm writing a Chess matchmaking system based on a Lobby view with gaming rooms, general chat etc. So far I have a working prototype but I have big doubts regarding some things I did with the server. Writing a gaming lobby server is a new programming experience to me and so I don't have a clear nor precise programming model for it. I also couldn't find a paper that describes how it should work. I ordered "Java Network Programming 3rd edition" from Amazon and still waiting for shipment, hopefully I'll find some useful examples/information in this book. Meanwhile, I'd like to gather your opinions and see how you would handle some things so I can learn how to write a server correctly. Here are a few questions off the top of my head: (may be more will come) First, let's define what a server does. It's primary functionality is to hold TCP connections with clients, listen to the events they generate and dispatch them to the other players. But is there more to it than that? Should I use one thread per client? If so, 300 clients = 300 threads. Isn't that too much? What hardware is needed to support that? And how much bandwidth does a lobby consume then approx? What kind of data structure should be used to hold the clients' sockets? How do you protect it from concurrent modification (eg. a player enters or exists the lobby) when iterating through it to dispatch an event without hurting throughput? Is ConcurrentHashMap the correct answer here, or are there some techniques I should know? When a user enters the lobby, what mechanism would you use to transfer the state of the lobby to him? And while this is happening, where do the other events bubble up? Screenshot : http://imageshack.us/photo/my-images/695/sansrewyh.png/

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  • What is the steps to make a frame work for a company? [on hold]

    - by bbb
    we want to make a frame work for our company. Our company mission is developing web applications and CMS and websites. Till now we had a lot of problems with the various types of codding. we didnt have a frame work and every programmer codes as he wants and it was too hard for the others to edit them. Now we want to make a frame work for the company. We want to make an archive of dll files that are written by our self our other and make the programmers to use just from them and we want to make a frame work for the type of codding. WE NEED A STRUCTURE FOR THE COMPANY. I dont know how to do this and what is the first and second and third step to do this. I need some guidance about it. For example I say that the frame work should contains the followings: The base should be SOLID The method should be Code-First The standards should be Naming Convention The type should be 3 layer programming The method should be MVC We should use from our dll archive The UI should be with HTML and CSS And using from Bootstrap Am I right or not or is it complete or...???

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