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• Is programming in layers real?

  - by Aura

  I am fairly new in product development and I am trying to work over a product. The problem that I have realized is that people draw diagrams and charts showing different modules and layers. But as I am working alone (I am my own team) I got a bit confused about the interaction I am facing in the development within the programs and I am wondering whether developing a product in modules is real or not? Maybe I am not a great programmer, but I see no boundaries when data start to travel from frontend to backend.

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• What is the general definition of something that can be included or excluded?

  - by gutch

  When an application presents a user with a list of items, it's pretty common that it permits the user to filter the items. Often a 'filter' feature is implemented as a set of include or exclude rules. For example: include all emails from [email protected], and exclude those emails without attachments I've seen this include/exclude pattern often; for example Maven and Google Analytics filter things this way. But now that I'm implementing something like this myself, I don't know what to call something that could be either included or excluded. In specific terms: If I have a database table of filter rules, each of which either includes or excludes matching items, what is an appropriate name of the field that stores include or exclude? When displaying a list of filters to a user, what is a good way to label the include or exclude value? (as a bonus, can anyone recommend a good implementation of this kind of filtering for inspiration?)

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• Box2dWeb positioning relative to HTML5 Canvas

  - by Joe

  I'm new with HTML5 canvas and Box2DWeb and I'm trying to make an Asteroids game. So far I think I'm doing okay, but one thing I'm struggling to comprehend is how positioning works in relation to the canvas. I understand that Box2DWeb is only made to deal with physical simulation, but I don't know how to deal with positioning on the canvas. The canvas is 100% viewport and thus can vary size. I want to fill the screen with some asteroids, but if I hardcore certain values such as bodyDef.position.x = Math.random() * 50; the asteroid may appear off canvas for someone with a smaller screen? Can anybody help me understand how I can deal with relative positioning on the canvas?

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• Interface extension

  - by user877329

  Suppose that I have an input stream interface, which defines a method for reading data. I also have a seekable interface which defines a method for seeking. A natural way of defining a input file is then to implement both input stream and seekable. I want to construct a data decoder from the input stream interface so I can read data from a file or from another stream. The problem is that I also want to implement seek functionality to the data decoder, since I want to be able to step individual records not raw bytes. This is not possible if I only provide an input stream, which does not have the bytewise seek method. Should I skip the seekable interface and add the seek method to input stream instead and force all streams to at least leave it as a nop.

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• Patterns for a tree of persistent data with multiple storage options?

  - by Robin Winslow

  I have a real-world problem which I'll try to abstract into an illustrative example. So imagine I have data objects in a tree, where parent objects can access children, and children can access parents: // Interfaces interface IParent<TChild> { List<TChild> Children; } interface IChild<TParent> { TParent Parent; } // Classes class Top : IParent<Middle> {} class Middle : IParent<Bottom>, IChild<Top> {} class Bottom : IChild<Middle> {} // Usage var top = new Top(); var middles = top.Children; // List<Middle> foreach (var middle in middles) { var bottoms = middle.Children; // List<Bottom> foreach (var bottom in bottoms) { var middle = bottom.Parent; // Access the parent var top = middle.Parent; // Access the grandparent } } All three data objects have properties that are persisted in two data stores (e.g. a database and a web service), and they need to reflect and synchronise with the stores. Some objects only request from the web service, some only write to it. Data Mapper My favourite pattern for data access is Data Mapper, because it completely separates the data objects themselves from the communication with the data store: class TopMapper { public Top FetchById(int id) { var top = new Top(DataStore.TopDataById(id)); top.Children = MiddleMapper.FetchForTop(Top); return Top; } } class MiddleMapper { public Middle FetchById(int id) { var middle = new Middle(DataStore.MiddleDataById(id)); middle.Parent = TopMapper.FetchForMiddle(middle); middle.Children = BottomMapper.FetchForMiddle(bottom); return middle; } } This way I can have one mapper per data store, and build the object from the mapper I want, and then save it back using the mapper I want. There is a circular reference here, but I guess that's not a problem because most languages can just store memory references to the objects, so there won't actually be infinite data. The problem with this is that every time I want to construct a new Top, Middle or Bottom, it needs to build the entire object tree within that object's Parent or Children property, with all the data store requests and memory usage that that entails. And in real life my tree is much bigger than the one represented here, so that's a problem. Requests in the object In this the objects request their Parents and Children themselves: class Middle { private List<Bottom> _children = null; // cache public List<Bottom> Children { get { _children = _children ?? BottomMapper.FetchForMiddle(this); return _children; } set { BottomMapper.UpdateForMiddle(this, value); _children = value; } } } I think this is an example of the repository pattern. Is that correct? This solution seems neat - the data only gets requested from the data store when you need it, and thereafter it's stored in the object if you want to request it again, avoiding a further request. However, I have two different data sources. There's a database, but there's also a web service, and I need to be able to create an object from the web service and save it back to the database and then request it again from the database and update the web service. This also makes me uneasy because the data objects themselves are no longer ignorant of the data source. We've introduced a new dependency, not to mention a circular dependency, making it harder to test. And the objects now mask their communication with the database. Other solutions Are there any other solutions which could take care of the multiple stores problem but also mean that I don't need to build / request all the data every time?

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• Traverse tree with results. Maybe type in Java?

  - by Angelo.Hannes

  I need to check a tree's node state. It can either be OK or NOT_OK. But that state is dependent on its children. So for a node to be OK, every of its children needs to be OK. If one or more of its children is NOT_OK the whole node is NOT_OK. To determine the state of a node I need to aggregate some properties of the node. So I thought of two possible implementations. And they are more or less covered in this question: Why is Option/Maybe considered a good idea and checked exceptions are not? Exception I could pass the properties up the recursion path, and throw an exception if something went wrong. Maybe I implement an Maybe type and let it either hold an error or the aggregated properties. Maybe it is more an Either. I tend towards the last option. And I'm thinking of an enum with two objects. Where I can additionally set those aggregated properties. Am I on the right track? I'm not familiar with the new JDK8 functional stuff. But I'm stuck on JDK7 anyway, so please focus on JDK7.

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• Managing accounts on a private website for a real-life community

  - by Smudge

  I'm looking at setting-up a walled-in website for a real-life community of people, and I was wondering if anyone has any experience with managing member accounts for this kind of thing. Some conditions that must be met: This community has a set list of real-life members, each of whom would be eligible for one account on the website. We don't expect or require that they all sign-up. It is purely opt-in, but we anticipate that many of them would be interested in the services we are setting up. Some of the community members emails are known, but some of them have fallen off the grid over the years, so ideally there would be a way for them to get back in touch with us through the public-facing side of the site. (And we'd want to manually verify the identity of anyone who does so). Their names are known, and for similar projects in the past we have assigned usernames derived from their real-life names. This time, however, we are open to other approaches, such as letting them specify their own username or getting rid of usernames entirely. The specific web technology we will use (e.g. Drupal, Joomla, etc) is not really our concern right now -- I am more interested in how this can be approached in the abstract. Our database already includes the full member roster, so we can email many of them generated links to a page where they can create an account. (And internally we can require that these accounts be paired with a known member). Should we have them specify their own usernames, or are we fine letting them use their registered email address to log-in? Are there any paradigms for walled-in community portals that help address security issues if, for example, one of their email accounts is compromised? We don't anticipate attempted break-ins being much of a threat, because nothing about this community is high-profile, but we do want to address security concerns. In addition, we want to make the sign-up process as painless for the members as possible, especially given the fact that we can't just make sign-ups open to anyone. I'm interested to hear your thoughts and suggestions! Thanks!

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• How to explain bad software to non-technical people?

  - by mtutty

  In discussing software development with non-technical people (customers, business owners, project sponsors, etc.), I often resort to analogies and metaphors. It's relatively easy and effective to use a "house" or other metaphor for describing the size and complexity of new development. However, we often inherit someone else's code or data, and this approach doesn't seem to hold up as well when trying to explain why we're gutting something that already seems to work. Of course we can point to cycle time and cost to be saved in the future but this generally means nothing to business folks. I know doctors can say "just take this pill," but I'm not sure that software devs have the same authority. Ideas? EDIT: Let me add a bit to the discussion. The specific project I'm talking about has customers that don't realize (or care) about specific aspects of the system we're retiring (i.e., they think it was just fine): The system would save a NEW RECORD every time someone updated a field The system contained tables for reference data. These tables had new records added every day, even though they were duplicates of previous records. And there was no way to tie the reference data used for a particular case at the time it was closed. This is like 99% of the data in the old system. The field NAMES also have spaces, apostrophes and other inappropriate characters in them, making everything harder to work with. In addition to the incredible amount of duplicate data, they have around 1000 XLS files with data they want added to the system. Previously, they would do a spreadsheet for each case in the database, IN ADDITION TO what they typed into the database. Getting rid of this old, unneeded information and piping in the XLS data comprises about 80% of the total project effort, and was not something we could accurately predict. I'm trying to find a concrete way to describe how bad this thing was, mostly so that the customer will understand why the migration process has been so time-consuming. The actual coding was done pretty quickly and the new system works fine, but without the old data they won't be happy. Sorry to get into the weeds, but most of the answers I've seen so far are pretty basic scope/schedule/cost things. I've been doing this for 15 years, so this really is more of a reflective, philosophical question - but without some of the details it can be difficult to really appreciate the awful beauty of this problem.

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• Consistency vs. Usability?

  - by dsimcha

  When designing an API, consistency often aids usability. However, sometimes they conflict where an extra API feature can be added to streamline a common case. It seems like there's somewhat of a divide over what to do here. Some designs (the Java standard library come to mind) favor consistency even if it makes common cases more verbose. Others (the Python standard library comes to mind) favor usability even if it means treating the common case as "special" to make it easier. What is your opinion on how consistency and usability should be balanced?

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• C++: calling non-member functions with the same syntax of member ones

  - by peoro

  One thing I'd like to do in C++ is to call non-member functions with the same syntax you call member functions: class A { }; void f( A & this ) { /* ... */ } // ... A a; a.f(); // this is the same as f(a); Of course this could only work as long as f is not virtual (since it cannot appear in A's virtual table. f doesn't need to access A's non-public members. f doesn't conflict with a function declared in A (A::f). I'd like such a syntax because in my opinion it would be quite comfortable and would push good habits: calling str.strip() on a std::string (where strip is a function defined by the user) would sound a lot better than calling strip( str );. most of the times (always?) classes provide some member functions which don't require to be member (ie: are not virtual and don't use non-public members). This breaks encapsulation, but is the most practical thing to do (due to point 1). My question here is: what do you think of such feature? Do you think it would be something nice, or something that would introduce more issues than the ones it aims to solve? Could it make sense to propose such a feature to the next standard (the one after C++0x)? Of course this is just a brief description of this idea; it is not complete; we'd probably need to explicitly mark a function with a special keyword to let it work like this and many other stuff.

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• Why do most programming languages only support returning a single value from a function?

  - by M4N

  Is there a reason or an explanation why functions in most(?) programming languages are designed to support any number of input parameters but only one return value? In most languages, it is possible to "work around" that limitation, e.g. by using out-parameters, returning pointers or by defining/returning structs/classes. But it seems strange, that programming languages were not designed to support multiple return values in a more "natural" way.

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• Creating meaningful and engaging quests

  - by user384918

  Kill X number of monsters. Gather Y number of items (usually by killing X number of monsters). Deliver this NPC's package to this other NPC who is far far away. etc. Yeah. These quests are easy to implement, easy to complete, but also very boring after the first few times. It's kind of disingenuous to call them quests really; they're more like chores or errands. What ideas for quests have people seen that were well designed, immersive, and rewarding? What specific things did the developers do that made it so? What are some ideas you would use (or have used) to make quests more interesting?

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• best way to send messages to all subscribers with multiple subscriptions and multiple providers

  - by coding_idiot

  I'm writing an application in which - Many users can subsribe to posts made by another users. So for a single publisher there can be many subscribers. When a message is posted by an user X, all users who have subscribed to messages of User X will be sent an email. How to achieve this ? I'm thinking of using publish-subscribe pattern. And then I came through JMS. Which is the best JMS implementation to use according to your experience ? Or else what else solution do you propose to the given problem ? Shall I go for a straight-forward solution ?: User x posts a message, I find all users (from database) who subscribe to user x and then for every user, I call the sendEmail() method. [EDIT] My intention here is not to send-emails. I'm really sorry if it wasn't clear. I also have to send kind of system-notifications apart from Email to all subscribers. Right now, I've implemented the email-sending as a threadPool

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• what knowledge would I need to make a good simulation games

  - by Skeith

  I have an idea for a game like theme park but don't know how simulation games are made. I am not some noob on his first game so I appreciated constructive answers instead of "its hard, don't do it". What I want is to know how simulation game mechanics are put together. I figure it would be heaver on the AI than normal games and not knowing much about AI would like to know some programming techniques I should look into for this style game. specific techniques please not just a book on ai. what sort of architecture would be used? I guess it would have some sort of probability engine with pre designed events that are triggered based on the AI state. Would it use a FSM or be purely event driven ? Any information on how a sims game functions would be cool.

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• Java word scramble game [closed]

  - by Dan

  I'm working on code for a word scramble game in Java. I know the code itself is full of bugs right now, but my main focus is getting a vector of strings broken into two separate vectors containing hints and words. The text file that the strings are taken from has a colon separating them. So here is what I have so far. public WordApp() { inputRow = new TextInputBox(); inputRow.setLocation(200,100); phrases = new Vector <String>(FileUtilities.getStrings()); v_hints = new Vector<String>(); v_words = new Vector<String>(); textBox = new TextBox(200,100); textBox.setLocation(200,200); textBox.setText(scrambled + "\n\n Time Left: \t" + seconds/10 + "\n Score: \t" + score); hintBox = new TextBox(200,200); hintBox.setLocation(300,400); hintBox.hide(); Iterator <String> categorize = phrases.iterator(); while(categorize.hasNext()) { int index = phrases.indexOf(":"); String element = categorize.next(); v_words.add(element.substring(0,index)); v_hints.add(element.substring(index +1)); phrases.remove(index); System.out.print(index); } The FileUtilities file was given to us by the pofessor, here it is. import java.util.*; import java.io.*; public class FileUtilities { private static final String FILE_NAME = "javawords.txt"; //------------------ getStrings ------------------------- // // returns a Vector of Strings // Each string is of the form: word:hint // where word contains no spaces. // The words and hints are read from FILE_NAME // // public static Vector<String> getStrings ( ) { Vector<String> words = new Vector<String>(); File file = new File( FILE_NAME ); Scanner scanFile; try { scanFile = new Scanner( file); } catch ( IOException e) { System.err.println( "LineInput Error: " + e.getMessage() ); return null; } while ( scanFile.hasNextLine() ) { // read the word and follow it by a colon String s = scanFile.nextLine().trim().toUpperCase() + ":"; if( s.length()>1 && scanFile.hasNextLine() ) { // append the hint and add to collection s+= scanFile.nextLine().trim(); words.add(s); } } // shuffle Collections.shuffle(words); return words; } }

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• How does URL Rewriting affect SEO?

  - by Costa

  The following paragraph is from SEO Google Guide Google is good at crawling all types of URL structures, even if they're quite complex, but spending the time to make your URLs as simple as possible for both users and search engines can help. Some webmasters try to achieve this by rewriting their dynamic URLs to static ones; while Google is fine with this, we'd like to note that this is an advanced procedure and if done incorrectly, could cause crawling issues with your site. What makes URL re-writing implementation incorrect for GoogleBot? I am using Asp.net 3.5 framework.

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• does class reference itself static anti pattern in prism

  - by Michael Riva

  I have an application and my desing approach look like this: class Manager { public int State; static Manager _instance = null; public static Manager Instance { get { return _instance; } set { if (_instance == value) return; _instance = value; } } public Manager() { State = 0; Instance=this; } } class Module1 { public void GetState() { Console.WriteLine(Manager.Instance.State); } } class Module2 { public void GetState() { Console.WriteLine(Manager.Instance.State); } } class Module3 { public void GetState() { Console.WriteLine(Manager.Instance.State); } } Manager class already registered in Bootstrapper like : protected override void ConfigureContainer() { base.ConfigureContainer(); Container.RegisterType<Manager>(new ContainerControlledLifetimeManager()); } protected override void InitializeModules() { Manager man= Container.Resolve<Manager>(); } Question is do I need to define my manager object as static in its field to be able to reach its state? Or this is anti pattern or bad for performance?

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• Master Data Management

  - by Logicalj

  I am looking for a very flexible, easy to integrate and dynamic application with as many features as possible for Master Data Management. As Master Data Management is used to Manage Operational Data, Analytical Data and Master Data so, I want guidance about "What is exactly expected from Master Data Management and What are the Basic and Challenging Scenarios to be covered or resolved in Master Data Management". Please guide me with all the possible aspects of Master Data Management like Data Cleansing, Data Management and Start Data Analyzing, etc.

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• Writing a dynamic achievement system without hardcoding rules into the application

  - by imaginative

  I really enjoyed the solution provided here for groundwork on writing an achievement framework. The problem I have is I have game designers that would like to be able to insert achievements into a CMS at runtime. In a way, it sounds insane and complex to do this, but is it really? I think the concept of having to do a hard push of the application for every new achievement is cumbersome. I would love to be able to give our designers the capability to put together new achievements by entering them into a database. It shouldn't matter what tool I'm using, but for those interested, my backend is being written in JRuby (Ruby on top of the JVM). What are some possible ways of going about abstracting the logic in the aforementioned link even further so that rules can be interpreted at runtime?

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• A few questions about how JavaScript works

  - by KayoticSully

  I originally posted on Stack Overflow and was told I might get some better answers here. I have been looking deeply into JavaScript lately to fully understand the language and have a few nagging questions that I can not seem to find answers to (Specifically dealing with Object Oriented programming. I know JavaScript is meant to be used in an OOP manner I just want to understand it for the sake of completeness). Assuming the following code: function TestObject() { this.fA = function() { // do stuff } this.fB = testB; function testB() { // do stuff } } TestObject.prototype = { fC : function { // do stuff } } What is the difference between functions fA and fB? Do they behave exactly the same in scope and potential ability? Is it just convention or is one way technically better or proper? If there is only ever going to be one instance of an object at any given time, would adding a function to the prototype such as fC even be worthwhile? Is there any benefit to doing so? Is the prototype only really useful when dealing with many instances of an object or inheritance? And what is technically the "proper" way to add methods to the prototype the way I have above or calling TestObject.prototype.functionName = function(){} every time? I am looking to keep my JavaScript code as clean and readable as possible but am also very interested in what the proper conventions for Objects are in the language. I come from a Java and PHP background and am trying to not make any assumptions about how JavaScript works since I know it is very different being prototype based. Also are there any definitive JavaScript style guides or documentation about how JavaScript operates at a low level? Thanks!

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• Should an object know its own ID?

  - by xenoterracide

  obj.id seems fairly common and also seems to fall within the range of something an object could know about itself. I find myself asking why should my object know its own id? It doesn't seem to have a reason to have it? One of the main reason for it existing is retrieve it, and so my repositories need to know it, and thus use it for database interaction. I also once encountered a problem where I wanted to serialize an object to JSON for a RESTful API where the id did not seem to fit in the payload, but only the URI and including it in the object made that more difficult. Should an object know it's own id? why or why not?

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• Database structure for various items

  - by XGouchet

  I'm building a sqlite database for an android app which will hold a list of items, each of which have different characteristics. Some of the characteristics are available for all objects, some are only relevant for a subset of objects. For example, all my items have a name, a description, an image. Some items will also have an expiration date, others wont. Some will have a size, some wont. Etc... How should I build my Database, as I don't know how many characteristics may be added in the future, and knowing I should be able to filter the list by any characteristic ?

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• What are good ways to find collaborators for a coding weekend?

  - by tarrasch

  Not sure if this belongs here, feel free to push it somewhere else if needed. When i was at university we would sometimes come together into a room full of beer and fast food and crank out software in a weekend. Unfortunately the group has kind of split up and its just not possible any more. My question is now: Where can i find like-minded people on the Internet that would like to do something like this? I have an idea what i wanted to do next, but of course other people have ideas too.

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• Creating an online community - use templates or self-develop?

  - by ican ican

  PHPMotion, Joomla or develop my own? I'm thinking of developing a common interest online community. It will be have UGC, stats, etc.. functionality, and perhaps an online store. Though cost is an issue at this time, I want to be professional and effective. Should I use existing free platform templates, like PHP, Joomla, or should I develop my own? What are the advantages/disadvantages of either option? As a rough estimate, how much will it cost me to develop and manage my own? And how long will it take. In general what should I be careful about on this journey?

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• Splitting Logic, Data, Layout and "Hacks"

  - by fjdumont

  Sure, we all heard of programming patterns such as MVVM, MVC and such. But that isn't really what I'm looking into as Layout, Data and Logic is already pretty much split up (XML-Layout markup, Database, insert your language of choice here). The platform I am developing for is hard to maintain over the updated versions and older OSes. The project significantly grew up over the last few months and dealing with different platform versions really is a pain. For example simply disabling an user interface control for all existing versions took me around 40 lines of code in the logic layer, wrangling around with invocation, delegation, singletons that provide UI handling and so on. Is there a clean way to keep track of those "hacks" by maybe excluding it into separate classes or even packages? Should I overwrite existing framework code in order to handle my requirements correctly? If so, does that concept have a name?

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