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• initial Class design: access modifiers and no-arg constructors

  - by yas

  Context: Student working through Class design in personal/side project for Summer. I've never written anything implemented by others or had to maintain code. Trying to maximize encapsulation and imagining what would make code easy to maintain. Concept: Tight/Loose Class design where Tight and Loose refer to access modifiers and constructors. Tight: initially, everything, including setters, is private and a no-arg constructor is not provided (only a full constructor). Loose: not Tight Exceptions: the obvious like toString Reasoning: If code, at the very beginning, is tight, then it should be guaranteed that changes, with respect to access/creation, should never damage existing implementations. The loosening of code happens incrementally and must be thought through, justified, and safe (validated). Benefit: Existing implementing code should not break if changes are made later. Cost: Takes more time to create. Since this is my own thinking, I hope to get feedback as to whether I should push to work this way. Good idea or bad idea?

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• Using default parameters for 404 error (PHP with mvc design)?

  - by user1175327

  I have a custom made Framework (written in PHP). It all works very good, but i have some doubts about a certain thing. Right now when a user call this url for example: http://host.com/user/edit/12 Which would resolve to: user = userController edit = editAction() in userController 12 = treated as a param But suppose the controller 'userController' doesn't exist. Then i could throw a 404. But on the other hand, the url could also be used as params for the indexController (which is the default controller). So in that case: controller = indexController user = could be an action in indexController, otherwise treated as a param edit = treated as a param 12 = treated as a param That is actually how it works right now in my framework. So basically, i never throw a 404. I could ofcourse say that only params can be given if the controller name is explicitly named in the URL. So if i want the above url: http://host.com/user/edit/12 To be invoked by the indexController, in the indexAction. Then i specifically have to tell what controller and action it uses in the URL. So the URL should become: http://host.com/index/index/user/edit/12 index = indexController index (2nd one) = the action method user = treated as a param edit = treated as a param 12 = treated as a param That way, when a controller doesn't exist, i don't reroute everything as a param to the index controller and simply throw a 404 error. Now my question is, which one is more preffered? Should i allow both options to be configurable in a config file? Or should i always use one of them. Simply because that's the only and best way to do it?

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• Building general programming skills?

  - by toleero

  I currently am quite new to programming, I've had exposure to a few languages (C#, PHP, JavaScript, VB, and some others) and I'm quite new to OOP. I was just wondering what is the best way to build up general programming/problem solving skills without being language specific? I was thinking maybe of something like Project Euler but more geared towards newbies? Thanks! Edit: I am looking at getting into Game Scripting/Programming, I'm already in Games but in a different discipline :)

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• Interview Questions in OOP

  - by Fero

  Hi all, I faced the below interview questions in OOP under PHP language. Kindly clear my clarifications regarding this. I am very confused. As i am a beginner to OOP i got too confused. Could anyone clarify these things clearly? Difference between Abstract class and interface. Interviewer : Let us consider abstract class contains three abstract methods such as a,b,c and interface contains three methods a,b,c. In this case these do the same functionality. Then why are going for abstract and why are we going for interface. Me : ? static keyword. Interviewer: We call static method without creating object by using scope resolution operator in PHP. As well as we can able to call concrete methods also. Then what is need of static keyword there? Me : .... final keyword. Interviewer: Give me any scenario of using final keyword. Me : For db connection related method Interviewer: Other than that? Me: ... Constructor. Interviewer: What is the use of constructor? Me : There is no need for object to access this. It will call automatically when the class calls. Interviewer: Other than that? Me : .... Thanks in advance...

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• What is a good design pattern / lib for iOS 5 to synchronize with a web service?

  - by Junto

  We are developing an iOS application that needs to synchronize with a remote server using web services. The existing web services have an "operations" style rather than REST (implemented in WCF but exposing JSON HTTP endpoints). We are unsure of how to structure the web services to best fit with iOS and would love some advice. We are also interested in how to manage the synchronization process within iOS. Without going into detailed specifics, the application allows the user to estimate repair costs at a remote site. These costs are broken down by room and item. If the user has an internet connection this data can be sent back to the server. Multiple photographs can be taken of each item, but they will be held in a separate queue, which sends when the connection is optimal (ideally wifi). Our backend application controls the unique ids for each room and item. Thus, each time we send these costs to the server, the server echoes the central database ids back, thus, that they can be synchronized in the mobile app. I have simplified this a little, since the operations contract is actually much larger, but I just want to illustrate the basic requirements without complicating matters. Firstly, the web service architecture: We currently have two operations: GetCosts and UpdateCosts. My assumption is that if we used a strict REST architecture we would need to break our single web service operations into multiple smaller services. This would make the services much more chatty and we would also have to guarantee a delivery order from the app. For example, we need to make sure that containing rooms are added before the item. Although this seems much more RESTful, our perception is that these extra calls are expensive connections (security checks, database calls, etc). Does the type of web api (operation over service focus) determine chunky vs chatty? Since this is mobile (3G), are we better handling lots of smaller messages, or a few large ones? Secondly, the iOS side. What is the current advice on how to manage data synchronization within the iOS (5) app itself. We need multiple queues and we need to guarantee delivery order in each queue (and technically, ordering between queues). The server needs to control unique ids and other properties and echo them back to the application. The application then needs to update an internal database and when re-updating, make sure the correct ids are available in the update message (essentially multiple inserts and updates in one call). Our backend has a ton of business logic operating on these cost estimates. We don't want any of this in the app itself. Currently the iOS app sends the cost data, and then the server echoes that data back with populated ids (and other data). The existing cost data is deleted and the echoed response data is added to the client database on the device. This is causing us problems, because any photos might not have been sent, but the original entity tree has been removed and replaced. Obviously updating the costs tree rather than replacing it would remove this problem, but I'm not sure if there are any nice xcode libraries out there to do such things. I welcome any advice you might have.

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• Pros and cons of developing modern services in Java

  - by r3mus

  I'm interested in the philosophical and architectural justification (or lack thereof) in using Java to develop in today's modern world (exclude mobile/embedded platforms of course). Why would one choose to develop (or not develop) a back-end in Java? Why would one choose to develop (or not develop) a front-end UI in Java? Why do large enterprises lean towards developing in Java rather than adopt more modern (and standardized) technologies? *disclaimer: I'm not a fan of Java in the enterprise, I'm simply curious what drives enterprises to continue the trend.

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• Should I forward the a call to .Equals onto .Equals<T>?

  - by Jaimal Chohan

  So, I've got you bog standard c# object, overriding Equalsand implementing IEquatable public override int GetHashCode() { return _name.GetHashCode(); } public override bool Equals(object obj) { return Equals(obj as Tag) } #region IEquatable<Tag> Members public bool Equals(Tag other) { if (other == null) return false; else return _name == other._name; } #endregion Now, for some reason, I used to think that forwarding the calls from Equals into Equals was bad, no idea why, perhaps I read it a long time ago, anyway I'd write separate (but logically same) code for each method. Now I think forwarding Equals to Equals is okay, for obvious reasons, but for the life me I can't remember why I thought it wasn't before. Any thoughts?

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• How to be a zero-bug programmer?

  - by Elaine

  My boss ever told me that as a good programmer, who should be able to ensure the code he/she changed must be reliable, correct, thoroughly self-verified, who should completely understand what all the results and impacts that he/she did or revised will cause. I did try my best to be as this kind of programmer, test again and again. But.. bugs are still there. How could I be a zero-bug programmer? know every char of my code will cause and effect?

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• Why is Windows registry needed?

  - by Job

  As I have debugged problems in com, side by side, dealt with dll hell, all while hating the windows registry with passion, I was wondering why is it needed. I never felt compelled to read an entire book on registry best practices, and then just "get it". I have, however, used Linux and Mac OS, and look at the ways one can install multiple versions of Python and its libraries on the same *nix computer. Because registry has somewhat of a free (albeit ugly) format, and is used for all sorts of purposes, I have never understood what essential problem it is trying to solve. For instance, Microsoft does not want you to have two different versions of MS Office installed side by side. They use registry to enforce this during installation. This limitation is artificial, in my opinion. If they really cared to allow a different behavior, they could have adjusted their architecture accordingly. In Mac OS you can install and remove apps by just dropping them into a particular folder. So, A) What essential problem it is trying to solve? B) How do other operating systems solve it?

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• Interfacing the payment systems

  - by etranger

  Hello all. I'm a complete newbie to using online payment systems for web projects, and can't really think of where to start. Let's assume that web system in question needs to generate some income online, and the business idea/functionality is in place, while organizing cash flow is the only unsolved problem. Points of interest are how the custom developed software interfaces to payment systems, and how the resulting income is available to the owner. I do understand that there are probably hundreds of systems out there, but to be more specific on which of them suit, I'd have to know how they work, and that's where I don't feel like understanding much. Thanks in advance.

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• Android, OpenGL and extending GLSurfaceView?

  - by Spoon Thumb

  This question is part-technical, part-meta, part-subjective and very specific: I'm an indie game dev working on android, and for the past 6 months I've struggled and finally succeeded in making my own 3D game app for android. So I thought I'd hop on SO and help out others struggling with android and openGL-ES However, the vast majority of questions relate to extending GLSurfaceView. I made my whole app without extending GLSurfaceView (and it runs fine). I can't see any reason at all to extend GLSurfaceView for the majority of questions I come across. Worse, the android documentation implies that you ought to, but gives no detailed explaination of why or what the pros/cons are vs not extending and doing everything through implementing your own GLSurfaceView.Renderer as I did Still, the sheer volume of questions where the problem is purely to do with extending GLSurfaceView is making me wonder whether actually there is some really good reason for doing it that way vs the way I've been doing it (and suggesting in my answers to others to do). So, is there something I'm missing? Should I stop answering questions in the meantime? Android openGL documentation

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• What are the differences between abstract classes, interfaces, and when to use them

  - by user66662

  Recently I have started to wrap my head around OOP, and I am now to the point where the more I read about the differences between Abstract classes and Interfaces the more confused I become. So far, neither can be instantiated. Interfaces are more or less structural blueprints that determine the skeleton and abstracts are different by being able to partially develop code. I would like to learn more about these through my specific situation. Here is a link to my first question if you would like a little more background information: What is a good design model for my new class? Here are two classes I created: class Ad { $title; $description $price; function get_data($website){ } function validate_price(){ } } class calendar_event { $title; $description $start_date; function get_data($website){ //guts } function validate_dates(){ //guts } } So, as you can see these classes are almost identical. Not shown here, but there are other functions, like get_zip(), save_to_database() that are common across my classes. I have also added other classes Cars and Pets which have all the common methods and of course properties specific to those objects (mileage, weight, for example). Now I have violated the DRY principle and I am managing and changing the same code across multiple files. I intend on having more classes like boats, horses, or whatever. So is this where I would use an interface or abstract class? From what I understand about abstract classes I would use a super class as a template with all of the common elements built into the abstract class, and then add only the items specifically needed in future classes. For example: abstract class content { $title; $description function get_data($website){ } function common_function2() { } function common_function3() { } } class calendar_event extends content { $start_date; function validate_dates(){ } } Or would I use an interface and, because these are so similar, create a structure that each of the subclasses are forced to use for integrity reasons, and leave it up to the end developer who fleshes out that class to be responsible for each of the details of even the common functions. my thinking there is that some 'common' functions may need to be tweaked in the future for the needs of their specific class. Despite all that above, if you believe I am misunderstanding the what and why of abstracts and interfaces altogether, by all means let a valid answer to be stop thinking in this direction and suggest the proper way to move forward! Thanks!

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• Strategies for invoking subclass methods on generic objects

  - by Brad Patton

  I've run into this issue in a number of places and have solved it a bunch of different ways but looking for other solutions or opinions on how to address. The scenario is when you have a collection of objects all based off of the same superclass but you want to perform certain actions based only on instances of some of the subclasses. One contrived example of this might be an HTML document made up of elements. You could have a superclass named HTMLELement and subclasses of Headings, Paragraphs, Images, Comments, etc. To invoke a common action across all of the objects you declare a virtual method in the superclass and specific implementations in all of the subclasses. So to render the document you could loop all of the different objects in the document and call a common Render() method on each instance. It's the case where again using the same generic objects in the collection I want to perform different actions for instances of specific subclass (or set of subclasses). For example (an remember this is just an example) when iterating over the collection, elements with external links need to be downloaded (e.g. JS, CSS, images) and some might require additional parsing (JS, CSS). What's the best way to handle those special cases. Some of the strategies I've used or seen used include: Virtual methods in the base class. So in the base class you have a virtual LoadExternalContent() method that does nothing and then override it in the specific subclasses that need to implement it. The benefit being that in the calling code there is no object testing you send the same message to each object and let most of them ignore it. Two downsides that I can think of. First it can make the base class very cluttered with methods that have nothing to do with most of the hierarchy. Second it assumes all of the work can be done in the called method and doesn't handle the case where there might be additional context specific actions in the calling code (i.e. you want to do something in the UI and not the model). Have methods on the class to uniquely identify the objects. This could include methods like ClassName() which return a string with the class name or other return values like enums or booleans (IsImage()). The benefit is that the calling code can use if or switch statements to filter objects to perform class specific actions. The downside is that for every new class you need to implement these methods and can look cluttered. Also performance could be less than some of the other options. Use language features to identify objects. This includes reflection and language operators to identify the objects. For example in C# there is the is operator that returns true if the instance matches the specified class. The benefit is no additional code to implement in your object hierarchy. The only downside seems to be the lack of using something like a switch statement and the fact that your calling code is a little more cluttered. Are there other strategies I am missing? Thoughts on best approaches?

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• Are there any concerns with using a static read-only unit of work so that it behaves like a cache?

  - by Rowan Freeman

  Related question: How do I cache data that rarely changes? I'm making an ASP.NET MVC4 application. On every request the security details about the user will need to be checked with the area/controller/action that they are accessing to see if they are allowed to view it. The security information is stored in the database. For example: User Permission UserPermission Action ActionPermission A "Permission" is a token that is applied to an MVC action to indicate that the token is required in order to access the action. Once a user is given the permission (via the UserPermission table) then they have the token and can therefore access the action. I've been looking in to how to cache this data (since it rarely changes) so that I'm only querying in-memory data and not hitting a database (which is a considerable performance hit at the moment). I've tried storing things in lists, using a caching provider but I either run in to problems or performance doesn't improve. One problem that I constantly run in to is that I'm using lazy loading and dynamic proxies with EntityFramework. This means that even if I ToList() everything and store them somewhere static, the relationships are never populated. For example, User.Permissions is an ICollection but it's always null. I don't want to Include() everything because I'm trying to keep things simple and generic (and easy to modify). One thing I know is that an EntityFramework DbContext is a unit of work that acts with 1st-level caching. That is, for the duration of the unit of work, everything that is accessed is cached in memory. I want to create a read-only DbContext that will exist indefinitely and will only be used to read about permission data. Upon testing this it worked perfectly; my page load times went from 200ms+ to 20ms. I can easily force the data to refresh at certain intervals or simply leave it to refresh when the application pool is recycled. Basically it will behave like a cache. Note that the rest of the application will interact with other contexts that exist per request as normal. Is there any disadvantage to this approach? Could I be doing something different?

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• UI Controls Copyright

  - by user3692481

  I'm developing a cross-platform computer software. It will run on Windows and Mac OS X. For user experience reasons, I want it to have the same graphic on both platforms. I really like the Mac OS UI controls and I'd love to see them on the Windows version too. My question is: is it legal to "copy" UI components? I'm not going to copy icons or reproduce an existing Apple software. I would only "copy" some standard UI components such as Buttons, Progressbars, TreeView, ListView etc. You can see them here: http://i.stack.imgur.com/9YzYQ.png http://i.stack.imgur.com/MWR6B.jpg IMHO, they should not be copyrighted for two reasons: They are implicitly used by any Mac OS software There are a lot of Apps (for Windows and even Web-Apps) that are "inspired by" the Mac graphic. Am I right?

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• AngularJS: structuring a web application with multiple ng-apps

  - by mg1075

  The blogosphere has a number of articles on the topic of AngularJS app structuring guidelines such as these (and others): http://www.johnpapa.net/angular-app-structuring-guidelines/ http://codingsmackdown.tv/blog/2013/04/19/angularjs-modules-for-great-justice/ http://danorlando.com/angularjs-architecture-understanding-modules/ http://henriquat.re/modularizing-angularjs/modularizing-angular-applications/modularizing-angular-applications.html However, one scenario I have yet to come across for guidelines and best practices is the case where you have a large web application containing multiple "mini-spa" apps, and the mini-spa apps all share a certain amount of code. I am not referring to the case of trying to have multiple ng-app declarations on the same page; rather, I mean different sections of a large site that have their own, unique ng-app declaration. As Scott Allen writes in his OdeToCode blog: One scenario I haven't found addressed very well is the scenario where multiple apps exist in the same greater web application and require some shared code on the client. Are there any recommended approaches to take, pitfalls to avoid, or good sample structures of this scenario that you can point to?

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• Ninject/DI: How to correctly pass initialisation data to injected type at runtime

  - by MrLane

  I have the following two classes: public class StoreService : IStoreService { private IEmailService _emailService; public StoreService(IEmailService emailService) { _emailService = emailService; } } public class EmailService : IEmailService { } Using Ninject I can set up bindings no problem to get it to inject a concrete implementation of IEmailService into the StoreService constructor. StoreService is actually injected into the code behind of an ASP.NET WebForm as so: [Ninject.Inject] public IStoreService StoreService { get; set; } But now I need to change EmailService to accept an object that contains SMTP related settings (that are pulled from the ApplicationSettings of the Web.config). So I changed EmailService to now look like this: public class EmailService : IEmailService { private SMTPSettings _smtpSettings; public void SetSMTPSettings(SMTPSettings smtpSettings) { _smtpSettings = smtpSettings; } } Setting SMTPSettings in this way also requires it to be passed into StoreService (via another public method). This has to be done in the Page_Load method in the WebForms code behind (I only have access to the Settings class in the UI layer). With manual/poor mans DI I could pass SMTPSettings directly into the constructor of EmailService and then inject EmailService into the StoreService constructor. With Ninject I don't have access to the instances of injected types outside of the objects they are injected to, so I have to set their data AFTER Ninject has already injected them via a separate public setter method. This to me seems wrong. How should I really be solving this scenario?

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• How can I set a time limit for a game?

  - by Haoda Fu

  I am learning the multi-threading and timer in C# now. But it seems I can't find a good solution. For example, I would like to see how many addition problems that I can solve within 1 min. I would like my program to have A digital clock to count for 60 seconds in the top of my Console. Print a math problem in the middle of my console wait for my input. When 60 seconds is done, stop the math problem challenges immediately (most of time, it is still waiting for my input, but we will stop it immediately). Count how many correct problems that I have solved. Two challenges of the program now. a) how can we make sure the print time and math problem do not mess up. b) how can we stop the math challenges part immediately after time is up

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• How to REALLY start thinking in terms of objects?

  - by Mr Grieves

  I work with a team of developers who all have several years of experience with languages such as C# and Java. Most of them are young enough to have been shown OOP as a standard way to develop software in university and are very comfortable with concepts such as inheritance, abstraction, encapsulation and polymorphism. Yet, many of them, and I have to include myself, still tend to create classes which are meant to be used in a very functional fashion. The resulting software is often several smaller classes which correctly represent business objects which get passed through larger classes which only supply ways to modify and use those objects (functions). Large complex difficult-to-maintain classes named Manager are usually the result of such behaviour. I can see two theoretical reasons why people might write this type of code: It's easy to start thinking of everything in terms of the database Deep down, for me, a computer handling a web request feels more like a functional operation than an object oriented operation when you think about Request Handlers, Threads, Processes, CPU Cores and CPU operations... I want source code which is easy to read and easy to modify. I have seen excellent examples of OO code which meet these objectives. How can I start writing code like this? How I can I really start thinking in an object oriented fashion? How can I share such a mentality with my colleagues?

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• How to present an Android Augmented Reality application?

  - by Egor

  I'm currently working on my diploma project - an application for Android that uses the Augmented Reality technology. I'll have to make a presentation of my app and I can't really think of a way to show this kind of application to the crowd. Anyone has ideas? Will really appreciate an elegant solution! EDIT The application shows users the information about the places around, some kind of Layar + Google Places. So the issue is that to use the application you must turn around with your device in hands to see the icons on the screen. Presentation would have been easier if I could just lay the device on the table and use the app.

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• Erlang node acts like it connects, but doesn't [migrated]

  - by Malfist

  I'm trying to setup a distributed network of nodes across a few firewalls and it's not going so well. My application is structured like this: there is a central server that always running a node ([email protected]) and my co-worker's laptops connect to it on startup. This works if we're all in the office, but if someone is at home, they can connect to the masternode, but they fail to connect to the other nodes in the swarm. I.E., erlang fails to gossip correctly. To correct this, I've change epmd's port number and changed the inet_dist_listen ports to a known open port (1755 and 7070 respectively). However, something fishy is going on. I can run net_adm:world() and it reports that it connects to master node, but when I run nodes() I get an empty array. Same with net_adm:ping('[email protected]'). See: Eshell V5.9 (abort with ^G) ([email protected])1> net_adm:world(). ['[email protected]'] ([email protected])2> nodes(). [] ([email protected])3> net_adm:ping('[email protected]'). pong ([email protected])4> nodes(). [] ([email protected])5> What's going on, and how can I fix it?

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• What advantages does developing applications for smartphones have over developing the same application as a web application?

  - by Alfredo O

  Let's take the Facebook application as an example. Why did they develop an application when the users could just access to their page and do the same? For me that represents more maintenance and more cost because for each feature added to the web application that feature will have to be added to the smartphone application as well. So why would I want to develop more than once (for each patform iOS, Android, etc) when I could just have one web application? What benefits do I get? The only one that comes to my mind is GPS feature. EDIT: My question is more oriented towards business applications that are going to be used only by some members of the company, it's not about selling the application (private use). So contrary to what some answers say about that by developing as a smartphone application it will benefit from more sells because of the "smartphone stores" for me this point is not important because the application is for private use. By developing the application as a web application it means that it can be accessed through smartphone browser and also in a PC (any capable browser), but developing as a native application would limit this to only some kind of smartphone so we would be limiting the use. On the other hand developing it as a web application means that in order to access the application an Internet connection must be available. So keeping this in mind how would you convince your boss to write the application for a given smartphone platform (iOS/Android) vs developing it as a web application?

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• What are the advantages of myBatis over Hibernate?

  - by Kshitiz Sharma

  This question originates from a comment I received on one of my questions - I'd rather drop hibernate in favor of mybatis instead of jdbc I've done some research on my own and understand the basic concept. But some insights can only be gained through actual experience. What are the advantages of myBatis that would make it worth learning a new framework? In what case would you avoid using it?

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• Is there any place to find real-world usage-style tutorials for programming languages?

  - by OleDid

  Let's face it. When you want to learn something completely new, be it mathematics or foreign languages, it's easiest to learn when you get real world scenarios in front of you, with theory applied. For example, trigonometry can be extremely interesting when applied to creation of 2D platform games. Norwegian can be really interesting to learn if you live in Norway. When I try to look at a new programming language, I always find these steps the hardest: What tools do I need to compile and how do I do it Introduction-step: Why is this programming language so cool? Where and how is it used? (The step I am looking for, real-world scenarios) The rest, deep diving into the language, pure theory and such, is often much easier if you have completed step 1 and 2. Because now you know what it's all about, and can just read the specification when you need to. What I ask is, do you have any recommendations for places I can find such material for programming languages? Be it websites or companies selling books in this style, I'm interested. Also, I am interested in all languages. (If I had found a "real-world usage" explained for even INTERCAL, I would be interested). In some other thread here, I found a book called "Seven Languages in Seven Weeks". This is kind of what I am looking for, but I believe there must be "more like this".

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• What browser do you build in? [closed]

  - by Ryan

  Lately I have been using Chrome, but I am starting to think I should use FF. What are the advantages and disadvantages of the various mainstream browsers (with an emphasis on Chrome and FF) when doing web development? Is it easier to start with clean code for a relatively conforming browser, and later add hacks/workarounds for acceptable display with less conforming browsers, or is it easier to work with a variety of browsers from the beginning, so we never have a page that's completely unacceptable with, for example, IE 6?

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