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• How to avoid big and clumsy UITableViewController on iOS?

  - by Johan Karlsson

  I have a problem when implementing the MVC-pattern on iOS. I have searched the Internet but seems not to find any nice solution to this problem. Many UITableViewController implementations seems to be rather big. Most examples I have seen lets the UITableViewController implement <UITableViewDelegate> and <UITableViewDataSource>. These implementations are a big reason why UITableViewControlleris getting big. One solution would be to create separate classes that implements <UITableViewDelegate> and <UITableViewDataSource>. Of course these classes would have to have a reference to the UITableViewController. Are there any drawbacks using this solution? In general I think you should delegate the functionality to other "Helper" classes or similar, using the delegate pattern. Are there any well established ways of solving this problem? I do not want the model to contain too much functionality, nor the view. I believe that the logic should really be in the controller class, since this is one of the cornerstones of the MVC-pattern. But the big question is: How should you divide the controller of a MVC-implementation into smaller manageable pieces? (Applies to MVC in iOS in this case) There might be a general pattern for solving this, although I am specifically looking for a solution for iOS. Please give an example of a good pattern for solving this issue. Please provide an argument why your solution is awesome.

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• How to build a 4x game?

  - by Marco

  I'm trying to study how succefully implement a 4x game. Area of interest: 1) map data: how to store stellars systems (graphs?), how to generate them and so on.. 2) multiplayer: how to organize code in a non graphical server and a client to display it 3) command system: what are patters to catch user and ai decisions and handle them, adding at first "explore" and "colonize" then "combat", "research", "spy" and so on (commands can affect ships, planets, research, etc..) 4) ai system: ai can use commands to expand, upgrade planets and ship I know is a big questions, so help is appreciated :D 1) Map data Best choice is have a graph to model a galaxy. A node is a stellar system and every system have a list of planets. Ship cannot travel outside of predefined paths, like in Ascendancy: http://www.abandonia.com/files/games/221/Ascendancy_2.png Every connection between two stellar systems have a cost, in turns. Generate a galaxy is only a matter of: - dimension: number of stellar systems, - variety: randomize number of planets and types (desertic, earth, etc..), - positions of each stellar system on game space - connections: assure that exist a path between every node, so graph is "connected" (not sure if this a matematically correct term) 2) Multiplayer Game is organized in turns: player 1, player 2, ai1, ai2. Server take care of all data and clients just diplay it and collect data change. Because is a turn game, latency is not a problem :D 3) Command system I would like to design a hierarchy of commands to take care of this aspect: abstract Genericcommand (target) ExploreCommand (Ship) extends genericcommand colonizeCommand (Ship) buildcommand(planet, object) and so on. In my head all this commands are stored in a queue for every planets, ships or reasearch center or spy, and each turn a command is sent to a server to apply command and change data state 4) ai system I don't have any idea about this. Is a big topic and what I want is a simple ai. Something like "expand and fight against everyone". I think about a behaviour tree to control ai moves, so I can develop an ai that try to build ships to expand and then colonize planets, upgrade them throught science and combat enemies. Could be done with a finite state machine too ? any ideas, resources, article are welcome!

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• Organizing MVC entities communication

  - by Stefano Borini

  I have the following situation. Imagine you have a MainWindow object who is layouting two different widgets, ListWidget and DisplayWidget. ListWidget is populated with data from the disk. DisplayWidget shows the details of the selection the user performs in the ListWidget. I am planning to do the following: in MainWindow I have the following objects: ListWidget ListView ListModel ListController ListView is initialized passing the ListWidget. ListViewController is initialized passing the View and the Model. Same happens for the DisplayWidget: DisplayWidget DisplayView DisplayModel DisplayController I initialize the DisplayView with the widget, and initialize the Model with the ListController. I do this because the DisplayModel wraps the ListController to get the information about the current selection, and the data to be displayed in the DisplayView. I am very rusty with MVC, being out of UI programming since a while. Is this the expected interaction layout for having different MVC triplets communicate ? In other words, MVC focus on the interaction of three objects. How do you put this interaction as a whole into a larger context of communication with other similar entities, MVC or not ?

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• JS closures - Passing a function to a child, how should the shared object be accessed

  - by slicedtoad

  I have a design and am wondering what the appropriate way to access variables is. I'll demonstrate with this example since I can't seem to describe it better than the title. Term is an object representing a bunch of time data (a repeating duration of time defined by a bunch of attributes) Term has some print functionality but does not implement the print functions itself, rather they are passed in as anonymous functions by the parent. This would be similar to how shaders can be passed to a renderer rather than defined by the renderer. A container (let's call it Box) has a Schedule object that can understand and use Term objects. Box creates Term objects and passes them to Schedule as required. Box also defines the print functions stored in Term. A print function usually takes an argument and uses it to return a string based on that argument and Term's internal data. Sometime the print function could also use data stored in Schedule, though. I'm calling this data shared. So, the question is, what is the best way to access this shared data. I have a lot of options since JS has closures and I'm not familiar enough to know if I should be using them or avoiding them in this case. Options: Create a local "reference" (term used lightly) to the shared data (data is not a primitive) when defining the print function by accessing the shared data through Schedule from Box. Example: var schedule = function(){ var sched = Schedule(); var t1 = Term( function(x){ // Term.print() return (x + sched.data).format(); }); }; Bind it to Term explicitly. (Pass it in Term's constructor or something). Or bind it in Sched after Box passes it. And then access it as an attribute of Term. Pass it in at the same time x is passed to the print function, (from sched). This is the most familiar way for my but it doesn't feel right given JS's closure ability. Do something weird like bind some context and arguments to print. I'm hoping the correct answer isn't purely subjective. If it is, then I guess the answer is just "do whatever works". But I feel like there are some significant differences between the approaches that could have a large impact when stretched beyond my small example.

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• How should I structure my database to gain maximum efficiently in this scenario?

  - by Bob Jansen

  I'm developing a PHP script that analyzes the web traffic of my clients websites. By placing a link to a javascript on the clients website (think of Google Analyses), my script harvests information like: the visitors IP address, reference link, current page link, user agent, etc. Now my clients can view these statistics via a control panel that I have build. These clients can also adjust profile settings, set firewall rules, create support tickets and pay invoices. Currently all the the traffic is stored in one table. You can imagine that this tabel would become very large as some my clients receive thousands of pageviews per day. Furthermore, all the traffic data of each client would be stored in the same table, creating a mess. This is the same for the firewall rules currently, and the invoice and support system. I'm looking for way to structure my database in a more organized way to hold large amounts of data of multiple users. This is the first project that I'm developing that deals with so much data, and would like to hear suggestions and tips. I was thinking of using multiple databases to structure the data. The main database will store users data (email,pass,id,etc) admin/website settings. Than each client will have an unique database labeled prefix_userid, which carry tables holding their traffic, invoice, and support ticket data. Would this be a solution, and would it slow down or speed up overall performances (that is spreading the data over muliple databases). I have a solid VPS, but would like to safe and be as effient as possible.

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• Making Modular, Reusable and Loosely Coupled MVC Components

  - by Dusan

  I am building MVC3 application and need some general guidelines on how to manage complex client side interaction between my components. Here is my definition of one component in general way: Component which has it's own controller, model and view. All of the component's logic is placed inside these three parts and component is sort of "standalone", it contains it's own form, data needed for interaction, updates itself with Ajax and so on. Beside this internal logic and behavior of the component, it needs to be able to "Talk" to the outside world. By this I mean it should provide data and events (sort of) so when this component gets embedded in pages can notify other components which then can update based on the current state and data. I have an idea to use client ViewModel (in java-script) which would hookup all relevant components on page and control interaction between them. This would make components reusable, modular - independent of the context in which they are used. How would you do this, I am a bit stuck as I do not know if this is a good approach and there is a technical possibility to achieve this using java-script/jquery. The confusing part is about update via Ajax, how to ensure that component is properly linked to ViewModel when component is Ajax updated (or even worse removed or dynamically added). Also, how should this ViewModel be constructed and which technicalities to use here and in components to work as synergy??? On the web, I have found the various examples of the similar approach, but they are oversimplified (even for dummies) or over specific and do not provide valuable resource or general solution for this kind of implementation. If you have some serious examples it would be, also, very helpful. Note: My aim is to make interactions between many components on the same page simpler and more robust and elegant.

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• .Net Application & Database Modularity/Reuse

  - by Martaver

  I'm looking for some guidance on how to architect an app with regards to modularity, separation of concerns and re-usability. I'm working on an application (ASP.Net, C#) that has distinctly generic chunks of functionality, that I'd love to be able to lift out, all layers, into re-usable components. This means the module handles the database schema, data access, API, everything so that the next time I want to use it I can just register the module and hook into it. Developing modules of re-usable functionality is a no-brainer, but what is really confusing me is what to do when it comes to handling a core re-usable database schema that serves the module's functionality. In an ideal world, I would register a module and it would ensure that the associated database schema exists in the DB. I would code on the assumption that the tables exist, calling the module's functionality through the DLL, agnostic of the database layer. Kind of like Enterprise Library's Caching/Logging Application Block, which can create a DB schema in the target DB to use as a data store. My Questions is: What do you think is the best way to achieve this, firstly, in terms design architecture, and secondly solution structure. What patterns/frameworks do you know that exist & support this kind of thing? My thoughts so far: I mostly use Entity Framework and SQL Server DB Projects. I thought about a 'black box' approach to modules of functionality. I could use use a code-first approach in EF4, and use the ObjectContext to create a database when the module is initialized. However this means that all of the entities that my module encapsulates would be disconnected from the rest of the application because they belonged to an abstracted ObjectContext. Further - Creating appropriate indexes and references between domain entities and the module's entities would be impossible to do practically. I've thought of adopting Enterprise Library and creating my own Application Blocks. I'm not sure how this would play nice with Entity Framework (if at all) though. I like the idea of building on proven patterns & practices to encapsulate established, reusable functionality. I thought of abandoning Entity Framework for the Module, and just creating a separate DB schema for the module with its own set of stored procedures & ADO.Net. Then deploying the script at run-time if interrogation shows that it doesn't exist. But once again, for application developing outside of the application, I would want to use Entity Framework and I would have to use the module separately, disconnected from the domain ObjectContext. Has anyone had experience developing these sorts of full-stack modules? What advice can you offer? Am I biting off more than I can chew?

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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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• In MVC , DAO should be called from Controller or Model

  - by tito

  I have seen various arguments against the DAO being called from the Controller class directly and also the DAO from the Model class.Infact I personally feel that if we are following the MVC pattern , the controller should not coupled with the DAO , but the Model class should invoke the DAO from within and controller should invoke the model class.Why because , we can decouple the model class apart from a webapplication and expose the functionalities for various ways like for a REST service to use our model class. If we write the DAO invocation in the controller , it would not be possible for a REST service to reuse the functionality right ? I have summarized both the approaches below. Approach #1 public class CustomerController extends HttpServlet { proctected void doPost(....) { Customer customer = new Customer("xxxxx","23",1); new CustomerDAO().save(customer); } } Approach #2 public class CustomerController extends HttpServlet { proctected void doPost(....) { Customer customer = new Customer("xxxxx","23",1); customer.save(customer); } } public class Customer { ........... private void save(Customer customer){ new CustomerDAO().save(customer); } } Note- Here is what a definition of Model is : Model: The model manages the behavior and data of the application domain, responds to requests for information about its state (usually from the view), and responds to instructions to change state (usually from the controller). In event-driven systems, the model notifies observers (usually views) when the information changes so that they can react. I would need an expert opinion on this because I find many using #1 or #2 , So which one is it ?

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• Turn-Based RPG Battle Instance Layout For Larger Groups

  - by SoulBeaver

  What a title, eh? I'm currently designing a videogame; a turn-based RPG like Final Fantasy (because everybody knows Final Fantasy). It's a 2D sprite game. These are my ideas for combat: -The player has a group of 15 members (main character included) -During battle, five of the group are designated as active, and appear in the battle. -These five may be switched out at leisure, or when one of the five die. -At any time, the Waiting members can cast buffs, be healed by the active members, or perform special attacks. -Battles should contain 10+ monsters at least. I'm aiming for 20, but I'm not sure if that's possible yet. -Battles should feel larger than normal due to the interaction of Waiting members, active members and the increased amount of monsters per battle. -The player has two rows in which to put the Active members: front and back. -Depending on the implementation, I might allow comboing of player attacks and skills. These are just design ideas, so beware! I have not been able to test this out yet- I have no idea yet if any of these ideas bunched together will make for a compelling game. What sounds good on paper doesn't necessarily have to be good in practice! What I'm asking now is how to create the layout for this. My starting point are the battles in Final Fantasy VI, with up to 5-6 monsters on the left and the characters on the right- monsters on both sides if it's a pincer attack. However, this view would not work feasible with my goal of 20 monsters and 5 characters. All the monsters on the left would appear cluttered unless I scale them far far back. If I create a pincer-like map, then there would be no real pincer-attack possible. If I space the monsters out I force the player to scroll the screen- a game mechanic I've come across and not enjoyed imho. My question is: does anybody have any layouts or guides for designing battle maps in turn-based RPGs, especially with a larger number of enemies taken into consideration? How should it look? I am not asking for specific combat mechanics, just the layout for the moment.

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• What are some internet trends that you've noticed over the past ~10 years? [closed]

  - by Michael

  I'll give an example of one that I've noticed: the number of web sites that ask for your email address (GOOG ID, YAHOO! ID, etc.) has skyrocketed. I can come up with no legitimate reason for this other than (1) password reset [other ways to do this], or (2) to remind you that you have an account there, based upon the time of your last visit. Why does a web site need to know your email address (Google ID, etc.) if all you want to do is... download a file (no legit reason whatsoever) play a game (no legit reason whatsoever) take an IQ test or search a database (no legit reason whatsoever) watch a video or view a picture (no legit reason whatsoever) read a forum (no legit reason whatsoever) post on a forum (mildly legit reason: password reset) newsletter (only difference between a newsletter and a blog is that you're more likely to forget about the web site than you are to forget about your email address -- the majority of web sites do not send out newsletters, however, so this can't be the justification) post twitter messages or other instant messaging (mildly legit reason: password reset) buy something (mildly legit reasons: password reset + giving you a copy of a receipt that they can't delete, as receipts stored on their server can be deleted) On the other hand, I can think of plenty of very shady reasons for asking for this information: so the NSA, CIA, FBI, etc. can very easily track what you do by reading your email or asking GOOG, etc. what sites you used your GOOG ID at to use the password that you provide for your account in order to get into your email account (most people use the same password for all of their accounts), find all of your other accounts in your inbox, and then get into all of those accounts sell your email address to spammers These reasons, I believe, are why you are constantly asked to provide your email address. I can come up with no other explanations whatsoever. Question 1: Can anyone think of any legitimate or illegitimate reasons for asking for someone's email address? Question 2: What are some other interesting internet trends of the past ~10 years?

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

  - by TMV

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

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• .NET app - Should we use SQL Server and duplicate some reference data from an external Oracle DB? Or use Oracle and have a DB link?

  - by Daventry

  We're looking to migrate some existing Excel/Access processes into a new system which will provide the users with a Silverlight frontend to run and view the reports instead of using MS Access. The initial idea was to have SQL Server 2008 as RDBMS. The problem is that we've got some static data such as country codes, counterparties, etc which live in an existing Oracle DB. Since we do not want to duplicate that data (if possible), we were thinking of having a DB link between SQL Server and Oracle, but our firm does not allow that. So the options are either duplicate the data or use Oracle as RDBMS - surprise, the firm does allow DB links between Oracle databases. The initial idea was also to use WCF RIA Services, Entity Framework, etc which we're not sure they play well with Oracle, that's why it was decided to go with SQL Server in the first place. Would you advise to go for Oracle so that we can just link the static data? Or use SQL Server 2008 and replicate it because it's "safer" to stay within the Microsoft land? To use or not to use Entity Framework and WCF RIA Services at all? Regards. UPDATE: Thanks everyone for your answers. Nothing is set in stone yet. We'll try to import the data instead of linking, as if the other DB goes down, our system can still carry on. We're likely to use SQL Server just because most developers are more experienced with it. Even if we used RIA Services, we can swap out the Data Access Layer and use other frameworks such those mentioned below.

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• How do you take into account usability and user requirements for your application?

  - by voroninp

  Our team supports BackOffice application: a mix of WinForm and WPF windows. (about 80 including dialogs). Really a kind of a Swiss Army Knife. It is used by developers, tech writers, security developers, testers. The requirements for new features come quite often and sometimes we play Wizard of Oz to decide which GUI our users like the most. And it usually happens (I admit it can be just my subjective interpretation of the reality) that one tiny detail giving the flavor of good usability to our app requires a lot of time. This time is being spent on 'fighting' with GUI framework making it act like we need. And it very difficult to make estimations for this type of tasks (at least for me and most members of our team). Scrum poker is not a help either. Management often considers this usability perfectionism to be a waste of time. On the other hand an accumulated affect of features where each has some little usability flaw frustrates users. But the same users want frequent releases and instant bug fixes. Hence, no way to get the positive feedback: there is always somebody who is snuffy. I constantly feel myself as competing with ourselves: more features - more bugs/tasks/architecture. We are trying to outrun the cart we are pushing. New technologies arrive and some of them can potentially help to improve the design or decrease task implementation time but these technologies require learning, prototyping and so on. Well, that was a story. And now is the question: How do you balance between time pressure, product quality, users and management satisfaction? When and how do you decide to leave the problem with not a perfect but to some extent acceptable solution, how often do you make these decisions? How do you do with your own satisfaction? What are your priorities? P.S. Please keep in mind, we are a BackOffice team, we have neither dedicated technical writer nor GUI designer. The tester have joined us recently. We've much work to do and much freedom concerning 'how'. I like it because it fosters creativity but I don't want to become too nerdy perfectionist.

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• A solution for a PHP website without a framework

  - by lortabac

  One of our customers asked us to add some dynamic functionality to an existent website, made of several static HTML pages. We normally work with an MVC framework (mostly CodeIgniter), but in this case moving everything to a framework would require too much time. Since it is not a big project, not having the full functionality of a framework is not a problem. But the question is how to keep code clean. The solution I came up with is to divide code in libraries (the application's API) and models. So inside HTML there will only be API calls, and readability will not be sacrificed. I implemented this with a sort of static Registry (sorry if I'm wrong, I am not a design pattern expert): <?php class Custom_framework { //Global database instance private static $db; //Registered models private static $models = array(); //Registered libraries private static $libraries = array(); //Returns a database class instance static public function get_db(){ if(isset(self::$db)){ //If instance exists, returns it return self::$db; } else { //If instance doesn't exists, creates it self::$db = new DB; return self::$db; } } //Returns a model instance static public function get_model($model_name){ if(isset(self::$models[$model_name])){ //If instance exists, returns it return self::$models[$model_name]; } else { //If instance doesn't exists, creates it if(is_file(ROOT_DIR . 'application/models/' . $model_name . '.php')){ include_once ROOT_DIR . 'application/models/' . $model_name . '.php'; self::$models[$model_name] = new $model_name; return self::$models[$model_name]; } else { return FALSE; } } } //Returns a library instance static public function get_library($library_name){ if(isset(self::$libraries[$library_name])){ //If instance exists, returns it return self::$libraries[$library_name]; } else { //If instance doesn't exists, creates it if(is_file(ROOT_DIR . 'application/libraries/' . $library_name . '.php')){ include_once ROOT_DIR . 'application/libraries/' . $library_name . '.php'; self::$libraries[$library_name] = new $library_name; return self::$libraries[$library_name]; } else { return FALSE; } } } } Inside HTML, API methods are accessed like this: <?php echo Custom_framework::get_library('My_library')->my_method(); ?> It looks to me as a practical solution. But I wonder what its drawbacks are, and what the possible alternatives.

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• Should library classes be wrapped before using them in unit testing?

  - by Songo

  I'm doing unit testing and in one of my classes I need to send a mail from one of the methods, so using constructor injection I inject an instance of Zend_Mail class which is in Zend framework. Example: class Logger{ private $mailer; function __construct(Zend_Mail $mail){ $this->mail=$mail; } function toBeTestedFunction(){ //Some code $this->mail->setTo('some value'); $this->mail->setSubject('some value'); $this->mail->setBody('some value'); $this->mail->send(); //Some } } However, Unit testing demands that I test one component at a time, so I need to mock the Zend_Mail class. In addition I'm violating the Dependency Inversion principle as my Logger class now depends on concretion not abstraction. Does that mean that I can never use a library class directly and must always wrap it in a class of my own? Example: interface Mailer{ public function setTo($to); public function setSubject($subject); public function setBody($body); public function send(); } class MyMailer implements Mailer{ private $mailer; function __construct(){ $this->mail=new Zend_Mail; //The class isn't injected this time } function setTo($to){ $this->mailer->setTo($to); } //implement the rest of the interface functions similarly } And now my Logger class can be happy :D class Logger{ private $mailer; function __construct(Mailer $mail){ $this->mail=$mail; } //rest of the code unchanged } Questions: Although I solved the mocking problem by introducing an interface, I have created a totally new class Mailer that now needs to be unit tested although it only wraps Zend_Mail which is already unit tested by the Zend team. Is there a better approach to all this? Zend_Mail's send() function could actually have a Zend_Transport object when called (i.e. public function send($transport = null)). Does this make the idea of a wrapper class more appealing? The code is in PHP, but answers doesn't have to be. This is more of a design issue than a language specific feature

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• How do you plan your asynchronous code?

  - by NullOrEmpty

  I created a library that is a invoker for a web service somewhere else. The library exposes asynchronous methods, since web service calls are a good candidate for that matter. At the beginning everything was just fine, I had methods with easy to understand operations in a CRUD fashion, since the library is a kind of repository. But then business logic started to become complex, and some of the procedures involves the chaining of many of these asynchronous operations, sometimes with different paths depending on the result value, etc.. etc.. Suddenly, everything is very messy, to stop the execution in a break point it is not very helpful, to find out what is going on or where in the process timeline have you stopped become a pain... Development becomes less quick, less agile, and to catch those bugs that happens once in a 1000 times becomes a hell. From the technical point, a repository that exposes asynchronous methods looked like a good idea, because some persistence layers could have delays, and you can use the async approach to do the most of your hardware. But from the functional point of view, things became very complex, and considering those procedures where a dozen of different calls were needed... I don't know the real value of the improvement. After read about TPL for a while, it looked like a good idea for managing tasks, but in the moment you have to combine them and start to reuse existing functionality, things become very messy. I have had a good experience using it for very concrete scenarios, but bad experience using them broadly. How do you work asynchronously? Do you use it always? Or just for long running processes? Thanks.

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• Proper library for enums

  - by Bobson

  I'm trying to refactor some code such that the display is separate from the implementation, and I'm not sure where to put the existing enums. My project is currently structured as follows: Utilities RemoteData (Depends on: Utilities) LocalData (Depends on: RemoteData, Utilities) RemoteWeb (Depends on: RemoteData, Utilities) LocalWeb (Depends on: RemoteData, LocalData, Utilities) I'm now trying to add "ViewLibrary (Depends on: Utilities)" to this list, and then adding it as a new dependency to both RemoteWeb and LocalWeb. It will contain a set of interfaces which the other two projects will implement, use to populate the view, and then consume the result. There's an enum which is currently used in all the projects except Utilities. It thus lives in the RemoteData project, because everything else depends on it. But this new ViewLibrary won't depend on either data project. So how will it know about this enum? Some options I see: Create a new project just for shared enum values. Add it to Utilities, even though it is related to data. Define it a second time in ViewLibrary, and require both RemoteWeb and LocalWeb to convert the one type into the other when they access the shared views. Add a dependency on RemoteData to the ViewLibrary, even though it's supposed to be independent of data-source. Are there any better options? Is this structure flawed to begin with?

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• Lazy Processing of Streams

  - by Giorgio

  I have the following problem scenario: I have a text file and I have to read it and split it into lines. Some lines might need to be dropped (according to criteria that are not fixed). The lines that are not dropped must be parsed into some predefined records. Records that are not valid must be dropped. Duplicate records may exist and, in such a case, they are consecutive. If duplicate / multiple records exist, only one item should be kept. The remaining records should be grouped according to the value contained in one field; all records belonging to the same group appear one after another (e.g. AAAABBBBCCDEEEFF and so on). The records of each group should be numbered (1, 2, 3, 4, ...). For each group the numbering starts from 1. The records must then be saved somewhere / consumed in the same order as they were produced. I have to implement this in Java or C++. My first idea was to define functions / methods like: One method to get all the lines from the file. One method to filter out the unwanted lines. One method to parse the filtered lines into valid records. One method to remove duplicate records. One method to group records and number them. The problem is that the data I am going to read can be too big and might not fit into main memory: so I cannot just construct all these lists and apply my functions one after the other. On the other hand, I think I do not need to fit all the data in main memory at once because once a record has been consumed all its underlying data (basically the lines of text between the previous record and the current record, and the record itself) can be disposed of. With the little knowledge I have of Haskell I have immediately thought about some kind of lazy evaluation, in which instead of applying functions to lists that have been completely computed, I have different streams of data that are built on top of each other and, at each moment, only the needed portion of each stream is materialized in main memory. But I have to implement this in Java or C++. So my question is which design pattern or other technique can allow me to implement this lazy processing of streams in one of these languages.

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• Development Approach: User Interface In or Domain Model Out?

  - by Berin Loritsch

  While I've never delivered anything using Smalltalk, my brief time playing with it has definitely left its mark. The only way to describe the experience is MVC the way it was meant to be. Essentially, all the heavy lifting for your application is done in the business objects (or domain model if you are so inclined). The standard controls are bound to the business objects in some way. For example, a text box is mapped to an object's field (the field itself is an object so it's easy to do). A button would mapped to a method. This is all done with a very simple and natural API. We don't have to think about binding objects, etc. It just works. Yet, in many newer languages and APIs you are forced to think from the outside in. First with C++ and MFC, and now with C# and WPF, Microsoft has gotten it's developer world hooked on GUI builders where you build your application by implementing event handlers. Java Swing development isn't so different, only you are writing the code to instantiate the controls on the form yourself. For some projects, there may never even be a domain model--just event handlers. I've been in and around this model for most of my carreer. Each way forces you to think differently. With the Smalltalk approach, your domain is smart while your GUI is dumb. With the default VisualStudio approach, your GUI is smart while your domain model (if it exists) is rather anemic. Many developers that I work with see value in the Smalltalk approach, and try to shoehorn that approach into the VisualStudio environment. WPF has some dynamic binding features that makes it possible; but there are limitations. Inevitably some code that belongs in the domain model ends up in the GUI classes. So, which way do you design/develop your code? Why? GUI first. User interaction is paramount. Domain first. I need to make sure the system is correct before we put a UI on it. There's pros and cons for either approach. Domain model fits in there with crystal cathedrals and pie in the sky. GUI fits in there with quick and dirty (sometimes really dirty). And for an added bonus: How do you make sure the code is maintainable?

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• The term "interface" in C++

  - by Flexo

  Java makes a clear distinction between class and interface. (I believe C# does also, but I have no experience with it). When writing C++ however there is no language enforced distinction between class and interface. Consequently I've always viewed interface as a workaround for the lack of multiple inheritance in Java. Making such a distinction feels arbitrary and meaningless in C++. I've always tended to go with the "write things in the most obvious way" approach, so if in C++ I've got what might be called an interface in Java, e.g.: class Foo { public: virtual void doStuff() = 0; ~Foo() = 0; }; and I then decided that most implementers of Foo wanted to share some common functionality I would probably write: class Foo { public: virtual void doStuff() = 0; ~Foo() {} protected: // If it needs this to do its thing: int internalHelperThing(int); // Or if it doesn't need the this pointer: static int someOtherHelper(int); }; Which then makes this not an interface in the Java sense anymore. Instead C++ has two important concepts, related to the same underlying inheritance problem: virtual inhertiance Classes with no member variables can occupy no extra space when used as a base "Base class subobjects may have zero size" Reference Of those I try to avoid #1 wherever possible - it's rare to encounter a scenario where that genuinely is the "cleanest" design. #2 is however a subtle, but important difference between my understanding of the term "interface" and the C++ language features. As a result of this I currently (almost) never refer to things as "interfaces" in C++ and talk in terms of base classes and their sizes. I would say that in the context of C++ "interface" is a misnomer. It has come to my attention though that not many people make such a distinction. Do I stand to lose anything by allowing (e.g. protected) non-virtual functions to exist within an "interface" in C++? (My feeling is the exactly the opposite - a more natural location for shared code) Is the term "interface" meaningful in C++ - does it imply only pure virtual or would it be fair to call C++ classes with no member variables an interface still?

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• Application workflow

  - by manseuk

  I am in the planning process for a new application, the application will be written in PHP (using the Symfony 2 framework) but I'm not sure how relevant that is. The application will be browser based, although there will eventually be API access for other systems to interact with the data stored within the application, again probably not relavent at this point. The application manages SIM cards for lots of different providers - each SIM card belongs to a single provider but a single customer might have many SIM cards across many providers. The application allows the user to perform actions against the SIM card - for example Activate it, Barr it, Check on its status etc Some of the providers provide an API for doing this - so a single access point with multiple methods eg activateSIM, getStatus, barrSIM etc. The method names differ for each provider and some providers offer methods for extra functions that others don't. Some providers don't have APIs but do offer these methods by sending emails with attachments - the attachments are normally a CSV file that contains the SIM reference and action required - the email is processed by the provider and replied to once the action has been complete. To give you an example - the front end of my application will provide a customer with a list of SIM cards they own and give them access to the actions that are provided by the provider of each specific SIM card - some methods may require extra data which will either be stored in the backend or collected from the user frontend. Once the user has selected their action and added any required data I will handle the process in the backend and provide either instant feedback, in the case of the providers with APIs, or start the process off by sending an email and waiting for its reply before processing it and updating the backend so that next time the user checks the SIM card its status is correct (ie updated by a backend process). My reason for creating this question is because I'm stuck !! I'm confused about how to approach the actual workflow logic. I was thinking about creating a Provider Interface with the most common methods getStatus, activateSIM and barrSIM and then implementing that interface for each provider. So class Provider1 implements Provider - Then use a Factory to create the required class depending on user selected SIM card and invoking the method selected. This would work fine if all providers offered the same methods but they don't - there are a subset which are common but some providers offer extra methods - how can I implement that flexibly ? How can I deal with the processes where the workflow is different - ie some methods require and API call and value returned and some require an email to be sent and the next stage of the process doesn't start until the email reply is recieved ... Please help ! (I hope this is a readable question and that this is the correct place to be asking) Update I guess what I'm trying to avoid is a big if or switch / case statement - some design pattern that gives me a flexible approach to implementing this kind of fluid workflow .. anyone ?

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• What is the right way to group this project into classes?

  - by sigil

  I originally asked this on SO, where it was closed and recommended that I ask it here instead. I'm trying to figure out how to group all the functions necessary for my project into classes. The goal of the project is to execute the following process: Get the user's FTP credentials (username & password). Check to make sure the credentials establish a valid connection to the FTP server. Query several Sharepoint lists and join the results of those queries to create a list of items that need to have action taken on them. Each item in the list has a folder. For each item: Zip the contents of the folder. Upload the folder to the FTP server using SFTP Update the item's Sharepoint data. Email the user an Excel report showing, e.g., Items without folder paths Items that failed to zip or upload Steps 2-5 are performed on a periodic basis; if step 2 returns an invalid connection, the user is alerted and the process returns to step 1. If at any point the user presses a certain key, the process terminates. I've defined the following set of classes, each of which is in its own .cs file: SFTP: file transfer processes DataHandler: Sharepoint data retrieval/querying/updating processes. Also makes and uploads the zip files. Exceptions: Not just one class, this is the .cs file where I have all of my exception classes. Report: Builds and sends the report. Program: The main class for running the program. I recognize that the DataHandler class is a god object, but I don't have a good idea of how to refactor it. I feel like it should be more fine-grained than just breaking it into Sharepoint, Zip, and Upload, but maybe that's it. Also, I haven't yet worked out how to combine the periodic behavior with the "wait for user input at any point in the process" part; I think that involves threads, which means other classes to manage the threads... I'm not that well-versed in design patterns, but is there one that fits this project well? If this is too big of a topic to neatly explain in an SO answer, I'll also accept a link to a good tutorial on what I'm trying to do here.

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• Is it good practice to keep 2 related tables (using auto_increment PK) to have the same Max of auto_increment ID when table1 got modified?

  - by Tum

  This question is about good design practice in programming. Let see this example, we have 2 interrelated tables: Table1 textID - text 1 - love.. 2 - men... ... Table2 rID - textID 1 - 1 2 - 2 ... Note: In Table1: textID is auto_increment primary key In Table2: rID is auto_increment primary key & textID is foreign key The relationship is that 1 rID will have 1 and only 1 textID but 1 textID can have a few rID. So, when table1 got modification then table2 should be updated accordingly. Ok, here is a fictitious example. You build a very complicated system. When you modify 1 record in table1, you need to keep track of the related record in table2. To keep track, you can do like this: Option 1: When you modify a record in table1, you will try to modify a related record in table 2. This could be quite hard in term of programming expecially for a very very complicated system. Option 2: instead of modifying a related record in table2, you decided to delete old record in table 2 & insert new one. This is easier for you to program. For example, suppose you are using option2, then when you modify record 1,2,3,....,100 in table1, the table2 will look like this: Table2 rID - textID 101 - 1 102 - 2 ... 200 - 100 This means the Max of auto_increment IDs in table1 is still the same (100) but the Max of auto_increment IDs in table2 already reached 200. what if the user modify many times? if they do then the table2 may run out of records? we can use BigInt but that make the app run slower? Note: If you spend time to program to modify records in table2 when table1 got modified then it will be very hard & thus it will be error prone. But if you just clear the old record & insert new records into table2 then it is much easy to program & thus your program is simpler & less error prone. So, is it good practice to keep 2 related tables (using auto_increment PK) to have the same Max of auto_increment ID when table1 got modified?

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• cakephp bake view Errors

  - by James

  I have previously baked a controller for a model that I have created. When attempting to bake the view using cakephp I get the following errors: Interactive Bake Shell --------------------------------------------------------------- [D]atabase Configuration [M]odel [V]iew [C]ontroller [P]roject [Q]uit What would you like to Bake? (D/M/V/C/P/Q) > v --------------------------------------------------------------- Bake View Path: /Applications/MAMP/htdocs/app/views/ --------------------------------------------------------------- Possible Controllers based on your current database: 1. Dealers 2. Products 3. Users Enter a number from the list above, type in the name of another controller, or 'q' to exit [q] > 2 Would you like to create some scaffolded views (index, add, view, edit) for this controller? NOTE: Before doing so, you'll need to create your controller and model classes (including associated models). (y/n) [n] > y Would you like to create the views for admin routing? (y/n) [y] > n Warning: mysql_query() expects parameter 2 to be resource, boolean given in /Applications/MAMP/htdocs/cake/libs/model/datasources/dbo/dbo_mysql.php on line 500 Warning: mysql_errno() expects parameter 1 to be resource, boolean given in /Applications/MAMP/htdocs/cake/libs/model/datasources/dbo/dbo_mysql.php on line 576 Warning: Invalid argument supplied for foreach() in /Applications/MAMP/htdocs/cake/libs/model/datasources/dbo/dbo_mysql.php on line 102 Warning: array_keys() expects parameter 1 to be array, boolean given in /Applications/MAMP/htdocs/cake/console/libs/tasks/view.php on line 263 Warning: mysql_query() expects parameter 2 to be resource, boolean given in /Applications/MAMP/htdocs/cake/libs/model/datasources/dbo/dbo_mysql.php on line 500 Warning: mysql_errno() expects parameter 1 to be resource, boolean given in /Applications/MAMP/htdocs/cake/libs/model/datasources/dbo/dbo_mysql.php on line 576 Warning: Invalid argument supplied for foreach() in /Applications/MAMP/htdocs/cake/libs/model/datasources/dbo/dbo_mysql.php on line 102 Warning: array_keys() expects parameter 1 to be array, boolean given in /Applications/MAMP/htdocs/cake/console/libs/tasks/view.php on line 382 Creating file /Applications/MAMP/htdocs/app/views/products/index.ctp Wrote /Applications/MAMP/htdocs/app/views/products/index.ctp Creating file /Applications/MAMP/htdocs/app/views/products/view.ctp Wrote /Applications/MAMP/htdocs/app/views/products/view.ctp Creating file /Applications/MAMP/htdocs/app/views/products/add.ctp Wrote /Applications/MAMP/htdocs/app/views/products/add.ctp Creating file /Applications/MAMP/htdocs/app/views/products/edit.ctp Wrote /Applications/MAMP/htdocs/app/views/products/edit.ctp --------------------------------------------------------------- View Scaffolding Complete. Anybody know why? Google hasn't been a whole lot of help. cakephp 1.2.6 under MAMP on OSX 10.6.2

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