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• How can I separate the user interface from the business logic while still maintaining efficiency?

  - by Uri

  Let's say that I want to show a form that represents 10 different objects on a combobox. For example, I want the user to pick one hamburguer from 10 different ones that contain tomatoes. Since I want to separate UI and logic, I'd have to pass the form a string representation of the hamburguers in order to display them on the combobox. Otherwise, the UI would have to dig into the objects fields. Then the user would pick a hamburguer from the combobox, and submit it back to the controller. Now the controller would have to find again said hamburguer based on the string representation used by the form (maybe an ID?). Isn't that incredibly inefficient? You already had the objects you wanted to pick one from. If you submited to the form the whole objects, and then returned a specific object, you wouldn't have to refind it later on since the form already returned a reference to that object. Moreover, if I'm wrong and you actually should send the whole object to the form, how can I isolate UI from logic?

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• Calculating the "power" of a player in a "Defend Your Castle" type game

  - by Jesse Emond

  I'm a making a "Defend Your Castle" type game, where each player has a castle and must send units to destroy the opponent's castle. It looks like this (and yeah, this is the actual game, not a quick paint drawing..): Now, I'm trying to implement the AI of the opponent, and I'd like to create 4 different AI levels: Easy, Normal, Hard and Hardcore. I've never made any "serious" AI before and I'd like to create a quite complete one this time. My idea is to calculate a player's "power" score, based on the current health of its castle and the individual "power" score of its units. Then, the AI would just try to keep a score close to the player's one(Easy would stay below it, Normal would stay near it and Hard would try to get above it). But I just don't know how to calculate a player's power score. There are just too many variables to take into account and I don't know how to properly use them to create one significant number(the power level). Could anyone help me out on this one? Here are the variables that should influence a player's power score: Current castle health, the unit's total health, damage, speed and attack range. Also, the player can have increased Income(the money bag), damage(the + Damage) and speed(the + speed)... How could I include them in the score? I'm really stuck here... Or is there an other way that I could implement AI for this type of game? Thanks for your precious time.

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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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• Collision Resolution

  - by ultifinitus

  Hey all, I'm making a simple side-scrolling game, and I would appreciate some input! My collision detection system is a simple bounding box detection, so it's really easy to implement. However my collision resolution is ridiculous! Currently I have a little formula like this: if (colliding(firstObject,secondObject)) firstObject.resolve_collision(yAxisOffset); if (colliding(firstObject,secondObject)) firstObject.resolve_collision(xAxisOffset); where yAxisOffset is only set if the first object's previous y position was outside the second object's collision frame, respectively xAxisOffset as well. Now this is working great, in general. However there is a single problem. When I have a stack of objects and I push the first object against that stack, the first object get's "stuck," on the stack. What's I think is happening is the object's collision system checks and resolves for collisions based on creation time, so If I check one axis, then the other, the object will "sink" object directly along the checking axis. This sinking action causes the collision detection routine to think there's a gap between our position and the other object's position, and when I finally check the object that I've already sunk into, my object's position is resolved to it's original position... All this is great, and I'm sure if I bang my head against a wall long enough i'll come up with a working algorithm, but I'd rather not =). So what in the heck do you think I should do? How could I change my collision resolution system to fix this? Here's the program (temporary link, not sure how long it'll last) (notes: arrow keys to navigate, click to drop block, x to jump) I'd appreciate any help you can offer!

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• Music Notation Editor - Refactoring view creation logic elseware

  - by Cyril Silverman

  Let me preface by saying that knowing some elementary music theory and music notation may be helpful in grasping the problem at hand. I'm currently building a Music Notation and Tablature Editor (in Javascript). But I've come to a point where the core parts of the program are more or less there. All functionality I plan to add at this point will really build off the foundation that I've created. As a result, I want to refactor to really solidify my code. I'm using an API called VexFlow to render notation. Basically I pass the parts of the editor's state to VexFlow to build the graphical representation of the score. Here is a rough and stripped down UML diagram showing you the outline of my program: In essence, a Part has many Measures which has many Notes which has many NoteItems (yes, this is semantically weird, as a chord is represented as a Note with multiple NoteItems, individual pitches or fret positions). All of the relationships are bi-directional. There are a few problems with my design because my Measure class contains the majority of the entire application view logic. The class holds the data about all VexFlow objects (the graphical representation of the score). It contains the graphical Staff object and the graphical notes. (Shouldn't these be placed somewhere else in the program?) While VexFlowFactory deals with actual creation (and some processing) of most of the VexFlow objects, Measure still "directs" the creation of all the objects and what order they are supposed to be created in for both the VexFlowStaff and VexFlowNotes. I'm not looking for a specific answer as you'd need a much deeper understanding of my code. Just a general direction to go in. Here's a thought I had, create an MeasureView/NoteView/PartView classes that contains the basic VexFlow objects for each class in addition to any extraneous logic for it's creation? but where would these views be contained? Do I create a ScoreView that is a parallel graphical representation of everything? So that ScoreView.render() would cascade down PartView and call render for each PartView and casade down into each MeasureView, etc. Again, I just have no idea what direction to go in. The more I think about it, the more ways to go seem to pop into my head. I tried to be as concise and simplistic as possible while still getting my problem across. Please feel free to ask me any questions if anything is unclear. It's quite a struggle trying to dumb down a complicated problem to its core parts.

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• How to handle a player's level and its consequent privileges?

  - by Songo

  I'm building a game similar to Mafia Wars where a player can do tasks for his gang and gain experience and thus advancing his level. The game is built using PHP and a Mysql database. In the game I want to limit the resources allowed to player based on his level. For example: ________| (Max gold) | (Max army size) | (Max moves) | ... Level 1 | 1000 | 100 | 10 | ... Level 2 | 1500 | 200 | 20 | ... Level 3 | 3000 | 300 | 25 | ... . . . In addition certain features of the game won't be allowed until a certain level is reached such as players under Level 10 can't trade in the game market, players under Level 20 can't create alliances,...etc. The way I have modeled it is by implementing a very loooong ACL (Access Control List) with about 100 entries (an entry for each level). However, I think there may be a simpler approach to this seeing that this feature have been implemented in many games before.

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• More Tables or More Databases?

  - by BuckWoody

  I got an e-mail from someone that has an interesting situation. He has 15,000 customers, and he asks if he should have a database for their data per customer. Without a LOT more data it’s impossible to say, of course, but there are some general concepts to keep in mind. Whenever you’re segmenting data, it’s all about boundary choices. You have not only boundaries around how big the data will get, but things like how many objects (tables, stored procedures and so on) that will be involved, if there are any cross-sections of data (do they share location or product information) and – very important – what are the security requirements? From the answer to these types of questions, you now have the choice of making multiple tables in a single database, or using multiple databases. A database carries some overhead – it needs a certain amount of memory for locking and so on. But it has a very clean boundary – everything from objects to security can be kept apart. Having multiple users in the same database is possible as well, using things like a Schema. But keeping 15,000 schemas can be challenging as well. My recommendation in complex situations like this is similar to a post on decisions that I did earlier – I lay out the choices on a spreadsheet in rows, and then my requirements at the top in the columns. I  give each choice a number based on how well it meets each requirement. At the end, the highest number wins. And many times it’s a mix – perhaps this person could segment customers into larger regions or districts or products, in a database. Within that database might be multiple schemas for the customers. Of course, he needs to query across all customers, that becomes another requirement. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Representing heightmaps, on disk and when drawing

  - by gardian06

  This is a conglomeration question when answering please specify which part you are addressing. I am looking at creating a maze type game that utilizes elevation. I have a few features I would like to have, but am unsure as to some of the implementation. I have done work doing fileIO maze generation (using a key to read the file, and then generate the level based on that file), but I am unsure how to think about this with elevation in the mix. I think height maps might be a good approach, but don't know how to represent them effectively. for a height map which is more beneficial XML(containing h[u,v] data and key definition), CSV (item1 is key reference, item2 is elevation), or another approach that I have not thought of yet? When it comes to placing the elevation values themselves what kind of deltah values are appropriate to have it noticeable at about a 60degree angle while not really effecting gravity driven physics (assuming some effect while moving up/down hill)? I am thinking of maybe going to procedural generation at some point, but am wondering if it is practical to have a procedurally generated grid (wall squares possibly same dimensions as the open space squares), or if designing to a thin wall open spaces is better? this decision will effect the amount of work need on the graphics end for uniform vs. irregular walls. EDIT: Game will be a elevation maze shooter. Levels/maps will be mazes with elevation the player has to negotiate. Elevations will have effects on "combat" vision, and movement.

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• Information Spilling Across Object Boundaries

  - by Winston Ewert

  Many times my business objects tend to have situations where information needs to cross object boundaries too often. When doing OO, we want information to be in one object and as much as possible all code dealing with that information should be in that object. However, business rules do not follow this principle giving me trouble. As an example suppose that we have an Order which has a number of OrderItems which refers to an InventoryItem which has a price. I invoke Order.GetTotal() which sums the result of OrderItem.GetPrice() which multiples a quantity by InventoryItem.GetPrice(). So far so good. But then we find out that some items are sold with a two for one deal. We can handle this by having OrderItem.GetPrice() do something like InventoryItem.GetPrice( quantity ) and letting InventoryItem deal with this. However, then we find out that the two-for-one deal only lasts for a particular time period. This time period needs to be based on the date of the order. Now we change OrderItem.GetPrice() to be InventoryItem.GetPrice( quatity, order.GetDate() ) But then we need to support different prices depending on how long the customer has been in the system: InventoryItem.GetPrice( quantity, order.GetDate(), order.GetCustomer() ) But then it turns out that the two-for-one deals apply not just to buying multiple of the same inventory item but multiple for any item in a InventoryCategory. At this point we throw up our hands and just give the InventoryItem the order item and allow it to travel over the object reference graph via accessors to get the information its needs: InventoryItem.GetPrice( this ) TL;DR I want to have coupling in objects, but business rules often force me to access information from all over the place in order to make particular decisions. Are there good techniques for dealing with this? Do others find the same problem?

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• Is having functionality in DB a road block to scalability?

  - by Estefany Velez

  I may not be able to give the right title to the question. But here it is, We are developing financial portal for wealth management. We are expecting over 10000 clients to use the application. The portal calculates various performance analytics based on the the technical analysis of the stock market. We developed lot of the functionality through Stored procedures, user defined functions, triggers etc. through Database. We thought we can gain huge performance boost doing stuff directly in database than through C# code. And we actually did get a huge performance boost. When I tried to brag about the achievement to our CTO, he counter questioned my decision of having functionality implemented in database rather than code. According to him such applications suffer scalability problems. In his words "These days things are kept in memory/cache. Clustered data is hard to manage over time. Facebook, Google have nothing in database. It is the era of thin servers and thick clients. DB is used only to store plain data and functionality should be completely decoupled from the database." Can you guys please give me some suggestions as to whether what he says is right. How to go about architect such an application?

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• Explicitly pass context object versus injecting with IoC

  - by SonOfPirate

  I have a layered service application where the service layer delegates operations into the domain layer for execution. Many of these operations need to know the context under which they are operation. (The context included the identity of the current user, culture information, etc. received from the caller.) For example, I have an API method that returns a list of announcements. The list is based on the current user's role and each announcement is localized to their culture. The API is a thin-facade that delegates to an Application Service in my domain layer. The Application Service method obviously needs to know the context of the current request/operation as another call to the same API from another user should result in a different list. Within this method, we also have logging that uses some of the context information so we a clear understanding of the context when the operation was performed (this is especially useful if something goes wrong.) While this is a contrived example, in the real world, my Application Services will coordinate operations with many collaborative components, any number of them also needing the context information. My choice is to pass the context to the Application Service which would then pass it with any calls to collaborators or have the IoC container satisfy the dependency the Application Service and any collaborators have on the context. I am wondering if it is considered good/bad, best practices/code smell, etc. if I pass the context object as a parameter to the domain methods or if injecting the context via an IoC container is preferred. (EDIT: I should mention that the context object is instantiated per-request.)

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• I know how to program, and how to learn how to program, but how/where do you learn how to make systems properly?

  - by Ryan

  There are many things that need to be considered when making a system, let's take for example a web based system where users log in and interact with each other, creating and editing content. Now I have to think about security, validation (I don't even think I am 100% sure what that entails), "making sure users don't step on each others feet" (term for this?), preventing errors in many cases, making sure database data doesn't become problematic through unexpected... situations? All these things I don't know how or where to learn, is there a book on this kind of stuff? Like I said there seems to be a huge difference between writing code and actually writing the right code, know what I mean? I feel like my current programming work lacks much of what I have described and I can see the problems it causes later, and then the problems are much harder to solve because data exists and people are using it. So can anyone point me to books or resources or the proper subset of programming(?) for this type of learning? PS: feel free to correct my tags, I don't know what I am talking about. Edit: I assume some of the examples I wrote apply to other types of systems too, I just don't know any other good examples because I've been mostly involved in web work.

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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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• Updating an Entity through a Service

  - by GeorgeK

  I'm separating my software into three main layers (maybe tiers would be a better term): Presentation ('Views') Business logic ('Services' and 'Repositories') Data access ('Entities' (e.g. ActiveRecords)) What do I have now? In Presentation, I use read-only access to Entities, returned from Repositories or Services, to display data. $banks = $banksRegistryService->getBanksRepository()->getBanksByCity( $city ); $banksViewModel = new PaginatedList( $banks ); // some way to display banks; // example, not real code I find this approach quite efficient in terms of performance and code maintanability and still safe as long as all write operations (create, update, delete) are preformed through a Service: namespace Service\BankRegistry; use Service\AbstractDatabaseService; use Service\IBankRegistryService; use Model\BankRegistry\Bank; class Service extends AbstractDatabaseService implements IBankRegistryService { /** * Registers a new Bank * * @param string $name Bank's name * @param string $bik Bank's Identification Code * @param string $correspondent_account Bank's correspondent account * * @return Bank */ public function registerBank( $name, $bik, $correspondent_account ) { $bank = new Bank(); $bank -> setName( $name ) -> setBik( $bik ) -> setCorrespondentAccount( $correspondent_account ); if( null === $this->getBanksRepository()->getDefaultBank() ) $this->setDefaultBank( $bank ); $this->getEntityManager()->persist( $bank ); return $bank; } /** * Makes the $bank system's default bank * * @param Bank $bank * @return IBankRegistryService */ public function setDefaultBank( Bank $bank ) { $default_bank = $this->getBanksRepository()->getDefaultBank(); if( null !== $default_bank ) $default_bank->setDefault( false ); $bank->setDefault( true ); return $this; } } Where am I stuck? I'm struggling about how to update certain fields in Bank Entity. Bad solution #1: Making a series of setters in Service for each setter in Bank; - seems to be quite reduntant, increases Service interface complexity and proportionally decreases it's simplicity - something to avoid if you care about code maitainability. I try to follow KISS and DRY principles. Bad solution #2: Modifying Bank directly through it's native setters; - really bad. If you'll ever need to move modification into the Service, it will be pain. Business logic should remain in Business logic layer. Plus, there are plans on logging all of the actions and maybe even involve user permissions (perhaps, through decorators) in future, so all modifications should be made only through the Service. Possible good solution: Creating an updateBank( Bank $bank, $array_of_fields_to_update) method; - makes the interface as simple as possible, but there is a problem: one should not try to manually set isDefault flag on a Bank, this operation should be performed through setDefaultBank method. It gets even worse when you have relations that you don't want to be directly modified. Of course, you can just limit the fields that can be modified by this method, but how do you tell method's user what they can and cannot modify? Exceptions?

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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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• Automated testing tool development challenges (for embedded software)

  - by Karthi prime

  My boss want to come up with the proposal for the following tool: An IDE: Able to build, compile, debug, via JTAG programming for the micro-controller. A Test Suite, reads the code in the IDE, auto generates the test cases, and it gives the in-target unit testing results(which is done by controlling code execution in the micro-controller via IDE). A no-overhead code coverage tool which interacts with the test suite and IDE. My work is to obtain the high level architecture of this tool, so as to proceed further. My current knowledge: There are tool-chains available from the chip manufacturer for the micro-controllers which can be utilized along with an open-source IDE like Eclipse, and along with an open-source burner, a complete IDE for a micro-controller can be done. Test cases can be auto-generated by reading the source file through the process of parsing, scripting, based on keywords. Test suite must be able to command the IDE to control, through breakpoints, and read the register contents from the microcontroller - This enables the in-target unit testing. An no-overhead code coverage should be done by no-overhead code instrumentation so as to execute those in the resource constraint environment of the micro-controller. I have the following questions: Any advice on the validity of my understanding? What are the challenges I will have during the development? What are the helpful open-source tools regarding this? What is the development time for this software? Thanks

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• whats the name of this pattern?

  - by Wes

  I see this a lot in frameworks. You have a master class which other classes register with. The master class then decides which of the registered classes to delegate the request to. An example based passed in class may be something this. public interface Processor { public boolean canHandle(Object objectToHandle); public void handle(Object objectToHandle); } public class EvenNumberProcessor extends Processor { public boolean canHandle(Object objectToHandle) { if (!isNumeric(objectToHandle)){ return false } return isEven(objectToHandle); } public void handle(objectToHandle) { //Optionally call canHandleAgain to ensure the calling class is fufilling its contract doSomething(); } } public class OddNumberProcessor extends Processor { public boolean canHandle(Object objectToHandle) { if (!isNumeric(objectToHandle)){ return false } return isOdd(objectToHandle); } public void handle(objectToHandle) { //Optionally call canHandleAgain to ensure the calling class is fufilling its contract doSomething(); } } //Can optionally implement processor interface public class processorDelegator { private List processors; public void addProcessor(Processor processor) { processors.add(processor); } public void process(Object objectToProcess) { //Lookup relevant processor either by keeping a list of what they can process //Or query each one to see if it can process the object. chosenProcessor=chooseProcessor(objectToProcess); chosenProcessor.handle(objectToProcess); } } Note there are a few variations I see on this. In one variation the sub classes provide a list of things they can process which the ProcessorDelegator understands. The other variation which is listed above in fake code is where each is queried in turn. This is similar to chain of command but I don't think its the same as chain of command means that the processor needs to pass to other processors. The other variation is where the ProcessorDelegator itself implements the interface which means you can get trees of ProcessorDelegators which specialise further. In the above example you could have a numeric processor delegator which delegates to an even/odd processor and a string processordelegator which delegates to different strings. My question is does this pattern have a name.

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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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• two-part dice pool mechanic

  - by bythenumbers

  I'm working on a dice mechanic/resolution system based off of the Ghost/Echo (hereafter shortened to G/E) tabletop RPG. Specifically, since G/E can be a little harsh with dealing out consequences and failure, I was hoping to soften the system and add a little more player control, as well as offer the chance for players to evolve their characters into something unique, right from creation. So, here's the mechanic: Players roll 2d12 against the two statistics for their character (each is a number from 2-11, and may be rolled above or below depending on the nature of the action attempted, rolling your stat exactly always fails). Depending on the success for that roll, they add dice to the pool rolled for a modified G/E style action. The acting player gets two dice anyhow, and I am debating offering a bonus die for each success, or a single bonus die for succeeding on both of the statistic-compared rolls. One the size of the dice pool is set, the entire pool is rolled, and the players are allowed to assign rolled dice to a goal and a danger. Assigned results are judged as follows: 1-4 means the attempted goal fails, or the danger comes true. 5-8 is a partial success at the goal, or partially avoiding the danger. 9-12 means the goal is achieved, or the danger avoided. My concerns are twofold: Firstly, that the two-stage action is too complicated, with two rolls to judge separately before anything can happen. Secondly, that the statistics involved go too far in softening the game. I've run some basic simulations, and the approximate statistics follow: 2 dice (up to) 3 dice (up to) 4 dice failure ~33% ~25% ~20% partial ~33% ~35% ~35% success ~33% ~40% ~45% I'd appreciate any advice that addresses my concerns or offers to refine my simulation (right now the first roll is statistically modeled as sign(1d12-1d12), where 0 is a success).

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• I need an approach to the problem of preventing inserting duplicate records into the database

  - by Maurice

  Apologies is this question is asked on the incorrect "stack" A webservice that I call returns a list of data. The data from the webservice is updated periodically, so a call to the webservice done in one hour could return the same data as a call done in an hour. Also, the data is returned based on a start and end date. We have multiple users that can run the webservice search, and duplicate data is most likely to be returned (especially for historical data). However I don't want to insert this duplicate data in the database. I've created a db table in which the data is stored (most important columns are) Id int autoincrement PK Date date not null --The date to which the data set belongs. LastUpdate date not null --The date the data set was last updated. UserName varchar(50) --The name of the user doing the search. I use sql server 2008 express with c# 4.0 and visual studio 2010. Entity Framework is used as the ORM. If stored procedures could be avoided in the proposed solution, then that will be a plus. Another way of looking interpreting what I'm asking a solution for is as follows: I have a million unique records in my table. A user does a new search. The search results from the user contains around 300k of the data that is already in the db. An efficient solution to finding an inserting only the unique records is needed.

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• Nested Entities and calculation on leaf entity property - SQL or NoSQL approach

  - by Chandu

  I am working on a hobby project called Menu/Recipe Management. This is how my entities and their relations look like. A Nutrient has properties Code and Value An Ingredient has a collection of Nutrients A Recipe has a Collection of Ingredients and occasionally can have a collection of other recipes A Meal has a Collection of Recipes and Ingredients A Menu has a Collection of Meals The relations can be depicted as In one of the pages, for a selected menu I need to display the effective nutrients information calculated based on its constituents (Meals, Recipes, Ingredients and the corresponding nutrients). As of now am using SQL Server to store the data and I am navigating the chain from my C# code, starting from each meal of the menu and then aggregating the nutrient values. I think this is not an efficient way as this calculation is being done every time the page is requested and the constituents change occasionally. I was thinking about a having a background service that maintains a table called MenuNutrients ({MenuId, NutrientId, Value}) and will populate/update this table with the effective nutrients when any of the component (Meal, Recipe, Ingredient) changes. I feel that a GraphDB would be a good fit for this requirement, but my exposure to NoSQL is limited. I want to know what are the alternative solutions/approaches to this requirement of displaying the nutrients of a given menu. Hope my description of the scenario is clear.

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• generating maps

  - by gardian06

  This is a conglomeration question when answering please specify which part you are addressing. I am looking at creating a maze type game that utilizes elevation. I have a few features I would like to have, but am unsure as to some of the implementation. I have done work doing fileIO maze generation (using a key to read the file, and then generate the level based on that file), but I am unsure how to think about this with elevation in the mix. I think height maps might be a good approach, but don't know how to represent them effectively. for a height map which is more beneficial XML(containing h[u,v] data and key definition), CSV (item1 is key reference, item2 is elevation), or another approach that I have not thought of yet? When it comes to placing the elevation values themselves what kind of deltah values are appropriate to have it noticeable at about a 60degree angle while not really effecting gravity driven physics (assuming some effect while moving up/down hill)? I am thinking of maybe going to procedural generation at some point, but am wondering if it is practical to have a procedurally generated grid (wall squares possibly same dimensions as the open space squares), or if designing to a thin wall open spaces is better? this decision will effect the amount of work need on the graphics end for uniform vs. irregular walls. EDIT: game will be a elevation maze shooter. levels/maps will be mazes with elevation the player has to negotiate. elevations will have effects on "combat" vision, and movement

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• Layout Columns - Equal Height

  - by Kyle

  I remember first starting out using tables for layouts and learned that I should not be doing that. I am working on a new site and can not seem to do equal height columns without using tables. Here is an example of the attempt with div tags. <div class="row"> <div class="column">column1</div> <div class="column">column2</div> <div class="column">column3</div> <div style="clear:both"></div> </div> Now what I tried with that was doing making columns float left and setting their widths to 33% which works fine, I use the clear:both div so that the row would be the size of the biggest column, but the columns will be different sizes based on how much content they have. I have found many fixes which mostly involve css hacks and just making it look like its right but that's not what I want. I thought of just doing it in javascript but then it would look different for those who choose to disable their javascript. The only true way of doing it that I can think of is using tables since the cells all have equal heights in the same row. But I know its bad to use tables. After searching forever I than came across this: http://intangiblestyle.com/lab/equal-height-columns-with-css/ What it seems to do is exactly the same as tables since its just setting its display exactly like tables. Would using that be just as bad as using tables? I honestly can't find anything else that I could do. edit @Su' I have looked into "faux columns" and do not think that is what I want. I think I would be able to implement better designs for my site using the display:table method. I posted this question because I just wasn't sure if I should since I have always heard its bad using tables in website layouts.

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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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• How to Structure a Trinary state in DB and Application

  - by ABMagil

  How should I structure, in the DB especially, but also in the application, a trinary state? For instance, I have user feedback records which need to be reviewed before they are presented to the general public. This means a feedback reviewer must see the unreviewed feedback, then approve or reject them. I can think of a couple ways to represent this: Two boolean flags: Seen/Unseen and Approved/Rejected. This is the simplest and probably the smallest database solution (presumably boolean fields are simple bits). The downside is that there are really only three states I care about (unseen/approved/rejected) and this creates four states, including one I don't care about (a record which is seen but not approved or rejected is essentially unseen). String column in the DB with constants/enum in application. Using Rating::APPROVED_STATE within the application and letting it equal whatever it wants in the DB. This is a larger column in the db and I'm concerned about doing string comparisons whenever I need these records. Perhaps mitigatable with an index? Single boolean column, but allow nulls. A true is approved, a false is rejected. A null is unseen. Not sure the pros/cons of this solution. What are the rules I should use to guide my choice? I'm already thinking in terms of DB size and the cost of finding records based on state, as well as the readability of code the ends up using this structure.

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