Search Results

Search found 44734 results on 1790 pages for 'model based design'.

Page 212/1790 | < Previous Page | 208 209 210 211 212 213 214 215 216 217 218 219  | Next Page >

  • How one could use a live editor

    - by Sathvik
    I was thinking about a live editing environment where code / a source file is synchronized so that, changes made by one user would be carried across to all others editing the file. Something like Google Wave, but for code. Could this kind of an environment be better for the code, as changes are shared instantly? (with revision-control, of course) Has anyone tried (or has had a need for) using a shared environment for code?

    Read the article

  • Triggering Data Changes in N-Tier

    - by Ryan Kinal
    I've been studying n-tier architectures as of late, particularly in VB.NET with Entity Framework and/or LINQ to SQL. I understand the basic concepts, but have been wondering about best practices in regard to triggering CRUD-type operations from user input/action. So, the arcitecture looks something like the following: [presentation layer] - [business layer] - [data layer] - (database) Getting information from the database into the presentation layer is simple and abstracted. It's just a matter of instantiating a new object from the business layer, which in turn uses the data layer to get at the correct information. However, saving (updating and inserting), and deleting seem to require particular APIs on the relevant business objects. I have to assume this is standard practice, unless a business object will save itself on various operations (which seems inefficient), or on disposal (which seems like it just wouldn't work, or may be unwieldy and unreliable). Should my "savable" business objects all implement a particular "ISavable" or "IDatabaseObject" interface? Is this a recognized (anti-)pattern? Are there other, better patterns I should be using that I'm just unaware of? The TLDR question, I suppose, is How does the presentation layer trigger database changes?

    Read the article

  • Are null references really a bad thing?

    - by Tim Goodman
    I've heard it said that the inclusion of null references in programming languages is the "billion dollar mistake". But why? Sure, they can cause NullReferenceExceptions, but so what? Any element of the language can be a source of errors if used improperly. And what's the alternative? I suppose instead of saying this: Customer c = Customer.GetByLastName("Goodman"); // returns null if not found if (c != null) { Console.WriteLine(c.FirstName + " " + c.LastName + " is awesome!"); } else { Console.WriteLine("There was no customer named Goodman. How lame!"); } You could say this: if (Customer.ExistsWithLastName("Goodman")) { Customer c = Customer.GetByLastName("Goodman") // throws error if not found Console.WriteLine(c.FirstName + " " + c.LastName + " is awesome!"); } else { Console.WriteLine("There was no customer named Goodman. How lame!"); } But how is that better? Either way, if you forget to check that the customer exists, you get an exception. I suppose that a CustomerNotFoundException is a bit easier to debug than a NullReferenceException by virtue of being more descriptive. Is that all there is to it?

    Read the article

  • How to handle monetary values in PHP and MySql?

    - by Songo
    I've inherited a huge pile of legacy code written in PHP on top of a MySQL database. The thing I noticed is that the application uses doubles for storage and manipulation of data. Now I came across of numerous posts mentioning how double are not suited for monetary operations because of the rounding errors. However, I have yet to come across a complete solution to how monetary values should be handled in PHP code and stored in a MySQL database. Is there a best practice when it comes to handling money specifically in PHP? Things I'm looking for are: How should the data be stored in the database? column type? size? How should the data be handling in normal addition, subtraction. multiplication or division? When should I round the values? How much rounding is acceptable if any? Is there a difference between handling large monetary values and low ones? Note: A VERY simplified sample code of how I might encounter money values in everyday life: $a= $_POST['price_in_dollars']; //-->(ex: 25.06) will be read as a string should it be cast to double? $b= $_POST['discount_rate'];//-->(ex: 0.35) value will always be less than 1 $valueToBeStored= $a * $b; //--> any hint here is welcomed $valueFromDatabase= $row['price']; //--> price column in database could be double, decimal,...etc. $priceToPrint=$valueFromDatabase * 0.25; //again cast needed or not? I hope you use this sample code as a means to bring out more use cases and not to take it literally of course. Bonus Question If I'm to use an ORM such as Doctrine or PROPEL, how different will it be to use money in my code.

    Read the article

  • is there a checklist that a small website should

    - by Mecon
    I am not a web developer - this would be my first foray. I can do HTML/CSS/Javascript, but never created a website for a company. If anybody is creating a site for small company (expecting some 10-15 static pages), what kinda things would it need to have? I am thinking of the following: Make the eventual owner buy in his/her name: Domain name, Web Hosting package and Email package. Q - DO Web Developers generally ask their clients to buy this stuff and then ask them to share their passwords? OR - Do Web Developers ship the source files to clients so that they can upload it? Create Cross Browser compatible HTML+CSS+javascript pages Add SEO stuff like Meta tags and xml file for crawler Buy professional images from stock website Q - IS there is a best-practice for this step? Add Copyright stuff. Q - ANY idea about how to do this? Add Faceboook widgets, so people can 'like' my website. Register website somewhere so that its searchable from multiple search-engine/yellopages. Q - DOES such a thing exist? Please check my checklist :) and let me know what you think could be missing? Thanks!

    Read the article

  • What kind of graphics would you like better? [ pictures ] [closed]

    - by Roger Travis
    I am looking forward to make an android game, something angrybirds style. I've already made my own engine and now have to decide what kind of graphics should I make. It could be either realistic, like that or a doodle-style like this Right now the first one looks more appealing to me... on the other hand, doodle-graphics are very easy to draw and their transparency doesn't seem to slow down the engine much. What do you think?

    Read the article

  • How to handle new domain names?

    - by michael
    I have a new product which I'll call a pen ink reloader. I have a website using my products name, for example, www.inkywink.com which I want to have accessed by searches for keywords such as "pen ink", "pen out of ink" "ink for pens" etc. , since nobody knows that a pen ink reloader exists. I see that its quite difficult to get on front page for these keywords since they have lots of competition. However I notice that the exact phrases I want to rank highly for are available as domains. I purchase "www.penink.com" and "penoutofink.com" which for arguments sake are highly searched and the perfect keywords to get eyes on my money site www.inkywink.com . Two questions: 1. What is my best option to leverage those names so that they appear near top of searches so that I can get traffic to my money site? Do I just have them redirect 301 to inkywink.com or should I create small original content on each with links to my main site? 2. If I just have them redirected to inkywink.com, am I able to use keywords in metatag and headers for each site separately or do they all automatically obtain the same headers and tags as the site to which theyre redirected ? Thanks to anyone who can help as I'm a real newbie to all this.

    Read the article

  • Implementing traffic conditions in TORCS

    - by user1837811
    I am working on a project about "Effects of Traffic conditions and Track Complexity on Car Driving Behavior". Is it possible to implement traffic in TORCS, or should I use another car simulator? By the word "traffic" I mean there are cars running on both tracks in both directions and I can detect the distances, direction and speed of these cars. Depending on this information I can decide whether I should slow down, speed up and calculate the correct timing to overtake.

    Read the article

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

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

    Read the article

  • "Best fit" to avoid reuse of object instances in a collection

    - by Simon
    Imagine I have a collection of object instances which represent activities for a user to undertake. Dependent on user attributes, I have to randomly select instances to present activities to the user. For some users, I need to present more activities to them than there are available activities in which case, I want to use the following algorithm. If all available activities have already been presented to the user, then re-select a "used" activity, selecting the earliest presented activity ordered by frequency of use. In other words, try to reduce repetition and where repetition is unavoidable, use the instances which have been repeated less often and were presented furthest back in time. Before I go on to code that algorithm, I wondered if there is some existing pattern I can re-use? [EDIT] "Furthest back in time" is not relevant as I will pass the algorithm an ordered collection of used instances where the first entry is the first presented.

    Read the article

  • Avoiding null in a controller

    - by Kevin Burke
    I'm trying to work through how to write this code. def get(params): """ Fetch a user's details, or 404 """ user = User.fetch_by_id(params['id']) if not user: abort(404) # Render some template for the user... What's the best way to handle the case where the lookup fails? One principle says you should avoid returning null values from functions. These lead to mistakes and AttributeErrors etc. later on in the file. Another idea is to have fetch_by_id raise a ValueError or similar if no user exists with that id. However there's a general principle that you shouldn't use exceptions for control flow, either, which doesn't help much. What could be done better in this case?

    Read the article

  • Splitting Logic, Data, Layout and "Hacks"

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

    Read the article

  • Centrally managing 100+ websites without bankrupting a small company

    - by palintropos
    I'm mainly interested in opinions on the trade-offs between having a single central server all the websites connect to as opposed to each website mirroring a subset of the master database with all the products in it. For example, will I run into severe performance issues (or even security issues, or restrictions) making queries to an offsite database? Will we hit scalability issues we can't handle early on from the sheer bandwidth required to maintain this? If we do go with something like a script that keeps smaller databases (each containing a subset of the central master data) in sync, what sorts of issues will we likely encounter there? I would really like the opinions of people far more knowledgeable than I am regarding the pros and cons of both setups and what headaches we are likely to encounter. CLARIFICATION: This should not be viewed as a question about whether we should implement one database vs multiple databases. This question has been answered numerous times. The question is regarding the pros and cons for a deployment like this having the ability to manage all the websites centrally (one server) vs trying to keep them all in sync if they each have their own db (multiple servers). REAL-WORLD EXAMPLE: We are a t-shirt company, and we have individual websites for our different kinds of t-shirts, but we're looking at a central order management integrated with our single shopping cart (which is ColdFusion + MySQL). Now, let's say we have a t-shirt that's on 10 of our websites and we change an image for it. Ideally we would change that in one place and the change would propagate, but how would we set this up?

    Read the article

  • Gathering IP address and workstation information; does it belong in a state class?

    - by p.campbell
    I'm writing an enterprisey utility that collects exception information and writes to the Windows Event Log, sends an email, etc. This utility class will be used by all applications in the corporation: web, BizTalk, Windows Services, etc. Currently this class: holds state given to it via public properties calls out to .NET Framework methods to gather information about runtime details. Included are call to various properties and methods from System.Environment, Reflection details, etc. This implementation has the benefit of allowing all those callers not to have to make these same calls themselves. This means less code for the caller to forget, screw up, etc. Should this state class (please what's the phrase I'm looking for [like DTO]?) know how to resolve/determine runtime details (like the IP address and machine name that it's running on)? It seems to me on second thought that it's meant to be a class that should hold state, and not know how to call out to the .NET Framework to find information. var myEx = new AppProblem{MachineName="Riker"}; //Will get "Riker 10.0.0.1" from property MachineLongDesc Console.WriteLine("full machine details: " + myEx.MachineLongDesc); public class AppProblem { public string MachineName{get;set;} public string MachineLongDesc{ get{ if(string.IsNullOrEmpty(this.MachineName) { this.MachineName = Environment.MachineName; } return this.MachineName + " " + GetCurrentIP(); } } private string GetCurrentIP() { return System.Net.Dns.GetHostEntry(this.MachineName) .AddressList.First().ToString(); } } This code was written by hand from memory, and presented for simplicity, trying to illustrate the concept.

    Read the article

  • Would it be possible to build a client portal on Squarespace6?

    - by aBathologist
    I'm helping a family member set up a site which will need to include a secure client portal, providing access to documents and a simple database. I have been encouraging them to go with a more established, open source CSM like drupal or joomla, whose capability in this area is evident. However, they have a strong preference for Squarespace. Does any one know if it would be possible to accomplish this with the new developer platform for squarespace 6? I've spent well over an hour searching google, the squarespace site and stackexchange, but can't seem to find any clear answer to this question. I'm grateful for any insight you all can provide.

    Read the article

  • What is a 'good number' of exceptions to implement for my library?

    - by Fuzz
    I've always wondered how many different exception classes I should implement and throw for various pieces of my software. My particular development is usually C++/C#/Java related, but I believe this is a question for all languages. I want to understand what is a good number of different exceptions to throw, and what the developer community expect of a good library. The trade-offs I see include: More exception classes can allow very fine grain levels of error handling for API users (prone to user configuration or data errors, or files not being found) More exception classes allows error specific information to be embedded in the exception, rather than just a string message or error code More exception classes can mean more code maintenance More exception classes can mean the API is less approachable to users The scenarios I wish to understand exception usage in include: During 'configuration' stage, which might include loading files or setting parameters During an 'operation' type phase where the library might be running tasks and doing some work, perhaps in another thread Other patterns of error reporting without using exceptions, or less exceptions (as a comparison) might include: Less exceptions, but embedding an error code that can be used as a lookup Returning error codes and flags directly from functions (sometimes not possible from threads) Implemented an event or callback system upon error (avoids stack unwinding) As developers, what do you prefer to see? If there are MANY exceptions, do you bother error handling them separately anyway? Do you have a preference for error handling types depending on the stage of operation?

    Read the article

  • Level Representation in a 2D Game

    - by meszar.imola
    I would like to create a 2D game, where a character should move on a stage/level. My stage would be static, constructed some little cubes, similar to the well-known Mario game: some of the elements should represent an element of the way where the character can step, but if the element is missing, the character should fall. My problem is, how to represent this programmatically? My first thought was to represent the stage with a vector, which should contain boolean elements, depending on the state of the element on the stage - if it's missing or not. But this means, I have to verify at my character's x or y position change if it has a stage element under or not (if not, to simulate the falling of the character) - I think it is not the best practice, it's not the beautiful solution. Can you help me with some advice, how to represent the stage?

    Read the article

  • Should an object know its own ID?

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

    Read the article

  • How to name setter that does data conversion?

    - by IAdapter
    I'm struggling with how to name this method, I don't like the "set" prefix, because I feel it should be reserved for normal "dumb" setters and some tools might not like it (i did not check it in checkstyle, pmd, etc., but I got a feeling they won't like it.) for example (in java, but I feel its language agnostic) public void setActionListenerClicked(boolean actionListenerClicked) { this.actionListenerClicked = actionListenerClicked ? "1" : "0"; } The only purpose of this method is ONLY to set, this method is needed and cannot be joined with any other (because of framework used). P.S. I DO know that question is similar to How to name multi-setter?, but I feel its not the same question.

    Read the article

  • Using 'new' in a projection?

    - by davenewza
    I wish to project a collection from one type (Something) to another type (SomethingElse). Yes, this is a very open-eneded question, but which of the two options below do you prefer? Creating a new instance using new: var result = query.Select(something => new SomethingElse(something)); Using a factory: var result = query.Select(something => SomethingElse.FromSomething(something)); When I think of a projection, I generally think of it as a conversion. Using new gives me this idea that I'm creating new objects during a conversion, which doesn't feel right. Semantically, SomethingElse.FromSomething() most definitely fits better. Although, the second option does require addition code to setup a factory, which could become unnecessarily compulsive.

    Read the article

  • Player & Level class structure in 2D python console game?

    - by Markus Meskanen
    I'm trying to create a 2D console game, where I have a player who can freely move around in a level (~map, but map is a reserved keyword) and interfere with other objects. Levels construct out of multiple Blocks, such as player(s), rocks, etc. Here's the Block class: class Block(object): def __init__(self, x=0, y=0, char=' ', solid=False): self.x = x self.y = y self.char = char self.solid = solid As you see, each block has a position (x, y) and a character to represent the block when it's printed. Each block also has a solid attribute, defining whether it can overlap with other solids or not. (Two solid blocks cannot overlap) I've now created few subclasses from Block (Rock might be useless for now) class Rock(Block): def __init__(self, x=0, y=0): super(Rock, self).__init__(x, y, 'x', True) class Player(Block): def __init__(self, x=0, y=0): super(Player, self).__init__(x, y, 'i', True) def move_left(self, x=1): ... # How do I make sure Player wont overlap with rocks? self.x -= x And here's the Level class: class Level(object): def __init__(self, name='', blocks=None): self.name = name self.blocks = blocks or [] Only way I can think of is to store a Player instance into Level's attributes (self.player=Player(), or so) and then give Level a method: def player_move_left(self): for block in self.blocks: if block.x == self.player.x - 1 and block.solid: return False But this doesn't really make any sense, why have a Player class if it can't even be moved without Level? Imo. player should be moved by a method inside Player. Am I wrong at something here, if not, how could I implement such behavior?

    Read the article

  • What are the advantages of storing xml in a relational database?

    - by Chris
    I was poking around the AdventureWorks database today and I noticed that a number of tables (HumanResources.JobCandidate and Sales.Individual for example) have a column which is storing xml data. What I would to know is, what is the advantage of storing basically a database table row's worth of data in another table's column? Doesn't this make it difficult to query off of this information? Or is the assumption that the data won't need to be queried and just needs to be stored?

    Read the article

  • Programming Languages

    - by Shannon
    I realize this will be a very vague question, but please bear with me. I have a concept for an open-world game, hand to hand combat, with a fairly open storyline, but there is an issue. I'm not sure which programming language to use, as I'm fairly new to programming. I am considering c++, but I would like to hear your opinions on which language you believe would support this type of game most efficiently. Pros and cons would be appreciated.

    Read the article

  • Semantic coupling vs. large class

    - by user106587
    I have hardware I communicate with via TCP. This hardware accepts ~40 different commands/requests with about 20 different responses. I've created a HardwareProxy class which has a TcpClient to send and receive data. I didn't like the idea of having 40 different methods to send the commands/requests, so I started down the path of having a single SendCommand method which takes an ICommand and returns an IResponse, this results in 40 different SpecificCommand classes. The problem is this requires semantic coupling, i.e. the method that invokes SendCommand receives an IResponse which it has to downcast to SpecificResponse, I use a future map which I believe ensures the appropriate SpecificResponse, but I get the impression this code smells. Besides the semantic coupling, ICommand and IResponse are essentially empty abstract classes (Marker Interfaces) and this seems suspicious to me. If I go with the 40 methods I don't think I have broken the single responisbility principle as the responsibility of the HardwareProxy class is to act as the hardware, which has all of these commands. This route is just ugly, plus I'd like to have Asynchronous versions, so there'd be about 80 methods. Is it better to bite the bullet and have a large class, accept the coupling and MarkerInterfaces for a smaller soultuion, or am I missing a better way? Thanks.

    Read the article

  • EAV - is it really bad in all scenarios?

    - by Giedrius
    I'm thinking to use EAV for some of the stuff in one of the projects, but all questions about it in stackoverflow end up to answers calling EAV an anti pattern. But I'm wondering, if is it that wrong in all cases? Let's say shop product entity, it has common features, like name, description, image, price, etc., that take part in logic many places and has (semi)unique features, like watch and beach ball would be described by completely different aspects. So I think EAV would fit for storing those (semi)unique features? All this is assuming, that for showing product list, it is enough info in product table (that means no EAV is involved) and just when showing one product/comparing up to 5 products/etc. data saved using EAV is used. I've seen such approach in Magento commerce and it is quite popular, so may be there are cases, when EAV is reasonable?

    Read the article

< Previous Page | 208 209 210 211 212 213 214 215 216 217 218 219  | Next Page >