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  • Is premature optimization really the root of all evil?

    - by Craig Day
    A colleague of mine today committed a class called ThreadLocalFormat, which basically moved instances of Java Format classes into a thread local, since they are not thread safe and "relatively expensive" to create. I wrote a quick test and calculated that I could create 200,000 instances a second, asked him was he creating that many, to which he answered "nowhere near that many". He's a great programmer and everyone on the team is highly skilled so we have no problem understanding the resulting code, but it was clearly a case of optimizing where there is no real need. He backed the code out at my request. What do you think? Is this a case of "premature optimization" and how bad is it really?

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  • Javascript: Avoid this and new - further reading? [closed]

    - by Thomas Deutsch
    I do not want this to end in a sort of religious discussion, i want to collect some sources for further reading on this topic. As shown here: Node.js Style and Structure Point 1: Avoid this and new you can find a good example when it could be better to use closures instead of a prototype, and to make every argument explicit. Ok, i agree - could be nice, but i need to know more. Can anyone recommend a good link? Would this make my code 100% object-pattern-free ? (no factory-, repository-, module- pattern?)

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  • Self-Executing Anonymous Function vs Prototype

    - by Robotsushi
    In Javascript there are a few clearly prominent techniques for create and manage classes/namespaces in javascript. I am curious what situations warrant using one technique vs. the other. I want to pick one and stick with it moving forward. I write enterprise code that is maintained and shared across multiple teams, and I want to know what is the best practice when writing maintainable javascript ? I tend to prefer Self-Executing Anonymous Functions however I am curious what the community vote is on these techniques. Prototype : function obj() { } obj.prototype.test = function() { alert('Hello?'); }; var obj2 = new obj(); obj2.test(); Self-Closing Anonymous Function : //Self-Executing Anonymous Function (function( skillet, $, undefined ) { //Private Property var isHot = true; //Public Property skillet.ingredient = "Bacon Strips"; //Public Method skillet.fry = function() { var oliveOil; addItem( "\t\n Butter \n\t" ); addItem( oliveOil ); console.log( "Frying " + skillet.ingredient ); }; //Private Method function addItem( item ) { if ( item !== undefined ) { console.log( "Adding " + $.trim(item) ); } } }( window.skillet = window.skillet || {}, jQuery )); //Public Properties console.log( skillet.ingredient ); //Bacon Strips //Public Methods skillet.fry(); //Adding Butter & Fraying Bacon Strips //Adding a Public Property skillet.quantity = "12"; console.log( skillet.quantity ); //12 //Adding New Functionality to the Skillet (function( skillet, $, undefined ) { //Private Property var amountOfGrease = "1 Cup"; //Public Method skillet.toString = function() { console.log( skillet.quantity + " " + skillet.ingredient + " & " + amountOfGrease + " of Grease" ); console.log( isHot ? "Hot" : "Cold" ); }; }( window.skillet = window.skillet || {}, jQuery )); //end of skillet definition try { //12 Bacon Strips & 1 Cup of Grease skillet.toString(); //Throws Exception } catch( e ) { console.log( e.message ); //isHot is not defined } I feel that I should mention that the Self-Executing Anonymous Function is the pattern used by the jQuery team. Update When I asked this question I didn't truly see the importance of what I was trying to understand. The real issue at hand is whether or not to use new to create instances of your objects or to use patterns which do not require constructors of the use of the new keyword. I added my own answer, because in my opinion we should make use of patterns which don't use the new keyword. For more information please see my answer.

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  • 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?

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  • Implementing new required feature after software release

    - by TiagoBrenck
    Fake Scenario There is a software that was released 1 year ago. The software is to map and register all kind of animals on our planet. When the software was released, the client only needed to know the scientific name of the animal, a flag if it is in risk of extinction and a scale of dangerous(that is a fake software and specification, I don't want to discuss this here). There are already 100.000 animals records saved on DB. New Feature One year later, the client wants a new feature. It is really important to him to know the animals classes, and this is a required field. So he asks me to put a field to input the animal class, and this field is required. Or maybe where this animal was discovered. Problem I have already 100.000 recorded animals without a class or where it was discovered, but I need to insert a new column to storage this information and this column can't be null. I don't have a default value for this situation (there isn't a default animal class or where it was discovered). I don't want to keep the requirement rule only on my software, my DB must have this requirement too(I like to keep business rules on DB too). What are the alternatives to solve this situation? I am on a situation that this new feature cannot be previewed or reviewed for the existing records. The time already passed and I can't go back on time to get it

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

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

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  • The balance between client and server functionality

    - by Eugen Martynov
    I want to bring the discussion that started in our teams and get your opinion about it. Assume we have an user account which could have different credentials for authentication and associated email to recover. An user has possibility to do signup with an email or use his social profile to complete signup process. As an Rest API from the backend to client looks like: Create account Authorise Update user data Link social account Register email Verify email In addition our BE is distributed and divided between several services/servers/clusters. So different calls are related to different end points. In case of the social sign up some of steps should be skipped or simplified. For example, with Facebook signup we could already skip email registration and verification step (we ask email permission form user), linking the social account and pre-fill user displayed name. So we proposed to have another end point which will hide/combine different calls on BE and return whole process result to the clients. The pros for this approach: No more duplication of functionality between clients Speed up the networking and user experience The cons for this approach: Additional work for backend Probably most complex scenarios in future updates I would like to get your opinion or experience with this situation. Especially if you already experienced point #2 from against reasons.

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  • Options for Application Registry

    - by Matt Felzani
    I work for a small software company (about 200 people building 8-10 applications) and I was hoping to get some advice on products that might be out there to manage the information of which clients are using which versions of our products? The most fundamental relationship would be that a "product" has "versions" and a given "version" is used by a "client." Uses would be: Determine which clients use which products Determine which clients are on which versions of a product Determine which clients are exposed to which vulnerabilities because of the version they use Determine which clients cannot move to a new version because of a vulnerability in the new version that they may hit Determine which clients should be approached for an upgrade Any thoughts or product reviews would be greatly appreciated! Thanks in advance.

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  • 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?

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  • Should I use a config file or database for storing business rules?

    - by foiseworth
    I have recently been reading The Pragmatic Programmer which states that: Details mess up our pristine code—especially if they change frequently. Every time we have to go in and change the code to accommodate some change in business logic, or in the law, or in management's personal tastes of the day, we run the risk of breaking the system—of introducing a new bug. Hunt, Andrew; Thomas, David (1999-10-20). The Pragmatic Programmer: From Journeyman to Master (Kindle Locations 2651-2653). Pearson Education (USA). Kindle Edition. I am currently programming a web app that has some models that have properties that can only be from a set of values, e.g. (not actual example as the web app data confidential): light-type = sphere / cube / cylinder The light type can only be the above three values but according to TPP I should always code as if they could change and place their values in a config file. As there are several incidents of this throughout the app, my question is: Should I store possibly values like these in: a config file: 'light-types' = array(sphere, cube, cylinder), 'other-type' = value, 'etc = etc-value a single table in a database with one line for each config item a database with a table for each config item (e.g. table: light_types; columns: id, name) some other way? Many thanks for any assistance / expertise offered.

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  • Using Dynamic LINQ to get a filter for my Web API

    - by Espo
    We are considering using the Dynamic.CS linq-sample included in the "Samples" directory of visual studio 2008 for our WebAPI project to allow clients to query our data. The interface would be something like this (In addition to the normal GET-methods): public HttpResponseMessage List(string filter = null); The plan is to use the dynamic library to parse the "filter"-variable and then execute the query agains the DB. Any thoughts if this is a good idea? Is it a security problem?

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  • 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.

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  • Is programming in layers real?

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

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  • share distribution question

    - by facebook-100000781341887
    Hi, I just developed a facebook game(mifia like), but the graphic I make is not good, because it is reference with some existing photo, trace with AI, and coloring it. Therefore, I invite my friend to join me, he is a graphic designer, own a company with his friend (I know both of them), for the share, I expect at least 70% for me, and at most 30% for them (both of them want to join). Therefore, they give me a counter offer, 60% for me and 40% for them, of course, I feel their counter offer is unacceptable because they only build the image in part time, and all the other work just like coding, webhosting...etc, is what I do in full time. Why they said they worth 40% is that they will make a good graphic, they can provide a advertise channel(on local magazine), etc... Actually, I don't think the game need advertisement on local magazine because the game is not target for local... Please give me some comments on this issue(is the share fair? what is the importance of the image of the game, is it worth more than 30%), or can anyone share the experience on this. Thanks in advance.

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  • What is best way to manage all images in a big project, inline images, background images, css sprite images?

    - by metal-gear-solid
    How do you manage all images in a big project, inline images, background images, css sprite images? Do you follow any naming convention? Do you create sub-folders to manage images? In a big project how to make it easy to find for new people in the development team if any images which they want to use (because it's in new PSD they received from designer) is already available in images folder of project and how they can find it easily.

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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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  • What are common patterns for handling possible pluralization in message properties?

    - by C. Ross
    Obviously users like to see text properly pluralized, and pluralization schemes vary in the various written languages one may encounter. When internationalizing an app, what pattern(s) are useful for handling messages with possible pluralization? What about messages with multiple possible pluralization? For example: "N review(s):" One pattern would be reviews.title.singular="{0} review:" reviews.title.singular="{0} reviews:" And this may not support all languages. Or a more complicated case: "Found M question(s) with N comment(s)." This would be difficult to support in English?

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  • What is the difference between "data hiding" and "encapsulation"?

    - by Software Engeneering Learner
    I'm reading "Java concurrency in practice" and there is said: "Fortunately, the same object-oriented techniques that help you write well-organized, maintainable classes - such as encapsulation and data hiding -can also help you create thread-safe classes." The problem #1 - I never heard about data hiding and don't know what it is. The problem #2 - I always thought that encapsulation is using private vs public, and is actually the data hiding. Can you please explain what data hiding is and how it differs from encapsulation?

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  • Cliché monsters to populate a steampunk fantasy setting dwarven dungeon?

    - by Alexander Gladysh
    I'm looking for a list of cliché monsters for a steampunk computer game (assume one kind or another of casual rogue-like RPG), to populate lower levels of ancient dwarven-built dungeons. Dwarves are a technology/science race in the setting I am aiming for. The world is a low-magic one. I'm stuck after listing various mechanical golems, gigantic spiders (every dungeon must have some of them!), and maybe a mechanical barlog as a megaboss. What would player expect? What are the key cultural references for such setting? I know a couple of games with suitable steampunk dwarves, but none are detailed enough in the underworld monsters area. Please point me in the right direction. (If you have a single funny monster suggestion, please mention it in comments, not in answer. ;-) )

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  • Traverse tree with results. Maybe type in Java?

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

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  • does class reference itself static anti pattern in prism

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

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  • 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?

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  • 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.

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  • Database structure for various items

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

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  • What is MVC, really?

    - by NickC
    As a serious programmer, how do you answer the question What is MVC? In my mind, MVC is sort of a nebulous topic — and because of that, if your audience is a learner, then you're free to describe it in general terms that are unlikely to be controversial. However, if you are speaking to a knowledgeable audience, especially an interviewer, I have a hard time thinking of a direction to take that doesn't risk a reaction of "well that's not right!...". We all have different real-world experience, and I haven't truly met the same MVC implementation pattern twice. Specifically, there seem to be disagreements regarding strictness, component definition, separation of parts (what piece fits where), etc. So, how should I explain MVC in a way that is correct, concise, and uncontroversial?

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