Search Results

Search found 71115 results on 2845 pages for 'file patterns'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 154/2845 | < Previous Page | 150 151 152 153 154 155 156 157 158 159 160 161  | Next Page >

  • What design pattern shall I use in this question?

    - by iyad al aqel
    To be frank, this is a homework question, so I'll tell you my opinion. Can you let me know my mistakes rather than giving me the solution? This is the question : Assume a restaurant that only offers the following two types of meals: (a) a full meal and (b)an economic meal. The full meal consists of the following food items and is served in the following order: 1. Appetizer 2. Drink 3. Main dish 4. Dessert Meanwhile the economic meal consists of the following food items and is served in the following order: 1. Drink 2. Main dish Identify the most appropriate design pattern that can be used to allow a customer to only order using one of the two types of meals provided and that the meal components must be served in the given order. I'm confused between the Factory and the Iterator and using them both together. Using the factory Pattern we can create the two meals full and economic and provide the user with with a base object class that will decide upon. But how can we enforce the ordering of the elements, I thought of using the iterator along that will iterate through the the composite of the two created factories sort of speak. What do you think?

    Read the article

  • Naming remote proxy classes

    - by Tobbe
    What are some good names for the client and server side classes that communicate over the network when implementing a remote proxy? The classes are often called stub and skelleton but I don't find those names very "intention revealing". Are there any other (better) alternatives?

    Read the article

  • Expose subset of a class - design question

    - by thanikkal
    Suppose i have a product class with about close to 100 properties. Now for some operations (Say tax calculation) i dont really need this bulky product type, rather only a subset that has price related properties. I am not sure if i should create different snap shots(class) of products that just has the properties that i am interested in. what would be the ideal approach so that i don't unnecessarily pass around unsought fluff? Thanks in advance.

    Read the article

  • Pattern for UI configuration

    - by TERACytE
    I have a Win32 C++ program that validates user input and updates the UI with status information and options. Currently it is written like this: void ShowError() { SetIcon(kError); SetMessageString("There was an error"); HideButton(kButton1); HideButton(kButton2); ShowButton(kButton3); } void ShowSuccess() { SetIcon(kError); std::String statusText (GetStatusText()); SetMessageString(statusText); HideButton(kButton1); HideButton(kButton2); ShowButton(kButton3); } // plus several more methods to update the UI using similar mechanisms I do not likes this because it duplicates code and causes me to update several methods if something changes in the UI. I am wondering if there is a design pattern or best practice to remove the duplication and make the functionality easier to understand and update. I could consolidate the code inside a config function and pass in flags to enable/disable UI items, but I am not convinced this is the best approach. Any suggestions and ideas?

    Read the article

  • Are there any MVP Frameworks projects out there?

    - by Greg Malcolm
    MVC is used a number of popular frameworks. To name just a few, Ruby on Rails, ASP.NET MVC, Monorail, Spring MVC. Are there any equivalent frameworks using any variant of MVP? Most of the examples I've found online seem to be custom implementations of the pattern rather than reusable frameworks. Suggestions need not be specific to any particular programming language, my interest is mostly academic.

    Read the article

  • Events and references pattern

    - by serhio
    In a project I have the following relation between BO and GUI By e.g. G could represent a graphic with time lines, C a TimeLine curve, P - points of that curve and T the time that represents each point. Each GUI object is associated with the BO corresponding object. When T changes GUI P captures the Changed event and changes its location. So, when G should be modified, it modifies internally its objects and as result T changes, P moves and the GuiG visually changes, everything is OK. But there is an inconvenient of this architecture... BO should not be recreated, because this will breack the link between BO and GUIO. In particular, GUI P should always have the same reference of T. If in a business logic I do by e.g. P1.T = new T(this.T + 10) GUI_P1 will not move anymore, because it wait an event from the reference of former P1.T object, that does not belongs to P1 anymore. So the solution was to always modify the existing objects, not to recreate it. But here is an other inconvenient: performance. Say I have a ready newC object that should replace the older one. Instead of doing G1.C = newC I should do foreach T in foreach P in C replace with T from P from newC. Is there an other more optimal way to do it?

    Read the article

  • what happens to running/blocked runnables when executorservice is shutdown()

    - by prmatta
    I posted a question about a thread pattern today, and almost everyone suggested that I look into the ExecutorService. While I was looking into the ExecutorService, I think I am missing something. What happens if the service has a running or blocked threads, and someone calls ExecutorService.shutdown(). What happens to threads that are running or blocked? Does the ExecutorService wait for those threads to complete before it terminates? The reason I ask this is because a long time ago when I used to dabble in Java, they deprecated Thread.stop(), and I remember the right way of stopping a thread was to use sempahores and extend Thread when necessary: public void run () { while (!this.exit) { try { block(); //do something } catch (InterruptedException ie) { } } } public void stop () { this.exit = true; if (this.thread != null) { this.thread.interrupt(); this.thread = null; } } How does ExecutorService handle running threads?

    Read the article

  • Find First Specific Byte in a Byte[] Array c#

    - by divinci
    Hi there, I have a byte array and wish to find the first occurance (if any) of a specific byte. Can you guys help me with a nice, elegant and efficient way to do it? /// Summary /// Finds the first occurance of a specific byte in a byte array. /// If not found, returns -1. public int GetFirstOccurance(byte byteToFind, byte[] byteArray) { }

    Read the article

  • How should I implement items that are normalized in the Database, in Object Oriented Design?

    - by Jonas
    How should I implement items that are normalized in the Database, in Object Oriented classes? In the database I have a big table of items and a smaller of groups. Each item belong to one group. This is how my database design look like: +----------------------------------------+ | Inventory | +----+------+-------+----------+---------+ | Id | Name | Price | Quantity | GroupId | +----+------+-------+----------+---------+ | 43 | Box | 34.00 | 456 | 4 | | 56 | Ball | 56.50 | 3 | 6 | | 66 | Tin | 23.00 | 14 | 4 | +----+------+-------+----------+---------+ Totally 3000 lines +----------------------+ | Groups | +---------+------+-----+ | GroupId | Name | VAT | +---------+------+-----+ | 4 | Mini | 0.2 | | 6 | Big | 0.3 | +---------+------+-----+ Totally 10 lines I will use the OOP classes in a GUI, where the user can edit Items and Groups in the inventory. It should also be easy to do calculations with a bunch of items. The group information like VAT are needed for the calculations. I will write an Item class, but do I need a Group class? and if I need it, should I keep them in a global location or how do I access it when I need it for Item-calculations? Is there any design pattern for this case?

    Read the article

  • What are the responsibilities of the data layer?

    - by alimac83
    I'm working on a project where I had to add a data layer to my application. I've always thought that the data layer is purely responsible for CRUD functions ie. shouldn't really contain any logic but should simply retrieve data for the business layer to manipulate. However I'm a little confused with my project because I'm not sure whether I've structured my app correctly for this scenario. Basically I'm trying to retrieve a list of products from the database that fall within a certain pricing threshold. At the moment I have a function in my data layer that basically returns all products where price min threshold and price < max threshold. But it got me thinking that maybe this is incorrect. Should the data layer simply return a list of ALL products and then the business logic do the filtering? I'm pretty confused over whether the data layer should simply provide methods that allow the business layer to get raw data or whether it should be responsible for getting filtered data too? If anyone has an article or something explaining this in detail it'd be very helpful. Thanks

    Read the article

  • HTML Submit button vs AJAX based Post (ASP.NET MVC)

    - by Graham
    I'm after some design advice. I'm working on an application with a fellow developer. I'm from the Webforms world and he's done a lot with jQuery and AJAX stuff. We're collaborating on a new ASP.MVC 1.0 app. He's done some pretty amazing stuff that I'm just getting my head around, and used some 3rd party tools etc. for datagrids etc. but... He rarely uses Submit buttons whereas I use them most of the time. He uses a button but then attaches Javascript to it that calls an MVC action which returns a JSON object. He then parses the object to update the datagrid. I'm not sure how he deals with server-side validation - I think he adds a message property to the JSON object. A sample scenario would be to "Save" a new record that then gets added to the gridview. The user doesn't see a postback as such, so he uses jQuery to disable the UI whilst the controller action is running. TBH, it looks pretty cool. However, the way I'd do it would be to use a Submit button to postback, let the ModelBinder populate a typed model class, parse that in my controller Action method, update the model (and apply any validation against the model), update it with the new record, then send it back to be rendered by the View. Unlike him, I don't return a JSON object, I let the View (and datagrid) bind to the new model data. Both solutions "work" but we're obviously taking the application down different paths so one of us has to re-work our code... and we don't mind whose has to be done. What I'd prefer though is that we adopt the "industry-standard" way of doing this. I'm unsure as to whether my WebForms background is influencing the fact that his way just "doesn't feel right", in that a "submit" is meant to submit data to the server. Any advice at all please - many thanks.

    Read the article

  • Immutable classes in C++

    - by ereOn
    Hi, In one of my projects, I have some classes that represent entities that cannot change once created, aka. immutable classes. Example : A class RSAKey that represent a RSA key which only has const methods. There is no point changing the existing instance: if you need another one, you just create one. My objects sometimes are heavy and I enforced the use of smart pointers to avoid copy. So far, I have the following pattern for my classes: class RSAKey : public boost::noncopyable, public boost::enable_shared_from_this<RSAKey> { public: /** * \brief Some factory. * \param member A member value. * \return An instance. */ static boost::shared_ptr<const RSAKey> createFromMember(int member); /** * \brief Get a member. * \return The member. */ int getMember() const; private: /** * \brief Constructor. * \param member A member. */ RSAKey(int member); /** * \brief Member. */ const int m_member; }; So you can only get a pointer (well, a smart pointer) to a const RSAKey. To me, it makes sense, because having a non-const reference to the instance is useless (it only has const methods). Do you guys see any issue regarding this pattern ? Are immutable classes something common in C++ or did I just created a monster ? Thank you for your advices !

    Read the article

  • "Circuit breaker" for net.msmq?

    - by Alex
    Hi, The Circuit Breaker pattern, from the book Release It!, protects a service from requests while it is failing (or recovering). The net.msmq binding used with transactions give us nice retry and poison message capabilities. But I am missing the implementation of such a "Circuit breaker" pattern. A service is put under even heavier load by retries while it is already in a failure condition (like DB connectivity issues causing loads of blocked threads etc.). Anyone knows about a behavior extension or similar that explicitly closes the service host when defined failure thresholds have been exceeded? Cheers, Alex

    Read the article

  • Dependency Injection: I don't get where to start!

    - by Andy
    I have several articles about Dependency Injection, and I can see the benefits, especially when it comes to unit testing. The units can me loosely coupled, and mocking of dependencies can be made. The trouble is - I just don't get where to start. Consider this snippet below of (much edited for the purpose of this post) code that I have. I am instantiating a Plc object from the main form, and passing in a communications mode via the Connect method. In it's present form it becomes hard to test, because I can't isolate the Plc from the CommsChannel to unit test it. (Can I?) The class depends on using a CommsChannel object, but I am only passing in a mode that is used to create this channel within the Plc itself. To use dependancy injection, I should really pass in an already created CommsChannel (via an 'ICommsChannel' interface perhaps) to the Connect method, or maybe via the Plc constructor. Is that right? But then that would mean creating the CommsChannel in my main form first, and this doesn't seem right either, because it feels like everything will come back to the base layer of the main form, where everything begins. Somehow it feels like I am missing a crucial piece of the puzzle. Where do you start? You have to create an instance of something somewhere, but I'm struggling to understand where that should be. public class Plc() { public bool Connect(CommsMode commsMode) { bool success = false; // Create new comms channel. this._commsChannel = this.GetCommsChannel(commsMode); // Attempt connection success = this._commsChannel.Connect(); return this._connected; } private CommsChannel GetCommsChannel(CommsMode mode) { CommsChannel channel; switch (mode) { case CommsMode.RS232: channel = new SerialCommsChannel( SerialCommsSettings.Default.ComPort, SerialCommsSettings.Default.BaudRate, SerialCommsSettings.Default.DataBits, SerialCommsSettings.Default.Parity, SerialCommsSettings.Default.StopBits); break; case CommsMode.Tcp: channel = new TcpCommsChannel( TCPCommsSettings.Default.IP_Address, TCPCommsSettings.Default.Port); break; default: // Throw unknown comms channel exception. } return channel; } }

    Read the article

  • In a PHP project, how do you organize and access your helper objects?

    - by Pekka
    How do you organize and manage your helper objects like the database engine, user notification, error handling and so on in a PHP based, object oriented project? Say I have a large PHP CMS. The CMS is organized in various classes. A few examples: the database object user management an API to create/modify/delete items a messaging object to display messages to the end user a context handler that takes you to the right page a navigation bar class that shows buttons a logging object possibly, custom error handling etc. I am dealing with the eternal question, how to best make these objects accessible to each part of the system that needs it. my first apporach, many years ago was to have a $application global that contained initialized instances of these classes. global $application; $application->messageHandler->addMessage("Item successfully inserted"); I then changed over to the Singleton pattern and a factory function: $mh =&factory("messageHandler"); $mh->addMessage("Item successfully inserted"); but I'm not happy with that either. Unit tests and encapsulation become more and more important to me, and in my understanding the logic behind globals/singletons destroys the basic idea of OOP. Then there is of course the possibility of giving each object a number of pointers to the helper objects it needs, probably the very cleanest, resource-saving and testing-friendly way but I have doubts about the maintainability of this in the long run. Most PHP frameworks I have looked into use either the singleton pattern, or functions that access the initialized objects. Both fine approaches, but as I said I'm happy with neither. I would like to broaden my horizon on what is possible here and what others have done. I am looking for examples, additional ideas and pointers towards resources that discuss this from a long-term, real-world perspective. Also, I'm interested to hear about specialized, niche or plain weird approaches to the issue. Bounty I am following the popular vote in awarding the bounty, the answer which is probably also going to give me the most. Thank you for all your answers!

    Read the article

  • What is there so useful in the Decorator Pattern? My example doesn't work

    - by Green
    The book says: The decorator pattern can be used to extend (decorate) the functionality of a certain object I have a rabbit animal. And I want my rabbit to have, for example, reptile skin. Just want to decorate a common rabbit with reptile skin. I have the code. First I have abstract class Animal with everythig that is common to any animal: abstract class Animal { abstract public function setSleep($hours); abstract public function setEat($food); abstract public function getSkinType(); /* and more methods which for sure will be implemented in any concrete animal */ } I create class for my rabbit: class Rabbit extends Animal { private $rest; private $stomach; private $skinType = "hair"; public function setSleep($hours) { $this->rest = $hours; } public function setFood($food) { $this->stomach = $food; } public function getSkinType() { return $this->$skinType; } } Up to now everything is OK. Then I create abstract AnimalDecorator class which extends Animal: abstract class AnimalDecorator extends Animal { protected $animal; public function __construct(Animal $animal) { $this->animal = $animal; } } And here the problem comes. Pay attention that AnimalDecorator also gets all the abstract methods from the Animal class (in this example just two but in real can have many more). Then I create concrete ReptileSkinDecorator class which extends AnimalDecorator. It also has those the same two abstract methods from Animal: class ReptileSkinDecorator extends AnimalDecorator { public function getSkinColor() { $skin = $this->animal->getSkinType(); $skin = "reptile"; return $skin; } } And finaly I want to decorate my rabbit with reptile skin: $reptileSkinRabbit = ReptileSkinDecorator(new Rabbit()); But I can't do this because I have two abstract methods in ReptileSkinDecorator class. They are: abstract public function setSleep($hours); abstract public function setEat($food); So, instead of just re-decorating only skin I also have to re-decorate setSleep() and setEat(); methods. But I don't need to. In all the book examples there is always ONLY ONE abstract method in Animal class. And of course it works then. But here I just made very simple real life example and tried to use the Decorator pattern and it doesn't work without implementing those abstract methods in ReptileSkinDecorator class. It means that if I want to use my example I have to create a brand new rabbit and implement for it its own setSleep() and setEat() methods. OK, let it be. But then this brand new rabbit has the instance of commont Rabbit I passed to ReptileSkinDecorator: $reptileSkinRabbit = ReptileSkinDecorator(new Rabbit()); I have one common rabbit instance with its own methods in the reptileSkinRabbit instance which in its turn has its own reptileSkinRabbit methods. I have rabbit in rabbit. But I think I don't have to have such possibility. I don't understand the Decarator pattern right way. Kindly ask you to point on any mistakes in my example, in my understanding of this pattern. Thank you.

    Read the article

  • Grasp Controller, Does it really need a UI to exist?

    - by dbones
    I have a Domain model which can be in multiple states, and if these states go out of a given range it the domain should automatically react. For example I have a Car which is made of multiple things which have measurements the Engine - Rev counter and Temperature the Fuel Tank - capacity Is is plaseable to have a CarStateController, which observses the engine and the tank, and if these states go out of range IE the engine temperature goes above range, turn the engine fan on?? There is no UI, (you could argue it would show a light on the dash board, but for this case it does not) is this a valid use of a GRASP controller pattern? if not what is this CarStateController Called? Or have I completely missed the point and this should be the State Pattern?

    Read the article

  • C# event or delegate or other solution?

    - by user295734
    Looking for some help or programmng ideas or mayeb there is some pattern that would help. Have an application that needs to fire alot of events sequentially, it could up to 100 or more unique events, it will be dynamic depeneding on the situation. Trying to find the best practice for doing this. My main idea right now is to create a list of objects iterate thru them, and fire each event. This seems wrong, or bad practice. Or maybe have one object and pass a list or params into one event? Or am I missing some feature in .NET that i could be using or implementing?

    Read the article

  • What are good strategies for organizing single class per query service layer?

    - by KallDrexx
    Right now my Asp.net MVC application is structured as Controller - Services - Repositories. The services consist of aggregate root classes that contain methods. Each method is a specific operation that gets performed, such as retrieving a list of projects, adding a new project, or searching for a project etc. The problem with this is that my service classes are becoming really fat with a lot of methods. As of right now I am separating methods out into categories separated by #region tags, but this is quickly becoming out of control. I can definitely see it becoming hard to determine what functionality already exists and where modifications need to go. Since each method in the service classes are isolated and don't really interact with each other, they really could be more stand alone. After reading some articles, such as this, I am thinking of following the single query per class model, as it seems like a more organized solution. Instead of trying to figure out what class and method you need to call to perform an operation, you just have to figure out the class. My only reservation with the single query per class method is that I need some way to organize the 50+ classes I will end up with. Does anyone have any suggestions for strategies to best organize this type of pattern?

    Read the article

  • Application Design: Single vs. Multiple Hits to the DB

    - by shyneman
    I'm building a service that performs a set of configured activities based on the type of request that it receives. Each activity involves going to the database and retrieving/updating some kind of information. The logic for each activity can be generalized and re-used across different request types. The activities may need to participate in a transaction for the duration of the servicing the request. One option, I'm considering is having each activity maintain its own access to DAL/database. This fully encapsulates the activity into a stand-alone re-usable piece, but hitting the database multiple times for one request doesn't seem like a viable option. I don't really know how to easily implement the concept of a transaction across the multiple activities here either. The second option is to encapsulate ALL the activities into one big activity and hit the database once. But this does not allow re-use and configuration of these activities for different requests. Does anyone have any suggestions and input about what should be the best way to approach my problem? Thanks for any help.

    Read the article

  • One executable with cmd-line params or just many satellite executables?

    - by Nikos Baxevanis
    I design an application back-end. For now, it is a .NET process (a Console Application) which hosts various communication frameworks such as Agatha and NServiceBus. I need to periodically update my datastore with values (coming from the application while it's running). I found three possible ways: Accept command line arguments, so I can call my console app with -update. On start up a background thread will periodically invoke the update method. Create an updater.exe app which will do the updates, but I will have code duplication since in some way it will need to query the data from the source in order to save it to the datastore. Which one is better?

    Read the article

  • Passing data between objects in Chain of Responsibility pattern

    - by AbrahamJP
    While implementing the Chain of Responsibility pattern, i came across a dilemma om how to pass data between objects in the chain. The datatypes passed between object in the chain can differ for each object. As a temporary fix I had created a Static class containing a stack where each object in the chain can push the results to the stack while the next object in the chain could pop the results from the stack. Here is a sample code on what I had implemented. public interface IHandler { void Process(); } public static class StackManager { public static Stack DataStack = new Stack(); } //This class doesn't require any input to operate public class OpsA : IHandler { public IHandler Successor {get; set; } public void Process() { //Do some processing, store the result into Stack var ProcessedData = DoSomeOperation(); StackManager.DataStack.Push(ProcessedData); if(Successor != null) Successor(); } } //This class require input data to operate upon public class OpsB : IHandler { public IHandler Successor {get; set; } public void Process() { //Retrieve the results from the previous Operation var InputData = StackManager.DataStack.Pop(); //Do some processing, store the result into Stack var NewProcessedData = DoMoreProcessing(InputData); StackManager.DataStack.Push(NewProcessedData); if(Successor != null) Successor(); } } public class ChainOfResponsibilityPattern { public void Process() { IHandler ProcessA = new OpsA(); IHandler ProcessB = new OpsB(); ProcessA.Successor = ProcessB; ProcessA.Process(); } } Please help me to find a better approach to pass data between handlers objects in the chain.

    Read the article

  • multiple classes with same methods - best pattern

    - by Tony
    I have a few classes in my current project where validation of Email/Website addresses is necessary. The methods to do that are all the same. I wondered what's the best way to implement this, so I don't need to have these methods copy pasted everywhere? The classes themselves are not necessarily related, they only have those validation methods in common.

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 150 151 152 153 154 155 156 157 158 159 160 161  | Next Page >