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  • Does overloading Grails static 'mapping' property to bolt on database objects violate DRY?

    - by mikesalera
    Does Grails static 'mapping' property in Domain classes violate DRY? Let's take a look at the canonical domain class: class Book {      Long id      String title      String isbn      Date published      Author author      static mapping = {             id generator:'hilo', params:[table:'hi_value',column:'next_value',max_lo:100]      } } or: class Book { ...         static mapping = {             id( generator:'sequence', params:[sequence_name: "book_seq"] )     } } And let us say, continuing this thought, that I have my Grails application working with HSQLDB or MySQL, but the IT department says I must use a commercial software package (written by a large corp in Redwood Shores, Calif.). Does this change make my web application nobbled in development and test environments? MySQL supports autoincrement on a primary key column but does support sequence objects, for example. Is there a cleaner way to implement this sort of 'only when in production mode' without loading up the domain class?

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  • Register all GUI components as Observers or pass current object to next object as a constructor argu

    - by Jack
    First, I'd like to say that I think this is a common issue and there may be a simple or common solution that I am unaware of. Many have probably encountered a similar problem. Thanks for reading. I am creating a GUI where each component needs to communicate (or at least be updated) by multiple other components. Currently, I'm using a Singleton class to accomplish this goal. Each GUI component gets the instance of the singleton and registers itself. When updates need to be made, the singleton can call public methods in the registered class. I think this is similar to an Observer pattern, but the singleton has more control. Currently, the program is set up something like this: class c1 { CommClass cc; c1() { cc = CommClass.getCommClass(); cc.registerC1( this ); C2 c2 = new c2(); } } class c2 { CommClass cc; c2() { cc = CommClass.getCommClass(); cc.registerC2( this ); C3 c3 = new c3(); } } class c3 { CommClass cc; c3() { cc = CommClass.getCommClass(); cc.registerC3( this ); C4 c4 = new c4(); } } etc. Unfortunately, the singleton class keeps growing larger as more communication is required between the components. I was wondering if it's a good idea to instead of using this singleton, pass the higher order GUI components as arguments in the constructors of each GUI component: class c1 { c1() { C2 c2 = new c2( this ); } } class c2 { C1 c1; c2( C1 c1 ) { this.c1 = c1 C3 c3 = new c3( c1, this ); } } class c3 { C1 c1; C2 c2; c3( C1 c1, C2 c2 ) { this.c1 = c1; this.c2 = c2; C4 c4 = new c4( c1, c2, this ); } } etc. The second version relies less on the CommClass, but it's still very messy as the private member variables increase in number and the constructors grow in length. Each class contains GUI components that need to communicate through CommClass, but I can't think of a good way to do it. If this seems strange or horribly inefficient, please describe some method of communication between classes that will continue to work as the project grows. Also, if this doesn't make any sense to anyone, I'll try to give actual code snippets in the future and think of a better way to ask the question. Thanks.

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  • How implement the Open Session in View pattern in NHibernate?

    - by MCardinale
    I'm using ASP.NET MVC + NHibernate + Fluent NHibernate and having a problem with lazy loading. Through this question (http://stackoverflow.com/questions/2519964/how-to-fix-a-nhibernate-lazy-loading-error-no-session-or-session-was-closed), I've discovered that I have to implement the Open Session in View pattern , but I don't know how. In my repositories classes, I use methods like this public ImageGallery GetById(int id) { using(ISession session = NHibernateSessionFactory.OpenSession()) { return session.Get<ImageGallery>(id); } } public void Add(ImageGallery imageGallery) { using(ISession session = NHibernateSessionFactory.OpenSession()) { using(ITransaction transaction = session.BeginTransaction()) { session.Save(imageGallery); transaction.Commit(); } } } And this is my Session Factory helper class: public class NHibernateSessionFactory { private static ISessionFactory _sessionFactory; private static ISessionFactory SessionFactory { get { if(_sessionFactory == null) { _sessionFactory = Fluently.Configure() .Database(MySQLConfiguration.Standard.ConnectionString(MyConnString)) .Mappings(m => m.FluentMappings.AddFromAssemblyOf<ImageGalleryMap>()) .ExposeConfiguration(c => c.Properties.Add("hbm2ddl.keywords", "none")) .BuildSessionFactory(); } return _sessionFactory; } } public static ISession OpenSession() { return SessionFactory.OpenSession(); } } Someone could help me to implements Open Session in View pattern? Thank you.

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  • Circular Dependency Solution

    - by gfoley
    Our current project has ran into a circular dependency issue. Our business logic assembly is using classes and static methods from our SharedLibrary assembly. The SharedLibrary contains a whole bunch of helper functions, such as a SQL Reader class, Enumerators, Global Variables, Error Handling, Logging and Validation. The SharedLibrary needs access to the Business objects, but the Business objects need access to SharedLibrary. The old developers solved this obvious code smell by replicating the functionality of the business objects in the shared library (very anti-DRY). I've spent a day now trying to read about my options to solve this but i'm hitting a dead end. I'm open to the idea of architecture redesign, but only as a last resort. So how can i have a Shared Helper Library which can access the business objects, with the business objects still accessing the Shared Helper Library?

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  • Need an ASP.NET MVC long running process with user feedback

    - by Jason
    I've been trying to create a controller in my project for delivering what could turn out to be quite complex reports. As a result they can take a relatively long time and a progress bar would certainly help users to know that things are progressing. The report will be kicked off via an AJAX request, with the idea being that periodic JSON requests will get the status and update the progress bar. I've been experimenting with the AsyncController as that seems to be a nice way of running long processes without tying up resources, but it doesn't appear to give me any way of checking on the progress (and seems to block further JSON requests and I haven't discovered why yet). After that I've tried resorting to storing progress in a static variable on the controller and reading the status from that - but to be honest that all seems a bit hacky! All suggestions gratefully accepted!

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  • Builder pattern and singletons

    - by Berryl
    Does anyone have any links to some code they like that shows a good example of this in c#? As an example of bad code, here is what a builder I have now looks like. I'm trying to have a way to keep the flexibility of the builder pattern but not rebuild the properties. Cheers, Berryl public abstract class ActivityBuilder { public abstract ActivityBuilder Build(); public bool IsBuilt { get; protected set; } public IEnumerable<Project> Projects { get { if(_projects==null) { Build(); } return _projects; } } protected IEnumerable<Project> _projects; // .. other properties }

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  • Unit of Work Pattern in .Net

    - by Jazza
    Does anyone have any concrete examples of a simple Unit of Work pattern in C# or Visual Basic that would handle the following scenario? I'm writing a WinForms application in which a customer can have multiple addresses associated with it. The user can add, edit and delete addresses belonging to the customer before the customer is saved back to the database. Therefore, at the time of saving, all the original addresses need to be deleted from the database and the new addresses added in a single transaction.

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  • How to effectively measure developer's work hours?

    - by twk
    I have a few software developers working for my projects and I would like to provide them a way to register time they spent on real development. There is good will to register development hours, no force, but we try to avoid techniques like excel sheets register because this is so uncomfortable. I can track svn commits, but this is unreliable. Developers also helps supporting different projects during the day, so assuming they work on one project by whole day is not true. I've seen utilities that popups a message every hour to confirm the project you're working on but this is annoying. Some kind of active-window-title-anaylzer might help (you can get solution name from there in the case of Visual Studio) but I have no experience with such idea. If you have any experience with programmers/designers work hours registration, please share with me. Thanks

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  • Is Multiple Iterators is possible in php?

    - by artvolk
    Good day! I know that C# allows multiple iterators using yield, like described here: http://stackoverflow.com/questions/1754041/is-multiple-iterators-is-possible-in-c In PHP there is and Iterator interface. Is it possible to implement more than one iteration scenario for a class?

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  • Is there a way of using one method to handle others to avoid code duplication?

    - by Artur
    I wonder if there is a way of writing a method or a class that would add to any method some code that is shared between many methods. The methods return different things and some of them are just void. Below is a part of the code that is duplicated in the methods. StartTimer(MethodBase.GetCurrentMethod().Name); try { // Actual method body } catch (Exception ex) { bool rethrow = ExceptionPolicy.HandleException(ex, "DALPolicy"); if (rethrow) { throw; } } finally { StopTimer(MethodBase.GetCurrentMethod().Name); } Any help would be greatly appreciated.

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  • when to use the abstract factory pattern?

    - by hguser
    Hi: I want to know when we need to use the abstract factory pattern. Here is an example,I want to know if it is necessary. The UML THe above is the abstract factory pattern, it is recommended by my classmate. THe following is myown implemention. I do not think it is necessary to use the pattern. And the following is some core codes: package net; import java.io.IOException; import java.util.HashMap; import java.util.Map; import java.util.Properties; public class Test { public static void main(String[] args) throws IOException, InstantiationException, IllegalAccessException, ClassNotFoundException { DaoRepository dr=new DaoRepository(); AbstractDao dao=dr.findDao("sql"); dao.insert(); } } class DaoRepository { Map<String, AbstractDao> daoMap=new HashMap<String, AbstractDao>(); public DaoRepository () throws IOException, InstantiationException, IllegalAccessException, ClassNotFoundException { Properties p=new Properties(); p.load(DaoRepository.class.getResourceAsStream("Test.properties")); initDaos(p); } public void initDaos(Properties p) throws InstantiationException, IllegalAccessException, ClassNotFoundException { String[] daoarray=p.getProperty("dao").split(","); for(String dao:daoarray) { AbstractDao ad=(AbstractDao)Class.forName(dao).newInstance(); daoMap.put(ad.getID(),ad); } } public AbstractDao findDao(String id) {return daoMap.get(id);} } abstract class AbstractDao { public abstract String getID(); public abstract void insert(); public abstract void update(); } class SqlDao extends AbstractDao { public SqlDao() {} public String getID() {return "sql";} public void insert() {System.out.println("sql insert");} public void update() {System.out.println("sql update");} } class AccessDao extends AbstractDao { public AccessDao() {} public String getID() {return "access";} public void insert() {System.out.println("access insert");} public void update() {System.out.println("access update");} } And the content of the Test.properties is just one line: dao=net.SqlDao,net.SqlDao So any ont can tell me if this suitation is necessary?

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  • Producer/consumer in Grails?

    - by Mulone
    Hi all, I'm trying to implement a Consumer/Producer app in Grails, after several unsuccessful attempts at implementing concurrent threads. Basically I want to store all the events coming from a clients (through separate AJAX calls) in a single queue and then process such a queue in a linear way as soon as new events are added. This looks like a Producer/Consumer problem: http://en.wikipedia.org/wiki/Producer-consumer_problem How can I implement this in Grails (maybe with a timer or even better by generating an event 'process queue')? Basically I'd like to a have a singleton service waiting for new events in the queue and processing them linearly (even if the queue is loaded by several concurrent processes). Any hints? Cheers!

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  • Representing game states in Tic Tac Toe

    - by dacman
    The goal of the assignment that I'm currently working on for my Data Structures class is to create a of Quantum Tic Tac Toe with an AI that plays to win. Currently, I'm having a bit of trouble finding the most efficient way to represent states. Overview of current Structure: AbstractGame Has and manages AbstractPlayers (game.nextPlayer() returns next player by int ID) Has and intializes AbstractBoard at the beginning of the game Has a GameTree (Complete if called in initialization, incomplete otherwise) AbstractBoard Has a State, a Dimension, and a Parent Game Is a mediator between Player and State, (Translates States from collections of rows to a Point representation Is a StateConsumer AbstractPlayer Is a State Producer Has a ConcreteEvaluationStrategy to evaluate the current board StateTransveralPool Precomputes possible transversals of "3-states". Stores them in a HashMap, where the Set contains nextStates for a given "3-state" State Contains 3 Sets -- a Set of X-Moves, O-Moves, and the Board Each Integer in the set is a Row. These Integer values can be used to get the next row-state from the StateTransversalPool SO, the principle is Each row can be represented by the binary numbers 000-111, where 0 implies an open space and 1 implies a closed space. So, for an incomplete TTT board: From the Set<Integer> board perspective: X_X R1 might be: 101 OO_ R2 might be: 110 X_X R3 might be: 101, where 1 is an open space, and 0 is a closed space From the Set<Integer> xMoves perspective: X_X R1 might be: 101 OO_ R2 might be: 000 X_X R3 might be: 101, where 1 is an X and 0 is not From the Set<Integer> oMoves perspective: X_X R1 might be: 000 OO_ R2 might be: 110 X_X R3 might be: 000, where 1 is an O and 0 is not Then we see that x{R1,R2,R3} & o{R1,R2,R3} = board{R1,R2,R3} The problem is quickly generating next states for the GameTree. If I have player Max (x) with board{R1,R2,R3}, then getting the next row-states for R1, R2, and R3 is simple.. Set<Integer> R1nextStates = StateTransversalPool.get(R1); The problem is that I have to combine each one of those states with R1 and R2. Is there a better data structure besides Set that I could use? Is there a more efficient approach in general? I've also found Point<-State mediation cumbersome. Is there another approach that I could try there? Thanks! Here is the code for my ConcretePlayer class. It might help explain how players produce new states via moves, using the StateProducer (which might need to become StateFactory or StateBuilder). public class ConcretePlayerGeneric extends AbstractPlayer { @Override public BinaryState makeMove() { // Given a move and the current state, produce a new state Point playerMove = super.strategy.evaluate(this); BinaryState currentState = super.getInGame().getBoard().getState(); return StateProducer.getState(this, playerMove, currentState); } } EDIT: I'm starting with normal TTT and moving to Quantum TTT. Given the framework, it should be as simple as creating several new Concrete classes and tweaking some things.

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  • Factory Method Pattern using Generics-C#

    - by nanda
    Just I am learning Generics.When i have an Abstract Method pattern like : //Abstract Product interface IPage { string pageType(); } //Concerete Product 1 class ResumePage : IPage { public string pageType() { return "Resume Page"; } } //Concrete Product 2 class SummaryPage : IPage { public string pageType() { return "SummaryPage"; } } //Fcatory Creator class FactoryCreator { public IPage CreateOnRequirement(int i) { if (i == 1) return new ResumePage(); else { return new SummaryPage(); } } } //Client/Consumer void Main() { FactoryCreator c = new FactoryCreator(); IPage p; p = c.CreateOnRequirement(1); Console.WriteLine("Page Type is {0}", p.pageType()); p = c.CreateOnRequirement(2); Console.WriteLine("Page Type is {0}", p.pageType()); Console.ReadLine(); } how to convert the code using generics?

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  • Fluid Design bugs in ie7

    - by Qwibble
    Hey guys, I've created a dummy layout for my latest design, but when I resize the window in ie7 to check that the min-width works, it kicks the content area to below the sidebar, whereas in all other browsers (including ie6) it behaves exactly as it should do. Demo Link Can anyone see what the problem is that's causing this random couple extra pixels that kick it off?

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  • ViewModel updates after Model server roundtrip

    - by Pavel Savara
    I have stateless services and anemic domain objects on server side. Model between server and client is POCO DTO. The client should become MVVM. The model could be graph of about 100 instances of 20 different classes. The client editor contains diverse tab-pages all of them live-connected to model/viewmodel. My problem is how to propagate changes after server round-trip nice way. It's quite easy to propagate changes from ViewModel to DTO. For way back it would be possible to throw away old DTO and replace it whole with new one, but it will cause lot of redrawing for lists/DataTemplates. I could gather the server side changes and transmit them to client side. But the names of fields changed would be domain/DTO specific, not ViewModel specific. And the mapping seems nontrivial to me. If I should do it imperative way after round-trip, it would break SOC/modularity of viewModels. I'm thinking about some kind of mapping rule engine, something like automappper or emit mapper. But it solves just very plain use-cases. I don't see how it would map/propagate/convert adding items to list or removal. How to identify instances in collections so it could merge values to existing instances. As well it should propagate validation/error info. Maybe I should implement INotifyPropertyChanged on DTO and try to replay server side events on it ? And then bind ViewModel to it ? Would binding solve the problems with collection merges nice way ? Is EventAgregator from PRISM useful for that ? Is there any event record-replay component ? Is there better client side pattern for architecture with server side logic ?

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  • What's the best practice way to convert enum to string?

    - by dario
    Hi. I have enum like this: public enum ObectTypes { TypeOne, TypeTwo, TypeThree, ... TypeTwenty } then I need to convert this enum to string. Now Im doing this that way: public string ConvertToCustomTypeName(ObjectTypes typeObj) { string result = string.Empty; switch (typeObj) { case ObjectTypes.TypeOne: result = "This is type T123"; break; case ObjectTypes.TypeTwo: result = "This is type T234"; break; ... case ObjectTypes.TypeTwenty: result = "This is type last"; break; } return result; } Im quite sure that there is better way do do this, Im looking for some good practice solution. Thanks in advance.

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  • What is the best testing pattern for checking that parameters are being used properly?

    - by Joseph
    I'm using Rhino Mocks to try to verify that when I call a certain method, that the method in turn will properly group items and then call another method. Something like this: //Arrange var bucketsOfFun = new BucketGame(); var balls = new List<IBall> { new Ball { Color = Color.Red }, new Ball { Color = Color.Blue }, new Ball { Color = Color.Yellow }, new Ball { Color = Color.Orange }, new Ball { Color = Color.Orange } }; //Act bucketsOfFun.HaveFunWithBucketsAndBalls(balls); //Assert ??? Here is where the trouble begins for me. My method is doing something like this: public void HaveFunWithBucketsAndBalls(IList<IBall> balls) { //group all the balls together according to color var blueBalls = GetBlueBalls(balls); var redBalls = GetRedBalls(balls); // you get the idea HaveFunWithABucketOfBalls(blueBalls); HaveFunWithABucketOfBalls(redBalls); // etc etc with all the different colors } public void HaveFunWithABucketOfBalls(IList<IBall> colorSpecificBalls) { //doing some stuff here that i don't care about //for the test i'm writing right now } What I want to assert is that each time I call HaveFunWithABucketOfBalls that I'm calling it with a group of 1 red ball, then 1 blue ball, then 1 yellow ball, then 2 orange balls. If I can assert that behavior then I can verify that the method is doing what I want it to do, which is grouping the balls properly. Any ideas of what the best testing pattern for this would be?

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  • Is ASP.NET MVC is really MVC? Or how to separate model from controller?

    - by Andrey
    Hi all, This question is a bit rhetorical. At some point i got a feeling that ASP.NET MVC is not that authentic implementation of MVC pattern. Or i didn't understood it. Consider following domain: electric bulb, switch and motion detector. They are connected together and when you enter the room motion detector switches on the bulb. If i want to represent them as MVC: switch is model, because it holds the state and contains logic bulb is view, because it presents the state of model to human motion detector is controller, because it converts user actions to generic model commands Switch has one private field (On/Off) as a State and two methods (PressOn, PressOff). If you call PressOn when it is Off it goes to On, if you call it again state doesn't change. Bulb can be replaced with buzzer, motion detector with timer or button, but the model still represent the same logic. Eventually system will have same behavior. This is how i understand classical MVC decomposition, please correct me if i am wrong. Now let's decompose it in ASP.Net MVC way. Bulb is still a view Controller will be switch + motion detector Model is some object that will just pass state to bulb. So the logic that defines behavior moves to controller. Question 1: Is my understanding of MVC and ASP.NET MVC correct? Question 2: If yes, do you agree that ASP.NET MVC is not 100% accurate implementation? And back to life. The final question is how to separate model from controller in case of ASP.NET MVC. There can be two extremes. Controller does basic stuff and call model to do all the logic. Another is controller does all the logic and model is just something like class with properties that is mapped to DB. Question 3: Where should i draw the line between this extremes? How to balance? Thanks, Andrey

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  • Are Icon design UI guidelines still valid ?

    - by Pavel Lahoda
    Found UI guidelines of Launcher icon design http://d.android.com/guide/practices/ui_guidelines/icon_design.html but System Icons in recent Android releases doesn't seem to follow these guidelines (icons are flat instead simplified 3D perspective, as described in document). Are they already obsolete and what are the current guidelines ?

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  • How to avoid using this in a constructor

    - by Paralife
    I have this situation: interface MessageListener { void onMessageReceipt(Message message); } class MessageReceiver { MessageListener listener; public MessageReceiver(MessageListener listener, other arguments...) { this.listener = listener; } loop() { Message message = nextMessage(); listener.onMessageReceipt(message); } } and I want to avoid the following pattern: (Using the this in the Client constructor) class Client implements MessageListener { MessageReceiver receiver; MessageSender sender; public Client(...) { receiver = new MessageReceiver(this, other arguments...); sender = new Sender(...); } . . . @Override public void onMessageReceipt(Message message) { if(Message.isGood()) sender.send("Congrtulations"); else sender.send("Boooooooo"); } } The reason why i need the above functionality is because i want to call the sender inside the onMessageReceipt() function, for example to send a reply. But I dont want to pass the sender into a listener, so the only way I can think of is containing the sender in a class that implements the listener, hence the above resulting Client implementation. Is there a way to achive this without the use of 'this' in the constructor? It feels bizare and i dont like it, since i am passing myself to an object(MessageReceiver) before I am fully constructed. On the other hand, the MessageReceiver is not passed from outside, it is constructed inside, but does this 'purifies' the bizarre pattern? I am seeking for an alternative or an assurance of some kind that this is safe, or situations on which it might backfire on me.

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  • Which Code Should Go Where in MVC Structure

    - by Oguz
    My problem is in somewhere between model and controller.Everything works perfect for me when I use MVC just for crud (create, read, update, delete).I have separate models for each database table .I access these models from controller , to crud them . For example , in contacts application,I have actions (create, read, update, delete) in controller(contact) to use model's (contact) methods (create, read, update, delete). The problem starts when I try to do something more complicated. There are some complex processes which I do not know where should I put them. For example , in registering user process. I can not just finish this process in user model because , I have to use other models too (sending mails , creating other records for user via other models) and do lots of complex validations via other models. For example , in some complex searching processes , I have to access lots of models (articles, videos, images etc.) Or, sometimes , I have to use apis to decide what I will do next or which database model I will use to record data So where is the place to do this complicated processes. I do not want to do them in controllers , Because sometimes I should use these processes in other controllers too. And I do not want to put these process in models because , I use models as database access layers .May be I am wrong,I want to know . Thank you for your answer .

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  • Can you find a pattern to sync files knowing only dates and filenames?

    - by Robert MacLean
    Imagine if you will a operating system that had the following methods for files Create File: Creates (writes) a new file to disk. Calling this if a file exists causes a fault. Update File: Updates an existing file. Call this if a file doesn't exist causes a fault. Read File: Reads data from a file. Enumerate files: Gets all files in a folder. Files themselves in this operating system only have the following meta data: Created Time: The original date and time the file was created, by the Create File method. Modified Time: The date and time the file was last modified by the Update File method. If the file has never been modified, this will equal the Create Time. You have been given the task of writing an application which will sync the files between two directories (lets call them bill and ted) on a machine. However it is not that simple, the client has required that The application never faults (see methods above). That while the application is running the users can add and update files and those will be sync'd next time the application runs. Files can be added to either the ted or bill directories. File names cannot be altered. The application will perform one sync per time it is run. The application must be almost entirely in memory, in other words you cannot create a log of filenames and write that to disk and then check that the next time. The exception to point 6 is that you can store date and times between runs. Each date/time is associated with a key labeled A through J (so you have 10 to use) so you can compare keys between runs. There is no way to catch exceptions in the application. Answer will be accepted based on the following conditions: First answer to meet all requirements will be accepted. If there is no way to meet all requirements, the answer which ensures the smallest amount of missed changes per sync will be accepted. A bounty will be created (100 points) as soon as possible for the prize. The winner will be selected one day before the bounty ends. Please ask questions in the comments and I will gladly update and refine the question on those.

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