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  • C# Inheritence: Choosing what repository based on type of inherited class

    - by Oskar Kjellin
    I have been making a program that downloads information about movies from the internet. I have a base class Title, which represents all titles. Movie, Serie and Episode are inherited from that class. To save them to the database I have 2 services, MovieService and SerieService. They in turn call repositories, but that is not important here. I have a method Save(Title title) which I am not very happy with. I check for what type the title is and then call the correct service. I would like to perhaps write like this: ITitleService service = title.GetService(); title.GetSavedBy(service); So I have an abstract method on Title that returns an ITitleSaver, which will return the correct service for the instance. My question is how should I implement ITitleSaver? If I make it accept Title I will have to cast it to the correct type before calling the correct overload. Which will lead to having to deal with casting once again. What is the best approach to dealing with this? I would like to have the saving logic in the corresponding class.

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  • WPF tree data binding

    - by Am
    Hi, I have a well defined tree repository. Where I can rename items, move them up, down, etc. Add new and delete. The data is stored in a table as follows: Index Parent Label Left Right 1 0 root 1 14 2 1 food 2 7 3 2 cake 3 4 4 2 pie 5 6 5 1 flowers 8 13 6 5 roses 9 10 7 5 violets 11 12 Representing the following tree: (1) root (14) (2) food (7) (8) flowers (13) (3) cake (4) (5) pie (6) (9) roeses (10) (11) violets (12) or root food cake pie flowers roses violets Now, my problem is how to represent this in a bindable way, so that a TreeView can handle all the possible data changes? Renaming is easy, all I need is to make the label an updatble field. But what if a user moves flowers above food? I can make the relevant data changes, but they cause a complete data change to all other items in the tree. And all the examples I found of bindable hierarchies are good for non static trees.. So my current (and bad) solution is to reload the displayed tree after relocation change. Any direction will be good. Thanks

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  • Dependency injection and factory

    - by legenden
    Trying to figure out how to best handle the following scenario: Assume a RequestContext class which has a dependency to an external service, such as: public class RequestContext : IRequestContext { private readonly ServiceFactory<IWeatherService> _weatherService; public RequestContext(ServiceFactory<IWeatherService> weatherService, UserLocation location, string query) { _weatherService = weatherService; ... What sort of dependency should I require in the class that will ultimately instantiate RequestContext? It could be ServiceFactory<IWeatherService>, but that doesn't seem right, or I could create an IRequestContextFactory for it along the lines of: public class RequestContextFactory : IRequestContextFactory { private readonly ServiceFactory<IWeatherService> _weatherService; public RequestContextFactory(ServiceFactory<IWeatherService> weatherService) { _weatherService = weatherService; } public RequestContext Create(UserLocation location, string query) { return new RequestContext(_weatherService, location, query); } } And then pass the IRequestContextFactory through constructor injection. This seems like a good way to do it, but the problem with this approach is that I think it hinders discoverability (devs must know about the factory and implement it, which is not really apparent). Is there a better/more discoverable way that I'm missing?

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  • Is factory method proper design for my problem?

    - by metdos
    Hello Everyone, here is my problem and I'm considering to use factory method in C++, what are your opinions ? There are a Base Class and a lot of Subclasses. I need to transfer objects on network via TCP. I will create objects in first side, and using this object I will create a byte array TCP message, and send it to other side. On the other side I will decompose TCP message, I will create object and I will add this object to a polymorphic queue.

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  • In a DDD approach, is this example modelled correctly?

    - by Tag
    Just created an acc on SO to ask this :) Assuming this simplified example: building a web application to manage projects... The application has the following requirements/rules. 1) Users should be able to create projects inserting the project name. 2) Project names cannot be empty. 3) Two projects can't have the same name. I'm using a 4-layered architecture (User Interface, Application, Domain, Infrastructure). On my Application Layer i have the following ProjectService.cs class: public class ProjectService { private IProjectRepository ProjectRepo { get; set; } public ProjectService(IProjectRepository projectRepo) { ProjectRepo = projectRepo; } public void CreateNewProject(string name) { IList<Project> projects = ProjectRepo.GetProjectsByName(name); if (projects.Count > 0) throw new Exception("Project name already exists."); Project project = new Project(name); ProjectRepo.InsertProject(project); } } On my Domain Layer, i have the Project.cs class and the IProjectRepository.cs interface: public class Project { public int ProjectID { get; private set; } public string Name { get; private set; } public Project(string name) { ValidateName(name); Name = name; } private void ValidateName(string name) { if (name == null || name.Equals(string.Empty)) { throw new Exception("Project name cannot be empty or null."); } } } public interface IProjectRepository { void InsertProject(Project project); IList<Project> GetProjectsByName(string projectName); } On my Infrastructure layer, i have the implementation of IProjectRepository which does the actual querying (the code is irrelevant). I don't like two things about this design: 1) I've read that the repository interfaces should be a part of the domain but the implementations should not. That makes no sense to me since i think the domain shouldn't call the repository methods (persistence ignorance), that should be a responsability of the services in the application layer. (Something tells me i'm terribly wrong.) 2) The process of creating a new project involves two validations (not null and not duplicate). In my design above, those two validations are scattered in two different places making it harder (imho) to see whats going on. So, my question is, from a DDD perspective, is this modelled correctly or would you do it in a different way?

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  • XSLT fails to load huge XML doc after matching certain elements

    - by krisvandenbergh
    I'm trying to match certain elements using XSLT. My input document is very large and the source XML fails to load after processing the following code (consider especially the first line). <xsl:template match="XMI/XMI.content/Model_Management.Model/Foundation.Core.Namespace.ownedElement/Model_Management.Package/Foundation.Core.Namespace.ownedElement"> <rdf:RDF> <rdf:Description rdf:about=""> <xsl:for-each select="Foundation.Core.Class"> <xsl:for-each select="Foundation.Core.ModelElement.name"> <owl:Class rdf:ID="@Foundation.Core.ModelElement.name" /> </xsl:for-each> </xsl:for-each> </rdf:Description> </rdf:RDF> </xsl:template> Apparently the XSLT fails to load after "Model_Management.Model". The PHP code is as follows: if ($xml->loadXML($source_xml) == false) { die('Failed to load source XML: ' . $http_file); } It then fails to perform loadXML and immediately dies. I think there are two options now. 1) I should set a maximum executing time. Frankly, I don't know how that I do this for the built-in PHP 5 XSLT processor. 2) Think about another way to match. What would be the best way to deal with this? The input document can be found at http://krisvandenbergh.be/uml_pricing.xml Any help would be appreciated! Thanks.

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  • Factory Method and Cyclic Dependancy

    - by metdos
    If I'm not wrong, because of its nature in factory method there is cyclic dependency: Base class needs to know subclasses because it creates them, and subclasses need to know base class. Having cyclic dependency is bad programming practice, is not it? Practically I implemented a factory, I have problem above, even I added #ifndef MYCLASS_H #define MYCLASS_H #endif I'm still getting Compiler Error C2504 'class' : base class undefined And this error disappers when I remove subclass include from base class header.

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  • get particular string using regex java

    - by hussain
    i want to know how to get the string from group of string String j = "<a href=\"/watch?v=4Qx-lBqOqiQ&feature=popular\" onclick=\"\" onmousedown=\"yt.analytics.urchinTracker(\'/Events/Home/PersonalizedHome/POP/Logged_Out');\" ><span class=\"video-thumb video-thumb-220 \" id=\"video-thumb-4Qx-lBqOqiQ-8821469\"><img src=\"http://i1.ytimg.com/vi/4Qx-lBqOqiQ/hqdefault.jpg\" class=\"vimg220\" alt=\"Dog Squirrel Chasing A Squirrel\" title=\"Dog Squirrel Chasing A Squirrel\" onclick=\";yt.www.watch.watch5.IEshenanigans(event, this)\"><span class=\"video-time\"><span>1:08</span></span><span class=\"video-actions\"><button class=\"yt-uix-button-short yt-uix-button yt-uix-button-arrowbutton\" onclick=\"; return false;\" type=\"button\"> <img class=\"yt-uix-button-arrow\" src=\"http://s.ytimg.com/yt/img/pixel-vfl73.gif\" alt=\"\"> hai</a>"; i want to get the string href=\"/watch?v=4Qx-lBqOqiQ&feature=popular\" and src=\"http://i1.ytimg.com/vi/4Qx-lBqOqiQ/hqdefault.jpg\" thanks and advance

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  • What is the appropriate terminology in Java when building remote proxies?

    - by Uri
    Suppose that I am implementing a remote proxy in Java to an object that is likely to reside on a remote server but may reside locally. There's my real object on the remote server, there's the local implementation (the proxy itself), and there's the interface I provide to my program which hides the details of where the object actually is. The local representation may contact a local or a remote implementation of the object. What is the standard terminology in Java for these things? What should I name my interfaces/classes? I've seen the terms Subjects, Images, and Implementations thrown around (probably from the GOF days), but I wonder what is acceptable way to do the naming for a framework written in Java.

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  • Excel Matching problem with logic expression

    - by abelenky
    (I understand Excel is only borderline programming) I have a block of data that represents the steps in a process and the possible errors: ProcessStep Status FeesPaid OK FormRecvd OK RoleAssigned OK CheckedIn Not Checked In. ReadyToStart Not Ready for Start I want to find the first Status that is not "OK". I have attempted this: =Match("<>""OK""", StatusRange, 0) which is supposed to return the index of the first element in the range that is NOT-EQUAL (<) to "OK" But this doesn't work, instead returning #N/A. I expect it to return 4 (index #4, in a 1-based index, representing that CheckedIn is the first non-OK element) Any ideas how to do this?

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  • Managing Strategy objects with Hibernate & Spring

    - by Francois
    This is a design question better explained with a Stack Overflow analogy: Users can earn Badges. Users, Badges and Earned Badges are stored in the database. A Badge’s logic is run by a Badge Condition Strategy. I would prefer not to have to store Badge Condition Strategies in the database, because they are complex tree structure objects. How do I associate a Badge stored in the database with its Badge Condition Strategy? I can only think of workaround solutions. For example: create 1 class per badge and use a SINGLE_TABLE inheritance strategy. Or get the badge from the database, and then programmatically lookup and inject the correct Badge Condition Strategy. Thanks for suggesting a better design.

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  • How to engineer features for machine learning

    - by Ivo Danihelka
    Do you have some advices or reading how to engineer features for a machine learning task? Good input features are important even for a neural network. The chosen features will affect the needed number of hidden neurons and the needed number of training examples. The following is an example problem, but I'm interested in feature engineering in general. A motivation example: What would be a good input when looking at a puzzle (e.g., 15-puzzle or Sokoban)? Would it be possible to recognize which of two states is closer to the goal?

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  • Understanding Domain Driven Design

    - by Nihilist
    Hi I have been trying to understand DDD for few weeks now. Its very confusing. I dont understand how I organise my projects. I have lot of questions on UnitOfWork, Repository, Associations and the list goes on... Lets take a simple example. Album and Tracks. Album: AlbumId, Name, ListOf Tracks Tracks: TrackId, Name Question1: Should i expose Tracks as a IList/IEnumerabe property on Album ? If that how do i add an album ? OR should i expose a ReadOnlyCollection of Tracks and expose a AddTrack method? Question2: How do i load Tracks for Album [assuming lazy loading]? should the getter check for null and then use a repository to load the tracks if need be? Question3: How do we organise the assemblies. Like what does each assembly have? Model.dll - does it only have the domain entities? Where do the repositories go? Interfaces and implementations both. Can i define IAlbumRepository in Model.dll? Infrastructure.dll : what shold this have? Question4: Where is unit of work defined? How do repository and unit of work communicate? [ or should they ] for example. if i need to add multiple tracks to album, again should this be defined as AddTrack on Album OR should there a method in the repository? Regardless of where the method is, how do I implement unit of work here? Question5: Should the UI use Infrastructure..dll or should there be ServiceLayer? Do my quesitons make sense? Regards

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  • "Session is Closed!" - NHibernate

    - by Alexis Abril
    This is in a web application environment: An initial request is able to successfully complete, however any additional requests return a "Session is Closed" response from the NHibernate framework. I'm using a HttpModule approach with the following code: public class MyHttpModule : IHttpModule { public void Init(HttpApplication context) { context.EndRequest += ApplicationEndRequest; context.BeginRequest += ApplicationBeginRequest; } public void ApplicationBeginRequest(object sender, EventArgs e) { CurrentSessionContext.Bind(SessionFactory.Instance.OpenSession()); } public void ApplicationEndRequest(object sender, EventArgs e) { ISession currentSession = CurrentSessionContext.Unbind( SessionFactory.Instance); currentSession.Dispose(); } public void Dispose() { } } SessionFactory.Instance is my singleton implementation, using FluentNHibernate to return an ISessionFactory object. In my repository class, I attempt to use the following syntax: public class MyObjectRepository : IMyObjectRepository { public MyObject GetByID(int id) { using (ISession session = SessionFactory.Instance.GetCurrentSession()) return session.Get<MyObject>(id); } } This allows code in the application to be called as such: IMyObjectRepository repo = new MyObjectRepository(); MyObject obj = repo.GetByID(1); I have a suspicion my repository code is to blame, but I'm not 100% sure on the actual implementation I should be using. I found a similar issue on SO here. I too am using WebSessionContext in my implementation, however, no solution was provided other than writing a custom SessionManager. For simple CRUD operations, is a custom session provider required apart from the built in tools(ie WebSessionContext)?

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  • Regular expression to match one of two video ID's in a Google Video URL

    - by Baldur
    I need to grab the video ID from a Google Video URL. There are two different types of URLs that I need to be able to match: http://video.google.com/videoplay?docid=-3498228245415745977# where I need to be able to match -3498228245415745977 (note the dash; -), and video.google.com/videoplay?docid=-3498228245415745977#docid=2728972720932273543 where I need to match 2728972720932273543. Is there any good regular expression that can match this? This is what I've got so far: @"docid=(-?\d{19}+)" since the video ID seems to be 19 characters except when it's prefixed with the dash. I'm using C# (of which I have very little experience) if that changes anything. P.s. I would also appreciate you review my regular expressions for YouTube (@"[\?&]v=([^&#])";), RedTube (@"/(\d{1,6})") and Vimeo (@"/(\d*)"). I do not expect users to enter the full URL and thus do not match the ^http://\\.?sitename+\\.\\w{2,3}.

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  • Entity Framework Generic Repository Error

    - by Jeff Ancel
    I am trying to create a very generic generics repository for my Entity Framework repository that has the basic CRUD statements and uses an Interface. I have hit a brick wall head first and been knocked over. Here is my code, written in a console application, using a Entity Framework Model, with a table named Hurl. Simply trying to pull back the object by its ID. Here is the full application code. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data.Objects; using System.Linq.Expressions; using System.Reflection; using System.Data.Objects.DataClasses; namespace GenericsPlay { class Program { static void Main(string[] args) { var hs = new HurlRepository(new hurladminEntity()); var hurl = hs.Load<Hurl>(h => h.Id == 1); Console.Write(hurl.ShortUrl); Console.ReadLine(); } } public interface IHurlRepository { T Load<T>(Expression<Func<T, bool>> expression); } public class HurlRepository : IHurlRepository, IDisposable { private ObjectContext _objectContext; public HurlRepository(ObjectContext objectContext) { _objectContext = objectContext; } public ObjectContext ObjectContext { get { return _objectContext; } } private Type GetBaseType(Type type) { Type baseType = type.BaseType; if (baseType != null && baseType != typeof(EntityObject)) { return GetBaseType(type.BaseType); } return type; } private bool HasBaseType(Type type, out Type baseType) { Type originalType = type.GetType(); baseType = GetBaseType(type); return baseType != originalType; } public IQueryable<T> GetQuery<T>() { Type baseType; if (HasBaseType(typeof(T), out baseType)) { return this.ObjectContext.CreateQuery<T>("[" + baseType.Name.ToString() + "]").OfType<T>(); } else { return this.ObjectContext.CreateQuery<T>("[" + typeof(T).Name.ToString() + "]"); } } public T Load<T>(Expression<Func<T, bool>> whereCondition) { return this.GetQuery<T>().Where(whereCondition).First(); } public void Dispose() { if (_objectContext != null) { _objectContext.Dispose(); } } } } Here is the error that I am getting: System.Data.EntitySqlException was unhandled Message="'Hurl' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly., near escaped identifier, line 3, column 1." Source="System.Data.Entity" Column=1 ErrorContext="escaped identifier" ErrorDescription="'Hurl' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly." This is where I am attempting to extract this information from. http://blog.keithpatton.com/2008/05/29/Polymorphic+Repository+For+ADONet+Entity+Framework.aspx

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  • Repository vs Data Access

    - by vdh_ant
    Hi guys In the context of the n-tier application, is there a difference between what you would consider your data access classes to be and your repositories? I tend to think yes but I just wanted to see what other thought. My thinking is that the job of the repository is just to contain and execute the raw query itself, where as the data access class would create the context, execute the repository (passing in the context), handle mapping the data model to the domain model and return the result back up... What do you guys think? Also do you see any of this changing in a Linq to XML scenario (assuming that you change the context for the relevant XDocument)? Cheers Anthony

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  • C#/ASP.NET MVC 4 Instantiate Object Derived From Interface In Factory Method

    - by Chris
    Currently have a Factory class that features a GetSelector function, which returns a concrete implementation of ISelector. I have several different classes that implement ISelector and based on a setting I would like to receive the appropriate ISelector back. public interface ISelector { string GetValue(string Params); } public class XmlSelector : ISelector { public string GetValue(string Params) { // open XML file and get value } } public static class SelectorFactory { public static ISelector GetSelector() { return new XmlSelector(); // Needs changing to look at settings } } My question is what is the best way to store the setting? I am aware of using AppSettings etc. but I'm not sure whether I want to have to store strings in the web.config and perform a switch on it - just seems to be really tightly coupled in that if a new implementation of ISelector is made, then the Factory would need to be changed. Is there any way of perhaps storing an assembly name and instantiating based on that? Thanks, Chris

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  • How to make a Generic Repository?

    - by chobo2
    Hi I am wondering if anyone has any good tutorials(or maybe even a library that is already made and well documented) on making a generic repository. I am using currently linq to sql but it might change so I don't know if you can make a generic repository that would take little to no changes if I would say switch to entity framework. Thanks

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  • Supporting more than one codebase in ANSI-C

    - by Ilker Murat Karakas
    I am working on a project, with an associated Ansi-C code base. (let me call this the 'main' codebase). I now am confronted with a typical problem (stated below), which I believe I would be able to solve much easily if I had an object-oriented language at hand. The problem is this: I will have to start more than one codebases; i.e. I will have to start supporting a parallel codebase (even maybe more in the future). The initial codebases for all the new (i.e. parallel) codebases will initially be identical as the old (i.e. 'main') codebase. As we are talking about the 'C' language, I have till now been thinking of adding '#ifdef' statements to code, and writing the branch-spacific code inside those 'ifdef' blocks. Hoping that I made the problem clear (enough!), I would like to hear thoughts on clever patterns that would help me handle this problem elegantly in Ansi C. Cheers

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  • Finding partial substrings within a string

    - by Peter Chang
    I have two strings which must be compared for similarity. The algorithm must be designed to find the maximal similarity. In this instance, the ordering matters, but intervening (or missing) characters do not. Edit distance cannot be used in this case for various reasons. The situation is basically as follows: string 1: ABCDEFG string 2: AFENBCDGRDLFG the resulting algorithm would find the substrings A, BCD, FG I currently have a recursive solution, but because this must be run on massive amounts of data, any improvements would be greatly appreciated

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  • A maximum character limit on the preg functions?

    - by animuson
    On my site I use output buffering to grab all the output and then run it through a process function before sending it out to the browser (I don't replace anything, just break it into more manageable pieces). In this particular case, there is a massive amount of output because it is listing out a label for every country in the database (around 240 countries). The problem is that in full, my preg_match functions seems to get skipped over, it does absolutely nothing and returns no matches. However, if I remove parts of the labels (no particular part, just random pieces to reduce characters) then the preg_match functions works again. It doesn't seem to matter what I remove from the label, it just seems to be that as long as I remove so many characters. Is there some sort of cap on what the preg functions can handle or will it time out if there is too much data to be scanned over?

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  • MVVM- View Model-View Model Communications

    - by user275561
    How do I go about having two view models communicate with one another using MVVM Light. I know how to use the messenger class and register etc.. Here is my Scenario A Settings View ---> a Settings View Model . . . A MainPage View ---> A MainPage ViewModel If something changes in the Settings View it will Message back to the Settings View Model. So then I want the Settings View Model to communicate to the MainPage View Model about what changed. THe MainPage ViewModel will then tell the View.

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  • Is there anything wrong with my Factory class?

    - by Alex
    class PieceFactory { @SuppressWarnings("rawtypes") public Piece createPiece(String pieceType) throws Throwable{ Class pieceClass = Class.forName(pieceType); Piece piece = (Piece) pieceClass.newInstance(); return piece; } } I'm not all used to handling exceptions yet therefore I'm just throwing them, but everywhere I use a method that uses this factory it tells me I have to throw exceptions like throwable. For example, in one of my classes I have a method that instantiates a lot of objects using the method that uses the factory. I can use the method in that class by just throwing the exception, however it won't work if I try to pass a reference to that class to another class and then use the method from there. Then it forces me to try catch the exception. I probably don't need a factory but it seemed interesting and I'd like to try to use patterns. The reason I created the factory was that I have 6 subclasses of Piece and I wan't to use a method to instantiate them by passing the type of subclass I want as an argument to the method.

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