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  • Where does the 'method' implementation go? (I'm a newbie)

    - by Spokane-Dude
    I have this code: #import "SQLiteDB.h" @implementation SQLiteDB @synthesize db, dbPath, databaseKey; @end //-------------- check for database or create it ----------------| - (void)checkForDatabase { NSFileManager *filemanager = [NSFileManager defaultManager]; NSString *databasePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingString:@"/ppcipher.s3db"]; if(![filemanager fileExistsAtPath:databasePath]) { //Database doesn't exist yet, so we create it... NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingString:@"/ppcipher.s3db"]; sqlite3 *db; if(sqlite3_open(databasePath, db) == SQLITE_OK) { } } } It's complaining that "method definition not in @implementation context". So where does it go? (I tried in the .h file, but still get the error)

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  • Looking to Implement/Upgrade Your MDM Solution? OOW Has the Session For You

    - by Mala Narasimharajan
    By Bala Mahalingam  Hurray!  Oracle Open World next week.  Oh my God!  I need to plan my calendar for MDM focused sessions. The implementation/upgrade of Oracle Master Data Management solution is an art & science combined. This year at Open World, we have a dedicated session focused on sharing two great implementation stories of Oracle Customer Hub. Also hear from Oracle on the implementation/upgrade approach and methodology for Oracle Master Data Management and Data Quality applications. Here are some of the questions that you might be thinking around the implementation of Oracle MDM solution. If you are in the process of implementation / upgrade or evaluating the options for implementation of MDM solution and you would like to hear directly from T-Mobile and Sony on their roadmap and implementation experience, then I would highly recommend this session.     Hope to see you at Oracle Open World 2012 and stay in touch via our future blogs. Look here for a list of all the MDM sessions at OpenWorld.

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  • Is this how dynamic language copes with dynamic requirement?

    - by Amumu
    The question is in the title. I want to have my thinking verified by experienced people. You can add more or disregard my opinion, but give me a reason. Here is an example requirement: Suppose you are required to implement a fighting game. Initially, the game only includes fighters, who can attack each other. Each fighter can punch, kick or block incoming attacks. Fighters can have various fighting styles: Karate, Judo, Kung Fu... That's it for the simple universe of the game. In an OO like Java, it can be implemented similar to this way: abstract class Fighter { int hp, attack; void punch(Fighter otherFighter); void kick(Fighter otherFighter); void block(Figther otherFighter); }; class KarateFighter extends Fighter { //...implementation...}; class JudoFighter extends Fighter { //...implementation... }; class KungFuFighter extends Fighter { //...implementation ... }; This is fine if the game stays like this forever. But, somehow the game designers decide to change the theme of the game: instead of a simple fighting game, the game evolves to become a RPG, in which characters can not only fight but perform other activities, i.e. the character can be a priest, an accountant, a scientist etc... At this point, to make it more generic, we have to change the structure of our original design: Fighter is not used to refer to a person anymore; it refers to a profession. The specialized classes of Fighter (KaraterFighter, JudoFighter, KungFuFighter) . Now we have to create a generic class named Person. However, to adapt this change, I have to change the method signatures of the original operations: class Person { int hp, attack; List<Profession> skillSet; }; abstract class Profession {}; class Fighter extends Profession { void punch(Person otherFighter); void kick(Person otherFighter); void block(Person otherFighter); }; class KarateFighter extends Fighter { //...implementation...}; class JudoFighter extends Fighter { //...implementation... }; class KungFuFighter extends Fighter { //...implementation ... }; class Accountant extends Profession { void calculateTax(Person p) { //...implementation...}; void calculateTax(Company c) { //...implementation...}; }; //... more professions... Here are the problems: To adapt to the method changes, I have to fix the places where the changed methods are called (refactoring). Every time a new requirement is introduced, the current structural design has to be broken to adapt the changes. This leads to the first problem. Rigid structure makes it hard for code reuse. A function can only accept the predefined types, but it cannot accept future unknown types. A written function is bound to its current universe and has no way to accommodate to the new types, without modifications or rewrite from scratch. I see Java has a lot of deprecated methods. OO is an extreme case because it has inheritance to add up the complexity, but in general for statically typed language, types are very strict. In contrast, a dynamic language can handle the above case as follow: ;;fighter1 punch fighter2 (defun perform-punch (fighter1 fighter2) ...implementation... ) ;;fighter1 kick fighter2 (defun perform-kick (fighter1 fighter2) ...implementation... ) ;;fighter1 blocks attacks from fighter2 (defun perform-block (fighter1 fighter2) ...implementation... ) fighter1 and fighter2 can be anything as long as it has the required data for calculation; or methods (duck typing). You don't have to change from the type Fighter to Person. In the case of Lisp, because Lisp only has a single data structure: list, it's even easier to adapt to changes. However, other dynamic languages can have similar behaviors as well. I work primarily with static languages (mainly C and Java, but working with Java was a long time ago). I started learning Lisp and some other dynamic languages this year. I can see how it helps improving my productivity.

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  • Adding SQL Cache Dependencies to the Loosely coupled .NET Cache Provider

    - by Rhames
    This post adds SQL Cache Dependency support to the loosely coupled .NET Cache Provider that I described in the previous post (http://geekswithblogs.net/Rhames/archive/2012/09/11/loosely-coupled-.net-cache-provider-using-dependency-injection.aspx). The sample code is available on github at https://github.com/RobinHames/CacheProvider.git. Each time we want to apply a cache dependency to a call to fetch or cache a data item we need to supply an instance of the relevant dependency implementation. This suggests an Abstract Factory will be useful to create cache dependencies as needed. We can then use Dependency Injection to inject the factory into the relevant consumer. Castle Windsor provides a typed factory facility that will be utilised to implement the cache dependency abstract factory (see http://docs.castleproject.org/Windsor.Typed-Factory-Facility-interface-based-factories.ashx). Cache Dependency Interfaces First I created a set of cache dependency interfaces in the domain layer, which can be used to pass a cache dependency into the cache provider. ICacheDependency The ICacheDependency interface is simply an empty interface that is used as a parent for the specific cache dependency interfaces. This will allow us to place a generic constraint on the Cache Dependency Factory, and will give us a type that can be passed into the relevant Cache Provider methods. namespace CacheDiSample.Domain.CacheInterfaces { public interface ICacheDependency { } }   ISqlCacheDependency.cs The ISqlCacheDependency interface provides specific SQL caching details, such as a Sql Command or a database connection and table. It is the concrete implementation of this interface that will be created by the factory in passed into the Cache Provider. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace CacheDiSample.Domain.CacheInterfaces { public interface ISqlCacheDependency : ICacheDependency { ISqlCacheDependency Initialise(string databaseConnectionName, string tableName); ISqlCacheDependency Initialise(System.Data.SqlClient.SqlCommand sqlCommand); } } If we want other types of cache dependencies, such as by key or file, interfaces may be created to support these (the sample code includes an IKeyCacheDependency interface). Modifying ICacheProvider to accept Cache Dependencies Next I modified the exisitng ICacheProvider<T> interface so that cache dependencies may be passed into a Fetch method call. I did this by adding two overloads to the existing Fetch methods, which take an IEnumerable<ICacheDependency> parameter (the IEnumerable allows more than one cache dependency to be included). I also added a method to create cache dependencies. This means that the implementation of the Cache Provider will require a dependency on the Cache Dependency Factory. It is pretty much down to personal choice as to whether this approach is taken, or whether the Cache Dependency Factory is injected directly into the repository or other consumer of Cache Provider. I think, because the cache dependency cannot be used without the Cache Provider, placing the dependency on the factory into the Cache Provider implementation is cleaner. ICacheProvider.cs using System; using System.Collections.Generic;   namespace CacheDiSample.Domain.CacheInterfaces { public interface ICacheProvider<T> { T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry); T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry, IEnumerable<ICacheDependency> cacheDependencies);   IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry); IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry, IEnumerable<ICacheDependency> cacheDependencies);   U CreateCacheDependency<U>() where U : ICacheDependency; } }   Cache Dependency Factory Next I created the interface for the Cache Dependency Factory in the domain layer. ICacheDependencyFactory.cs namespace CacheDiSample.Domain.CacheInterfaces { public interface ICacheDependencyFactory { T Create<T>() where T : ICacheDependency;   void Release<T>(T cacheDependency) where T : ICacheDependency; } }   I used the ICacheDependency parent interface as a generic constraint on the create and release methods in the factory interface. Now the interfaces are in place, I moved on to the concrete implementations. ISqlCacheDependency Concrete Implementation The concrete implementation of ISqlCacheDependency will need to provide an instance of System.Web.Caching.SqlCacheDependency to the Cache Provider implementation. Unfortunately this class is sealed, so I cannot simply inherit from this. Instead, I created an interface called IAspNetCacheDependency that will provide a Create method to create an instance of the relevant System.Web.Caching Cache Dependency type. This interface is specific to the ASP.NET implementation of the Cache Provider, so it should be defined in the same layer as the concrete implementation of the Cache Provider (the MVC UI layer in the sample code). IAspNetCacheDependency.cs using System.Web.Caching;   namespace CacheDiSample.CacheProviders { public interface IAspNetCacheDependency { CacheDependency CreateAspNetCacheDependency(); } }   Next, I created the concrete implementation of the ISqlCacheDependency interface. This class also implements the IAspNetCacheDependency interface. This concrete implementation also is defined in the same layer as the Cache Provider implementation. AspNetSqlCacheDependency.cs using System.Web.Caching; using CacheDiSample.Domain.CacheInterfaces;   namespace CacheDiSample.CacheProviders { public class AspNetSqlCacheDependency : ISqlCacheDependency, IAspNetCacheDependency { private string databaseConnectionName;   private string tableName;   private System.Data.SqlClient.SqlCommand sqlCommand;   #region ISqlCacheDependency Members   public ISqlCacheDependency Initialise(string databaseConnectionName, string tableName) { this.databaseConnectionName = databaseConnectionName; this.tableName = tableName; return this; }   public ISqlCacheDependency Initialise(System.Data.SqlClient.SqlCommand sqlCommand) { this.sqlCommand = sqlCommand; return this; }   #endregion   #region IAspNetCacheDependency Members   public System.Web.Caching.CacheDependency CreateAspNetCacheDependency() { if (sqlCommand != null) return new SqlCacheDependency(sqlCommand); else return new SqlCacheDependency(databaseConnectionName, tableName); }   #endregion   } }   ICacheProvider Concrete Implementation The ICacheProvider interface is implemented by the CacheProvider class. This implementation is modified to include the changes to the ICacheProvider interface. First I needed to inject the Cache Dependency Factory into the Cache Provider: private ICacheDependencyFactory cacheDependencyFactory;   public CacheProvider(ICacheDependencyFactory cacheDependencyFactory) { if (cacheDependencyFactory == null) throw new ArgumentNullException("cacheDependencyFactory");   this.cacheDependencyFactory = cacheDependencyFactory; }   Next I implemented the CreateCacheDependency method, which simply passes on the create request to the factory: public U CreateCacheDependency<U>() where U : ICacheDependency { return this.cacheDependencyFactory.Create<U>(); }   The signature of the FetchAndCache helper method was modified to take an additional IEnumerable<ICacheDependency> parameter:   private U FetchAndCache<U>(string key, Func<U> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry, IEnumerable<ICacheDependency> cacheDependencies) and the following code added to create the relevant System.Web.Caching.CacheDependency object for any dependencies and pass them to the HttpContext Cache: CacheDependency aspNetCacheDependencies = null;   if (cacheDependencies != null) { if (cacheDependencies.Count() == 1) // We know that the implementations of ICacheDependency will also implement IAspNetCacheDependency // so we can use a cast here and call the CreateAspNetCacheDependency() method aspNetCacheDependencies = ((IAspNetCacheDependency)cacheDependencies.ElementAt(0)).CreateAspNetCacheDependency(); else if (cacheDependencies.Count() > 1) { AggregateCacheDependency aggregateCacheDependency = new AggregateCacheDependency(); foreach (ICacheDependency cacheDependency in cacheDependencies) { // We know that the implementations of ICacheDependency will also implement IAspNetCacheDependency // so we can use a cast here and call the CreateAspNetCacheDependency() method aggregateCacheDependency.Add(((IAspNetCacheDependency)cacheDependency).CreateAspNetCacheDependency()); } aspNetCacheDependencies = aggregateCacheDependency; } }   HttpContext.Current.Cache.Insert(key, value, aspNetCacheDependencies, absoluteExpiry.Value, relativeExpiry.Value);   The full code listing for the modified CacheProvider class is shown below: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Caching; using CacheDiSample.Domain.CacheInterfaces;   namespace CacheDiSample.CacheProviders { public class CacheProvider<T> : ICacheProvider<T> { private ICacheDependencyFactory cacheDependencyFactory;   public CacheProvider(ICacheDependencyFactory cacheDependencyFactory) { if (cacheDependencyFactory == null) throw new ArgumentNullException("cacheDependencyFactory");   this.cacheDependencyFactory = cacheDependencyFactory; }   public T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) { return FetchAndCache<T>(key, retrieveData, absoluteExpiry, relativeExpiry, null); }   public T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry, IEnumerable<ICacheDependency> cacheDependencies) { return FetchAndCache<T>(key, retrieveData, absoluteExpiry, relativeExpiry, cacheDependencies); }   public IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) { return FetchAndCache<IEnumerable<T>>(key, retrieveData, absoluteExpiry, relativeExpiry, null); }   public IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry, IEnumerable<ICacheDependency> cacheDependencies) { return FetchAndCache<IEnumerable<T>>(key, retrieveData, absoluteExpiry, relativeExpiry, cacheDependencies); }   public U CreateCacheDependency<U>() where U : ICacheDependency { return this.cacheDependencyFactory.Create<U>(); }   #region Helper Methods   private U FetchAndCache<U>(string key, Func<U> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry, IEnumerable<ICacheDependency> cacheDependencies) { U value; if (!TryGetValue<U>(key, out value)) { value = retrieveData(); if (!absoluteExpiry.HasValue) absoluteExpiry = Cache.NoAbsoluteExpiration;   if (!relativeExpiry.HasValue) relativeExpiry = Cache.NoSlidingExpiration;   CacheDependency aspNetCacheDependencies = null;   if (cacheDependencies != null) { if (cacheDependencies.Count() == 1) // We know that the implementations of ICacheDependency will also implement IAspNetCacheDependency // so we can use a cast here and call the CreateAspNetCacheDependency() method aspNetCacheDependencies = ((IAspNetCacheDependency)cacheDependencies.ElementAt(0)).CreateAspNetCacheDependency(); else if (cacheDependencies.Count() > 1) { AggregateCacheDependency aggregateCacheDependency = new AggregateCacheDependency(); foreach (ICacheDependency cacheDependency in cacheDependencies) { // We know that the implementations of ICacheDependency will also implement IAspNetCacheDependency // so we can use a cast here and call the CreateAspNetCacheDependency() method aggregateCacheDependency.Add( ((IAspNetCacheDependency)cacheDependency).CreateAspNetCacheDependency()); } aspNetCacheDependencies = aggregateCacheDependency; } }   HttpContext.Current.Cache.Insert(key, value, aspNetCacheDependencies, absoluteExpiry.Value, relativeExpiry.Value);   } return value; }   private bool TryGetValue<U>(string key, out U value) { object cachedValue = HttpContext.Current.Cache.Get(key); if (cachedValue == null) { value = default(U); return false; } else { try { value = (U)cachedValue; return true; } catch { value = default(U); return false; } } }   #endregion } }   Wiring up the DI Container Now the implementations for the Cache Dependency are in place, I wired them up in the existing Windsor CacheInstaller. First I needed to register the implementation of the ISqlCacheDependency interface: container.Register( Component.For<ISqlCacheDependency>() .ImplementedBy<AspNetSqlCacheDependency>() .LifestyleTransient());   Next I registered the Cache Dependency Factory. Notice that I have not implemented the ICacheDependencyFactory interface. Castle Windsor will do this for me by using the Type Factory Facility. I do need to bring the Castle.Facilities.TypedFacility namespace into scope: using Castle.Facilities.TypedFactory;   Then I registered the factory: container.AddFacility<TypedFactoryFacility>();   container.Register( Component.For<ICacheDependencyFactory>() .AsFactory()); The full code for the CacheInstaller class is: using Castle.MicroKernel.Registration; using Castle.MicroKernel.SubSystems.Configuration; using Castle.Windsor; using Castle.Facilities.TypedFactory;   using CacheDiSample.Domain.CacheInterfaces; using CacheDiSample.CacheProviders;   namespace CacheDiSample.WindsorInstallers { public class CacheInstaller : IWindsorInstaller { public void Install(IWindsorContainer container, IConfigurationStore store) { container.Register( Component.For(typeof(ICacheProvider<>)) .ImplementedBy(typeof(CacheProvider<>)) .LifestyleTransient());   container.Register( Component.For<ISqlCacheDependency>() .ImplementedBy<AspNetSqlCacheDependency>() .LifestyleTransient());   container.AddFacility<TypedFactoryFacility>();   container.Register( Component.For<ICacheDependencyFactory>() .AsFactory()); } } }   Configuring the ASP.NET SQL Cache Dependency There are a couple of configuration steps required to enable SQL Cache Dependency for the application and database. From the Visual Studio Command Prompt, the following commands should be used to enable the Cache Polling of the relevant database tables: aspnet_regsql -S <servername> -E -d <databasename> –ed aspnet_regsql -S <servername> -E -d CacheSample –et –t <tablename>   (The –t option should be repeated for each table that is to be made available for cache dependencies). Finally the SQL Cache Polling needs to be enabled by adding the following configuration to the <system.web> section of web.config: <caching> <sqlCacheDependency pollTime="10000" enabled="true"> <databases> <add name="BloggingContext" connectionStringName="BloggingContext"/> </databases> </sqlCacheDependency> </caching>   (obviously the name and connection string name should be altered as required). Using a SQL Cache Dependency Now all the coding is complete. To specify a SQL Cache Dependency, I can modify my BlogRepositoryWithCaching decorator class (see the earlier post) as follows: public IList<Blog> GetAll() { var sqlCacheDependency = cacheProvider.CreateCacheDependency<ISqlCacheDependency>() .Initialise("BloggingContext", "Blogs");   ICacheDependency[] cacheDependencies = new ICacheDependency[] { sqlCacheDependency };   string key = string.Format("CacheDiSample.DataAccess.GetAll");   return cacheProvider.Fetch(key, () => { return parentBlogRepository.GetAll(); }, null, null, cacheDependencies) .ToList(); }   This will add a dependency of the “Blogs” table in the database. The data will remain in the cache until the contents of this table change, then the cache item will be invalidated, and the next call to the GetAll() repository method will be routed to the parent repository to refresh the data from the database.

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  • How to play non buffered .wav with MediaStreamSource implementation in Silverlight 4?

    - by kyrisu
    Background I'm trying to stream a wave file in Silverlight 4 using MediaStreamSource implementation found here. The problem is I want to play the file while it's still buffering, or at least give user some visual feedback while it's buffering. For now my code looks like that: private void button1_Click(object sender, RoutedEventArgs e) { HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(new Uri(App.Current.Host.Source, "../test.wav")); //request.ContentType = "audio/x-wav"; request.AllowReadStreamBuffering = false; request.BeginGetResponse(new AsyncCallback(RequestCallback), request); } private void RequestCallback(IAsyncResult ar) { this.Dispatcher.BeginInvoke(delegate() { HttpWebRequest request = (HttpWebRequest)ar.AsyncState; HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(ar); WaveMediaStreamSource wavMss = new WaveMediaStreamSource(response.GetResponseStream()); try { me.SetSource(wavMss); } catch (InvalidOperationException) { // This file is not valid } me.Play(); }); } The problem is that after settings request.AllowREadStreamBuffer to false the stream does not support seeking and the above mentioned implementation throws an exception (keep in mind I've put some of the position setting logic into if(stream.CanSeek) block): Read is not supported on the main thread when buffering is disabled Question Is there a way to play wav stream without buffering it in advance?

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  • Implementation help... Subclass NSManagedObject?

    - by Canada Dev
    I'm working on an app where I have some products that I download in a list. The downloaded products are displayed in a table and each will is showing a detail view with more information. These same products can be saved as a favorite, and for this I am using Core Data. I'd like to be able to re-use a bunch of views for displaying the products, which means the stores object and the downloaded object would have to be the same kind. Now, how would I go about best implementing the objects? Can I make a class such as this: FavoriteProduct : NSManageObject // implementation and then subclass Product : FavoriteProduct // implementation ? The CD class just doesn't give me everything. What would be the best way to merge these two object classes so I have as little work ahead of me in terms of implementing the different views for each object? Basically, I just want to be able to call the same methods, etc. on the Product objects as I would on the ones that are FavoriteProduct objects, and re-use views for both kinds. There's only a bit of difference between the two (one is of course stored as a favorite and has some extra values such as notes, tags, while the Product one doesn't). Thanks in advance

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  • Should '#include' and 'using' statements be repeated in both header and implementation files (C++)?

    - by Dr. Monkey
    I'm fairly new to C++, but my understanding is that a #include statement will essentially just dump the contents of the #included file into the location of that statement. This means that if I have a number of '#include' and 'using' statements in my header file, my implementation file can just #include the header file, and the compiler won't mind if I don't repeat the other statements. What about people though? My main concern is that if I don't repeat the '#include', 'using', and also 'typedef' (now that I think of it) statements, it takes that information away from the file in which it's used, which could lead to confusion. I am just working on small projects at the moment where it won't really cause any issues, but I can imagine that in larger projects with more people working on them it could become a significant issue. An example follows: //Unit.h #include <string> #include <ostream> #include "StringSet.h" using std::string; using std::ostream; class Unit { public: //public members private: //private members //unrelated side-question: should private members //even be included in the header file? } ; //Unit.cpp #include "Unit.h" //The following are all redundant from a compiler perspective: #include <string> #include <ostream> #include "StringSet.h" using std::string; using std::ostream; //implementation goes here

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  • Is False == 0 and True == 1 in Python an implementation detail or guaranteed by the language?

    - by EOL
    Is it guaranteed that False == 0 and True == 1, in Python? For instance, is it in any way guaranteed that the following code will always produce the same results, whatever the version of Python (existing and in the foreseeable future)? 0 == False # True 1 == True # True ['zero', 'one'][False] # is 'zero' Any reference to the official documentation would be much appreciated! Other comments would be appreciated too… :) Edit: As noted in many answers, bool inherits from int. The question can therefore be recast as: "Is this an implementation detail that might change in the future, or does the documentation officially say that programmers can rely on booleans inheriting from integers?". This question is relevant for writing robust code that won't fail because of implementation details! Edit 2: The original question is still open, I believe (even though I accepted what I thought was the closest answer): even though Python 3 officially recognizes booleans as integers, I have not yet seen any official integer values for False and True… It therefore looks to me like it is best to stay clear from the assumption that False==0 and True==1.

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  • Force calling the derived class implementation within a generic function in C#?

    - by Adam Hardy
    Ok so I'm currently working with a set of classes that I don't have control over in some pretty generic functions using these objects. Instead of writing literally tens of functions that essentially do the same thing for each class I decided to use a generic function instead. Now the classes I'm dealing with are a little weird in that the derived classes share many of the same properties but the base class that they are derived from doesn't. One such property example is .Parent which exists on a huge number of derived classes but not on the base class and it is this property that I need to use. For ease of understanding I've created a small example as follows: class StandardBaseClass {} // These are simulating the SMO objects class StandardDerivedClass : StandardBaseClass { public object Parent { get; set; } } static class Extensions { public static object GetParent(this StandardDerivedClass sdc) { return sdc.Parent; } public static object GetParent(this StandardBaseClass sbc) { throw new NotImplementedException("StandardBaseClass does not contain a property Parent"); } // This is the Generic function I'm trying to write and need the Parent property. public static void DoSomething<T>(T foo) where T : StandardBaseClass { object Parent = ((T)foo).GetParent(); } } In the above example calling DoSomething() will throw the NotImplemented Exception in the base class's implementation of GetParent(), even though I'm forcing the cast to T which is a StandardDerivedClass. This is contrary to other casting behaviour where by downcasting will force the use of the base class's implementation. I see this behaviour as a bug. Has anyone else out there encountered this?

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  • Jboss Seam: Enabling Debug page on WebLogic 10.3.2 (11g)

    - by Markos Fragkakis
    Hi all, SKIP TO UPDATE 3 I want to enable the Seam debug page on Weblogic 10.3.2 (11g). So, I have done the following: I have the jboss-seam and jboss-seam-debug jars as dependency in both my ejb and web maven projects (both are modules of my superproject) I put this context parameter in my web.xml: <context-param> <param-name>org.jboss.seam.core.init.debug</param-name> <param-value>true</param-value> </context-param> Now, when I hit the URL of my application, I get the debug page with this exception (full stacktrace at the end of the post): Caused by java.lang.IllegalStateException with message: "No phase id bound to current thread (make sure you do not have two SeamPhaseListener instances installed)" From posts I read it seems that this is somehow related to two jars of jboss-seam or jboss-seam-debug being in the classpath. I opened my ear file and only one of each is present (in the ear) whereas the war itself has no libraries in the WEB-INF/lib. I have also read of another way to initialize debug page using the components.xml. I also tried to include the following components.xml in the WEB-INF, but it didn't work either: <?xml version="1.0" encoding="UTF-8"?> <components xmlns="http://jboss.com/products/seam/components" xmlns:core="http://jboss.com/products/seam/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://jboss.com/products/seam/core http://jboss.com/products/seam/core-2.2.xsd http://jboss.com/products/seam/components http://jboss.com/products/seam/components-2.2.xsd"> <core:init debug="true"/> </components> Any suggestions on what to do to enable the debug page correctly? Cheers! Full stacktrace: org.jboss.seam.contexts.PageContext.getPhaseId(PageContext.java:163) org.jboss.seam.contexts.PageContext.isBeforeInvokeApplicationPhase(PageContext.java:175) org.jboss.seam.contexts.PageContext.getCurrentWritableMap(PageContext.java:91) org.jboss.seam.contexts.PageContext.remove(PageContext.java:105) org.jboss.seam.Component.newInstance(Component.java:2141) org.jboss.seam.Component.getInstance(Component.java:2021) org.jboss.seam.Component.getInstance(Component.java:2000) org.jboss.seam.Component.getInstance(Component.java:1994) org.jboss.seam.Component.getInstance(Component.java:1967) org.jboss.seam.Component.getInstance(Component.java:1962) org.jboss.seam.faces.FacesPage.instance(FacesPage.java:92) org.jboss.seam.core.ConversationPropagation.restorePageContextConversationId(ConversationPropagation.java:84) org.jboss.seam.core.ConversationPropagation.restoreConversationId(ConversationPropagation.java:57) org.jboss.seam.jsf.SeamPhaseListener.afterRestoreView(SeamPhaseListener.java:391) org.jboss.seam.jsf.SeamPhaseListener.afterServletPhase(SeamPhaseListener.java:230) org.jboss.seam.jsf.SeamPhaseListener.afterPhase(SeamPhaseListener.java:196) com.sun.faces.lifecycle.Phase.handleAfterPhase(Phase.java:175) com.sun.faces.lifecycle.Phase.doPhase(Phase.java:114) com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:104) com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) javax.faces.webapp.FacesServlet.service(FacesServlet.java:265) weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227) weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125) weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:292) weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26) weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56) org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:178) org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290) org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:388) org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:515) weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83) org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:60) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:40) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:90) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.web.HotDeployFilter.doFilter(HotDeployFilter.java:53) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158) weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56) weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27) weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56) weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3592) weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321) weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121) weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2202) weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2108) weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1432) weblogic.work.ExecuteThread.execute(ExecuteThread.java:201) weblogic.work.ExecuteThread.run(ExecuteThread.java:173) UPDATE 1: Now the debug page does not appear at all. When I ask for http://localhost/myapp/debug.xhtml I get a page with: myapp/debug.xhtml the same as any page that does not exist. I opened the .ear and the following jboss jars are in: jboss-seam-debug-2.2.0.GA.jar jboss-el-1.0_02.CR4.jar jboss-seam-2.2.0.GA.jar My current configuration: <?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org /2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <display-name>PRS 6.0</display-name> <session-config> <session-timeout>30</session-timeout> </session-config> <!-- The default behavior of JSF is to map the incoming request for a JSF view identifier (view ID for short) to a JSP file with the file extension .jsp. To get JSF to look for a Facelets template instead, we must register the .xhtml extension as the default suffix for JSF views --> <context-param> <param-name>javax.faces.DEFAULT_SUFFIX</param-name> <param-value>.xhtml</param-value> </context-param> <context-param> <param-name>javax.faces.STATE_SAVING_METHOD</param-name> <param-value>server</param-value> </context-param> <context-param> <param-name>javax.faces.CONFIG_FILES</param-name> <param-value> /WEB-INF/faces-config/application.xml </param-value> </context-param> <context-param> <param-name>facelets.REFRESH_PERIOD</param-name> <param-value>2</param-value> </context-param> <context-param> <param-name>facelets.DEVELOPMENT</param-name> <param-value>true</param-value> </context-param> <context-param> <param-name>facelets.SKIP_COMMENTS</param-name> <param-value>true</param-value> </context-param> <context-param> <param-name>com.sun.faces.verifyObjects</param-name> <param-value>false</param-value> </context-param> <context-param> <param-name>org.ajax4jsf.VIEW_HANDLERS</param-name> <param-value>com.sun.facelets.FaceletViewHandler</param-value> </context-param> <context-param> <param-name>org.ajax4jsf.COMPRESS_SCRIPT</param-name> <param-value>true</param-value> </context-param> <context-param> <param-name>org.ajax4jsf.COMPRESS_STYLE</param-name> <param-value>true</param-value> </context-param> <context-param> <param-name>org.ajax4jsf.xmlparser.ORDER</param-name> <param-value>NONE</param-value> </context-param> <context-param> <param-name>org.richfaces.SKIN</param-name> <param-value>blueSky</param-value> </context-param> <context-param> <param-name>org.richfaces.CONTROL_SKINNING</param-name> <param-value>enable</param-value> </context-param> <context-param> <param-name>org.richfaces.LoadStyleStrategy</param-name> <param-value>ALL</param-value> </context-param> <context-param> <param-name>org.richfaces.LoadScriptStrategy</param-name> <param-value>ALL</param-value> </context-param> <!-- Seam Filter --> <!-- (MUST BE FIRST)--> <filter> <filter-name>Seam Filter</filter-name> <filter-class>org.jboss.seam.servlet.SeamFilter</filter-class> </filter> <filter-mapping> <filter-name>Seam Filter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <!-- RichFaces filter --> <filter> <display-name>RichFaces Filter</display-name> <filter-name>richfaces</filter-name> <filter-class>org.ajax4jsf.Filter</filter-class> <init-param> <description>Set the size limit for uploaded files as attachments in bytes. (max 5MB)</description> <param-name>maxRequestSize</param-name> <param-value>5242880</param-value> </init-param> </filter> <filter-mapping> <filter-name>richfaces</filter-name> <servlet-name>Faces Servlet</servlet-name> <dispatcher>REQUEST</dispatcher> <dispatcher>FORWARD</dispatcher> <dispatcher>INCLUDE</dispatcher> </filter-mapping> <listener> <listener-class> XX.XXXX.XXX.prs.web.listeners.ResourceInitializationListener</listener-class> </listener> <listener> <listener-class>com.sun.faces.config.ConfigureListener</listener-class> </listener> <listener> <listener-class>XX.XXXX.XXX.prs.web.listeners.EJBInjectionListener</listener-class> </listener> <!-- Seam Listener--> <listener> <listener-class>org.jboss.seam.servlet.SeamListener</listener-class> </listener> <!-- Faces Servlet --> <servlet> <servlet-name>Faces Servlet</servlet-name> <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>Faces Servlet</servlet-name> <url-pattern>*.xhtml</url-pattern> </servlet-mapping> -- Seam Resource Servlet-- org.jboss.seam.servlet.SeamResourceServlet-- -- -- Seam Resource Servlet-- /seam/resource/*-- -- <welcome-file-list> <welcome-file>index.xhtml</welcome-file> </welcome-file-list> </web-app> faces.config <?xml version="1.0" encoding="UTF-8"?> <faces-config xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-facesconfig_1_2.xsd" version="1.2"> <application> <locale-config> <default-locale>en</default-locale> <supported-locale>en</supported-locale> </locale-config> <view-handler>com.sun.facelets.FaceletViewHandler</view-handler> <el-resolver>org.jboss.seam.el.SeamELResolver</el-resolver> <resource-bundle> <base-name>XX.XXXX.XXX.prs.web.messages.messages</base-name> <var>msgs</var> </resource-bundle> <resource-bundle> <base-name>XX.XXXX.XXX.prs.web.messages.validation</base-name> <var>val</var> </resource-bundle> </application> <lifecycle> <phase-listener>XX.XXXX.XXX.prs.web.listeners.SetFocusListener</phase-listener> </lifecycle> <!-- <lifecycle>--> <!-- <phase-listener>XX.XXXX.XXX.prs.web.listeners.DebugPhaseListener</phase-listener> --> <converter> <converter-for-class>XX.XXXX.XXX.prs.model.Applicant</converter-for-class> <converter-class> XX.XXXX.XXX.prs.web.common.converters.ApplicantConverter</converter-class> </converter> <validator> <validator-id>EmailValidator</validator-id> <validator-class>XX.XXXX.XXX.prs.web.common.validators.EmailValidator</validator-class> </validator> </faces-config> components.xml <?xml version="1.0" encoding="UTF-8"?> <components xmlns="http://jboss.com/products/seam/components" xmlns:core="http://jboss.com/products/seam/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://jboss.com/products/seam/core http://jboss.com/products/seam/core-2.2.xsd http://jboss.com/products/seam/components http://jboss.com/products/seam/components-2.2.xsd"> <core:init debug="true" /> <core:manager concurrent-request-timeout="500" conversation-timeout="1200000" conversation-id-parameter="cid" parent-conversation-id-parameter="pid" /> UPDATE 2: These guys here have the same problem. They have an outer EAR project containing the inner WAR project. They discuss that this may be related to how jars end up in the projects. I use Maven, and I had set it to create "Skinny Wars", that is excluding all jar dependencies from the inner WAR project, so that it remains small in size. All its dependencies are contained in the EAR and are used by all other modules. I changed the settings of the maven-war-plugin to leave inside the war the web-specific jars (the ones mentioned in the link, like RichFaces, jboss-seam-debug, Facelets etc). However, the problem has reverted to its previous form. I now get the debug page, whatever link I press, with the initial exception. Caused by java.lang.IllegalStateException with message: "No phase id bound to current thread (make sure you do not have two SeamPhaseListener instances installed)" UPDATE 3: The structure of the application .ear is the following: application.ear |--> APP-INF | |--> classes |--> lib (all jar dependencies go here, including the WAR dependencies, EJB module dependencies) |-->META_INF | |--> application.xml | |--> data-sources.xml | |--> MANIFEST.MF | |--> weblogic.xml | |--> weblogic-application.xml |--> jboss-seam-2.2.0.GA.jar |--> myEjbModule1.jar |--> myEjbModule2.jar |--> myEjbModule3.jar |--> myEjbModule4.jar |--> myWar.war (NO libraries in WEB-INF/lib, finds everything in EAR/lib) When deploying .ear application WITHOUT debug enabled (not including the jboss-seam-debug.jar in the ear), the application is loaded correctly. When deploying WITH jboss-seam-debug.jar in the EAR (EAR/lib directory), the application does not appear, but ONLY the debug page with the following exception (stacktrace at the end): Exception during request processing: Caused by java.lang.IllegalStateException with message: "No phase id bound to current thread (make sure you do not have two SeamPhaseListener instances installed)" When "JBoss-izing" the same EAR (remove hibernate jars, which are provided by JBoss, and move all libraries from EAR/lib to EAR root), the application loads correctly. BOTH the application AND the debug page appear correctly. Full stacktrace: org.jboss.seam.contexts.PageContext.getPhaseId(PageContext.java:163) org.jboss.seam.contexts.PageContext.isBeforeInvokeApplicationPhase(PageContext.java:175) org.jboss.seam.contexts.PageContext.getCurrentWritableMap(PageContext.java:91) org.jboss.seam.contexts.PageContext.remove(PageContext.java:105) org.jboss.seam.Component.newInstance(Component.java:2141) org.jboss.seam.Component.getInstance(Component.java:2021) org.jboss.seam.Component.getInstance(Component.java:2000) org.jboss.seam.Component.getInstance(Component.java:1994) org.jboss.seam.Component.getInstance(Component.java:1967) org.jboss.seam.Component.getInstance(Component.java:1962) org.jboss.seam.faces.FacesPage.instance(FacesPage.java:92) org.jboss.seam.core.ConversationPropagation.restorePageContextConversationId(ConversationPropagation.java:84) org.jboss.seam.core.ConversationPropagation.restoreConversationId(ConversationPropagation.java:57) org.jboss.seam.jsf.SeamPhaseListener.afterRestoreView(SeamPhaseListener.java:391) org.jboss.seam.jsf.SeamPhaseListener.afterServletPhase(SeamPhaseListener.java:230) org.jboss.seam.jsf.SeamPhaseListener.afterPhase(SeamPhaseListener.java:196) com.sun.faces.lifecycle.Phase.handleAfterPhase(Phase.java:175) com.sun.faces.lifecycle.Phase.doPhase(Phase.java:114) com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:104) com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) javax.faces.webapp.FacesServlet.service(FacesServlet.java:265) weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227) weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125) weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:292) weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26) weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56) org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:530) weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83) org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:40) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:90) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:178) org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290) org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:388) org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:515) org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:56) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:60) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.web.HotDeployFilter.doFilter(HotDeployFilter.java:53) org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69) org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158) weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56) weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27) weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56) weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3592) weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321) weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121) weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2202) weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2108) weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1432) weblogic.work.ExecuteThread.execute(ExecuteThread.java:201) weblogic.work.ExecuteThread.run(ExecuteThread.java:173)

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  • Is there any working implementation of reverse mode automatic differentiation for Haskell?

    - by Ian Fiske
    The closest-related implementation in Haskell I have seen is the forward mode at http://hackage.haskell.org/packages/archive/fad/1.0/doc/html/Numeric-FAD.html. The closest related related research appears to be reverse mode for another functional language related to Scheme at http://www.bcl.hamilton.ie/~qobi/stalingrad/. I see reverse mode in Haskell as kind of a holy grail for a lot of tasks, with the hopes that it could use Haskell's nested data parallelism to gain a nice speedup in heavy numerical optimization.

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  • Using IoC and Dependency Injection, how do I wrap an existing implementation with a new layer of imp

    - by Dividnedium
    I'm trying to figure out how this would be done in practice, so as not to violate the Open Closed principle. Say I have a class called HttpFileDownloader that has one function that takes a url and downloads a file returning the html as a string. This class implements an IFileDownloader interface which just has the one function. So all over my code I have references to the IFileDownloader interface and I have my IoC container returning an instance of HttpFileDownloader whenever an IFileDownloader is Resolved. Then after some use, it becomes clear that occasionally the server is too busy at the time and an exception is thrown. I decide that to get around this, I'm going to auto-retry 3 times if I get an exception, and wait 5 seconds in between each retry. So I create HttpFileDownloaderRetrier which has one function that uses HttpFileDownloader in a for loop with max 3 loops, and a 5 second wait between each loop. So that I can test the "retry" and "wait" abilities of the HttpFileDownloadRetrier I have the HttpFileDownloader dependency injected by having the HttpFileDownloaderRetrier constructor take an IFileDownloader. So now I want all Resolving of IFileDownloader to return the HttpFileDownloaderRetrier. But if I do that, then HttpFileDownloadRetrier's IFileDownloader dependency will get an instance of itself and not of HttpFileDownloader. So I can see that I could create a new interface for HttpFileDownloader called IFileDownloaderNoRetry, and change HttpFileDownloader to implement that. But that means I'm changing HttpFileDownloader, which violates Open Closed. Or I could implement a new interface for HttpFileDownloaderRetrier called IFileDownloaderRetrier, and then change all my other code to refer to that instead of IFileDownloader. But again, I'm now violating Open Closed in all my other code. So what am I missing here? How do I wrap an existing implementation (downloading) with a new layer of implementation (retrying and waiting) without changing existing code? Here's some code if it helps: public interface IFileDownloader { string Download(string url); } public class HttpFileDownloader : IFileDownloader { public string Download(string url) { //Cut for brevity - downloads file here returns as string return html; } } public class HttpFileDownloaderRetrier : IFileDownloader { IFileDownloader fileDownloader; public HttpFileDownloaderRetrier(IFileDownloader fileDownloader) { this.fileDownloader = fileDownloader; } public string Download(string url) { Exception lastException = null; //try 3 shots of pulling a bad URL. And wait 5 seconds after each failed attempt. for (int i = 0; i < 3; i++) { try { fileDownloader.Download(url); } catch (Exception ex) { lastException = ex; } Utilities.WaitForXSeconds(5); } throw lastException; } }

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  • What am I not getting about this abstract class implementation?

    - by Schnapple
    PREFACE: I'm relatively inexperienced in C++ so this very well could be a Day 1 n00b question. I'm working on something whose long term goal is to be portable across multiple operating systems. I have the following files: Utilities.h #include <string> class Utilities { public: Utilities() { }; virtual ~Utilities() { }; virtual std::string ParseString(std::string const& RawString) = 0; }; UtilitiesWin.h (for the Windows class/implementation) #include <string> #include "Utilities.h" class UtilitiesWin : public Utilities { public: UtilitiesWin() { }; virtual ~UtilitiesWin() { }; virtual std::string ParseString(std::string const& RawString); }; UtilitiesWin.cpp #include <string> #include "UtilitiesWin.h" std::string UtilitiesWin::ParseString(std::string const& RawString) { // Magic happens here! // I'll put in a line of code to make it seem valid return ""; } So then elsewhere in my code I have this #include <string> #include "Utilities.h" void SomeProgram::SomeMethod() { Utilities *u = new Utilities(); StringData = u->ParseString(StringData); // StringData defined elsewhere } The compiler (Visual Studio 2008) is dying on the instance declaration c:\somepath\somecode.cpp(3) : error C2259: 'Utilities' : cannot instantiate abstract class due to following members: 'std::string Utilities::ParseString(const std::string &)' : is abstract c:\somepath\utilities.h(9) : see declaration of 'Utilities::ParseString' So in this case what I'm wanting to do is use the abstract class (Utilities) like an interface and have it know to go to the implemented version (UtilitiesWin). Obviously I'm doing something wrong but I'm not sure what. It occurs to me as I'm writing this that there's probably a crucial connection between the UtilitiesWin implementation of the Utilities abstract class that I've missed, but I'm not sure where. I mean, the following works #include <string> #include "UtilitiesWin.h" void SomeProgram::SomeMethod() { Utilities *u = new UtilitiesWin(); StringData = u->ParseString(StringData); // StringData defined elsewhere } but it means I'd have to conditionally go through the different versions later (i.e., UtilitiesMac(), UtilitiesLinux(), etc.) What have I missed here?

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  • Where can I find a good software implementation plan template?

    - by Corpsekicker
    This is not "programming" related as much as it is "software engineering" related. I am required to produce an implementation for additional functionality to a complete system. All I am armed with is knowledge of the existing architecture and a functional spec with visual requirements, user stories and use cases. Is there a standardised way to go about this? I suck at documentation.

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  • Which implementation of OrderedDict should be used in python2.6?

    - by Jorge Vargas
    As some of you may know in python2.7/3.2 we'll get OrderedDict with PEP372 however one of the reason the PEP existed was because everyone did their own implementation and they were all sightly incompatible. So which one of the 8 current implementations link text is backwards compatible with the 2.7 odict from python 2.7 in a way we can start using that now and depend on 2.7 in a couple of months?

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  • what should I take into consideration when choosing a session implementation?

    - by Satoru.Logic
    Hi, all. Yesterday, my supervisor told me that tmp-file-based session should be THE answer to session implementation, and I should abandon any idea of making sessions persistent. He argues that file-based session is much faster and eaiser to use than other choices like db-based or memcached-based implementations. What he said was really a shock to my past learning experience, so please tell me whether he was wrong and why? Thanks in advance.

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