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• why won't Eclipse use the compiler I specify for my project?

  - by codeman73

  I'm using Eclipse 3.3. In my project, I've set the compiler compliance level to 5.0 In the build path for the project. I've added the Java 1.5 JDK in the Installed JREs section and am referencing that System Library in my project build path. However, I'm getting compile errors for a class that implements PreparedStatement for not implementing abstract methods that only exist in Java 1.6 PreparedStatement. Specifically, the methods setAsciiStream(int, InputStream, long) and setAsciiStream(int, InputStream) Strangely enough, it worked when we were compiling it against Java 1.4, which it was originally written for. We added the JREs for Java 1.4 and referenced that system library in the project, and set the project's compiler level to 1.4, and it works fine. But when I do the same changes to try to point to Java 5.0, it instead uses Java 6. Any ideas why? I wrote a similar question earlier, here: http://stackoverflow.com/questions/2540548/how-do-i-get-eclipse-to-use-a-different-compiler-version-for-java I know how you're supposed to choose a different compiler but it seems Eclipse isn't taking it. It seems to be defaulting to Java 6, even though I have deleted all Java 6 JDKs and JREs that I could find. I've also updated the -vm option in my eclipse.ini to point to the Java5 JDK.

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• what libraries or platforms should I use to build web apps that provide real-time, asynchronous data

  - by Daniel Sterling

  This is a less a question with a simple, practical answer and more a question to foster discussion on the real-time data exchange topic. I'll begin with an example: Google Wave is, at its core, a real-time asynchronous data synchronization engine. Wave supports (or plans to support) concurrent (real-time) document collaboration, disconnected (offline) document editing, conflict resolution, document history and playback with attribution, and server federation. A core part of Wave is the Operational Transformation engine: http://www.waveprotocol.org/whitepapers/operational-transform The OT engine manages document state. Changes between clients are merged and each client has a sane and consistent view of the document at all times; the final document is eventually consistent between all connected clients. My question is: is this system abstract or general enough to be used as a library or generic framework upon which to build web apps that synchronize real-time, asynchronous state in each client? Is the Wave protocol directly used by any current web applications (besides Google's client)? Would it make sense to directly use it for generic state synchronization in a web app? What other existing libraries or frameworks would you consider using when building such a web app? How much code in such an app might be domain-specific logic vs generic state synchronization logic? Or, put another way, how leaky might the state synchronization abstractions be? Comments and discussion welcomed!

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• iPhone OS: Why is my managedModelObject not complying with Key Value Coding?

  - by nickthedude

  Ok so I'm trying to build this stat tracker for my app and I have built a data model object called statTracker that keeps track of all the stuff I want it to. I can set and retrieve values using the selectors, but if I try and use KVC (ie setValue: forKey: ) everything goes bad and says my StatTracker class is not KVC compliant: valueForUndefinedKey:]: the entity StatTracker is not key value coding-compliant for the key "timesLauched".' 2010-05-18 15:55:08.573 here's the code that is triggering it: NSArray *statTrackerArray = [[NSArray alloc] init]; statTrackerArray = [[CoreDataSingleton sharedCoreDataSingleton] getStatTracker]; NSNumber *number1 = [[NSNumber alloc] init]; number1 = [NSNumber numberWithInt:(1 + [[(StatTracker *)[statTrackerArray objectAtIndex:0] valueForKey:@"timesLauched"] intValue])]; [(StatTracker *)[statTrackerArray objectAtIndex:0] setValue:number1 forKey:@"timesLaunched" ]; NSError *error; if (![[[CoreDataSingleton sharedCoreDataSingleton] managedObjectContext] save:&error]) { NSLog(@"error writing to db"); } Not sure if this is enough code for you folks let me know what you need if you do need more. This would be so sweet if I could use KVC because I could then abstract all this stat tracking stuff into a single method call with a string argument for the value in question. At least that is what I hope to accomplish here. I'm actually now understanding the power of KVC but now I'm just trying to figure out how to make it work. Thanks! Nick

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• Order in many to many relation in Django model

  - by Pietro Speroni

  I am writing a small website to store the papers I have written. The relation papers<- author is important, but the order of the name of the authors (which one is First Author, which one is second order, and so on) is also important. I am just learning Django so I don't know much. In any case so far I have done: from django.db import models class author(models.Model): Name = models.CharField(max_length=60) URLField = models.URLField(verify_exists=True, null=True, blank=True) def __unicode__(self): return self.Name class topic(models.Model): TopicName = models.CharField(max_length=60) def __unicode__(self): return self.TopicName class publication(models.Model): Title = models.CharField(max_length=100) Authors = models.ManyToManyField(author, null=True, blank=True) Content = models.TextField() Notes = models.TextField(blank=True) Abstract = models.TextField(blank=True) pub_date = models.DateField('date published') TimeInsertion = models.DateTimeField(auto_now=True) URLField = models.URLField(verify_exists=True,null=True, blank=True) Topic = models.ManyToManyField(topic, null=True, blank=True) def __unicode__(self): return self.Title This work fine in the sense that I now can define who the authors are. But I cannot order them. How should I do that? Of course I could add a series of relations: first author, second author,... but it would be ugly, and would not be flexible. Any better idea? Thanks

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• Get instance of type inheriting from base class, implementing interface, using StructureMap

  - by Ben

  Continuing on my quest for a good plugin implementation I have been testing the StructureMap assembly scanning features. All plugins will inherit from abstract class PluginBase. This will provide access to common application services such as logging. Depending on it's function, each plugin may then implement additional interfaces, for example, IStartUpTask. I am initializing my plugins like so: Scan(x => { x.AssembliesFromPath(HttpContext.Current.Server.MapPath("~/Plugins"), assembly => assembly.GetName().Name.Contains("Extension")); x.AddAllTypesOf<PluginBase>(); }); The difficulty I am then having is how to work against the interface (not the PluginBase) in code. It's easy enough to work with PluginBase: var plugins = ObjectFactory.GetAllInstances<PluginBase>(); foreach (var plugin in plugins) { } But specific functionality (e.g. IStartUpTask.RunTask) is tied to the interface, not the base class. I appreciate this may not be specific to structuremap (perhaps more a question of reflection). Thanks, Ben

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• Discriminator based on joined property

  - by Andrew

  Suppose I have this relationship: abstract class Base { int Id; int JoinedId; ... } class Joined { int Id; int Discriminator; ... } class Sub1 : Base { ... } class Sub2 : Base { ... } for the following tables: table Base ( Id int, JoinedId int, ... ) table Joined ( Id int, Discriminator int, ... ) I would like to set up a table-per-hierarchy inheritance mapping for the Base, Sub1, Sub2 relationships, but using the Disciminator property from the Joined class as the discriminator. Here's the general idea for the mapping file: <class name="Base" table="Base"> <id name="Id"><generator class="identity"/></id> <discriminator /> <!-- ??? or <join> or <many-to-one>? --> <subclass name="Sub1" discriminator-value="1">...</subclass> <subclass name="Sub2" discriminator-value="2">...</subclass> </class> Is there any way of accomplishing something like this with the <discriminator>, <join>, or <many-to-one>? NHiberante seems to assume the discriminator is a column on the given table (which makes sense to me.. I know this is unorthodox). Thanks.

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• Hierarchy / Flyweight / Instancing Problem in Python

  - by Dan

  Here is the problem I am trying to solve, (I have simplified the actual problem, but this should give you all the relevant information). I have a hierarchy like so: 1.A 1.B 1.C 2.A 3.D 4.B 5.F (This is hard to illustrate - each number is the parent, each letter is the child). Creating an instance of the 'letter' objects is expensive (IO, database costs, etc), so should only be done once. The hierarchy needs to be easy to navigate. Children in the hierarchy need to have just one parent. Modifying the contents of the letter objects should be possible directly from the objects in the hierarchy. There needs to be a central store containing all of the 'letter' objects (and only those in the hierarchy). 'letter' and 'number' objects need to be possible to create from a constructor (such as Letter(**kwargs) ). It is perfectably acceptable to expect that when a letter changes from the hierarchy, all other letters will respect the same change. Hope this isn't too abstract to illustrate the problem. What would be the best way of solving this? (Then I'll post my solution) Here's an example script: one = Number('one') a = Letter('a') one.addChild(a) two = Number('two') a = Letter('a') two.addChild(a) for child in one: child.method1() for child in two: print '%s' % child.method2()

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• Spring-MVC Problem using @Controller on controller implementing an interface

  - by layne

  I'm using spring 2.5 and annotations to configure my spring-mvc web context. Unfortunately, I am unable to get the following to work. I'm not sure if this is a bug (seems like it) or if there is a basic misunderstanding on how the annotations and interface implementation subclassing works. For example, @Controller @RequestMapping("url-mapping-here") public class Foo { @RequestMapping(method=RequestMethod.GET) public void showForm() { ... } @RequestMapping(method=RequestMethod.POST) public String processForm() { ... } } works fine. When the context starts up, the urls this handler deals with are discovered, and everything works great. This however does not: @Controller @RequestMapping("url-mapping-here") public class Foo implements Bar { @RequestMapping(method=RequestMethod.GET) public void showForm() { ... } @RequestMapping(method=RequestMethod.POST) public String processForm() { ... } } When I try to pull up the url, I get the following nasty stack trace: javax.servlet.ServletException: No adapter for handler [com.shaneleopard.web.controller.RegistrationController@e973e3]: Does your handler implement a supported interface like Controller? org.springframework.web.servlet.DispatcherServlet.getHandlerAdapter(DispatcherServlet.java:1091) org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:874) org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:809) org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:571) org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:501) javax.servlet.http.HttpServlet.service(HttpServlet.java:627) However, if I change Bar to be an abstract superclass and have Foo extend it, then it works again. @Controller @RequestMapping("url-mapping-here") public class Foo extends Bar { @RequestMapping(method=RequestMethod.GET) public void showForm() { ... } @RequestMapping(method=RequestMethod.POST) public String processForm() { ... } } This seems like a bug. The @Controller annotation should be sufficient to mark this as a controller, and I should be able to implement one or more interfaces in my controller without having to do anything else. Any ideas?

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• Setting spring bean property value using ref-bean

  - by Apache Fan

  Hi, I am trying to set a property value using spring. <bean id="velocityPropsBean" class="com.test.CustomProperties" abstract="false" singleton="true" lazy-init="false" autowire="default" dependency-check="default"> <property name="properties"> <props> <prop key="resource.loader">file</prop> <prop key="file.resource.loader.cache">true</prop> <prop key="file.resource.loader.class">org.apache.velocity.runtime.resource.loader.FileResourceLoader</prop> <prop key="file.resource.loader.path">NEED TO INSERT VALUE AT STARTUP</prop> </props> </property> </bean> <bean id="velocityResourcePath" class="java.lang.String" factory-bean="velocityHelper" factory-method="getLoaderPath"/> Now what i need to do is insert the result from getLoaderPath into file.resource.loader.path. The value of getLoaderPath changes so it has to be loaded at server startup. Any thoughts how i can inset the velocityResourcePath value to the property?

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• howto distinguish composition and self-typing use-cases

  - by ayvango

  Scala has two instruments for expressing object composition: original self-type concept and well known trivial composition. I'm curios what situations I should use which in. There are obvious differences in their applicability. Self-type requires you to use traits. Object composition allows you to change extensions on run-time with var declaration. Leaving technical details behind I can figure two indicators to help with classification of use cases. If some object used as combinator for a complex structure such as tree or just have several similar typed parts (1 car to 4 wheels relation) than it should use composition. There is extreme opposite use case. Lets assume one trait become too big to clearly observe it and it got split. It is quite natural that you should use self-types for this case. That rules are not absolute. You may do extra work to convert code between this techniques. e.g. you may replace 4 wheels composition with self-typing over Product4. You may use Cake[T <: MyType] {part : MyType} instead of Cake { this : MyType => } for cake pattern dependencies. But both cases seem counterintuitive and give you extra work. There are plenty of boundary use cases although. One-to-one relations is very hard to decide with. Is there any simple rule to decide what kind of technique is preferable? self-type makes you classes abstract, composition makes your code verbose. self-type gives your problems with blending namespaces and also gives you extra typing for free (you got not just a cocktail of two elements but gasoline-motor oil cocktail known as a petrol bomb). How can I choose between them? What hints are there? Update: Let us discuss the following example: Adapter pattern. What benefits it has with both selt-typing and composition approaches?

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• Is It Incorrect to Make Domain Objects Aware of The Data Access Layer?

  - by Noah Goodrich

  I am currently working on rewriting an application to use Data Mappers that completely abstract the database from the Domain layer. However, I am now wondering which is the better approach to handling relationships between Domain objects: Call the necessary find() method from the related data mapper directly within the domain object Write the relationship logic into the native data mapper (which is what the examples tend to do in PoEAA) and then call the native data mapper function within the domain object. Either it seems to me that in order to preserve the 'Fat Model, Skinny Controller' mantra, the domain objects have to be aware of the data mappers (whether it be their own or that they have access to the other mappers in the system). Additionally it seems that Option 2 unnecessarily complicates the data access layer as it creates table access logic across multiple data mappers instead of confining it to a single data mapper. So, is it incorrect to make the domain objects aware of the related data mappers and to call data mapper functions directly from the domain objects? Update: These are the only two solutions that I can envision to handle the issue of relations between domain objects. Any example showing a better method would be welcome.

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• How to prevent linq-to-sql designer undo my changing

  - by anonim.developer

  Dear All, Thanks for your attention in advance, I’ve met an issue with LINQ-2-SQL designer in VS 2008 SP1 which has made me CRAZY. I use Linq2sql as my DAL. It seems Linq2sql speeds up coding in the first step but lots of issues arise in feature specifically with table or object inheritance. In this case I have a class Entity that all other entity classes generated by Linq2sql designer inherit from. public abstract class Entity { public virtual Guid ID { get; protected set; } } public partial class User : monius.Data.Entity { } And the following generated by L2S designer (DataModel.designer.cs) [Column(Storage = "_ID", AutoSync = AutoSync.OnInsert, DbType = "UniqueIdentifier NOT NULL", IsPrimaryKey = true, IsDbGenerated = true, UpdateCheck = UpdateCheck.Never)] [DataMember(Order = 1)] public System.Guid ID { get { return this._ID; } set { if ((this._ID != value)) { this.OnIDChanging(value); this.SendPropertyChanging(); this._ID = value; this.SendPropertyChanged("ID"); this.OnIDChanged(); } } } When I compile the code VS warns me that Warning 1 'User.ID' hides inherited member 'Entity.ID'. To make the current member override that mplementation, add the override keyword. Otherwise add the new keyword. That warning is obvious and I have to change the code generated by L2S designer (DataModel.designer.cs) to […] public override System.Guid ID { … protected set … } And the code compiled with no error or warning and everyone is happy. But that is not the end of story. As soon as I made changes to entities of the diagram (dbml) or even I open dbml file to view it, any change manually I made to designer has been vanished and POOF! Redo AGAIN. That is a painful job. Now I wonder if there is a way to force L2S designer not changing portions of auto-generated code. I’ll be appreciated if someone kindly helps me with this issue.

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• How to create a fully lazy singleton for generics

  - by Brendan Vogt

  I have the following code implementation of my generic singleton provider: public sealed class Singleton<T> where T : class, new() { Singleton() { } public static T Instance { get { return SingletonCreator.instance; } } class SingletonCreator { static SingletonCreator() { } internal static readonly T instance = new T(); } } This sample was taken from 2 articles and I merged the code to get me what I wanted: http://www.yoda.arachsys.com/csharp/singleton.html and http://www.codeproject.com/Articles/11111/Generic-Singleton-Provider. This is how I tried to use the code above: public class MyClass { public static IMyInterface Initialize() { if (Singleton<IMyInterface>.Instance == null // Error 1 { Singleton<IMyInterface>.Instance = CreateEngineInstance(); // Error 2 Singleton<IMyInterface>.Instance.Initialize(); } return Singleton<IMyInterface>.Instance; } } And the interface: public interface IMyInterface { } The error at Error 1 is: 'MyProject.IMyInterace' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method 'MyProject.Singleton<T>' The error at Error 2 is: Property or indexer 'MyProject.Singleton<MyProject.IMyInterface>.Instance' cannot be assigned to -- it is read only How can I fix this so that it is in line with the 2 articles mentioned above? Any other ideas or suggestions are appreciated.

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• Why are my Fluent NHibernate SubClass Mappings generating redundant columns?

  - by Brook

  I'm using Fluent NHibernate 1.x build 694, built against NH 3.0 I have the following entities public abstract class Card { public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual string Description { get; set; } public virtual Product Product { get; set; } public virtual Sprint Sprint { get; set; } } public class Story:Card { public virtual double Points { get; set; } public virtual int Priority { get; set; } public virtual IList<Task> Tasks { get; set; } } And the following mappings public class CardMap:ClassMap<Card> { public CardMap() { Id(c => c.Id) .Index("Card_Id"); Map(c => c.Name) .Length(50) .Not.Nullable(); Map(c => c.Description) .Length(1024) .Not.Nullable(); References(c=>c.Product) .Not.Nullable(); References(c=>c.Sprint) .Nullable(); } } public class StoryMap : SubclassMap<Story> { public StoryMap() { Map(s => s.Points); Map(s => s.Priority); HasMany(s => s.Tasks); } } When I generate my Schema, the tables are created as follows Card --------- Id Name Description Product_id Sprint_id Story ------------ Card_id Points Priority Product_id Sprint_id What I would have expected would have been to see the columns Product_id and Sprint_id ONLY in the Card table, not the Story table. What am I doing wrong or misunderstanding?

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• Django generic relation field reports that all() is getting unexpected keyword argument when no args

  - by Joshua

  I have a model which can be attached to to other models. class Attachable(models.Model): content_type = models.ForeignKey(ContentType) object_pk = models.TextField() content_object = generic.GenericForeignKey(ct_field="content_type", fk_field="object_pk") class Meta: abstract = True class Flag(Attachable): user = models.ForeignKey(User) flag = models.SlugField() timestamp = models.DateTimeField() I'm creating a generic relationship to this model in another model. flags = generic.GenericRelation(Flag) I try to get objects from this generic relation like so: self.flags.all() This results in the following exception: >>> obj.flags.all() Traceback (most recent call last): File "<console>", line 1, in <module> File "/usr/local/lib/python2.6/dist-packages/django/db/models/manager.py", line 105, in all return self.get_query_set() File "/usr/local/lib/python2.6/dist-packages/django/contrib/contenttypes/generic.py", line 252, in get_query_set return superclass.get_query_set(self).filter(**query) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 498, in filter return self._filter_or_exclude(False, *args, **kwargs) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 516, in _filter_or_exclude clone.query.add_q(Q(*args, **kwargs)) File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 1675, in add_q can_reuse=used_aliases) File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 1569, in add_filter negate=negate, process_extras=process_extras) File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 1737, in setup_joins "Choices are: %s" % (name, ", ".join(names))) FieldError: Cannot resolve keyword 'object_id' into field. Choices are: content_type, flag, id, nestablecomment, object_pk, timestamp, user >>> obj.flags.all(object_pk=obj.pk) Traceback (most recent call last): File "<console>", line 1, in <module> TypeError: all() got an unexpected keyword argument 'object_pk' What have I done wrong?

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• how do I get eclipse to use a different compiler version for Java?

  - by codeman73

  It seems like this should be a simple task, with the options in the Preferences menu for different JREs and the ability to set different compiler and build paths per project. However, it also seems to simply not work. For example, I have my JAVA_HOME set to a jre for Java 1.6. It's still not clear to me how Eclipse uses this, but it appears to be defaulting to this and not taking the project overrides. I have also installed Java 1.5, and added a JRE for this in eclipse in the Java-Installed JREs section. In my project, I've set the compiler compliance level to 1.5. In the build path for the project, I've added the System Library for the Java 1.5 JRE. However, I'm getting compile errors for a class that implements PreparedStatement for not implementing abstract methods that only exist in Java 1.6 PreparedStatement. Specifically, the methods setAsciiStream(int, InputStream, long) and setAsciiStream(int, InputStream) Strangely enough, it worked when we were compiling it against Java 1.4, which it was originally written for. We added the JREs for Java 1.4 and referenced that system library in the project, and set the project's compiler level to 1.4, and it works fine. But when I do the same changes to try to point to Java 1.5, it instead uses 1.6. Any ideas why?

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• Designing a general database interface in PHP

  - by lamas

  I'm creating a small framework for my web projects in PHP so I don't have to do the basic work over and over again for every new website. It is not my goal to create a second CakePHP or Codeigniter and I'm also not planning to build my websites with any of the available frameworks as I prefer to use things I've created myself in general. I have no problems in designing that framework when it comes to parts like the core structure, request handling, and so on but I'm getting stuck with designing the database interface for my modules. I've already thought about using the MVC pattern but thought that it would be a bit of a overkill. So the exact problem I'm facing is how my frameworks modules (viewCustomers could be a module, for example) should interact with the database. Is it a good idea to write SQL directly in PHP (mysql_query( 'SELECT firstname, lastname(.....))? How could I abstract a query like SELECT firstname, lastname FROM customers WHERE id=X Would MySQL helper functions like $this->db->get( array('firstname', 'lastname'), array('id'=>X) ) be a good idea? I suppose not because they actually make everything more complicated by requiring arrays to be created and passed. Is the Model pattern from MVC my only real option?

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• why is OOP hard for me?

  - by netrox

  I have trouble writing OOP in PHP... I understand the concept but I never create classes for my projects... mainly because it's often a small project and nothing complex. But when I read OOP, it seems more difficult to code than writing simple procedural statements. It also seems to take a lot of room as well with so many empty abstract classes and that can be easily lost in the land of objects... it's becoming like a junkyard to me. Also, I noticed that virtually all instructions on how to use OOP use "car" or "cat" or "dog" analogies. Hello... we're not dealing with animals or cars... we're dealing with windows or consoles. You can talk about analogies to death and I will never learn. What I want is see a code that's written to show how objects are created - not, "aCow-moo!" For example, I want to see a browser window object displaying say... three inputs. I want to see an "object" created to output a window with three inputs then I want to see how overriding works, like change the window object to display only two inputs instead of three inputs. I think that would make learning more easy, wouldn't it? Any recommended tutorials of that nature instead of quacks, moos, and woofs.

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• Should a new language compiler target the JVM?

  - by Pindatjuh

  I'm developing a new language. My initial target was to compile to native x86 for the Windows platform, but now I am in doubt. I've seen some new languages target the JVM (most notable Scala and Clojure). Ofcourse it's not possible to port every language easily to the JVM; to do so, it may lead to small changes to the language and it's design. So that's the reason behind this doubt, and thus this question: Is targetting the JVM a good idea, when creating a compiler for a new language? Or should I stick with x86? I have experience in generating JVM bytecode. Are there any workarounds to JVM's GC? The language has deterministic implicit memory management. How to produce JIT-compatible bytecode, such that it will get the highest speedup? Is it similar to compiling for IA-32, such as the 4-1-1 muops pattern on Pentium? I can imagine some advantages (please correct me if I'm wrong): JVM bytecode is easier than x86. Like x86 communicates with Windows, JVM communicates with the Java Foundation Classes. To provide I/O, Threading, GUI, etc. Implementing "lightweight"-threads.I've seen a very clever implementation of this at http://www.malhar.net/sriram/kilim/. Most advantages of the Java Runtime (portability, etc.) The disadvantages, as I imagined, are: Less freedom? On x86 it'll be more easy to create low-level constructs, while JVM has a higher level (more abstract) processor. Most disadvantages of the Java Runtime (no native dynamic typing, etc.)

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• Testing for interface implementation in WCF/SOA

  - by rabidpebble

  I have a reporting service that implements a number of reports. Each report requires certain parameters. Groups of logically related parameters are placed in an interface, which the report then implements: [ServiceContract] [ServiceKnownType(typeof(ExampleReport))] public interface IService1 { [OperationContract] void Process(IReport report); } public interface IReport { string PrintedBy { get; set; } } public interface IApplicableDateRangeParameter { DateTime StartDate { get; set; } DateTime EndDate { get; set; } } [DataContract] public abstract class Report : IReport { [DataMember] public string PrintedBy { get; set; } } [DataContract] public class ExampleReport : Report, IApplicableDateRangeParameter { [DataMember] public DateTime StartDate { get; set; } [DataMember] public DateTime EndDate { get; set; } } The problem is that the WCF DataContractSerializer does not expose these interfaces in my client library, thus I can't write the generic report generating front-end that I plan to. Can WCF expose these interfaces, or is this a limitation of the serializer? If the latter case, then what is the canonical approach to this OO pattern? I've looked into NetDataContractSerializer but it doesn't seem to be an officially supported implementation (which means it's not an option in my project). Currently I've resigned myself to including the interfaces in a library that is common between the service and the client application, but this seems like an unnecessary extra dependency to me. Surely there is a more straightforward way to do this? I was under the impression that WCF was supposed to replace .NET remoting; checking if an object implements an interface seems to be one of the most basic features required of a remoting interface?

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• URL naming conventions

  - by LookitsPuck

  So, this may be a can of worms. But I'm curious what your practices are? For example, let's say your website consists of the following needs (very basic): A landing page An information page for an event (static) A listing of places for that event (dynamic) An information page for each place With that said, how would you design your URLs? Typically, I'd do something like the following: www.domain.com/ - landing page [also accessible via www.domain.com/home] www.domain.com/event - event information page www.domain.com/places - listing of all places www.domain.com/places/{id} - place information page Now, here's a question. Just grammatically speaking, I have a hangup of referring to a given place in a url as being plural. Shouldn't it make more sense to go with this: www.domain.com/place/{id} as opposed to www.domain.com/places/{id} In some frameworks, you have a convention to follow (for example, ASP.NET MVC) by default. Yes, you can define custom routes to have /place/{id} route to the PlacesController. However, I'm just trying to keep this a bit abstract in discussion. With that being said, let's see for instance on another page of your site, you have a link, that when clicked, would open a modal popup populated with place information. Where you place that information? We could go with something like this: www.domain.com/ajax/places/{id} OR www.domain.com/places/{id} and serve based on the request header (that is, if requesting JSON, return JSON?}. Finally, for SEO reasons, typically I use a slug associated with a given resource. So, something like such: www.domain.com/ajax/places/{id}/london Where london is only there to add decoration to the link for SEO reasons. Is this sound? I ask all of these questions, because these are practices that I've been using for awhile, and I'd just like to see what other developers are doing or if I'm approaching things incorrectly. Thanks!

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• Passing IDisposable objects through constructor chains

  - by Matt Enright

  I've got a small hierarchy of objects that in general gets constructed from data in a Stream, but for some particular subclasses, can be synthesized from a simpler argument list. In chaining the constructors from the subclasses, I'm running into an issue with ensuring the disposal of the synthesized stream that the base class constructor needs. Its not escaped me that the use of IDisposable objects this way is possibly just dirty pool (plz advise?) for reasons I've not considered, but, this issue aside, it seems fairly straightforward (and good encapsulation). Codes: abstract class Node { protected Node (Stream raw) { // calculate/generate some base class properties } } class FilesystemNode : Node { public FilesystemNode (FileStream fs) : base (fs) { // all good here; disposing of fs not our responsibility } } class CompositeNode : Node { public CompositeNode (IEnumerable some_stuff) : base (GenerateRaw (some_stuff)) { // rogue stream from GenerateRaw now loose in the wild! } static Stream GenerateRaw (IEnumerable some_stuff) { var content = new MemoryStream (); // molest elements of some_stuff into proper format, write to stream content.Seek (0, SeekOrigin.Begin); return content; } } I realize that not disposing of a MemoryStream is not exactly a world-stopping case of bad CLR citizenship, but it still gives me the heebie-jeebies (not to mention that I may not always be using a MemoryStream for other subtypes). It's not in scope, so I can't explicitly Dispose () it later in the constructor, and adding a using statement in GenerateRaw () is self-defeating since I need the stream returned. Is there a better way to do this? Preemptive strikes: yes, the properties calculated in the Node constructor should be part of the base class, and should not be calculated by (or accessible in) the subclasses I won't require that a stream be passed into CompositeNode (its format should be irrelevant to the caller) The previous iteration had the value calculation in the base class as a separate protected method, which I then just called at the end of each subtype constructor, moved the body of GenerateRaw () into a using statement in the body of the CompositeNode constructor. But the repetition of requiring that call for each constructor and not being able to guarantee that it be run for every subtype ever (a Node is not a Node, semantically, without these properties initialized) gave me heebie-jeebies far worse than the (potential) resource leak here does.

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• Hibernate: deletes not cascading for self-referencing entities

  - by jwaddell

  I have the following (simplified) Hibernate entities: @Entity @Table(name = "package") public abstract class Package { protected Content content; @ManyToOne(cascade = {javax.persistence.CascadeType.ALL}) @JoinColumn(name = "content_id") @Fetch(value = FetchMode.JOIN) public Content getContent() { return content; } public void setContent(Content content) { this.content = content; } } @Entity @Table(name = "content") public class Content { private Set<Content> subContents = new HashSet<Content>(); @ManyToMany(fetch = FetchType.EAGER) @JoinTable(name = "subcontents", joinColumns = {@JoinColumn(name = "content_id")}, inverseJoinColumns = {@JoinColumn(name = "elt")}) @Cascade(value = {org.hibernate.annotations.CascadeType.DELETE, org.hibernate.annotations.CascadeType.REPLICATE}) @Fetch(value = FetchMode.SUBSELECT) public Set<Content> getSubContents() { return subContents; } public void setSubContents(Set<Content> subContents) { this.subContents = subContents; } } So a Package has a Content, and a Content is self-referencing in that it has many sub-Contents (which may contain sub-Contents of their own etc). The relationships are required to be ManyToOne (Package to Content) and ManyToMany (Content to sub-Contents) but for the case I am currently testing each sub-Content only relates to one Package or Content. The problem is that when I delete a Package and flush the session, I get a Hibernate error stating that I'm violating a foreign key constraint on table subcontents, with a particular content_id still referenced from table subcontents. I've tried specifically (recursively) deleting the Contents before deleting the Package but I get the same error. Is there a reason why this entity tree is not being deleted properly?

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• Password Confirmation in zend framework

  - by Behrang

  I add this class to library/My/Validate/PasswordConfirmation.php <?php require_once 'Zend/Validate/Abstract.php'; class My_Validate_PasswordConfirmation extends Zend_Validate_Abstract { const NOT_MATCH = 'notMatch'; protected $_messageTemplates = array( self::NOT_MATCH => 'Password confirmation does not match' ); public function isValid($value, $context = null) { $value = (string) $value; $this->_setValue($value); if (is_array($context)) { if (isset($context['password']) && ($value == $context['password'])) { return true; } } elseif (is_string($context) && ($value == $context)) { return true; } $this->_error(self::NOT_MATCH); return false; } } ?> then I create two field in my form like this : $userPassword = $this->createElement('password', 'user_password'); $userPassword->setLabel('Password: '); $userPassword->setRequired('true'); $this->addElement($userPassword); //create the form elements user_password repeat $userPasswordRepeat = $this->createElement('password', 'password_confirm'); $userPasswordRepeat->setLabel('Password repeat: '); $userPasswordRepeat->setRequired('true'); $userPasswordRepeat->addPrefixPath('My_Validate','My/Validate','validate'); $userPasswordRepeat->addValidator('PasswordConfirmation'); $this->addElement($userPasswordRepeat) everything is good but when i submit form always I get the 'Password confirmation does not match' message ? What's Wrong in my code

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• Why do case class companion objects extend FunctionN?

  - by retronym

  When you create a case class, the compiler creates a corresponding companion object with a few of the case class goodies: an apply factory method matching the primary constructor, equals, hashCode, and copy. Somewhat oddly, this generated object extends FunctionN. scala> case class A(a: Int) defined class A scala> A: (Int => A) res0: (Int) => A = <function1> This is only the case if: There is no manually defined companion object There is exactly one parameter list There are no type arguments The case class isn't abstract. Seems like this was added about two years ago. The latest incarnation is here. Does anyone use this, or know why it was added? It increases the size of the generated bytecode a little with static forwarder methods, and shows up in the #toString() method of the companion objects: scala> case class A() defined class A scala> A.toString res12: java.lang.String = <function0>

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