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  • OData &ndash; The easiest service I can create

    - by Jon Dalberg
    I wanted to create an OData service with the least amount of code so I fired up Visual Studio and got cracking. I decided to serve up a list of naughty words and make them read-only. Create a new web project. I created an empty MVC 2 application but MVC is not required for OData. Add a new WCF Data Service to the project. I named mine NastyWords.svc since I’m serving up a list of nasty words. Add a class to expose via the service: NastyWord 1: [DataServiceKey("Word")] 2: public class NastyWord 3: { 4: public string Word { get; set; } 5: }   I need to be able to uniquely identify instances of NastyWords for the DataService so I used the DataServiceKey attribute with the “Word” property as the key. I could have added an “ID” property which would have uniquely identified them and would then not need the “DataServiceKey” attribute because the DataService would apply some reflection and heuristics to guess at which property would be the unique identifier. However, the words themselves are unique so adding an “ID” property would be redundantly repetitive. Then I created a data source to expose my NastyWord objects to the service. This is just a simple class with IQueryable<T> properties exposing the entities for my service: 1: public class NastyWordsDataSource 2: { 3: private static IList<NastyWord> words = new List<NastyWord> 4: { 5: new NastyWord{ Word="crap"}, 6: new NastyWord{ Word="darn"}, 7: new NastyWord{ Word="hell"}, 8: new NastyWord{ Word="shucks"} 9: }; 10:   11: public NastyWordsDataSource() 12: { 13: NastyWords = words.AsQueryable(); 14: } 15:   16: public IQueryable<NastyWord> NastyWords { get; private set; } 17: }   Now I can go to the NastyWords.svc class and tell it which data source to use and which entities to expose: 1: public class NastyWords : DataService<NastyWordsDataSource> 2: { 3: // This method is called only once to initialize service-wide policies. 4: public static void InitializeService(DataServiceConfiguration config) 5: { 6: config.SetEntitySetAccessRule("*", EntitySetRights.AllRead); 7: config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; 8: } 9: }   Compile and browse to my NastWords.svc and weep with joy Now I can query my service just like any other OData service. Next time, I’ll modify this service to allow updates to sent so I can build up my list of nasty words. Enjoy!

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  • Refactoring and Open / Closed principle

    - by Giorgio
    I have recently being reading a web site about clean code development (I do not put a link here because it is not in English). One of the principles advertised by this site is the Open Closed Principle: each software component should be open for extension and closed for modification. E.g., when we have implemented and tested a class, we should only modify it to fix bugs or to add new functionality (e.g. new methods that do not influence the existing ones). The existing functionality and implementation should not be changed. I normally apply this principle by defining an interface I and a corresponding implementation class A. When class A has become stable (implemented and tested), I normally do not modify it too much (possibly, not at all), i.e. If new requirements arrive (e.g. performance, or a totally new implementation of the interface) that require big changes to the code, I write a new implementation B, and keep using A as long as B is not mature. When B is mature, all that is needed is to change how I is instantiated. If the new requirements suggest a change to the interface as well, I define a new interface I' and a new implementation A'. So I, A are frozen and remain the implementation for the production system as long as I' and A' are not stable enough to replace them. So, in view of these observation, I was a bit surprised that the web page then suggested the use of complex refactorings, "... because it is not possible to write code directly in its final form." Isn't there a contradiction / conflict between enforcing the Open / Closed Principle and suggesting the use of complex refactorings as a best practice? Or the idea here is that one can use complex refactorings during the development of a class A, but when that class has been tested successfully it should be frozen?

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  • Confused about implementing Single Responsibility Principle

    - by HichemSeeSharp
    Please bear with me if the question looks not well structured. To put you in the context of my issue: I am building an application that invoices vehicles stay duration in a parking. In addition to the stay service there are some other services. Each service has its own calculation logic. Here is an illustration (please correct me if the design is wrong): public abstract class Service { public int Id { get; set; } public bool IsActivated { get; set; } public string Name { get; set } public decimal Price { get; set; } } public class VehicleService : Service { //MTM : many to many public virtual ICollection<MTMVehicleService> Vehicles { get; set; } } public class StayService : VehicleService { } public class Vehicle { public int Id { get; set; } public string ChassisNumber { get; set; } public DateTime? EntryDate { get; set; } public DateTime? DeliveryDate { get; set; } //... public virtual ICollection<MTMVehicleService> Services{ get; set; } } Now, I am focusing on the stay service as an example: I would like to know at invoicing time which class(es) would be responsible for generating the invoice item for the service and for each vehicle? This should calculate the duration cost knowing that the duration could be invoiced partially so the like is as follows: not yet invoiced stay days * stay price per day. At this moment I have InvoiceItemsGenerator do everything but I am aware that there is a better design.

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  • Confusion about inheritance

    - by Samuel Adam
    I know I might get downvoted for this, but I'm really curious. I was taught that inheritance is a very powerful polymorphism tool, but I can't seem to use it well in real cases. So far, I can only use inheritance when the base class is an abstract class. Examples : If we're talking about Product and Inventory, I quickly assumed that a Product is an Inventory because a Product must be inventorized as well. But a problem occured when user wanted to sell their Inventory item. It just doesn't seem to be right to change an Inventory object to it's subtype (Product), it's almost like trying to convert a parent to it's child. Another case is Customer and Member. It is logical (at least for me) to think that a Member is a Customer with some more privileges. Same problem occurred when user wanted to upgrade an existing Customer to become a Member. A very trivial case is the Employee case. Where Manager, Clerk, etc can be derived from Employee. Still, the same upgrading issue. I tried to use composition instead for some cases, but I really wanted to know if I'm missing something for inheritance solution here. My composition solution for those cases : Create a reference of Inventory inside a Product. Here I'm making an assumption about that Product and Inventory is talking in a different context. While Product is in the context of sales (price, volume, discount, etc), Inventory is in the context of physical management (stock, movement, etc). Make a reference of Membership instead inside Customer class instead of previous inheritance solution. Therefor upgrading a Customer is only about instantiating the Customer's Membership property. This example is keep being taught in basic programming classes, but I think it's more proper to have those Manager, Clerk, etc derived from an abstract Role class and make it a property in Employee. I found it difficult to find an example of a concrete class deriving from another concrete class. Is there any inheritance solution in which I can solve those cases? Being new in this OOP thing, I really really need a guidance. Thanks!

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  • Augmenting functionality of subclasses without code duplication in C++

    - by Rob W
    I have to add common functionality to some classes that share the same superclass, preferably without bloating the superclass. The simplified inheritance chain looks like this: Element -> HTMLElement -> HTMLAnchorElement Element -> SVGElement -> SVGAlement The default doSomething() method on Element is no-op by default, but there are some subclasses that need an actual implementation that requires some extra overridden methods and instance members. I cannot put a full implementation of doSomething() in Element because 1) it is only relevant for some of the subclasses, 2) its implementation has a performance impact and 3) it depends on a method that could be overridden by a class in the inheritance chain between the superclass and a subclass, e.g. SVGElement in my example. Especially because of the third point, I wanted to solve the problem using a template class, as follows (it is a kind of decorator for classes): struct Element { virtual void doSomething() {} }; // T should be an instance of Element template<class T> struct AugmentedElement : public T { // doSomething is expensive and uses T virtual void doSomething() override {} // Used by doSomething virtual bool shouldDoSomething() = 0; }; class SVGElement : public Element { /* ... */ }; class SVGAElement : public AugmentedElement<SVGElement> { // some non-trivial check bool shouldDoSomething() { /* ... */ return true; } }; // Similarly for HTMLAElement and others I looked around (in the existing (huge) codebase and on the internet), but didn't find any similar code snippets, let alone an evaluation of the effectiveness and pitfalls of this approach. Is my design the right way to go, or is there a better way to add common functionality to some subclasses of a given superclass?

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  • Fixed Sized Buffer or Variable Buffers with C# Sockets

    - by Keagan Ladds
    I am busy designing a TCP Server class in C# that has events and allows the user of the class to define packets that the server can send a receive by registering a class that is derived from my "GenericPacket" class. My TCPListener uses Async methods such as .BeginReceive(..); My issue is that because I am using the .BeginReceive(); I need to specify a buffer size when I call the function. This means I cant read the whole packet if one of my defined packets is too big. I have thought of creating a fixed sized Header that gets read using .BeginRead(); and the read the rest using Stream.Read(); but this will lead to the whole server having to wait for this operation to complete. I would like to know if anyone has come across this before and I would appreciate any suggestions.

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  • Designing a plug-in system

    - by madflame991
    I'm working on a Java project and I would like to add a plug-in system. More precisely, I would like to let the user design his own module, pack it into a jar, leave it in a "plugins/" subfolder of my application and be done with it. I've managed to get a child classloader to instantiate objects of classes located in external jars, but now I'm facing a design dilemma: Say Joe makes a plug-in and he packs it in joeplugin.jar. I would really like Joe to have a class named "instantiation.Factory" and I would also like everyone to have this class with this exact location and name. (This factory class obviously implements a interface that I provide and through it I get what I want from the plug-in.) If Joe wouldn't be restricted in this way I would have to look into his entire jar for some class that implements my factory interface and I don't want to imagine how complicated things get. So my question is: should I enforce a strict naming convention for this single class? I have no idea how plug-in systems work.

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  • Group method parameter or individual parameter?

    - by Nassign
    I would like to ask on method parameters design consideration. I am usually deciding between using individual variables as parameters versus grouping them to a class or dictionary as one parameter. Is there such a rule when you should use individual parameter against using a class or a dictionary to group the parameter? Individual parameter - Straight forward, strongly typed Dictionary parameter - Very extensible, like HTTP request but cannot be strongly typed. Class parameter - Extensible by adding member to the class parameter, strongly typed. I am looking for a design reference on when to use which? Note: I am not sure if this question is valid in programmers but I definitely think it would be closed in stackoverflow, If it is still not valid, please point me to the proper page.

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  • Spring + JSR 303 Validation group is ignored [closed]

    - by nsideras
    we have a simple bean with JSR annotations public class CustomerDTO { private static final long serialVersionUID = 1L; private Integer id; @NotEmpty(message = "{customer.firstname.empty}") private String firstName; @NotEmpty(message = "{customer.lastname.empty}") private String lastName; @NotEmpty(groups={PasswordChange.class}, message="{password.empty}") private String password; @NotEmpty(groups={PasswordChange.class}, message="{confirmation.password.empty}") private String password2; } and we have a Spring Controller @RequestMapping(value="/changePassword", method = RequestMethod.POST) public String changePassword(@Validated({ PasswordChange.class }) @ModelAttribute("customerdto") CustomerDTO customerDTO, BindingResult result, Locale locale) { logger.debug("Change Password was submitted with information: " + customerDTO.toString()); try { passwordStrengthPolicy.checkPasswordStrength(locale, customerDTO.getPassword()); if (result.hasErrors()) { return "changePassword"; } logger.debug("Calling customer service changePassword: " + customerDTO); customerOnlineNewService.changePassword(customerDTO); } catch (PasswordNotChangedException e) { logger.error("Could not change password PasswordNotChangedException: " + customerDTO.toString()); return "changePassword"; } catch (PasswordNotSecureException e) { return "changePassword"; } return createRedirectViewPath("changePassword"); } Our problem is that when changePassword is invoked the validator ignores the group(PasswordChange.class) and validates only firstName and lastName which are not in the group. Any idea? Thank you very much for your time.

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  • Web Services Example - Part 2: Programmatic

    - by Denis T
    In this edition of the ADF Mobile blog we'll tackle part 2 of our Web Service examples.  In this posting we'll take a look at using a SOAP Web Service but calling it programmatically in code and parsing the return into a bean. Getting the sample code: Just click here to download a zip of the entire project.  You can unzip it and load it into JDeveloper and deploy it either to iOS or Android.  Please follow the previous blog posts if you need help getting JDeveloper or ADF Mobile installed.  Note: This is a different workspace than WS-Part1 Defining our Web Service: Just like our first installment, we are using the same public weather forecast web service provided free by CDYNE Corporation.  Sometimes this service goes down so please ensure you know it's up before reporting this example isn't working. We're going to concentrate on the same two web service methods, GetCityForecastByZIP and GetWeatherInformation. Defing the Application: The application setup is identical to the Weather1 version.  There are some improvements to the data that is displayed as part of this example though.  Now we are able to show the associated image along with each forecast line when using the Forecast By Zip feature.  We've also added the temperature Hi/Low values into the UI. Summary of Fundamental Changes In This Application The most fundamental change is that we're binding the UI to the Bean Data Controls instead of directly to the Web Service Data Controls.  This gives us much more flexibility to control the shape of the data and allows us to do caching of the data outside of the Web Service.  This way if your application is, say offline, your bean could still populate with data from a local cache and still show you some UI as opposed to completely failing because you don't have any connectivity. In general we promote this type of programming technique with ADF Mobile to insulate your application from any issues with network connectivity. What's different with this example? We have setup the Web Service DC the same way but now we have managed beans to process the data.  The following classes define the "Model" of our application:  CityInformation-CityForecast-Forecast, WeatherInformation-WeatherDescription.  We use WeatherBean for UI interaction to the model layer.  If you look through this example, we don't really do that much with the java code except use it to grab the image URL from the weather description.  In a more realistic example, you might be using some JDBC classes to persist the data to a local database. To have a good architecture it is always good to keep your model and UI layers separate.  This gets muddied if you start to use bindings on a page invoked from Java code and this java code starts to become your "model" layer.  Since bindings are page specific, your model layer starts to become entwined with your UI.  Not good!  To help with this, we've added some utility functions that let you invoke DC methods without having a binding and thus execute methods from your "model" layer without requiring a binding in your page definition.  We do this with the invokeDataControlMethod of the AdfmfJavaUtilities class.  An example of this method call is available in line 95 of WeatherInformation.java and line 93 of CityInformation.Java. What's a GenericType? Because Web Service Data Controls (and also URL Data Controls AKA REST) use generic name/value pairs to define their structure and don't have strongly typed objects, these are actually stored internally as GenericType objects.  The GenericType class is simply a property map of name/value pairs that can be hierarchical.  There are methods like getAttribute where you supply the index of the attribute or it's string property name.  Why is this important to know?  Because invokeDataControlMethod returns GenericType objects and developers either need to parse these GenericType objects themselves or use one of our helper functions. GenericTypeBeanSerializationHelper This class does exactly what it's name implies.  It's a helper class for developers to aid in serialization of GenericTypes to/from java objects.  This is extremely handy if you have a large GenericType object with many attributes (or you're just lazy like me!) and you just want to parse it out into a real java object you can use more easily.  Here you would use the fromGenericType method.  This method takes the class of the Java object you wish to return and the GenericType as parameters.  The method then parses through each attribute in the GenericType and uses reflection to set that same attribute in the Java class.  Then the method returns that new object of the class you specified.  This is obviously very handy to avoid a lot of shuffling code between GenericType and your own Java classes.  The reverse method, toGenericType is also available when you want to go the other way.  In this case you supply the string that represents the package location in the DataControl definition (Example: "MyDC.myParams.MyCollection") and then pass in the Java object you have that holds the data and a GenericType is returned to you.  Again, it will use reflection to calculate the attributes that match between the java class and the GenericType and call the getters/setters on those. Issues and Possible Improvements: In the next installment we'll show you how to make your web service calls asynchronously so your UI will fill dynamically when the service call returns but in the meantime you show the data you have locally in your bean fed from some local cache.  This gives your users instant delivery of some data while you fetch other data in the background.

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  • Name user object and user table correctly

    - by Marc
    It's maybe simple but I think about this every time I build a new application. How do you name the class for the current user of the application and for the orm class of the user table? Usually I have something like CurrentUser: Logged-in user, stored in session, info for last activity etc User: ORM Class (C# EF CodeFirst, but it doesn't matter) And yes, they could have the same name in different namespaces, but I don't really like that.

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  • How do I separate codes with classes?

    - by Trycon
    I have this main class: package javagame; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Graphics; import org.newdawn.slick.SlickException; import org.newdawn.slick.state.BasicGameState; import org.newdawn.slick.state.StateBasedGame; public class tests extends BasicGameState{ public boolean render=false; tests1 test = new tests1(); public tests(int test) { // TODO Auto-generated constructor stub } @Override public void init(GameContainer arg0, StateBasedGame arg1) throws SlickException { // TODO Auto-generated method stub } @Override public void render(GameContainer arg0, StateBasedGame arg1, Graphics g) throws SlickException { // TODO Auto-generated method stub if(render==true) { g.drawString("Hello",100,100); } } @Override public void update(GameContainer gc, StateBasedGame s, int delta) throws SlickException { // TODO Auto-generated method stub test.render=render; test.update(gc, s, delta); } @Override public int getID() { // TODO Auto-generated method stub return 1000; } } and its sub-class: package javagame; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Input; import org.newdawn.slick.state.StateBasedGame; public class tests1 { public boolean render; public void update(GameContainer gc, StateBasedGame s, int delta) { Input input = gc.getInput(); if(input.isKeyPressed(Input.KEY_X)) { render=true; } } } I was finding a way to prevent many codes in one class. I'm new to java. When I try running my game, then when I press X, it does not work. How am I suppose to fix that?

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  • Using Unity – Part 4

    - by nmarun
    In this part, I’ll be discussing about constructor and property or setter injection. I’ve created a new class – Product3: 1: public class Product3 : IProduct 2: { 3: public string Name { get; set; } 4: [Dependency] 5: public IDistributor Distributor { get; set; } 6: public ILogger Logger { get; set; } 7:  8: public Product3(ILogger logger) 9: { 10: Logger = logger; 11: Name = "Product 1"; 12: } 13:  14: public string WriteProductDetails() 15: { 16: StringBuilder productDetails = new StringBuilder(); 17: productDetails.AppendFormat("{0}<br/>", Name); 18: productDetails.AppendFormat("{0}<br/>", Logger.WriteLog()); 19: productDetails.AppendFormat("{0}<br/>", Distributor.WriteDistributorDetails()); 20: return productDetails.ToString(); 21: } 22: } This version has a property of type IDistributor and takes a constructor parameter of type ILogger. The IDistributor property has a Dependency attribute (Microsoft.Practices.Unity namespace) applied to it. IDistributor and its implementation are shown below: 1: public interface IDistributor 2: { 3: string WriteDistributorDetails(); 4: } 5:  6: public class Distributor : IDistributor 7: { 8: public List<string> DistributorNames = new List<string>(); 9:  10: public Distributor() 11: { 12: DistributorNames.Add("Distributor1"); 13: DistributorNames.Add("Distributor2"); 14: DistributorNames.Add("Distributor3"); 15: DistributorNames.Add("Distributor4"); 16: } 17: public string WriteDistributorDetails() 18: { 19: StringBuilder distributors = new StringBuilder(); 20: for (int i = 0; i < DistributorNames.Count; i++) 21: { 22: distributors.AppendFormat("{0}<br/>", DistributorNames[i]); 23: } 24: return distributors.ToString(); 25: } 26: } ILogger and the FileLogger have the following definition: 1: public interface ILogger 2: { 3: string WriteLog(); 4: } 5:  6: public class FileLogger : ILogger 7: { 8: public string WriteLog() 9: { 10: return string.Format("Type: {0}", GetType()); 11: } 12: } The Unity container creates an instance of the dependent class (the Distributor class) within the scope of the target object (an instance of Product3 class that will be called by doing a Resolve<IProduct>() in the calling code) and assign this dependent object to the attributed property of the target object. To add to it, property injection is a form of optional injection of dependent objects.The dependent object instance is generated before the container returns the target object. Unlike constructor injection, you must apply the appropriate attribute in the target class to initiate property injection. Let’s see how to change the config file to make this work. The first step is to add all the type aliases: 1: <typeAlias alias="Product3" type="ProductModel.Product3, ProductModel"/> 2: <typeAlias alias="ILogger" type="ProductModel.ILogger, ProductModel"/> 3: <typeAlias alias="FileLogger" type="ProductModel.FileLogger, ProductModel"/> 4: <typeAlias alias="IDistributor" type="ProductModel.IDistributor, ProductModel"/> 5: <typeAlias alias="Distributor" type="ProductModel.Distributor, ProductModel"/> Now define mappings for these aliases: 1: <type type="ILogger" mapTo="FileLogger" /> 2: <type type="IDistributor" mapTo="Distributor" /> Next step is to define the constructor and property injection in the config file: 1: <type type="IProduct" mapTo="Product3" name="ComplexProduct"> 2: <typeConfig extensionType="Microsoft.Practices.Unity.Configuration.TypeInjectionElement, Microsoft.Practices.Unity.Configuration"> 3: <constructor> 4: <param name="logger" parameterType="ILogger" /> 5: </constructor> 6: <property name="Distributor" propertyType="IDistributor"> 7: <dependency /> 8: </property> 9: </typeConfig> 10: </type> There you see a constructor element that tells there’s a property named ‘logger’ that is of type ILogger. By default, the type of ILogger gets resolved to type FileLogger. There’s also a property named ‘Distributor’ which is of type IDistributor and which will get resolved to type Distributor. On the calling side, I’ve added a new button, whose click event does the following: 1: protected void InjectionButton_Click(object sender, EventArgs e) 2: { 3: unityContainer.RegisterType<IProduct, Product3>(); 4: IProduct product3 = unityContainer.Resolve<IProduct>(); 5: productDetailsLabel.Text = product3.WriteProductDetails(); 6: } This renders the following output: This completes the part for constructor and property injection. In the next blog, I’ll talk about Arrays and Generics. Please see the code used here.

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  • Do you leverage the benefits of the open-closed principle?

    - by Kaleb Pederson
    The open-closed principle (OCP) states that an object should be open for extension but closed for modification. I believe I understand it and use it in conjunction with SRP to create classes that do only one thing. And, I try to create many small methods that make it possible to extract out all the behavior controls into methods that may be extended or overridden in some subclass. Thus, I end up with classes that have many extension points, be it through: dependency injection and composition, events, delegation, etc. Consider the following a simple, extendable class: class PaycheckCalculator { // ... protected decimal GetOvertimeFactor() { return 2.0M; } } Now say, for example, that the OvertimeFactor changes to 1.5. Since the above class was designed to be extended, I can easily subclass and return a different OvertimeFactor. But... despite the class being designed for extension and adhering to OCP, I'll modify the single method in question, rather than subclassing and overridding the method in question and then re-wiring my objects in my IoC container. As a result I've violated part of what OCP attempts to accomplish. It feels like I'm just being lazy because the above is a bit easier. Am I misunderstanding OCP? Should I really be doing something different? Do you leverage the benefits of OCP differently? Update: based on the answers it looks like this contrived example is a poor one for a number of different reasons. The main intent of the example was to demonstrate that the class was designed to be extended by providing methods that when overridden would alter the behavior of public methods without the need for changing internal or private code. Still, I definitely misunderstood OCP.

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  • how should I design Objects around this business requirement?

    - by brainydexter
    This is the business requirement: " A Holiday Package (e.g. New York NY Holiday Package) can be offered in different ways based on the Origin city: From New Delhi to NY From Bombay to NY NY itself ( Land package ) (Bold implies default selection) a. and b. User can fly from either New Delhi or Bombay to NY. c. NY is a Land package, where a user can reach NY by himself and is a standalone holidayPackage. " Let's say I have a class that represents HolidayPackage, Destination (aka City). public class HolidayPackage{ Destination holidayCity; ArrayList<BaseHolidayPackageVariant> variants; BaseHolidayPackageVariant defaultVariant; } public abstract class BaseHolidayPackageVariant { private Integer variantId; private HolidayPackage holidayPackage; private String holidayPackageType; } public class LandHolidayPackageVariant extends BaseHolidayPackageVariant{ } public class FlightHolidayPackageVariant extends BaseHolidayPackageVariant{ private Destination originCity; } What data structure/objects should I design to support: options a default within those options Sidenote: A HolidayPackage can also be offered in different ways based on Hotel selections. I'd like to follow a design which I can leverage to support that use case in the future. This is the backend design I have in mind.

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  • Object oriented wrapper around a dll

    - by Tom Davies
    So, I'm writing a C# managed wrapper around a native dll. The dll contains several hundred functions. In most cases, the first argument to each function is an opaque handle to a type internal to the dll. So, an obvious starting point for defining some classes in the wrapper would be to define classes corresponding to each of these opaque types, with each instance holding and managing the opaque handle (passed to its constructor) Things are a little awkward when dealing with callbacks from the dll. Naturally, the callback handlers in my wrapper have to be static, but the callbacks arguments invariable contain an opaque handle. In order to get from the static callback back to an object instance, I've created a static dictionary in each class, associating handles with class instances. In the constructor of each class, an entry is put into the dictionary, and this entry is then removed in the Destructors. When I receive a callback, I can then consult the dictionary to retrieve the class instance corresponding to the opaque reference. Are there any obvious flaws to this? Something that seems to be a problem is that the existence static dictionary means that the garbage collector will not act on my class instances that are otherwise unreachable. As they are never garbage collected, they never get removed from the dictionary, so the dictionary grows. It seems I might have to manually dispose of my objects, which is something absolutely would like to avoid. Can anyone suggest a good design that allows me to avoid having to do this?

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  • jQuery open and close nested ul nav depending on location

    - by firefusion
    I'm making a sub nav in wordpress and have a nested list style menu. An example of the HTML is below. Whichever is the current item has the li class "current_page_item". I need all child menus collapsed unless there is a current_page_item class on the parent or one of the children. <ul> <li class="current_page_item"><a href="#">Parent Item</a> <ul class="children"> <li><a href="#">Child page</a></li> <li><a href="#">Child page</a></li> <li><a href="#">Child page</a></li> <li><a href="#">Child page</a></li> </ul> </li> <li><a href="#">Parent Item</a> <ul class="children"> <li><a href="#">Child page</a></li> <li><a href="#">Child page</a></li> </ul> </li> <li><a href="#">Parent Item</a> <ul class="children"> <li><a href="#">Child page</a></li> <li><a href="#">Child page</a></li> </ul> </li> <li><a href="#">Parent Item</a></li> <li><a href="#">Parent Item</a></li> </ul> This so far, which works but i wonder if it can be improved as there is some flashing open and then closed again.... jQuery('ul.children').slideUp(); jQuery('li.current_page_item ul.children').slideDown('medium'); jQuery('li.current_page_item').parent().slideDown('medium');

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  • Annotation Processor for Superclass Sensitive Actions

    - by Geertjan
    Someone creating superclass sensitive actions should need to specify only the following things: The condition under which the popup menu item should be available, i.e., the condition under which the action is relevant. And, for superclass sensitive actions, the condition is the name of a superclass. I.e., if I'm creating an action that should only be invokable if the class implements "org.openide.windows.TopComponent",  then that fully qualified name is the condition. The position in the list of Java class popup menus where the new menu item should be found, relative to the existing menu items. The display name. The path to the action folder where the new action is registered in the Central Registry. The code that should be executed when the action is invoked. In other words, the code for the enablement (which, in this case, means the visibility of the popup menu item when you right-click on the Java class) should be handled generically, under the hood, and not every time all over again in each action that needs this special kind of enablement. So, here's the usage of my newly created @SuperclassBasedActionAnnotation, where you should note that the DataObject must be in the Lookup, since the action will only be available to be invoked when you right-click on a Java source file (i.e., text/x-java) in an explorer view: import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import org.netbeans.sbas.annotations.SuperclassBasedActionAnnotation; import org.openide.awt.StatusDisplayer; import org.openide.loaders.DataObject; import org.openide.util.NbBundle; import org.openide.util.Utilities; @SuperclassBasedActionAnnotation( position=30, displayName="#CTL_BrandTopComponentAction", path="File", type="org.openide.windows.TopComponent") @NbBundle.Messages("CTL_BrandTopComponentAction=Brand") public class BrandTopComponentAction implements ActionListener { private final DataObject context; public BrandTopComponentAction() { context = Utilities.actionsGlobalContext().lookup(DataObject.class); } @Override public void actionPerformed(ActionEvent ev) { String message = context.getPrimaryFile().getPath(); StatusDisplayer.getDefault().setStatusText(message); } } That implies I've created (in a separate module to where it is used) a new annotation. Here's the definition: package org.netbeans.sbas.annotations; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; @Retention(RetentionPolicy.SOURCE) @Target(ElementType.TYPE) public @interface SuperclassBasedActionAnnotation { String type(); String path(); int position(); String displayName(); } And here's the processor: package org.netbeans.sbas.annotations; import java.util.Set; import javax.annotation.processing.Processor; import javax.annotation.processing.RoundEnvironment; import javax.annotation.processing.SupportedAnnotationTypes; import javax.annotation.processing.SupportedSourceVersion; import javax.lang.model.SourceVersion; import javax.lang.model.element.Element; import javax.lang.model.element.TypeElement; import javax.lang.model.util.Elements; import org.openide.filesystems.annotations.LayerBuilder.File; import org.openide.filesystems.annotations.LayerGeneratingProcessor; import org.openide.filesystems.annotations.LayerGenerationException; import org.openide.util.lookup.ServiceProvider; @ServiceProvider(service = Processor.class) @SupportedAnnotationTypes("org.netbeans.sbas.annotations.SuperclassBasedActionAnnotation") @SupportedSourceVersion(SourceVersion.RELEASE_6) public class SuperclassBasedActionProcessor extends LayerGeneratingProcessor { @Override protected boolean handleProcess(Set annotations, RoundEnvironment roundEnv) throws LayerGenerationException { Elements elements = processingEnv.getElementUtils(); for (Element e : roundEnv.getElementsAnnotatedWith(SuperclassBasedActionAnnotation.class)) { TypeElement clazz = (TypeElement) e; SuperclassBasedActionAnnotation mpm = clazz.getAnnotation(SuperclassBasedActionAnnotation.class); String teName = elements.getBinaryName(clazz).toString(); String originalFile = "Actions/" + mpm.path() + "/" + teName.replace('.', '-') + ".instance"; File actionFile = layer(e).file( originalFile). bundlevalue("displayName", mpm.displayName()). methodvalue("instanceCreate", "org.netbeans.sbas.annotations.SuperclassSensitiveAction", "create"). stringvalue("type", mpm.type()). newvalue("delegate", teName); actionFile.write(); File javaPopupFile = layer(e).file( "Loaders/text/x-java/Actions/" + teName.replace('.', '-') + ".shadow"). stringvalue("originalFile", originalFile). intvalue("position", mpm.position()); javaPopupFile.write(); } return true; } } The "SuperclassSensitiveAction" referred to in the code above is unchanged from how I had it in yesterday's blog entry. When I build the module containing two action listeners that use my new annotation, the generated layer file looks as follows, which is identical to the layer file entries I hard coded yesterday: <folder name="Actions"> <folder name="File"> <file name="org-netbeans-sbas-impl-ActionListenerSensitiveAction.instance"> <attr name="displayName" stringvalue="Process Action Listener"/> <attr methodvalue="org.netbeans.sbas.annotations.SuperclassSensitiveAction.create" name="instanceCreate"/> <attr name="type" stringvalue="java.awt.event.ActionListener"/> <attr name="delegate" newvalue="org.netbeans.sbas.impl.ActionListenerSensitiveAction"/> </file> <file name="org-netbeans-sbas-impl-BrandTopComponentAction.instance"> <attr bundlevalue="org.netbeans.sbas.impl.Bundle#CTL_BrandTopComponentAction" name="displayName"/> <attr methodvalue="org.netbeans.sbas.annotations.SuperclassSensitiveAction.create" name="instanceCreate"/> <attr name="type" stringvalue="org.openide.windows.TopComponent"/> <attr name="delegate" newvalue="org.netbeans.sbas.impl.BrandTopComponentAction"/> </file> </folder> </folder> <folder name="Loaders"> <folder name="text"> <folder name="x-java"> <folder name="Actions"> <file name="org-netbeans-sbas-impl-ActionListenerSensitiveAction.shadow"> <attr name="originalFile" stringvalue="Actions/File/org-netbeans-sbas-impl-ActionListenerSensitiveAction.instance"/> <attr intvalue="10" name="position"/> </file> <file name="org-netbeans-sbas-impl-BrandTopComponentAction.shadow"> <attr name="originalFile" stringvalue="Actions/File/org-netbeans-sbas-impl-BrandTopComponentAction.instance"/> <attr intvalue="30" name="position"/> </file> </folder> </folder> </folder> </folder>

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  • Thunderbird cant open due to GLiB Error

    - by Elli
    i recently updated Lubuntu to 13.10 and now after some days Thunderbird stopped working. It just won't open. When i try to open it with the terminal i get the following text: user@user-rechner:~$ thunderbird (process:6231): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed (thunderbird:6231): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::sm-connect after class was initialised (thunderbird:6231): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::show-crash-dialog after class was initialised (thunderbird:6231): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::display after class was initialised (thunderbird:6231): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::default-icon after class was initialised GNOME-Tastaturkürzel-Verzeichnis »/home/user/.gnome2/accels« konnte nicht angelegt werden: Keine Berechtigung (Translation: gnome shortcut-directory could not be created - no permission) Now i reinstalled it once, deleted this .thunderbird folder in my home directory and it still won't work. I hope someone can help me. Thanks.

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  • Relationship DAO, Servlet, JSP and POJO [closed]

    - by John Hendrik
    Possible Duplicate: Relationship DAO, Servlet, JSP and POJO I want to implement a JSP, POJO, DAO and Servlet in my J2EE program. However, I don't fully understand how the relationship between these elements should be. Is the following (MVC) setup the right way to do it? Main class creates servlet(controller) Servlet has a DAO defined in its class DAO has a POJO defined in its class Servlet communicates with the view (JSP page) Please give your feedback.

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  • Splitting a tetris game apart - where to put time-management?

    - by nightcracker
    I am creating a tetris game in C++ & SDL, and I'm trying to do it "good" by making it object-oriented and keeping scopes small. So far I have the following structure: A main with some lowlevel SDL set up and handling input A game class that keeps track of score and provides the interface for main (move block down, etc) A map class that keeps track of the current game field, which blocks are where. Used by the game class. A block class that consists of the current falling block, used by game. A renderer class abstracting low level SDL to a format where you render "tetris blocks". Used by map and block. Now I have a though time where to place the time-management of this game. For example, where should be decided when a block bumps the bottom of the screen how long it takes the current block locks in place and a new block spawns? I also have an other unrelated question, is there some place where you can find some standard data on tetris like standard score tables, rulesets, timings, etc?

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  • Law of Demeter confusion [duplicate]

    - by user2158382
    This question already has an answer here: Rails: Law of Demeter Confusion 4 answers I am reading a book called Rails AntiPatterns and they talk about using delegation to to avoid breaking the Law of Demeter. Here is their prime example: They believe that calling something like this in the controller is bad (and I agree) @street = @invoice.customer.address.street Their proposed solution is to do the following: class Customer has_one :address belongs_to :invoice def street address.street end end class Invoice has_one :customer def customer_street customer.street end end @street = @invoice.customer_street They are stating that since you only use one dot, you are not breaking the Law of Demeter here. I think this is incorrect, because you are still going through customer to go through address to get the invoice's street. I primarily got this idea from a blog post I read: http://www.dan-manges.com/blog/37 In the blog post the prime example is class Wallet attr_accessor :cash end class Customer has_one :wallet # attribute delegation def cash @wallet.cash end end class Paperboy def collect_money(customer, due_amount) if customer.cash < due_ammount raise InsufficientFundsError else customer.cash -= due_amount @collected_amount += due_amount end end end The blog post states that although there is only one dot customer.cash instead of customer.wallet.cash, this code still violates the Law of Demeter. Now in the Paperboy collect_money method, we don't have two dots, we just have one in "customer.cash". Has this delegation solved our problem? Not at all. If we look at the behavior, a paperboy is still reaching directly into a customer's wallet to get cash out. Can somebody help me clear the confusion. I have been searching for the past 2 days trying to let this topic sink in, but it is still confusing.

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  • jQuery - discrepency between classname and selectors

    - by Ciel
    I have the following code that I wrote, which I personally found to be pretty nice. It takes a <ul> and it drops down the contents when clicked. But I am having a disconnect here in comprehension, and one I had to do what I feel is a 'dirty hack' to solve. The problem is that I do not want the class `'sidebar-dropdown-open' to be so 'hardwired' in the plugin. However I discovered that there is a very stark difference between... $('.sidebar-dropdown-open') and 'sidebar-dropdown-open and even '.sidebar-dropdown-open. I 'solved' this problem by including two different 'parameters' in my plugin, but I was wondering if someone might give me some insight as to how I could perform this better, and why this was behaving this way. wiring (document load) $(document).ready(function () { $('[data-role="sidebar-dropdown"]').drawer({ open: 'sidebar-dropdown-open', css: '.sidebar-dropdown-open' }); }); html <ul> <li class=" dropdown" data-role="sidebar-dropdown"> <a href="pages/.." class="remote">Link Text</a> <ul class="sub-menu light sidebar-dropdown-menu"> <li><a class="remote" href="pages/...">Link Text</a></li> <li><a class="remote" href="pages/...">Link Text</a></li> <li><a class="remote" href="pages/...">Link Text</a></li> </ul> </li> </ul> javascript (function ($) { $.fn.drawer = function (options) { // Create some defaults, extending them with any options that were provided var settings = $.extend({ open: 'open', css: '.open' }, options); return this.each(function () { $(this).on('click', function (e) { // slide up all open dropdown menus $(settings.css).not($(this)).each(function () { $(this).removeClass(settings.open); // retrieve the appropriate menu item var $menu = $(this).children(".dropdown-menu, .sidebar-dropdown-menu"); // slide down the one clicked on. $menu.slideUp('fast'); $menu.removeClass('active'); }); // mark this menu as open $(this).addClass(settings.open); // retrieve the appropriate menu item var $menu = $(this).children(".dropdown-menu, .sidebar-dropdown-menu"); // slide down the one clicked on. $menu.slideDown(100); $menu.addClass('active'); e.preventDefault(); e.stopPropagation(); }).on("mouseleave", function () { $(this).children(".dropdown-menu").hide().delay(300); }); }) }; })(jQuery); I have tried using settings.open and demanding that it just be a className (.open), etc. - but that does not seem to work. It seems to get ignored by the removeClass function.

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  • Proper method to update and draw from game loop?

    - by Lost_Soul
    Recently I've took up the challenge for myself to create a basic 2d side scrolling monster truck game for my little brother. Which seems easy enough in theory. After working with XNA it seems strange jumping into Java (which is what I plan to program it in). Inside my game class I created a private class called GameLoop that extends from Runnable, then in the overridden run() method I made a while loop that handles time and such and I implemented a targetFPS for drawing as well. The loop looks like this: @Override public void run() { long fpsTime = 0; gameStart = System.currentTimeMillis(); lastTime = System.currentTimeMillis(); while(game.isGameRunning()) { currentTime = System.currentTimeMillis(); long ellapsedTime = currentTime - lastTime; if(mouseState.leftIsDown) { que.add(new Dot(mouseState.getPosition())); } entities.addAll(que); game.updateGame(ellapsedTime); fpsTime += ellapsedTime; if(fpsTime >= (1000 / targetedFPS)) { game.drawGame(ellapsedTime); } lastTime = currentTime; } The problem I've ran into is adding of entities after a click. I made a class that has another private class that extends MouseListener and MouseMotionListener then on changes I have it set a few booleans to tell me if the mouse is pressed or not which seems to work great but when I add the entity it throws a CME (Concurrent Modification Exception) sometimes. I have all the entities stored in a LinkedList so later I tried adding a que linkedlist where I later add the que to the normal list in the update loop. I think this would work fine if it was just the update method in the gameloop but with the repaint() method (called inside game.drawGame() method) it throws the CME. The only other thing is that I'm currently drawing directly from the overridden paintComponent() method in a custom class that extends JPanel. Maybe there is a better way to go about this? As well as fix my CME? Thanks in advance!!!

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