Search Results

Search found 3838 results on 154 pages for 'abstract factory'.

Page 2/154 | < Previous Page | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >

• Why should I declare a class as an abstract class?

  - by Pied Piper

  I know the syntax, rules applied to abstract class and I want know usage of an abstract class Abstract class can not be instantiated directly but can be extended by other class What is the advantage of doing so? How it is different from an Interface? I know that one class can implement multiple interfaces but can only extend one abstract class. Is that only difference between an interface and an abstract class? I am aware about usage of an Interface. I have learned that from Event delegation model of AWT in Java. In which situations I should declare class as an abstract class? What is benefits of that?

  Read the article

• Interface vs Abstract Class (general OO)

  - by Kave

  Hi, I have had recently two telephone interviews where I've been asked about the differences between an Interface and an Abstract class. I have explained every aspect of them I could think of, but it seems they are waiting for me to mention something specific, and I dont know what it is. From my experience I think the following is true, if i am missing a major point please let me know: Interface: Every single Method declared in an Interface will have to be implemented in the subclass. Only Events, Delegates, Properties (C#) and Methods can exist in a Interface. A class can implement multiple Interfaces. Abstract Class Only Abstract methods have to be implemented by the subclass. An Abstract class can have normal methods with implementations. Abstract class can also have class variables beside Events, Delegates, Properties and Methods. A class can only implement one abstract class only due non-existence of Multi-inheritance in C#. 1) After all that the interviewer came up with the question What if you had an Abstract class with only abstract methods, how would that be different from an interface? I didnt know the answer but I think its the inheritance as mentioned above right? 2) An another interviewer asked me what if you had a Public variable inside the interface, how would that be different than in Abstract Class? I insisted you can't have a public variable inside an interface. I didn't know what he wanted to hear but he wasn't satisfied either. Many Thanks for clarification, Kave See Also: When to use an interface instead of an abstract class and vice versa Interfaces vs. Abstract Classes How do you decide between using an Abstract Class and an Interface?

  Read the article

• Workaround for abstract attributes in Java

  - by deamon

  In Scala I would write an abstract class with an abstract attribute path: abstract class Base { val path: String } class Sub extends Base { override val path = "/demo/" } Java doesn't know abstract attributes and I wonder what would be the best way to work around this limitation. My ideas: a) constructor parameter abstract class Base { protected String path; protected Base(String path) { this.path = path; } } class Sub extends Base { public Sub() { super("/demo/"); } } b) abstract method abstract class Base { // could be an interface too abstract String getPath(); } class Sub extends Base { public String getPath() { return "/demo/"; } } Which one do you like better? Other ideas? I tend to use the constructor since the path value should not be computed at runtime.

  Read the article

• org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager

  - by BilalFromParis

  when I add the code into my spring configuration file beans-hibernate.xml <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory" /> </bean> It doesn't work and I don't know why, can someone help me please ? My Dao Class is : public class CourseDaoImpl implements CourseDao { private SessionFactory sessionFactory; public void setSessionFactory(SessionFactory sessionFactory) { this.sessionFactory = sessionFactory; } @Transactional public void store(Course course) { sessionFactory.getCurrentSession().saveOrUpdate(course); } @Transactional public void delete(Long courseId) { Course course = (Course)sessionFactory.getCurrentSession().get(Course.class, courseId); sessionFactory.getCurrentSession().delete(course); } @Transactional(readOnly=true) public Course findById(Long courseId) { return (Course)sessionFactory.getCurrentSession().get(Course.class, courseId); } @Transactional public List<Course> findAll() { Query query = sessionFactory.getCurrentSession().createQuery("FROM Course"); return (List<Course>)query.list(); } } but : juil. 04, 2012 3:38:18 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh Infos: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@6ba8fb1b: startup date [Wed Jul 04 03:38:18 CEST 2012]; root of context hierarchy juil. 04, 2012 3:38:18 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions Infos: Loading XML bean definitions from class path resource [beans-hibernate.xml] juil. 04, 2012 3:38:19 AM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons Infos: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@5a7fed46: defining beans [org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,sessionFactory,transactionManager,courseDao]; root of factory hierarchy juil. 04, 2012 3:38:19 AM org.hibernate.annotations.common.Version INFO: HCANN000001: Hibernate Commons Annotations {4.0.1.Final} juil. 04, 2012 3:38:19 AM org.hibernate.Version logVersion INFO: HHH000412: Hibernate Core {4.1.3.Final} juil. 04, 2012 3:38:19 AM org.hibernate.cfg.Environment INFO: HHH000206: hibernate.properties not found juil. 04, 2012 3:38:19 AM org.hibernate.cfg.Environment buildBytecodeProvider INFO: HHH000021: Bytecode provider name : javassist juil. 04, 2012 3:38:19 AM org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure INFO: HHH000402: Using Hibernate built-in connection pool (not for production use!) juil. 04, 2012 3:38:19 AM org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure INFO: HHH000115: Hibernate connection pool size: 20 juil. 04, 2012 3:38:19 AM org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure INFO: HHH000006: Autocommit mode: false juil. 04, 2012 3:38:19 AM org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure INFO: HHH000401: using driver [org.hibernate.dialect.PostgreSQLDialect] at URL [jdbc:postgresql://localhost:5432/spring] juil. 04, 2012 3:38:19 AM org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure INFO: HHH000046: Connection properties: {user=Bilal, password=**} juil. 04, 2012 3:38:19 AM org.hibernate.dialect.Dialect INFO: HHH000400: Using dialect: org.hibernate.dialect.PostgreSQLDialect juil. 04, 2012 3:38:19 AM org.hibernate.engine.jdbc.internal.LobCreatorBuilder useContextualLobCreation INFO: HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4 juil. 04, 2012 3:38:19 AM org.hibernate.engine.transaction.internal.TransactionFactoryInitiator initiateService INFO: HHH000399: Using default transaction strategy (direct JDBC transactions) juil. 04, 2012 3:38:19 AM org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory INFO: HHH000397: Using ASTQueryTranslatorFactory juil. 04, 2012 3:38:19 AM org.hibernate.tool.hbm2ddl.SchemaUpdate execute INFO: HHH000228: Running hbm2ddl schema update juil. 04, 2012 3:38:19 AM org.hibernate.tool.hbm2ddl.SchemaUpdate execute INFO: HHH000102: Fetching database metadata juil. 04, 2012 3:38:19 AM org.hibernate.tool.hbm2ddl.SchemaUpdate execute INFO: HHH000396: Updating schema juil. 04, 2012 3:38:19 AM org.hibernate.tool.hbm2ddl.TableMetadata INFO: HHH000261: Table found: public.course juil. 04, 2012 3:38:19 AM org.hibernate.tool.hbm2ddl.TableMetadata INFO: HHH000037: Columns: [fee, id, title, end_date, begin_date] juil. 04, 2012 3:38:19 AM org.hibernate.tool.hbm2ddl.TableMetadata INFO: HHH000108: Foreign keys: [] juil. 04, 2012 3:38:19 AM org.hibernate.tool.hbm2ddl.TableMetadata INFO: HHH000126: Indexes: [course_pkey] juil. 04, 2012 3:38:19 AM org.hibernate.tool.hbm2ddl.SchemaUpdate execute INFO: HHH000232: Schema update complete juil. 04, 2012 3:38:19 AM org.springframework.beans.factory.support.DefaultSingletonBeanRegistry destroySingletons Infos: Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@5a7fed46: defining beans [org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,sessionFactory,transactionManager,courseDao]; root of factory hierarchy juil. 04, 2012 3:38:19 AM org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop INFO: HHH000030: Cleaning up connection pool [jdbc:postgresql://localhost:5432/spring] Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager' defined in class path resource [beans-hibernate.xml]: Invocation of init method failed; nested exception is java.lang.NoClassDefFoundError: org/hibernate/engine/SessionFactoryImplementor at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1455) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464) at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139) at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:83) at com.boutaya.bill.main.Main.main(Main.java:14) Caused by: java.lang.NoClassDefFoundError: org/hibernate/engine/SessionFactoryImplementor at org.springframework.orm.hibernate3.SessionFactoryUtils.getDataSource(SessionFactoryUtils.java:123) at org.springframework.orm.hibernate3.HibernateTransactionManager.afterPropertiesSet(HibernateTransactionManager.java:411) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1514) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1452) ... 12 more Caused by: java.lang.ClassNotFoundException: org.hibernate.engine.SessionFactoryImplementor at java.net.URLClassLoader$1.run(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) ... 16 more I think the problem is when I use the Class : org.springframework.orm.hibernate3.HibernateTransactionManager ???

  Read the article

• Create dynamic factory method in PHP (< 5.3)

  - by fireeyedboy

  How would one typically create a dynamic factory method in PHP? By dynamic factory method, I mean a factory method that will autodiscover what objects there are to create, based on some aspect of the given argument. Preferably without registering them first with the factory either. I'm OK with having the possible objects be placed in one common place (a directory) though. I want to avoid your typical switch statement in the factory method, such as this: public static function factory( $someObject ) { $className = get_class( $someObject ); switch( $className ) { case 'Foo': return new FooRelatedObject(); break; case 'Bar': return new BarRelatedObject(); break; // etc... } } My specific case deals with the factory creating a voting repository based on the item to vote for. The items all implement a Voteable interface. Something like this: Default_User implements Voteable ... Default_Comment implements Voteable ... Default_Event implements Voteable ... Default_VoteRepositoryFactory { public static function factory( Voteable $item ) { // autodiscover what type of repository this item needs // for instance, Default_User needs a Default_VoteRepository_User // etc... return new Default_VoteRepository_OfSomeType(); } } I want to be able to drop in new Voteable items and Vote repositories for these items, without touching the implementation of the factory.

  Read the article

• When to use abstract classes instead of interfaces and extension methods in C#?

  - by Gulshan

  "Abstract class" and "interface" are similar type of ideas, while interface being more abstract. One need of abstract classes was to provide method implementations for the derived classes. But in C#, that need has also been reduced by lately introduced extension methods. So, in C#, when should we use abstract classes instead of using interfaces and extension methods associated with the interface? And now, we can use 'Properties' in interfaces also. A notable example of interface+ extension methods is the Heavily used IEnumerable and it's helper methods. You use Linq and it's all by this extension methods!

  Read the article

• When to use abstract classes instead of interfaces and extension methods in C#?

  - by Gulshan

  "Abstract class" and "interface" are similar type of ideas, while interface being more abstract. One need of abstract classes was to provide method implementations for the derived classes. But in C#, that need has also been reduced by lately introduced extension methods. So, in C#, when should we use abstract classes instead of using interfaces and extension methods associated with the interface? And now, we can use 'Properties' in interfaces also. A notable example of interface+ extension methods is the Heavily used IEnumerable and it's helper methods. You use Linq and it's all by this extension methods!

  Read the article

• Should all public methods in an abstract class be marked virtual?

  - by Justin Pihony

  I recently had to update an abstract base class on some OSS that I was using so that it was more testable by making them virtual (I could not use an interface as it combined two). This got me thinking whether I should mark all of the methods that I needed virtual, or if I should mark every public method/property virtual. I generally agree with Roy Osherove that every method should be made virtual, but I came across this article that got me thinking about whether this was necessary or not. I am going to limit this down to abstract classes for simplicity, however (whether all concrete public methods should be virtual is especially debatable, I am sure). I could see where you might want to allow a sub-class to use a method, but not want it overriding the implementation. However, as long as you trust that Liskov's Substitution Principle will be followed, then why would you not allow it to be overriden? By marking it abstract, you are forcing a certain override anyway, so, it seems to me that all public methods inside of an abstract class should indeed be marked virtual. However, I wanted to ask in case there was something I might not be thinking. Should all public methods within an abstract class be made virtual?

  Read the article

• Why can't you call abstract functions from abstract classes in PHP?

  - by incrediman

  I've set up an abstract parent class, and a concrete class which extends it. Why can the parent class not call the abstract function? //foo.php <?php abstract class AbstractFoo{ abstract public static function foo(); public static function getFoo(){ return self::foo();//line 5 } } class ConcreteFoo extends AbstractFoo{ public static function foo(){ return "bar"; } } echo ConcreteFoo::getFoo(); ?> Error: Fatal error: Cannot call abstract method AbstractFoo::foo() in foo.php on line 5

  Read the article

• Why does C# allow abstract class with no abstract members?

  - by fatcat1111

  The C# spec, section 10.1.1.1, states: An abstract class is permitted (but not required) to contain abstract members. This allows me to create classes like this: public abstract class A { public void Main() { // it's full of logic! } } This is really a concrete class; it's only abstract in so far as one can't instantiate it. If inheritors don't actually have to provide implementation, then why call it abstract?

  Read the article

• Abstract Base Class or Class?

  - by Mohit Deshpande

  For my semester project, my team and I are supposed to make a .jar file (library, not runnable) that contains a game development framework and demonstrate the concepts of OOP. Its supposed to be a FRAMEWORK and another team is supposed to use our framework and vice-versa. So I want to know how we should start. We thought of several approaches: 1. Start with a plain class public class Enemy { public Enemy(int x, int y, int health, int attack, ...) { ... } ... } public class UserDefinedClass extends Enemy { ... } 2. Start with an abstract class that user-defined enemies have to inherit abstract members public abstract class Enemy { public Enemy(int x, int y, int health, int attack, ...) { ... } public abstract void draw(); public abstract void destroy(); ... } public class UserDefinedClass extends Enemy { ... public void draw() { ... } public void destroy() { ... } } 3. Create a super ABC (Abstract Base Class) that ALL inherit from public abstract class VectorEntity { ... } public abstract class Enemy extends VectorEntity { ... } public class Player extends VectorEntity { ... } public class UserDefinedClass extends Enemy { ... } Which should I use? Or is there a better way?

  Read the article

• Visual Studio: Design a UserControl class that derives from an abstract base class

  - by Marcel

  Hi All, I want to have an abstract base class for some of my custom UserControl's. The reason is obvious: they share some common properties and methods (a basic implementation of some elements of an interface actually), and I want to implement them only once. I have done this by defining my abstract base class: public abstract class ViewBase : UserControl, ISomeInterface Then I went to implement one of my views, as usual, with the designer: public partial class SpecialView : UserControl //all OK Up to here all is fine. Now I replace the derivation of my SpecialView class with the abstract base class: public partial class SpecialView : ViewBase //disrupts the designer Now, the designer in Visual Studio 2008 won't work anymore, stating: The designer must create an instance of type 'ViewBase' but it cannot because the type is declared as abstract. How can I circumvent this? I just do not want to have the same code copied for all those views. Info: there is a question question with virtual methods, instead of abstract classes, but there is no suitable solution for me.

  Read the article

• Implementing a configurable factory

  - by Decko

  I'm having difficulties finding out how to implement a 'configurable' behavior in a factory class in PHP. I've got at class, which takes another class as an argument in its constructor. The argument class could take a number of arguments in its constructor. An instance of my main class could look something like this $instance = new MyClass(new OtherClass(20, true)); $instance2 = new MyClass(new DifferentClass('test')); This is rather clumsy and has a number of problems and therefore I would like to move this into a factory class. The problem is that this factory somehow needs to know how to instantiate the argument class, as this class can have any number of arguments in the constructor. Preferably I would like to be able to do something like this $instance = Factory::build('OtherClass'); $instance2 = Factory::build('DifferentClass'); And let the factory retrieve the arguments from a configuration array or similar. Is there a proper solution to this problem?

  Read the article

• Problem deriving a user control from an abstract base class in website project

  - by Sprintstar

  In a Visual Studio website, I have created a user control. This control is derived from a class (in App_Code) that is itself derived from System.Web.UI.UserControl. This is an abstract class with an abstract method. I then try to implement that method in the user control, but I get the following errors from Visual Studio: Error 1 'WebUserControl.AbstractMethod()': no suitable method found to override C:\Users\User\Documents\Visual Studio 2010\WebSites\Delme\WebUserControl.ascx.cs 10 28 C:\...\Delme\ Error 2 'WebUserControl' does not implement inherited abstract member 'AbstractBaseClass.AbstractMethod()' c:\Users\User\AppData\Local\Temp\Temporary ASP.NET Files\delme\0eebaa86\f1a48678\App_Web_nrsbzxex.0.cs 14 Error 1 says that my override of the abstract method is invalid, it doesn't recognise the abstract method in the base class. Error 2 says that the partial class automatically built by asp.net doesn't implement the abstract method! Note that this works fine when the code is used in a Web Application project. Why is this happening?

  Read the article

• Figuring out what makes a C++ class abstract in VS2008

  - by suszterpatt

  I'm using VS2008 to build a plain old C++ program (not C++/CLI). I have an abstract base class and a non-abstract derived class, and building this: Base* obj; obj = new Derived(); fails with the error "'Derived': cannot instantiate abstract class". (It may be worth noting, however, that if I hover over Base with the cursor, VS will pop up a tooltip saying "class Base abstract", but hovering over Derived will only say "class Derived" (no "abstract")). The definitions of these classes are fairly large and I'd like to avoid manually checking if each method has been overridden. Can VS do this for me somehow? Any general tips on pinpointing the exact parts of the class' definition that make it abstract?

  Read the article

• How to generate a Program template by generating an abstract class

  - by Byron-Lim Timothy Steffan

  i have the following problem. The 1st step is to implement a program, which follows a specific protocol on startup. Therefore, functions as onInit, onConfigRequest, etc. will be necessary. (These are triggered e.g. by incoming message on a TCP Port) My goal is to generate a class for example abstract one, which has abstract functions as onInit(), etc. A programmer should just inherit from this base class and should merely override these abstract functions of the base class. The rest as of the protocol e.g. should be simply handled in the background (using the code of the base class) and should not need to appear in the programmers code. What is the correct design strategy for such tasks? and how do I deal with, that the static main method is not inheritable? What are the key-tags for this problem? (I have problem searching for a solution since I lack clear statements on this problem) Goal is to create some sort of library/class, which - included in ones code - results in executables following the protocol. EDIT (new explanation): Okay let me try to explain more detailled: In this case programs should be clients within a client server architecture. We have a client server connection via TCP/IP. Each program needs to follow a specific protocol upon program start: As soon as my program starts and gets connected to the server it will receive an Init Message (TcpClient), when this happens it should trigger the function onInit(). (Should this be implemented by an event system?) After onInit() a acknowledgement message should be sent to the server. Afterwards there are some other steps as e.g. a config message from the server which triggers an onConfig and so on. Let's concentrate on the onInit function. The idea is, that onInit (and onConfig and so on) should be the only functions the programmer should edit while the overall protocol messaging is hidden for him. Therefore, I thought using an abstract class with the abstract methods onInit(), onConfig() in it should be the right thing. The static Main class I would like to hide, since within it e.g. there will be some part which connects to the tcp port, which reacts on the Init Message and which will call the onInit function. 2 problems here: 1. the static main class cant be inherited, isn it? 2. I cannot call abstract functions from the main class in the abstract master class. Let me give an Pseudo-example for my ideas: public abstract class MasterClass { static void Main(string[] args){ 1. open TCP connection 2. waiting for Init Message from server 3. onInit(); 4. Send Acknowledgement, that Init Routine has ended successfully 5. waiting for Config message from server 6..... } public abstract void onInit(); public abstract void onConfig(); } I hope you get the idea now! The programmer should afterwards inherit from this masterclass and merely need to edit the functions onInit and so on. Is this way possible? How? What else do you recommend for solving this? EDIT: The strategy ideo provided below is a good one! Check out my comment on that.

  Read the article

• Why can't I create an abstract constructor on an abstract C# class?

  - by Anthony D

  I am creating an abstract class. I want each of my derived classes to be forced to implement a specific signature of constructor. As such, I did what I would have done has I wanted to force them to implement a method, I made an abstract one. public abstract class A { abstract A(int a, int b); } However I get a message saying the abstract modifier is invalid on this item. My goal was to force some code like this. public class B : A { public B(int a, int b) : base(a, b) { //Some other awesome code. } } This is all C# .NET code. Can anyone help me out? Update 1 I wanted to add some things. What I ended up with was this. private A() { } protected A(int a, int b) { //Code } That does what some folks are saying, default is private, and the class needs to implement a constructor. However that doesn't FORCE a constructor with the signature A(int a, int b). public abstract class A { protected abstract A(int a, int b) { } } Update 2 I should be clear, to work around this I made my default constructor private, and my other constructor protected. I am not really looking for a way to make my code work. I took care of that. I am looking to understand why C# does not let you do this.

  Read the article

• Make an abstract class or use a processor?

  - by Tim Murphy

  I'm developing a class to compare two directories and run an action when a directory/file in the source directory does not exist in destination directory. Here is a prototype of the class: public abstract class IdenticalDirectories { private DirectoryInfo _sourceDirectory; private DirectoryInfo _destinationDirectory; protected abstract void DirectoryExists(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); protected abstract void DirectoryDoesNotExist(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); protected abstract void FileExists(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); protected abstract void FileDoesNotExist(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory); public IdenticalDirectories(DirectoryInfo sourceDirectory, DirectoryInfo destinationDirectory) { ... } public void Run() { foreach (DirectoryInfo sourceSubDirectory in _sourceDirectory.GetDirectories()) { DirectoryInfo destinationSubDirectory = this.GetDestinationDirectoryInfo(subDirectory); if (destinationSubDirectory.Exists()) { this.DirectoryExists(sourceSubDirectory, destinationSubDirectory); } else { this.DirectoryDoesNotExist(sourceSubDirectory, destinationSubDirectory); } foreach (FileInfo sourceFile in sourceSubDirectory.GetFiles()) { FileInfo destinationFile = this.GetDestinationFileInfo(sourceFile); if (destinationFile.Exists()) { this.FileExists(sourceFile, destinationFile); } else { this.FileDoesNotExist(sourceFile, destinationFile); } } } } } The above prototype is an abstract class. I'm wondering if it would be better to make the class non-abstract and have the Run method receiver a processor? eg. public void Run(IIdenticalDirectoriesProcessor processor) { foreach (DirectoryInfo sourceSubDirectory in _sourceDirectory.GetDirectories()) { DirectoryInfo destinationSubDirectory = this.GetDestinationDirectoryInfo(subDirectory); if (destinationSubDirectory.Exists()) { processor.DirectoryExists(sourceSubDirectory, destinationSubDirectory); } else { processor.DirectoryDoesNotExist(sourceSubDirectory, destinationSubDirectory); } foreach (FileInfo sourceFile in sourceSubDirectory.GetFiles()) { FileInfo destinationFile = this.GetDestinationFileInfo(sourceFile); if (destinationFile.Exists()) { processor.FileExists(sourceFile, destinationFile); } else { processor.FileDoesNotExist(sourceFile, destinationFile); } } } } What do you see as the pros and cons of each implementation?

  Read the article

• How to create a dynamic array of an Abstract class?

  - by outsyncof

  Lets say I have an abstract class Cat that has a few concrete subclasses Wildcat, Housecat, etc. I want my array to be able to store pointers to a type of cat without knowing which kind it really is. When I try to dynamically allocate an array of Cat, it doesn't seem to be working. Please help? Cat* catArray = new Cat[200];

  Read the article

• Question regarding factory pattern

  - by eriks

  I have a factory class to build objects of base class B. The object (D) that uses this factory received a list of strings representing the actual types. What is the correct implementation: the factory receives an Enum (and uses switch inside the Create function) and D is responsible to convert the string to Enum. the factory receives a string and checks for a match to a set of valid strings (using ifs') other implementation i didn't think of.

  Read the article

• Writing a factory for classes that have required arguments

  - by Kyle Adams

  I understand the concept of factory pattern such that you give it something it spits out something of the same template back so if I gave a factory class apple, I expect to get many apples back with out having to instantiate a new apple ever time. what if that apple has a required argument of seed, or multiple required arguments of seed, step and leaf? how do you use factory pattern here? that is how do I use factory pattern to instantiate this: $apple = new Apple($seed, $stem, $leaf);

  Read the article

• UIHint can not resolve template in abstract models

  - by Reza Owliaei

  Assume an abstract model like this: public abstract class MyClass : BaseEntity { [UIHint("File")] public long? DocumentFileId { get; set; } } The problem is Cannot resolve template 'File', while there is File.cshtml in View editor templates. The point is, if I don't define MyClass as an abstract class, error will be solved. My question is, why editor template can not resolve in abstract classes, and how can I handle it?

  Read the article

• Derive abstract class from non-abstract class

  - by Jehof

  Is it OK to derive an abstract class from a non-abstract class or is there something wrong with this approach? Here´s a little example: public class Task { // Some Members } public abstract class PeriodicalTask : Task { // Represents a base class for task that has to be done periodicaly. // Some additional Members } public class DailyTask : PeriodicalTask { // Represents a Task that has to be done daily. // Some additional Members } public class WeeklyTask : PeriodicalTask { // Represents a Task that has to be done weekly. // Some additional Members } In the example above i do not want to make the class Task abstract, because i want to instantiate it directly. PeriodicalTask should inherit the functionality from Task and add some additional members but i do not want to instantiate it directly. Only derived class of PeriodicalTask should be instantiated.

  Read the article

• Design Patterns - Factory vs Abstract Factory

  - by JMSA

  What is the basic difference between Factory and Abstract Factory Patterns?

  Read the article

• abstract class NumberFormat - very confuse about getInstance()

  - by Alex

  Hi, I'm new to Java and I have a beginner question: NumberFormat is an abstract class and so I assume I can't make an instance of it. But there is a public static (factory?) method getInstance() that allow me to do NumberFormat nf = NumberFormat.getInstance(); I'm quite confuse. I'll be glad if someone could give me hints on: 1) If there is a public method to get an instance of this abstract class, why don't we have also a constructor? 2) This is an abstract class ; how can we have this static method giving us an instance of the class? 3) Why choosing such a design? If I assume it's possible to have an instance of an abstract class (???), I don't get why this class should be abstract at all. Thank you.

  Read the article

< Previous Page | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >