inheritance

问题 I have a base class and several derived classes. The base class looks like this: class Base { int type; //the derived type the object belongs to int nOfChildren; Base** children; //each child can be any of the derived types ... } Now I need to duplicate an instance of Base . Because of the recursion, a virtual method Base::duplicate() is needed. It also seems clear what should go in it: Base temp = new Base(); temp->type = temp; temp->nOfChildren = nOfChildren; temp->children = new Base*

问题 I am trying to create view that has functionality described in a view in am extending, but with different class names. What is happening is the ExpTypesView classes are ['nav','nav-pills'] and ['nav','nav-tabs']. How do i set it so they replace the classnames set in NavView? Resume.NavView = Em.View.extend({ tagName: 'ul', classNames: ['nav','nav-tabs'], currentPathDidChange: function(){ Ember.run.next( this, function() { $("ul li:has(>a.active)").addClass('active'); $("ul li:not(:has(>a

问题 This question has already been asked here -- more than twice, actually --, but I myself haven't been able to derive a solution to my problem from the posts. What I have is a library, with, among others, a class named A in it. From class A I need to access an std::map<> , but it is private. Also, and based on the possibilities I found in the post I mentioned, class A has no templated function. I'm actually able to recompile the library, so that I could simply change the visibility. However ,

问题 I've created a BaseModel class, which extends from Model. It seemed like everything was working fine, but now I've run into a problem when saving. I'm overriding the save() method in this BaseModel. I'd just like to add some attributes to the model before saving. So I do that, then call return parent::save($options); . The method signature is still the same: public function save(array $options = []) . It appears to be grabbing the name of the BaseModel class for the table name when performing

问题 We are trying to move from SOAP to REST and we stumbled across this issue Here party can be of type Individual or Organization. Sample XMLs <customer> <details> <party xsi:type="Individual"> <externalID>ABC123</externalID> <firstname>John</firstname> <lastname>Smith</lastname> </party> </details> </customer> <customer> <details> <party xsi:type="Organization"> <externalID>APPLE</externalID> <organizationName>Apple Inc</organizationName> <listingName>APPLE</listingName> </party> </details> <

问题 Suppose you have the following abstract java class: public abstract class AbstractRequestHandler<I,O> { I input; O output; } and the following child classes hierarchy: public abstract class AbstractUserRequestHandler<I extends User,O> extends AbstractRequestHandler<I,O>{...} public abstract class AbstractUniversityRequestHandler<I extends UniversityUser> extends AbstractUserRequestHandler<I,String>{...} public class StudentRequestHandler extends AbstractUniversityRequestHandler<Student>{...}

问题 I am trying to write a generic class to avoid code repetition. I would like to have generic methods for: Get Entity/Model from server by id. Get List of all Entities/Models from server. Send to server and save in db Entity/Model. It should work with Generic classes, e.g.: Services<PizzaProxy> factory = GWT.create(Services.class); factory.initialize(new SimpleEventBus()); GenericContext<PizzaProxy> context = factory.genericContext(); context.get().to(new Receiver<List<GenericProxy<PizzaProxy>>

问题 I am trying to write a generic class to avoid code repetition. I would like to have generic methods for: Get Entity/Model from server by id. Get List of all Entities/Models from server. Send to server and save in db Entity/Model. It should work with Generic classes, e.g.: Services<PizzaProxy> factory = GWT.create(Services.class); factory.initialize(new SimpleEventBus()); GenericContext<PizzaProxy> context = factory.genericContext(); context.get().to(new Receiver<List<GenericProxy<PizzaProxy>>

问题 I am running into a problem with javas generics and overriding methods. Imagine I have a deep tree-like class hierarchy. The top-level class defines a method foo which takes 1 argument of type Strategy. Strategy has a generic type parameter. Each class in my class hierarchy needs to override foo to limit the kind of Strategy it can be passed so that the generic type parameter of the strategy matches the declaring class. Below is an example: abstract static class TopLevelClass { static final

问题 Before this is marked as duplicate, I'm aware of this question, but in my case we are talking about const containers. I have 2 classes: class Base { }; class Derived : public Base { }; And a function: void register_objects(const std::set<Base*> &objects) {} I would like to invoke this function as: std::set<Derived*> objs; register_objects(objs); The compiler does not accept this. Why not? The set is not modifiable so there is no risk of non-Derived objects being inserted into it. How can I do