abstract-class

问题 So, here is a problem: I want to define an abstract class, let's say AbstractA , which does not require subclasses to implement any of its methods, but rather to extend its functionality. In terms of Java that would be interface class. Moreover, I want to be able to create an abstract subclass, let's say AbstractB , of the AbstractA with the same properties, but some methods redefining or extending base class methods. I don't want though to make class ( AbstractA ) abstract e.g. through the

问题 I am a new to Kotlin. I have two classes, one adapter and one fragment. When I want to call the adapter class in fragment I am getting the following warning: cannot create an instance of the abstract class in Kotlin . Below my fragment where I am getting the warning class FavouriteExercisesFragment : BaseMvpFragment(), FavoriteExerciseView { var adapter: FavoriteExerciseAdapter = FavoriteExerciseAdapter() // cannot create instance of abstract class in kotlin Below abstract adapter class class

问题 I've implemented an abstract class BaseMicroservice with the following methods: @abstractmethod def handle(self, message): pass def init_producer(self): self.producer = KafkaProducer(bootstrap_servers=self.config.get('kafka').get('bootstrap_servers'), value_serializer=lambda m: json.dumps(m).encode('utf-8')) self.is_prod_init = True whenever handle is called in one of the sub classes that implement this method, I want the first thing to be done to be init_producer. What's the best way to

问题 How do I access derived class in python from abstract class(interface class) without exposing derived class, by only exposing abstract class. I do not want to expose derived class for python. Is there any way that I can access derived class through abstract class? The example code is: Base.h class Base { public: virtual void Set(const std::vector<std::string>& AllParameters) = 0; }; struct BaseWrap : Base, wrapper<Base> { void Set(const std::vector<std::string>& AllParameters) { this->get

问题 I have this simple code in TypeScript: abstract class Config { readonly NAME: string; readonly TITLE: string; static CoreInterface: () => any } class Test implements Config { readonly NAME: string; readonly TITLE: string; } Even though the CoreInterface() member is missing in the Test class, TypeScript does not complain. Why is this? I need every derived class to provide some metadata about itself in the CoreInterface() static function. I know I could just extend the Config class and have

问题 If a set of inner classes are the only implementations (subclasses) of their outer abstract containing class, how does one instantiate them? abstract class A { inner class A1 : A() inner class A2 : A() } In other words, what is the syntax to construct an instance of A1 or A2 ? EDIT: ... outside the body of class A. 回答1: Are you looking for this? abstract class A { fun doSome() { // OK val a1 = A1() val a2 = A2() } inner class A1 : A() inner class A2 : A() } I think you probably want to

问题 Suppose I have the following four classess, out of which two are abstract and two are concrete: Abstract1 , Concrete1 , Abstract2 , Concrete2 . Concrete1 extends Abstract1 and Concrete2 extends Abstract2 . Suppose I have the following four classess, out of which two are abstract and two are concrete: AbstractProp , ConcreteProp , AbstractClass , ConcreteClass . ConcreteProp extends AbstractProp and ConcreteClass extends AbstractClass . The code for AbstractClass would look like the following:

问题 I have two C++ abstract classes Abs1 and Abs2 . Then I have: `A : public Abs1` `B : public Abs1` `C : public Abs2` `D : public Abs2` Now, I'm trying to create objects from command line arguments and I have to do rewrite the public factory function make_abstract in the linked question, something like: std::unique_ptr<Abs1> makeAbs1 (int argc, const char*argv[]) { if (argc == 1) { return nullptr; } const std::string name = argv[1]; if (name == "A") { return detail::make_abstract<A, std::tuple

问题 I have two C++ abstract classes Abs1 and Abs2 . Then I have: `A : public Abs1` `B : public Abs1` `C : public Abs2` `D : public Abs2` Now, I'm trying to create objects from command line arguments and I have to do rewrite the public factory function make_abstract in the linked question, something like: std::unique_ptr<Abs1> makeAbs1 (int argc, const char*argv[]) { if (argc == 1) { return nullptr; } const std::string name = argv[1]; if (name == "A") { return detail::make_abstract<A, std::tuple

问题 I have an abstract class Node which contains a pure virtual method stub matches , requiring another instance of a Node (i.e. instance of something that subclasses Node ) as a parameter. class Node; // forward declaration class Node { public: Node() : parentNode(this) {} virtual ~Node() {} Node* parentNode; virtual bool matches(const Node& node) const = 0; }; How can I implement matches in a subclass such that the parameter can be of the subclasses type as opposed to Node ? E.g. I want