inheritance

问题 I'm new to C# and wondered if there is something like private inheritance in C# (like in C++) ? My problem is as follows: I want to implement a queue (name it SpecialQueue) with the following changes: The queue has a maximum number of items that can be stored in it. If the queue is full and you insert a new item, one item will be automatically poped out of the queue (the first item in the queue) and the new item will be inserted to the end of the queue. Some methods (such as peek()) provided

问题 I know that super() and multi-inheritance have already been discussed here. But I did not find a solution, regarding my specific problem in python3. Let's assume we have: #! /usr/bin/env python3 class A(object): def __init__(self): super().__init__() def foo(self): print("The") class B(object): def __init__(self): super().__init__() def foo(self): print("world") class C(B): def __init__(self): super().__init__() def foo(self): super().foo() print("is") class D(A,C): def __init__(self): super(

问题 Has anyone really wanted and used inheritance support on ORM tools, and if yes which one do you think offers the best support? Or is ORM Inheritance a "pie in the sky" concept? 回答1: I like this question a lot. I've used ORM tools (Toplink, now eclipselink, Hibernate) for a while and I've always seen this as referenced in JPA documents but I've never really had a need for it. Basically my philosophy is the ORM is just there to prevent you from writing tedius code to pull out records for the

问题 I have a class Derived that inherits directly from two base classes, Base1 and Base2 . I'd like to know if it's safe, in general, to compare pointers to the base classes to determine if they are the same Derived object: Base1* p1; Base2* p2; /* * Stuff happens here. p1 and p2 now point to valid objects of either their * base type or Derived */ //assert(p1 == p2); //This is illegal assert(p1 == static_cast<Base1*>(p2)); //Is this ok? assert(static_cast<Derived*>(p1) == static_cast<Derived*>(p2

问题 I Knew there are plenty of articles/questions in stackoverflow describing about upcasting and downcasting in Java. And I knew what is upcasting and downcasting. But my question is not specfic to that. Upcasting - Conversion from child to parent - Compiler takes care. No cast is required Downcasting - Conversion from parent to child - Explicit cast is required public class Animal { public void getAnimalName(){ System.out.println("Parent Animal"); } } public class Dog extends Animal{ public

问题 How can I extend a class that is only accessible through reflection? Basically, I am trying to extend the com.samsung.bluetoothle.BluetoothLEClientProfile class that is found in the Galaxy S3 to enable communication it with my bluetooth LE device. The class is hidden and I need to extend it. 回答1: Add a dummy class in the right package ( com.samsung.bluetoothle ) in your project, then extend it. At runtime the system class will be loaded, and you should get the desired behaviour. 来源： https:/

问题 Say I have a Class called ParentClass and a Class called ChildClass The ParentClass is abstract and the ChildClass extends the ParentClass per Java terminology. Furthermore, the ParentClass has a constructor which takes an int as a parameter. Now in another class I want to instantiate the ChildClass . I have tried the two below ways: ChildClass obj1 = new ChildClass(5) ParentClass obj2 = new ChildClass(5) Java allows me to use any of the two above ways. My question is, is there actually any

问题 I have two classes I want to use in my new class. The first one implements a swipe to delete and the second enables a long press gesture: class DeleteItem: UITableViewCell { } class OpenDetail: UITableViewCell { } Since Swift doesn't allow a class to inherit from multiple classes the following example obviously won't work: class ItemViewCell: DeleteItem, OpenDetail { } So in order to create ItemViewCell and having both options, I'll have to have one of the classes to inherit from each other:

问题 I know following cyclic inheritance hierarchy is not allowed in Java. Compiler throws an error, but what I'm really interested is knowing the exact reason for the compilation failure. class A extends B{} class B extends C{} class C extends A{} // this will give you compile time error. What is the thing due to which the compiler will throw an error, the moment I write the code class C extends A{} 回答1: Such relation is simply not possible. It defines an infinite recursive class. In order to

问题 I am writing some templated pure virtual base classes that are multiply inherited and discovered a minor oddity in the process. The crux of it is, if you define the same method in two base classes, inheriting from both compiles and works fine and it appears that you only need a single definition in the derived class. I am curious as to what is going on behind the scenes here, is this correct and planned behaviour or a dangerous compiler oversight? See below for illustrative code sample: