derived-class

问题 I realize this looks to be an exact duplicate of Using XmlSerializer to serialize derived classes, but I cannot figure out how to get this working following the guidance from that same question: using System; using System.Text; using System.Xml; using System.Xml.Schema; using System.Xml.Serialization; namespace xmlSerializerLab { public class Utf8StringWriter : System.IO.StringWriter { public override Encoding Encoding => Encoding.UTF8; } [XmlRoot(ElementName = "Query", Namespace = "http:/

问题 Assume we have the type Noddy as defined in the tutorial on writing C extension modules for Python. Now we want to create a derived type, overwriting only the __new__() method of Noddy . Currently I use the following approach (error checking stripped for readability): PyTypeObject *BrownNoddyType = (PyTypeObject *)PyType_Type.tp_alloc(&PyType_Type, 0); BrownNoddyType->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE; BrownNoddyType->tp_name = "noddy.BrownNoddy"; BrownNoddyType->tp_doc =

问题 I believe Constructors and Destructors in base class cannot be inherited by derived classes of the base class. Is my understanding correct. 回答1: Your understanding is correct. For example, if you have class Base { Base(int i) {} }; class Derived: public Base {}; Derived d(3); This will not compile because the Base constructor is not inherited. Note that default and copy constructor are created by the compiler if possible, and call the corresponding constructor of base classes, therefore for

问题 Suppose we have created a Python module in C _xxx that contains an extension object xxx , and we do following: import _xxx class derived(_xxx.xxx): # ... d = derived() How does Python allocate memory for d behind the scenes? Eli Bendersky's article Python object creation sequence is the closest I've found, but it doesn't appear to cover this scenario. NOTE: there is already an answer HERE: I'm going to ask the author if he will consider migrating his answer here, as it is a good answer to a

问题 I have an abstract base class called Base that other programmers are to write implementations for. In some other part of the application, I want to catch all implementations that have been written and construct a single instance of each. If this could be done with no additional instructions to others beyond "implement Base", that would be beautiful. However, the code I have below, requires that each implementation register itself. It also doesn't work. #include <iostream> #include <vector>

问题 i have a base class A and a derived class B which are stored in the following folder structures. +myPackage (package Path) @A ( folder of class A ) A.m ( filename of class ) @B B.m Now i want to use class B which has the following head classdef B < A unfortunately this does not work because they are in different folders and i cannot import like this: import myPackage.* classdef B < A Is it possible to solve this without loosing the folder organisation? 回答1: I think if you write classdef B <

问题 i have a base class A and a derived class B which are stored in the following folder structures. +myPackage (package Path) @A ( folder of class A ) A.m ( filename of class ) @B B.m Now i want to use class B which has the following head classdef B < A unfortunately this does not work because they are in different folders and i cannot import like this: import myPackage.* classdef B < A Is it possible to solve this without loosing the folder organisation? 回答1: I think if you write classdef B <

问题 Here is a sample of code that annoys me: class Base { protected: virtual void foo() = 0; }; class Derived : public Base { private: Base *b; /* Initialized by constructor, not shown here Intended to store a pointer on an instance of any derived class of Base */ protected: virtual void foo() { /* Some implementation */ }; virtual void foo2() { this->b->foo(); /* Compilator sets an error: 'virtual void Base::foo() is protected' */ } }; How do you access to the protected overrided function?

问题 I have a generic, abstract class ( SuperClass ). I want to have there a main method, that would be a default main for each subclass and would do the same, but with proper subclass object that derived and called it. Like this: public abstract class SuperClass { // some code here... public static void main(String args[]) { // here instantiate the subclass // extending this SuperClass, and call // some methods } } public SubClass extends SuperClass { // here just implement some // abstract

问题 I have a generic, abstract class ( SuperClass ). I want to have there a main method, that would be a default main for each subclass and would do the same, but with proper subclass object that derived and called it. Like this: public abstract class SuperClass { // some code here... public static void main(String args[]) { // here instantiate the subclass // extending this SuperClass, and call // some methods } } public SubClass extends SuperClass { // here just implement some // abstract