inheritance

问题 I trying do write a C++ template-class which should be able to deal with "simple" types and with "Eigen::MatrixBase"-like types via the same interface. I manage to get thie desired behavior with two different simple types, but struggle to squeeze the Eigen-syntax into my minimal-example... Maybe someone can give me an advice? While looking around, this comes close to what i wanna have -- without Eigen. This looks similar as well. #ifndef __MINIMAL_H__ #define __MINIMAL_H__ #include <Eigen

问题 I trying do write a C++ template-class which should be able to deal with "simple" types and with "Eigen::MatrixBase"-like types via the same interface. I manage to get thie desired behavior with two different simple types, but struggle to squeeze the Eigen-syntax into my minimal-example... Maybe someone can give me an advice? While looking around, this comes close to what i wanna have -- without Eigen. This looks similar as well. #ifndef __MINIMAL_H__ #define __MINIMAL_H__ #include <Eigen

问题 Here's the documentation for the protected method: /** Converts jmusic score data into a MIDI Sequence */ protected javax.sound.midi.Sequence scoreToSeq(Score score) And I made this little class to extend the class that scoreToSeq method comes from: public class MidiSequence extends MidiSynth{ public Sequence getSequence(Score score){ MidiSynth synth = new MidiSynth(); Sequence sequence = null; try { // Here I get the error saying that the method has // protected access in MidiSynth sequence

问题 My question is regarding a child object maintaining the prototype chain of its parent object. In John Resig's Advanced Javascript slides (http://ejohn.org/apps/learn/#76) he writes that in order to maintain the prototype chain of a child object you must instantiate a new parent object. However through a couple quick tests I noticed that the prototype chain is maintained by just setting the child object prototype equal to the parent object prototype. Any clarification would be greatly

问题 In the Python data model reference section on slots there is a list of notes on using __slots__ . I am thoroughly confused by the 1st and 6th items, because they seem to be contradicting each other. First item: When inheriting from a class without __slots__ , the __dict__ attribute of that class will always be accessible, so a __slots__ definition in the subclass is meaningless. Sixth item: The action of a __slots__ declaration is limited to the class where it is defined. As a result,

问题 Can anyone explain the actual use of method hiding in C# with a valid example ? If the method is defined using the new keyword in the derived class, then it cannot be overridden. Then it is the same as creating a fresh method (other than the one mentioned in the base class) with a different name. Is there any specific reason to use the new keyword? 回答1: C# not only supports method overriding, but also method hiding. Simply put, if a method is not overriding the derived method, it is hiding it

问题 I understand the basic principles of inheritance in OOP, but I have a specific thing I am trying to do and want advice on how best to do it. Lets say I have a core class: class Core { .... } and I also have 2 or more other classes that extend this functionality class MyClass1 extends Core { .... } class MyClass2 extends Core { .... } and I also have a database class in which I perform my queries, I want to pass an instantiated object of the database class (possibly by reference) to each one

问题 I have an assignment and trying to understand something. I have an instruction to create two interfaces: IComparable and IPrintable . Also, I need to create a template called Interval . I am given the main function and I need to implement these classes accordingly so it will work as intended. This is the function I am currently implementing (the comments displays what the input should look like): void testDate() { Date independence(14, 5, 1948); cout << independence << endl; Date otherDate =

问题 I had the following tables: supernode (id bigint, name text) and subnode(id bigint, parent bigint references supernode(id), name text) . (massive simplification to illustrate the issue, obviously) But I want a subnode to be able to have either a supernode or another subnode as parent . In order to do this I create another table node(id bigint) and have them both inherit id from that node. So from scratch it'd be: create table node(id generated always as identity); create table supernode (name

问题 I had the following tables: supernode (id bigint, name text) and subnode(id bigint, parent bigint references supernode(id), name text) . (massive simplification to illustrate the issue, obviously) But I want a subnode to be able to have either a supernode or another subnode as parent . In order to do this I create another table node(id bigint) and have them both inherit id from that node. So from scratch it'd be: create table node(id generated always as identity); create table supernode (name