inheritance

问题 I was looking at a perf benchmark of Object.keys + forEach vs for-in with normal objects. This benchmark shows that Object.keys + forEach is 62% slower than the for-in approach. But what if you don't want to get the inherited properties ? for-in includes all non-native inherited objects, so we'll have to use hasOwnProperty to check. I tried to make another benchmark here doing exactly that. But now the for-in approach is 41% slower than Object.keys + forEach . update The above test was done

问题 I encountered a strange bug in python where using the __new__ method of a class as a factory would lead to the __init__ method of the instantiated class to be called twice. The idea was originally to use the __new__ method of the mother class to return a specific instance of one of her children depending on the parameters that are passed, without having to declare a factory function outside of the class. I know that using a factory function would be the best design-pattern to use here, but

问题 How do i call a function of a child class from parent class? Consider this: class whale { function __construct() { // some code here } function myfunc() { // how do i call the "test" function of fish class here?? } } class fish extends whale { function __construct() { parent::construct(); } function test() { echo "So you managed to call me !!"; } } 回答1: That's what abstract classes are for. An abstract class basically says: Whoever is inheriting from me, must have this function (or these

问题 Output of this program is "Method B". How can an instance of the parent object call the child class's function through a static_cast? To make things more confusing, if I make method() virtual, then this code outputs "Method A". Can anyone explain what is happening here? class A { public: void method() { cout << "Method A" << endl; } }; class B : public A { public: void method() { cout << "Method B" << endl; } }; int main() { A a; B* bptr = static_cast<B*>(&a); bptr->method(); } 来源： https:/

问题 If i have these 3 interfaces unit Interfaces; interface type IA = interface['{86367399-1601-4FDD-89CF-362E762D948E}'] procedure doSomething; end; IB = interface['{070B9364-4A57-4E5A-BBA7-FBF1C6A48C5A}'] procedure doSomething; end; IC =interface(IB)['{DAC8021C-42CB-40EC-A001-466909044EC3}'] procedure doSomething; end; implementation end. How do i resolve naming conficts in a class that implements IA and IC? I have no problem with IA and IC but how do i implement IB? type myClass = class

问题 I have a couple classes that have nearly identical code. Only a string or two is different between them. What I would like to do is to make them "x" from another class that defines those functions and then uses constants or something else to define those strings that are different. I'm not sure if "x" is inheritance or extending or what. That is what I need help with. For example: objectA.m: -(void)helloWorld { NSLog("Hello %@",child.name); } objectBob.m: #define name @"Bob" objectJoe.m

问题 I have a class: class ProjectService : public CProjectT<CSoapMSXMLInetClient> { ... } I have implemented HRESULT ConnectToServer(); function in this derived class. Then I instantiated an object and called a function: ProjectService project; project.f1(); now, f1() calls f2() and f2() calls ConnectToServer() . All of those functions are members of CProjectT<CSoapMSXMLInetClient> The problem here is, CProjectT<CSoapMSXMLInetClient>::ConnectToServer() is called instead of ProjectService:

问题 I've written a class trying to extend the native Javascript Array class with a custom class, let's call it MyClass . This is basically what it looks like: class MyClass extends Array constructor: (obj) -> @push.apply @, obj first: -> @slice 0, 1 Instantiating the class is no problem. Running this in the console: var myInstance = new MyClass(["1", "2"]) > ["1", "2"] myInstance instanceof MyClass > true myInstance instanceof Array > true works as exptected. The problem is that if I run:

问题 It is an inheritance, Record has a reference of SampleAsset and SampletAsset has a reference of SampleParticipant. In transaction I am sending record object and when i am printing it on console It is showing complete information of Sample asset and complete information of SampleParticipant, while I am trying to fetch it using get method it is not returning the complete information of the objects. Please check the screenshot: Record Object getObject SampleParticipant(owner) reference is not

问题 It is an inheritance, Record has a reference of SampleAsset and SampletAsset has a reference of SampleParticipant. In transaction I am sending record object and when i am printing it on console It is showing complete information of Sample asset and complete information of SampleParticipant, while I am trying to fetch it using get method it is not returning the complete information of the objects. Please check the screenshot: Record Object getObject SampleParticipant(owner) reference is not