multiple-inheritance

I have a class: class Base; Also I have an interface class Interface; Next i'm creating a class class Derived : public Base, public Interface; If I have Base *object = new Derived; How can i cast object to Interface ? (of course if i know than object is actually a derived class) EDIT: I've tried dynamic_cast and static_cast (not compiled). So let me explain the problem a bit more: I have: class Object {...} class ITouchResponder { public: virtual bool onTouchBegan(XTouch *touch) = 0; virtual void onTouchMoved(XTouch *touch) = 0; virtual void onTouchEnded(XTouch *touch) = 0; }; class Ball :

I have struggled with this design problem for some time. I will do my best to explain what I am trying to do and the various approached that I have seen, what I am trying and why. I work in a scientific computing environment where I deal with the same kinds of objects repeatedly. Imagine a galaxy which contains solar systems, each solar system contains planetary systems and each planetary system contains moons. To this end I think of the situation as a “has a” situation, and thus I have used composition to give the galaxy access to its solar systems, and each solar system access to the

I'm having a problem with QT regarding multiple enheritance because of QObject. I know that a lot of others have the same problems but I don't know how I should fix it. class NavigatableItem : public QObject { Q_OBJECT signals: void deselected(); void selected(); void activated(); }; class Button : public NavigatableItem, public QToolButton { Q_OBJECT ... } class MainMenuOption : public Button { Q_OBJECT ... } When I do this MainMenuOption* messages = new MainMenuOption(); connect(messages, SIGNAL(selected()), SLOT(onMenuOptionSelected())) I will get the error: QObject' is an ambiguous base of

From Wikipedia : Single responsibility principle states that every class should have a single responsibility, and that responsibility should be entirely encapsulated by the class. Does that mean implementing multiple interfaces violates this principle? I would say not by itself. A class can have one responsibility, but do multiple things in the process, and implement one interface for each set of things it needs to do to fulfill its responsibility. Also, interfaces in Java can be used to say things about what properties the class has (for example, Comparable and Serializable ), but not really

Is it possible to have a number of partial implementations of an abstract interface, and then collect these partial implementations into a single concrete class by using multiple inheritence? I have the following example code: #include <iostream> struct Base { virtual void F1() = 0; virtual void F2() = 0; }; struct D1 : Base { void F1() override { std::cout << __func__ << std::endl; } }; struct D2 : Base { void F2() override { std::cout << __func__ << std::endl; } }; // collection of the two partial implementations to form the concrete implementation struct Deriv : D1, D2 { using D1::F1; // I

Is it possible to create a spider which inherits the functionality from two base spiders, namely SitemapSpider and CrawlSpider? I have been trying to scrape data from various sites and realized that not all sites have listing of every page on the website, thus a need to use CrawlSpider. But CrawlSpider goes through a lot of junk pages and is kind of an overkill. What I would like to do is something like this: Start my Spider which is a subclass of SitemapSpider and pass regex matched responses to the parse_products to extract useful information method. Go to links matching the regex: /reviews/