It looks like you want to do virtual inheritance. Whether that turns out to actually be a good idea is another question, but here’s how you do it: class AbsBase {…}; class AbsInit: public virtual AbsBase {…}; class AbsWork: public virtual AbsBase {…}; class NotAbsTotal: public AbsInit, public AbsWork {…}; Basically, the default, non-virtual multiple … Read more
The error message indicates that you have two conflicting metaclasses somewhere in your hierarchy. You need to examine each of your classes and the QT classes to figure out where the conflict is. Here’s some simple example code that sets up the same situation: class MetaA(type): pass class MetaB(type): pass class A: __metaclass__ = MetaA … Read more
The answer to the duplicate operation is: To solve multiple inheritance issue a class implementing two interfaces providing a default implementation for the same method name and signature must provide an implementation of the method. [Full Article] My answer to your question is: Yes, it is a form of multiple inheritance, because you can inherit … Read more
does pa point to a valid A object? does pb point to a valid B object? Yes, the C* gets converted so that pa and pb point to the correct addresses. does pa == pb ? No, usually not. There can’t be an A object and a B object at the same address. Furthermore, does … Read more
super() is not broken — it just should not be considered the standard way of calling a method of the base class. This did not change with Python 3.x. The only thing that changed is that you don’t need to pass the arguments self, cls in the standard case that self is the first parameter … Read more
Actually, I have no good answer other than Java SHOULD have Multiple Inheritance. The whole point that interfaces should be able to replace the need for Multiple Inheritance is like the big lie that when repeated enough times becomes true. The argument is that Multiple Inheritance causes all these problems (la-di-dah), yet I keep hearing … Read more
It was a design decision of Java. You’ll never get it, so don’t worry too much about it. Although MI might help you make Mixins, that’s the only good MI will ever do you.
a.base1::start(); a.base2::start(); or if you want to use one specifically class derived:public base1,public base2 { public: using base1::start; };
Yes, you can do it. An interface can extend multiple interfaces, as shown here: interface Maininterface extends inter1, inter2, inter3 { // methods } A single class can also implement multiple interfaces. What if two interfaces have a method defining the same name and signature? There is a tricky point: interface A { void test(); … Read more
This has nothing to do with overriding functions. It has to do with conversions. It really doesn’t have to do with accessibility (i.e “private” or such) directly either. Here is a simpler example struct A { int a; }; struct B : A { }; struct C : B, A { }; // direct A … Read more