multiple-inheritance

I have a base class which derives from boost::enable_shared_from_this, and then another class which derives from both the base class and boost::enable_shared_from_this: #include <boost/enable_shared_from_this.hpp> #include <boost/shared_ptr.hpp> using namespace boost; class A : public enable_shared_from_this<A> { }; class B : public A , public enable_shared_from_this<B> { public: using enable_shared_from_this<B>::shared_from_this; }; int main() { shared_ptr<B> b = shared_ptr<B>(new B()); shared_ptr<B> b_ = b->shared_from_this(); return 0; } This compiles but at runtime it gives terminate

The net is overflowing with explanations of the "dreaded diamond problem" . So is StackOverflow. I think I understand that bit, but I fail to translate that knowledge into comprehending something similar yet different. My question begins as a pure C++ question, but the answer might well branch over into MS-COM specifics. The general problem question goes: class Base { /* pure virtual stuff */ }; class Der1 : Base /* Non-virtual! */ { /* pure virtual stuff */ }; class Der2 : Base /* Non-virtual! */ { /* pure virtual stuff */ }; class Join : virtual Der1, virtual Der2 { /* implementation stuff *

The following code doesn't work in Python 3.x, but it used to work with old-style classes: class Extender: def extension(self): print("Some work...") class Base: pass Base.__bases__ += (Extender,) Base().extension() Question is simple: How can I add dynamically (at runtime) a super class to a class in Python 3.x? But I'm ready the answer will be hard! ) Mykola Kharechko As for me it is impossible. But you can create new class dynamically: class Extender(object): def extension(self): print("Some work...") class Base(object): pass Base = type('Base', (Base, Extender, object), {}) Base()

I'm trying to find a good example for the use of multiple inheritance what cannot be done with normal interfaces. I think it's pretty hard to find such an example which cannot be modeled in another way. Edit: I mean, can someone name me a good real-world example of when you NEED to use multiple inheritance to implement this example as clean as possible. And it should not make use of multiple interfaces, just the way you can inherit multiple classes in C++. The following is a classic: class Animal { public: virtual void eat(); }; class Mammal : public Animal { public: virtual void breathe(); };

I'm working on a huge project that I didn't start. My task is to add some additional functionality to what already is there. I'm in a situation where I have to use virtual inheritance because I have a diamond model. The situation is depicted in the following illustration: Base class / \ / \ My new class A class that was there before (OldClass) \ / \ / \ / \ / My other new class For this to work, both the classes in the middle have to inherit from the base through public virtual instead of just public . So: class OldClass: public BaseClass {} has to become: class OldClass: public virtual

So I have a bunch of tables using SQLAlchemy that are modelled as objects which inherit from the result to a call to declarative_base() . Ie: Base = declarative_base() class Table1(Base): # __tablename__ & such here class Table2(Base): # __tablename__ & such here Etc. I then wanted to have some common functionality available to each of my DB table classes, the easiest way to do this according to the docs is to just do multiple inheritance: Base = declarative_base() class CommonRoutines(object): @classmethod def somecommonaction(cls): # body here class Table1(CommonRoutines, Base): # _

Can't find a way to do this, possibly because there is another way to do this? Some of my controllers extend AdminLayout and some of them extend ModLayout but I also need these pages to extend a LoggedIn Controller. class Profile extends AdminLayout, LoggedIn { However looking into there is no way to do this nicely. Is there a workaround? Assuming that you are using Codeigniter 2, this can be done by putting all you extended controller classes in the same file. In /application/core create a file called MY_Controller.php (don't forget to check the subclass prefix in config.php around line 109)