g++ “because the following virtual functions are pure” with abstract base class
Your SortedContainerImpl class has two separate Container base classes. One is virtual (via the SortedContainer class) and the other is non-virtual (via the ContainerImpl class). SortedContainerImpl has concrete implementations of Container::get_size() and Container::get(int) for the base that comes in from ContainerImpl, but not for the virtual base that comes in via SortedContainer. One way to … Read more