Saaa wrote:
from the list (private, protected, public) pick public.
Note the difference between peel and peal.
:)
public YellowBanana: Banana
{
void doStuff()
{
bool e = peel(); //visible from derived
//class when defined protected or public.
}
}
Banana a = new Banana();
bool f = a.peel(); //visible only when public
All non-static non-private non-template member functions are virtual.
(Rule only valid in D)
What does this mean: to be virtual?
Informally, "virtual" means "can be overridden". It only applies to
methods on classes. This definition is informal and ambiguous.
According to __traits in d2, "virtual" means "might have a vtbl entry".
A vtbl is a list of function pointers corresponding to the methods of a
class. Each instance of that class has a pointer to the same list.
Virtual dispatch just consists of pointing to a different vtbl with a
different function in that slot.
Anyway, the __traits definition maps to the following lemmas[1]:
- static is not virtual
- template is not virtual
- private is not virtual
On the other hand, final functions are virtual. If a final function does
not override a virtual function, the compiler can turn it into a free
function if that's more efficient. Or maybe not. If a final function
overrides a virtual function, it will certainly end up in the class vtbl.
Final functions are a bit questionable. If they override a virtual
method in a base class, they should certainly be considered virtual, but
you also sometimes need to know whether you can override a function.
That is when it's not final and it is virtual.
[1] It's a bit of a stretch to grant them this name, but if life gives
you lemmas, make lemma-ade.
